Test 50 Pound 800 Watt Amp vs 17 Pound 6400 Watt Amp

[@johnwetmore1527]

I am so glad you did this demonstration! I have been using professional sound equipment for over 40 years and own about 50 Crown amplifiers, all of which are old technology. I suspect that is why my back hurts so much. When Crown came out with their later amplifiers and started to talk "burst power" instead of continuous RMS, I talked to their engineers and was told that in some circumstances where low bass was needed, the old systems were actually better. For example on the Katy Perry song, Dark Horse, there is a very long tone, around 60 Hz. that would send any burst type amplifier into low power mode. In addition to professional sound, I use amplifiers in industrial situations, driving test systems where continuous sine wave power is needed. One great way to determine the real, continuous power of an amplifier is to look at the power cord and the rated input power. You can never put out continuous power greater than what you put in. Recently I was looking at some amplifiers very similar to Powersoft and noticed that the maximum input power was only around 1000 watts despite several thousand watts of "rated" output. My Crown MacroTech 5000 has a 3/4" diameter rubber cord! Thank you so much for the clear explanation of amplifier power! According to Crown engineers, a priority in their designs is weight and size because road crews no longer want sore backs.

[@DaveRat]

Very cool and wise and yes, continuous power out needs a big cord and breaker. Yes, burst power specs don't translate well to extended low frequency output. That said, newer amps like the powersoft will run on 120, 208, or 240 single phase or 3 phase, and when run at higher voltages the cable sizes can be thin and the amps tend to have increased duration burst power. In the amps I tested, the crest put out 400 continuous and the PowerSoft put out 540 watts continuos so even though smaller and lighter, the powersoft still has more output than the crest in continuos measurements as well, so that is another aspect to consider.

[@johnwetmore1527]

@@DaveRat I can see using a high burst power for mids and highs after my RG dynamic expander since it can add up to 20 dB. If I was going mobile again I would also consider running modern amplifiers but I am all but retired and just have a nightclub with a 10,000 watt (Continuous RMS) sound system. In general, sound equipment today is so much better than that of the past. I have a pair of Altec subwoofers that require a fork lift to move and my JBL line array subs blow these away.

[@DaveRat]

Agreed

[@jttech44]

"You can never put out continuous power greater than what you put in." Say that again for the kids in the back. It's amazing how many people don't understand this, ultimately continuous power is a simple thing to solve for, and it allows you to cut through the marketing BS to see what an amplifier actually produces, power wise because they might be able to lie on the box, but they cannot lie on the spec sheet and retain UL certs.

[@DaveRat]

Of course, we are way beyond that elementary concept for beginners. We are looking at the ability of amps to offer peak power profiles that more closely parallel the power needs of the music being reproduced and the ratings of the speakers that amps are connected to. The video shows 2 amps with similar RMS outputs and one amp that has a peak power 6db above the RMS. This peak power allows louder playback withoutsignificantly increasing ac power draw. And I demonstrate and you can hear how much louder the amp capable of processing clean 6 db peaks is. In the video. Or maybe watch the vid?

[@kelainefes]

There's many people that are advanced in their field but can only explain things to their peers, but there's very few people that are so advanced that they can make very complex subjects easy to understand for people that are not on their level. Dave absolutely belongs in the latter category. Thanks you so much for your videos Dave!

[@DaveRat]

Thank you and honored!

[@janedoe6350]

Albert Einstein once said: (and i'm paraphrasing) If you can't explain your knowledge to a 10 year old... then you don't truly understand it yourself.

[@DaveRat]

I do find that researching and doing these videos helps me understand things better and I learn something every time

[@FreeAssRecords]

@@DaveRat That is the most amazing and awesome statement, Dave. My pride in my rat tattoo has only grown over the years. Thank you for what you've done and what you continue to do.

[@DaveRat]

Thank you Dave! You rule! Saw a message on FB and will open and read soon.

[@djp_video]

This is the first time I've noticed the low frequency tones at the end of a video. Really gets the subwoofer going.

[@DaveRat]

🤙👍🤙

[@soniclab-cnc]

The Crest amps just sound great. I used a rig that was all Crest power and it had very musical low end, tight and punchy mids...nice easy to listen highs. Beautiful sounding with a ground stacked EV festival rig. 20 subs and 6 mid hi per side.

[@DaveRat]

Yes, agreed

[@TriAmpHiFi]

Ah, that feels good............... 🔈🔉🔊

[@DaveRat]

🤙👍🤙

[@peniku8]

It's important to note that speakers also handle power in a similar way: they tolerate high bursts but might burn up on long sustained signals, which is why the Powersoft amp makes much more sense in every way. If you hook up an old iron amp to a speaker, you're either giving up headroom for bursts or your amps will be able to put out way too much sustained power for the speakers. This is especially true for modern high density subs, with a lot of power in (relatively) small cabinets and drivers with high Xmax.

[@DaveRat]

True

[@ANATURALDREWSASTER]

I love that you found a way to accurately record and demonstrate the difference with music, amazing!

[@DaveRat]

🤙👍🤙 ha! Yes I'm glad somebody spotted that. The coolest part of the demo is being able to listen to exactly what the amp is putting out at a reasonable volume and not just look at pictures and graphs.

[@AragonDubs]

Dave, thanks for other free MASTER CLASS. The noise traces in the powersoft for me are inadmissible, looking for hearing healt and technical dignity. This demonstration stand at same level of your others. Dont stop! Cheers from Spain!

[@DaveRat]

Yes it's all about selecting the right tool for the job. And thank you

[@SunilKaranjikar]

This is an awesome way to demo burst Vs. continuous power. Thank you Dave !!

[@DaveRat]

👍🤙👍

[@TimpBizkit]

It's nice being able to hear the relative maximum loudness differences between the amplifiers, and that the 300 millisecond duration of full power is plenty for most music (apart from ghetto rap and some EDM, but then it may protect the speakers not having that sustained sine wave potential anyway). Cranking them up through speakers would be in most cases too loud to notice much difference unless in a field and the speakers are tough enough to handle both without power compression.

[@DaveRat]

Agreed.

[@ScottGrammer]

How many times did I carry Phase Linear 700's and Peavey CS-800's in and out of gigs? Wow. That was a long time ago.

[@DaveRat]

🤙👍👍

[@TriAmpHiFi]

Yeah, about 1982. And "Daryl Martini the Cosmic Weenie" was on-air for WBCN Boston. My word, yesterday was a long time ago now. 🔈🔉🔊

[@ScottGrammer]

@@TriAmpHiFi "I was so much older then, I'm much younger than that now."

[@patrickcarpenter6258]

Your passion is so refreshing.

[@DaveRat]

Thank you and awesome!

[@DeadKoby]

Personally, I like the Class AB amps better, BUT I can understand why the Class D amps are popular. If you've got a BIG rig, it's much less mass to move around.

[@ANATURALDREWSASTER]

Efficiency as well I think. Large class D amplifier clusters can get louder for the same power consumed vs class AB.

[@DaveRat]

They each have their advantages. Crusty amps can deliver really beautiful fast transience at very high levels and can also struggle with long extended bass notes. Class a B can sound smoother but they tend to fart and you need a lot of back muscle to move them around, they generate a lot of heat and use up a lot of power from the wall

[@ww6156]

Man i wish someone demo'd that for me when i was a student, that was great

[@DaveRat]

👍🤙👍

[@davidclark3603]

That was a brilliant video Dave! I wish I had your knowledge!

[@DaveRat]

Well you now have some and cool cool David!

[@ChickyNYC]

Dave, I met you years ago at Coachella (I was FOH for OMD) and was absolutely over the moon with your system and your support. Then, recently, your videos came up in my recommended list and I started binge-watching. I love your videos. Just wanted you to know.

[@DaveRat]

So cool! Great to see ya here Charles and thank you!!

[@CABohol]

The waveform of crest amp is nice, I'm still a fan of old topology amp like Class AB or Class H. I built a DIY Class D amp before with infineon chip but the high frequency response is very harsh unlike the old school class AB the response is very clear.

[@DaveRat]

For home hifi, the fan less class ab is the way to go. If you need to move or transport it, or it needs to be small ao draw less power, class D all the way

[@CABohol]

@@DaveRat true, class d is for outdoor use for its efficiency and weight.

[@DaveRat]

👍🤙🤙

[@Bill_N_ATX]

It’s amazing the technology that has brought us these lightweight but powerful amplifiers. In the old days, amplifier manufacturers built huge power supplies so that the output devices had ample clean power available on their power rails. Then along came switching power supplies and their fast, clean, and efficient ICs that made huge heavy transformers and capacitors unnecessary. Finally, someone made the intellectual leap to in effect just modulate the power supply and the modern amplifier was born. I don’t think they sound as good for critical listening but hell a lot of modern music sounds like bad distortion and audio processing artifacts to begin with. So, I’ll still be over here with a nice warm sounding tube amp with the kinds of distortion I like and the kids can use the type they like and we will all be happy. All kidding aside, having humped more than a few old Flame Linear, Crown, and “modern” QSCs, the new amps are awesome. Not only are they lighter and much more dense, they take a fraction of the power supply. Add in the swap to modern lighting with moving effects, color swaps , and LEDs, you don’t need to run the massive cables to a couple thousand amps of 208 for lighting and a 100 plus amps for sound in an arena gig. Much less hang thousand of par cans. Vari-light won.

[@DaveRat]

🤙👍🤙

[@valentinomiori605]

So on the new one is like the signal is passing through some sort of expander, that's a form of distortion. The old one on the other hand was very impressive to me, staying almost flat for that wide range. Also the new one has not a good reconstruction filter, the noise may be outside the audible range but it's not guaranteed to be inaudible as it can be distorted back into the audible spectrum, by the speakers for example.

[@DaveRat]

The new one is not an expander. It's more like a limiter where it lets all of the peaks through but the longer duration signals get compressed That said with normal music nothing gets compressed it just is louder lighter smaller and more powerful

[@jdrissel]

Any possibility of getting a lossless audio version of this? I would break out my good cans and a DAC to listen carefully. I thought I could hear some differences in the midrange but having KZbin in the audio path is only a little better than kite string and soup cans... I really wish they would allow those of us who pay for it to hear and see the full uploaded signal. Even 4k gets less color resolution than the camera likely recorded - I sure can see a and hear the difference between the local file and what KZbin streams back to me even for 4k captured on my phone with its tiny sensor and tiny mems mics. How much more is lost when a real video camera and real microphones are used? The audio difference is huge because I can hear it even over Bluetooth (though I have to be on LDAC to hear it over Bluetooth). This makes me think that KZbin is cutting audio quality down to at best APT-X HD quality.

[@DaveRat]

That's the kind of thing that I post for channel members on the channel member Telegram account. I've got other files related to videos that I've posted there and if I get an ask from that side I would gladly post it

[@Edwin-van-der-Putten]

Really great test, Dave!!!! very nice! Thanks for your work! :-)

[@DaveRat]

Thanknyou

[@mikeo5657]

Another excellent detailed explanation. Thank you Dave!!

[@DaveRat]

👍🤙👍

[@porkrinds9572]

Haha, just as I would suspect power soft goes to crap at around 16k and goes to other shit above 18K. This is, of course to be expected of its architecture. Switching in switching out, not the prettiest, but certainly the most efficient!

[@DaveRat]

I would not be so quick to judge and attribute aspects that are not audible to be significant or relevant. Having some frequency well above anything that any speaker can reproduce and audibility showing up on the output may not be ideal but also to claim that it's relevant maybe jumping to a false conclusion

[@jjdrummerboy1987]

I used to have 2 crest 9001 amps and a 4801. Or 4601? 🤷‍♂️ Anyways, those 9001's were heavy AF!

[@DaveRat]

Yes! They loved gravity

[@dylandylan11731]

Wow that powersoft has a pretty funky & fuzzy waveform - as you said; likely switching frequency psu doing what they do - It’s supposedly out of hearing range… But can it be accumulative ? Can it be compounded under certain conditions ?

[@DaveRat]

It's not ideal and be better if it wasn't there. You look closely there's actually two frequencies floating around on those waveforms. One appears to be in the 48K region and the other is maybe 500k or something. Being that the amp is the last thing in the signal chain and nearly all audio high frequency drivers are incapable of reproducing anything over 30k, and the audio cabling we use does not transmit those high frequencies very well, and the impedance of the voice coils tends to go very high for high frequencies pretty much blocking those out completely anyway. Additionally class D amps have pretty strict low pass filters at 22k or so so they won't regenerate those frequencies if they get back into the input somehow. And yes it'd be cool if they weren't there and also the amount of electronics and filtering needed to make sure they're not on the output is probably more detrimental than leaving them

[@Oogadoog]

I had the great pleasure to apprentice under Walter K. Dick (jbl, Alesis, Event, etc.) who has a great story about rated “watts”. There are so many ways to measure wattage output (peak, rms, blah blah). One day he was telling me that everyone originally agreed on a standard until the marketing team at Carver introduced their ratings that everyone tested and found they were inferior, so they started calling them “carver watts”. I don’t know for sure, but I think that was the origin of “peak watts”.

[@DaveRat]

Well car Hi-Fi had a big impact on those super high pequat ratings from small amps that didn't actually deliver more sound. Then cheap PA kind of jumped on the bandwagon. If my memory serves

[@soundman1402]

I used to work at a small sound and lighting store. We sold QSC amplifiers, and our bread and butter line was the PLX with its switch-mode power supply and Class H topology. We compared it on a pair of JBL dual-18s to a Crest 8001 and found that, despite similar power spec, the Crest amp had a lot more "girth" in the bass. They both seemed about as loud, but the bass from the Crest seemed more... Powerful? Your demonstration of the Powersoft's peak power may explain what was going on. Perhaps the PLX amp's power supply could not sustain those power output levels, so we got a big punch from the kick drum, but any loud, sustained bass notes fell off, whereas the Crest amp was able to sustain that output. Despite these sound quality differences, we still only ever took the PLX amps out for shows because they weighed 25 lbs each to the 8001's 80 lbs.

[@edtalktech]

PLX amps always seemed to have a reputation for not being ideal for bass. They were early innovators of SMPSU's and they have come a long way since then!

[@DaveRat]

I had the same experience with the qsc when comparing the Crest 7001 but it wasn't the PLX it was an older amp We AB compared The sound and the crest was punchy and full on the QSC kind of popped with no follow-through. I've tested numerous amplifiers over the years using a pulse and a block of four double 18 bins and had a wide variety of results. The first lightweight amp that performed well was the lab group in 6400 Now when comparing a Crest 7001 to a power soft X4, which of course is rated much higher power, The power soft dominates the 7001 and makes it sound broken. I think if you compare usable output level of a 1000 Watt Class D app to 1,000 w conventional amp, The conventional amp will win with anything that has low end to it. But if you compare the amps using metrics like equal weight equal cost, equal power draw from the wall, watts per pound, equal heat dissipation, and even Fidelity per dollar spent if you can measure that, you will find that the class D amp will win in nearly every way. I would say as a rule of thumb you want two to three times the wattage out of a Class D amp than you would want out of a conventional amp when used for subwoofers.

[@edtalktech]

@@DaveRat It's an interesting topic. Since by design modern switching amps should have a much much lower internal resistance than their analogue counterparts, they should absolutely destroy the older amps in terms of power output. I have always heard however, but never actually seen until now that power soft are clearly limiting the current thought the PSU. What surprises me even more is this is a 4ch amp driving one channel. I was under the (incorrect) assumption that the available PSU power was available for all channels, so for example on a 4ch amp driving 1ch to the rails would be able to do so without current limiting. What's also interesting is it seems there is a recovery period as at @10.22 that power doesn't come back immediately. I wonder how it would behave with 4 ohm or even 4 channels at 4 ohm.

[@DaveRat]

They spec that out and list symmetrical output power with all channels driven the same and asymmetrical output power with two of the channels driven 6db lower level as would happen with bi-amplification. I believe this symmetrical output is 1600 watts per channel all channels driven and the asymmetrical output is 1800 watts on two of the channels with the other two channels driven at 450 Watts. For my test I didn't really focus on getting the exact power measurement and I'm sure there was some power drop in the long extension cord I had running the amp reducing its output

[@zambotv8150]

Cool cool... I still have a pile of old school amps, they sound great but, my back gets sore just looking at them.... Shame there's no Vz5000,s anymore, they were terrifying beasties

[@DaveRat]

👍🤙👍

[@jdrissel]

It seems to me that the old amp was cleaner in the midrange. I suspect it was cleaner in the highs too, but it just doesn't get through on KZbin.

[@harrissoundlighting]

I would love to see you test the Admark K30 (which is what we use on our subs) They claim 3000W @ 8 ohms. They are killer little amps, but I'd like to see them benched to know the exact numbers. I'd be willing to send one to you, if you'd be interested.

[@ArtVandelayLTEX]

I love these unique experiements you do to get to the bottom of what's really going on. Thank you!

[@DaveRat]

Awesome thank you!

[@EstudioCallado]

Hi Dave. I see you are using the Crest 4801 a lot for your testings. I am from Argentina and thete are not many options to buy a pro amp here. I am looking for an amp for my home studio, as my main amp for my main monitor reference (wich are a pair of Rectilinear Research mini iii, old 4ohm speakers, not quite efficients but if you move them they sound really good). So I am in the search for an amp for them, my ambition was a Urei 6260 or a Yamaha P2200 but you can only find Crowns here. I was offered a Crest 4801. Would you recommend it for that task? I make mostly folk and acoustic music, with lots of dynamics, does the 4801 will give me all of that dynamics and nuances in the reproduction of the music? Is it a good choice for that or would you prefer an old Crown or Ashly for that? Those are my options here. Thanks a lot. Your channel nurtured me a lot and I am really gratefull. Best wishes for you!

[@DaveRat]

I think the crest 4801 and 7001 amps sound better than the old crowns and urie amps. I found the old crown in urie amps to have kind of a soft top end HF dull sound to them. Other apps to look at would be chevin or possible BGW though those don't sparkle well either.

[@jjdrummerboy1987]

Dave, Can you measure damping factor with this setup?

[@lunam7249]

the crest is prolly 300- 700...the powersoft can drive 0.1 ohm, so the damping is insane high!! 5-10000?

[@DaveRat]

Yeah that sounds in the right direction

[@zordmaker]

Great demo. Real amps, Real figures, A/B switching. Thats what we need. Well done Rat.

[@DaveRat]

👍🤙👍

[@jameslawford4057]

48kHz internal processing in the Powersoft, hence filtering at Nyquist.

[@DaveRat]

👍🤙👍

[@valentinomiori605]

If you want to know the real power of an amplifier, you should look for the rated power output of the PSU/transformer, or alternatively 50-80% of the rated power absorption (to account for losses). A 120 W RMS amplifier obviously cannot put out a 120 W flat signal (aka DC offset) if it has a 60 W rated PSU. You may get away with RMS rating only if it has specifications for 1. frequency spectrum eg 20-20'000 Hz 2. max distortion eg 1% THD max

[@DaveRat]

Yes and also the info I am showing in the vid is not hypothetical, these are tests that are showing what the amps actually do. The powersoft amp is 6db louder with music than the 400watt crest as I can hear in the vid. It specs at 1600 watts and as 6db louder which. Means it would need to produce 1600watts to achieve. That data matches the test

[@richmorpurgo5554]

I love what you do!!!

[@DaveRat]

🤙👍🤙

[@BlackenBurg]

Hey Dave, Great setup and demonstration! I remember you did a video demonstrating differences of amp clipping by nulling the signals. Do you think there is anyway to hear the differences in amp types by summing the signals from both the crest and powersoft? I’m just fascinated by how some genres of music might have different current draw characteristics and how that might change what sort of amp would be suitable. i.e. A class D amp struggling to keep up power with a really thick grungy guitar or a compressed edm track Love your work!

[@DaveRat]

I would like to do that I would need to find a class D amp that has no digital processing as the digital processor would cause a time offset preventing the null. I almost recall doing something similar to that with amplifiers I will ponder it

[@pkdude5334]

when you switched to the powersoft amp during the 50hz test, it was very noticeably louder and seemingly deeper with my sub

[@DaveRat]

👍🤙👍

[@mojoemurphy]

It's amazing how much more efficient the new amps are. I'm a big fan of the new light amps, with a mobile rig, the old iron just doesn't make much sense for me

[@DaveRat]

🔧👍🔧

[@bluelithium9808]

8 Ohm, less than 1% distortion, 20hz to 20khz, all channels driven continious makes 1600 watt amps 200 watt amps.

[@DaveRat]

Yep and since music typically has 10db or more peaks which puts the average power at 1/10 that, that would be 20amps continuous draw to drive clear clean undistorted music at full power. But... If you are are using the amp to listen to sine waves, you will only get about 500 watts per channel. Oh, also, that assumes worst case consumer power driving the amp. Being that this is a pro amp it can be can be powered from 120v, 208v, 240v single phase or 3 phase power. Which will increase things a bit when used in pro applications as it is designed.

[@N0B0DY_SP3C14L]

Wow, Dave. I can say that this time you honestly schooled me, and I am grateful. Awesome demonstration.

[@DaveRat]

🤙👍🤙

[@richardbelisle4807]

During my day as crown and others were putting out lighter digital amps….the question for me was are they true 20-20 amps especially when driving low end…

[@DaveRat]

Yeah loads of variables. Building a new load now to do more testing

[@richardbelisle4807]

During my day as crown and others were putting out lighter digital amps….the question for me was are they true 20-20 amps especially when driving low end…

[@DaveRat]

Yeah, the earlier and cheaper amps have some things to watch out for and many do not perform well outside of a specific use

[@artysanmobile]

That’s what some very enterprising manufacturers liked to call “music power.” It’s perfectly valid in almost all cases. Almost. EDM subwoofers beg to differ.

[@DaveRat]

Agreed and the question is, would an EDM subwoofer perform better on a Class AB amp rated at 1,000 Watts RMS that can do 1200 watt peaks or perform better on the Class D amp also rated at a 1000 watts RMS but can offer 4,000 w peaks? The class D could be lighter, smaller and draw less power from the wall due to efficiency and deliver the same power to the speakers RMS and offer the peaks as well. I don't disagree that having longer duration power delivery is important for more consistent signals. What I debate is whether Class A B amp is actually beneficial or just a larger more powerful yet smaller and lighter class D amp would do equally well or better

[@raygunsforronnie847]

@@DaveRat The last question is the pondering point. Doing a dubstep gig a dozen years ago on JBL 4880a with I Tech 8K power we could smell the VC heat at ~500W/ch continuous. Peaks on dub are mostly a matter of performer fader position choices, so from a genre standpoint the smaller, lighter, tastes great, less filling Class D amp *should* suffice in my example. For a rock show with lead kick drum, the time it takes the output power of the class D to taper down isn't an issue until the double kicks; having that 6dB of extra output for 250ms is just right. Big stiff power supplies are big, heavy, and expensive making that extra transient headroom even more resource consuming. Your demo of the Crest just on the edge of clip sounds very compressed compared to the PowerSoft at the same long term (clip) point. That makes me think the folks who advocate for the Crests have rosier memories and less painful backs than myself.

[@DaveRat]

I can fully relate to the skepticism of the claims from many amplifier manufacturers. Clearly audible issues will often not show up in specifications. At rat sound we used to do tests when any amplifier company came to the shop by running their amp bridge mono into four 16 ohm rat subs wired in parallel. Then we would use a pulse test and compare their amp to the amplifiers we were using which were Crest 7001 at the time. This test would clearly divulge any issues with the various amplifiers. I remember a QSC amp rated at 4000 Watts sounded like a wet tire compared to the 1800 watt Crest 7001. The lab group in FP6400 was comparable but only with three subs in parallel bridge mono. Adding the fourth sub sent the amp unstable. Putting a PowerSoft X4 on the subs clearly was more powerful and clear than the crest 7001. Developing a test that allows you to easily hear the difference is wise and I probably take that for granted more than I should as I have much experience in that realm. I will try and do a video down that line of testing so people can develop tests that work for them

[@edtalktech]

Just not ideal as a bass amplifier. I also bet the Crest amp will still be working in another 16 years time.. The power-soft perhaps not so likely.

[@DaveRat]

It's hard to know. The Crest runs hotter and heat accelerates failures. But that small fan may not last decades in the powersoft

[@Anamnesia]

I bought a Chevin Research A500 power amplifier back in '97. It's only 250W (at 8 ohms) per stereo channel, but while I could pay a LOT less for a large transformer based amplifier, the physical difference in weight of the Chevin Research switch-mode amplifier is what sold me! (Note: I'm aware that Switch Mode amplifiers also have "transformers" as a part of their circuitry)

[@DaveRat]

We have a load of 4 channel Chevin amps that sound great and work well Good amps

[@zolof911]

Chevin amps have a switch mode power supply with a linear output stage using mosfets instead of bipolar output transistors. Very fast slew rate and extended high-frequency response. Great sounding amps.

[@joaquinaguilar5942]

One might be lighter and powerful. but the other will outlive it by two decades and play fine while on fire at a show.

[@DaveRat]

Perhaps. Much of the degradation and failures and apps can be due to heat and the newer amps run much cooler Time will tell. Those old electrolytic caps are ticking time bombs of degradation. But I showed you love the old boat anchor amps they have a posterity pill like a vintage car that gets bad gas mileage

[@scottwillow332]

Give me a Crest Amp anyday. Nothing beats an iron/copper cored transformer to give you reliable continuous power output

[@DaveRat]

I too have an affinity for the older amps but also the reality is that we now experience less overheating, lighter weight, higher power, smaller size, reduced power draw, increased reliability and improved sound with modern class D amps. But also keep in mind we deploy hundreds and hundreds of thousands of watts for large festivals and world tours. We went from heavy amp racks and high failure rates to extreme reliability and more control in a smaller package. But for home Hi-Fi and the cool factor not unlike a muscle car having an older amp is fun

[@51bobtube]

So when you listen to very dynamic music the newer is better. When you listen to trance music or very bass heavy music the older amp will be more consistent. However at consistently high volume, the newer amp will stay at its "lower" level of power.

[@DaveRat]

Hmmm, or The newer amp has higher RMS and higher peak So it's smaller and better for consistent and peak music

[@jprieto727]

I wonder how that would compare to my Carvin DCM 2004L amp?

[@DaveRat]

I believe that amp is rated at 300 Watts per channel into 8 ohms so that would be a much smaller amp compared to the power soft rated at 1600 Watts per channel or the crest rated at 400 Watts per channel.

[@TimKaseyMythHealer]

Based on what your saying about peak power (not average power) the peak power will help a kick drum to thump better. I guess you can factor this into how you purchase a sub speaker power amp. I’ve always ignored it, but considering how a kick drum is only 50 to 60ms in duration. If the peak power is 2k watts, that would be something that should be considered when purchasing a sub speaker power amp.

[@DaveRat]

Yes the peak power rating if it lasts long enough duration is the rating that matters. That said, if it only lasts 100 milliseconds it's not going to work as well as an amp that has a peak power rating that lasts 250 to 350 milliseconds. Also for long extended bass notes the continuous power rating of a higher level can be useful

[@bingdong8571]

People hanging on to there class a ab amps for dear life. Let it go, class d is getting better everyday with no signs of slowing down. The pros already outweigh the cons and class d i only getting better at a rapid pace.

[@DaveRat]

🤙👍🤙 but yeah I was reluctant for a long time to embrace the newer technology but Class A B is definitely a niche amp at this point. But I still do like them like I do many old technologies like record albums and even cassette and 8-track tapes because they all have their nuances that are enjoyable

[@davidkent2804]

I wonder if the extra dynamic range helps or hurts heavily electronic material as compared to acoustic. Clearly, it enhances vocal and instrumental music.

[@DaveRat]

Having enough dynamic range is important. Anything that exceeds the capability of an older amp tends to manifest as clipping which is undesirable. That said having an amp that too much exceeds the speaker capabilities can result in damage to the speaker or undesirable sounds from the speaker. In general a class D app can offer more power, less weight, generate less heat, draw less power from the wall, while being smaller and outputting the same or more energy than conventional older amps

[@MrMotoden]

Current draw is also very interesting to test in a setup like this. Comparing different amps with sine wave signal at different frequencies and then music type signal plotted against AC current. Interesting to know when your venues might not have quite the power source you would like to have.

[@DaveRat]

Very true and that's a test for a different day. Though I can say that when we switched from conventional amps to Class D for a large format sound systems, our current draw from the mains dropped significantly and output volumes increased. That said the differential between average current draw and peak current draw increased

[@JayBeBerg]

Very cool video. I can understand why some speaker manufacturers use class-D for the woofers and A/B for the tweeter.

[@DaveRat]

Yes I can understand that and also modern class D amps from top end manufacturers have quite impressive sound. The new L-Acoustics amp that is two rack spaces and 1600 watts per channel and 8 ohms with 16 channels is amazingly impressive in its power output, power density add fidelity

[@RWL2012]

even Logitech did that in the Z-Cinema lol

[@weareallbeingwatched4602]

I have one of those crests. It heavy. Not like the Crown DC300 I use to keep doors open / as a stage weight, though... that *never gets switched on* Never. Don't do it. It's just a weight dude. Seriously. I've had her since 2003, she was found under a stage refitting an old venue, and I have found that it's just the thing as a stage weight that nobody will steal. People steal and mix up stage weights, so I keep buying them, whereas the good old DC300 has been with me faithfully for years and years. Funny that.

[@DaveRat]

That's so funny using an amplifier that was valuable and in extremely high demand has now dropped to absolutely unwanted. I say plug it in! What's the worst thing that could happen and fun!

[@weareallbeingwatched4602]

@@DaveRat oh she'll get used one day, but I want to get her restored and sorted out on a bench properly. It's a good amp, might even be useful as a bench power supply for fooling around with stuff. Needs some sort of meters, I would argue. Can even get a USB cable with a voltage & amperage indicator on it these days, so I want it "back to the future" modded with blinkenlights. The crown DC, she is happy just being heavy in the corner, and she comes along as a mascot on heavy gigs. I have kept many really big doors with automatic closers on open with it very successfully over the years with the unit. Was part of the paradise kensal green from clash era. But if you say plug her in, I should, certainly. What's the worst that could happen? Capacitor fire or exploding FETs, I'd say. Looks strong though, it is built for emergency nuclear warning systems and similar disaster duty rugged deployments. They couldn't get it out without removing the built in timber stage, so she probably works. Nobody touches good ol' DC, and you know who is working there if you see it holding the back door open. Light yoh spliff yes mon, but hold it down, and we certainly won't hurt you. Keep it tidy, dis na babylon system.

[@weareallbeingwatched4602]

​​​​​​​@@DaveRat in terms of elite over the top weight, I also own some *immaculate condition* made in german tube amplifiers, in time capsule condition, each stereo item of which fills up a four unit flightcase. 100w per channel with loads of overshoot into 8 ohms, and that's so heavy you can't take it on aeroplanes without excess baggage tickets even if you take it out of the rack case. Twenty six blimey kilos, and not a speck of metric dust or imperial corrosion. No way is that getting used as a doorstop out the back of the venue. The tube power rig stays in my living room. Mostly. She gets to go out on occasions, and it's got that welding machine power. Used appropriately is there a huge advantage to tube power? Not really, it often sounds exactly the same as the tranny stuff on a good day. Cleanness is key. Tube is really clean if you do it correctly. Extremely light and airy is the signature of high fidelity audio. Sounds like less, often. Less distortion is a lot less energy, dB per dB.

[@DaveRat]

🤙👍🤙

[@catherineescol7852]

Dave is the Most Reliable, Fact Based Audiophole Reviewer out there Some people whoe Review amplifiers and preamplifier, and Speakers are Ghost hunters and Alien Hunters, who hires 3 Writers to make their channel sounds good. DAVE knows the Physics of Audio Stuff, Speakers , HIfi Amplifiers , Dave is the real Golden 👂 Ear. Always delivers Facts , not hype

[@DaveRat]

Epic and thank you! I do try very hard to share info I think will be useful that is unbiased

[@lazygazzzer]

Great video, glad you did this demonstration of the differences between class D and old school amps. I think the old heavy weight amps have suffered badly in recent years due to misinformation about output wattage on the newer class D amps. People see an old amp rated at 400 watts output and think it's no good because they have seen some Chinese-made amp in the local electrical store with a claimed output of 5000+ watts. But if you look round the back of any of these amps you can bet you will find a 2 amp fuse on the mains input. If it's drawing so little current from the mains then where is it finding all this extra power for the 5000 watts output? Meanwhile if they powered-up the old school 400 watts amp, it would blow their ears off. Having said that I was quite impressed that the Powersoft amp went down to 3 Hz. Certainly a well designed Class D amp with good build quality and decent components would be the one to choose if you needed to power some earthquake inducing subs.

[@DaveRat]

Yes the same issue existed with class A B and older amps, crappy amp sounded bad no matter what they are rated at and good amps performed well.

[@x5-acousticguitarstuff.2]

GREAT VIDEO. tq

[@DaveRat]

🤙👍🤙

[@mycosys]

Its kinda wild that lil Crest still weighs as much as a Perreaux 6000B

[@DaveRat]

🤙👍🤙

[@MrArihaan]

I was wondering, why the light bulb?

[@DaveRat]

To add a visual aspect

[@RaymondSolo]

That Crest amp made after 2004? Thats about the time that Peavy bought them out. I have a 20X Crest mixer that was made before the closure of Crest's New Jearsy factory, it's no longer working very well. wouldn't be vary cost effent to have it fixed so I got a new Soundcraft Signature mixer to replace it. How do you think an old Crown Micro Tech would stack up to a Class D? I like the sound of the Class A/B amp's at least my Crown Power-Base and Power Tech's sound good to my ear.

[@DaveRat]

That amp is from the late 90s

[@RaymondSolo]

@@DaveRat That makes it a real Crest item. I take it has a New Jersey address on the ID?

[@DaveRat]

We bought and owned over a hundred crest amps back then bought from when they were released until 1990 or so. Still have a few pallets of them

[@Lu_Woods]

Curious if dogs prefer the Crest or the Powersoft. They might like the softer, more complex 20HZ signal the Powersoft produced ; ) Does the Crest sound better for high freq sources like cymbals etc.??

[@DaveRat]

It's hard to say, that crestamp goes up to 30k almost flat, and the power soft has the switching frequency overlaid. I think for ultra Hi-Fi applications the crest would be preferable

[@Lu_Woods]

@@DaveRat thanks for the reply. I use a Stewart Power amp for my bass, sounds pretty good...I guess I should A/B it with the Sunn2000S.

[@DaveRat]

👍🤙👍

[@WhiteTurtleDiver]

What is the amperage draw difference between these two amps?

[@DaveRat]

Great question. I did not test but... To the best of my knowledge, the 7001 (600 watt p ch version of the 4801) and the T904 both max out a 20 amp breaker at 120 volts when driven full power.

[@teodorzimta748]

Cool video , but as far as I remeber either the 4601 or the 4801, it's optimized to run high mid frequencies rather than fullrange.

[@DaveRat]

It was the 4601 that was designed and optimized for high frequency applications. The 4801 was the small brother to the 7001. The 8001 is the three rack space version with even more power and weight

[@TheMaddoxfam]

I loved watching the experiment but you never did a peak measurement for the crest, only the power soft. What does that crest spike at? When I did training for installed sound systems we were always told that a “good“ amplifier has a peak of at least double RMS.

[@DaveRat]

At 8 ohms the crest continuous measurement and peak measurement were the same because the 400 watts into 8 ohms matched its power supply voltage. At four ohms and two ohms the crust had additional power capabilities When I did the peak power test I brought both amps to clipping in the same manner so we saw the peak power of both amps

[@TheMaddoxfam]

@@DaveRat that’s what I was looking for, I missed that. Thanks!

[@DaveRat]

That said you bring up a great point, at four ohms and two ohms the voltage supply rails of the crest remain the same because the voltage rails are the same. So the theoretical peak power limit of the crest is 800 w per channel at 4 ohms and 1600 w per channel at 2 ohms. At those lower impedances the output of the crest is more similar to the power soft and that it can deliver much higher power than its RMS rating for short periods of time.

[@matthewseymour8972]

The small rig I used to run used all class D amps. I'd always get people telling me how inferior they were and they couldn't keep up with the old tin... True in very specific circumstances, but I had to move these things around so I did not care.

[@DaveRat]

Yes it's difficult to buy any gear at this point that doesn't have class D amps. All the self-powered gear and all the top end professional gear is based on Class D

[@janm2510]

Thanks!

[@DaveRat]

🤙👍🤙

[@JRo250]

Bottom line first: music is not about how loud you sound, it's how good you sound, loud. The main difference between these two amps is the amount of snake oil used by their respective marketing departments. Lookup the Crest PDF manual and you'll see fully disclosed technical details. In the manual, Crest will teach you the theory behind their design, how and why things work like they do, and show you in depth troubleshooting procedures (including schematics). The other amp has a bunch of asterisks showing what they *really* meant with their quoted figures.

[@DaveRat]

As a close friend of the Claudio Lastrucci, look him up, who is the designer for PowerSoft, holds many patents and is an absolutely brilliant innovator, I can say that there is no snake oil involved with the powersoft designs. I've learned much from him and one of the challenges with amp design is helping people understand that they don't need a dump truck to run an F1 race. The concept that an amp must have the capability of delivering full power continuously over long periods of time in order to reproduce a signal that has a four to one or 10 to 1 peak to average ratio, is a challenge indeed. That said I too love old boat anchor poweramps for their posterity, simplicity and coolness. And also know that having switched from those boat anchor poweramps to modern class D apps we have seen astronomical improvements in sound quality, amazing reductions in weight and size, reduced power draw, reduced heat generation, increased reliability, improved sound quality and the ability to reproduce much higher volume levels than we were able to before. For a deployment like we do when supplying sound for Coachella where we have over 800 large format boxes and well over a million watts of power, it's incomprehensible in this day and age to deploy older format amps. As you may or may not know, All the top world class sound systems for concerts events and festivals all use Class D amps at this point in time with the exception of a few esoteric EDM companies that have cool sound systems powered by older amps

[@JRo250]

@@DaveRat I'm sure the designer is brilliant. It's their marketing department calling it a 6kW amp that are not. I mean, it could be, for a millisecond, and so can many other amps.

[@DaveRat]

I don't think you can draw such a distinct line. The statement that the amp does not deliver 6,000 watts is an incorrect statement. The question is time frame. Perhaps using a car analogy may be helpful. If a dragster can't travel a hundred miles at its top speed is its top speed not valid, Even though it can reach the speed and it can be measured? Or is the only valid speed for a dragster the speed at which it can maintain for an extended period of time even though that is not how the dragster would ever be used? Since amplifiers tend to reproduce music which has short period bursts and are rarely used for long-term continuous signals, why would we hold the long-term continuous signal spec to be the valid spec rather than the short-term burst spec? That said not all short-term power specs are not equal and some manufacturers use very short periods of time while others use longer periods of time and there can be drastic sonic differences between the two. My experience is that powersoft does a very good job of using realistic parameters. And this is the crux of the test I did here. The amp claims to have 6 db more output power, and the test shows that it is 6 db louder and a conventional amp using music

[@JRo250]

@@DaveRat >The question is time frame. = which is exactly what I said. You can deliver a lot more power given a short enough time. The Crest will deliver it's claimed power all day long and will have headroom to handle peaks beyond that. I'm sure the other amp is great, just not at 6K Watts. The IEC C20 inlet connector on the amp is spec'd to 20A. The amp can operate from 90-250VAC input, but even at 250V@20A, that's 5kW. You can't output 6,400W for very long with a 5kW input. I appreciate the analogy and the rest of the comment.

[@DaveRat]

And yet the PowerSoft amp is 6db louder with music than the 400 watt crest.. so the music is playing at 1600 Watts but not 1600 watts? Hmmm The Crest hand no more output at 8 ohms without clipping as ithe 400 watts matched it's supply voltage. But yes, at 4 and 2 ohms, the crest had has additional peak power to offer

[@JaimeFon1961]

you should test the distortion level the new class D at higher frequencies should have more distortion, probably old watts has more quality than the new watts

[@DaveRat]

The distortion specs are ready available and the testing I have done shows it is not measurably different better or worse than the older amps.

[@7171jay]

I would imagine the newer amps might do just as well with harmonic distortion but what about intermodulation distortion?

[@DaveRat]

I haven't tested it but that said, when I was working has a consultant for EAW and they were analyzing various amplifiers for applications they were doing extensive tests on powersoft and a wide variety of all the apps out there and I remember being called into the office and shown the response curves and analysis data. And they were extremely oppressed with all aspects and found no major flaws in the modern amps. This was not the case for older amps and the powersoft was the best play measured

[@7171jay]

@DaveRat So were they oppressed or impressed? Freudian slip maybe??? ;)

[@JaimeFon1961]

@@DaveRat Thanks Dave for your response

[@dwmfty3111]

The difference between old and new is more party time 🎉

[@DaveRat]

🤙👍👍 clarity!!

[@klumpadistdas]

what about the damping factor?

[@DaveRat]

Class the amps and specifically the power soft amps are able to drive loads as low as one ohm or below. Hi damping factor is related to low internal impedance of the amplifier and having a low internal impedance allows it to drive low impedance loads The result is that class D amps have or are able to have a much higher damping factor and conventional amps. Of course using longer speaker cables dilutes damping factory regardless of the amp type

[@howardskeivys4184]

‘Old watts, new watts’! Excuse me - A watt is a watt is a watt, regardless, a volt times an amp! End of. As soon as you said that the T904 was capable of outputting 6400 watts, forgive the deliberate pun, but, I smelt a rat. A USA mains outlet can output a maximum of 1500 watts. A UK mains outlet can output a maximum of 3000 watts. Where does this unit get all it’s additional watts? Or, did you forget to mention that it requires 4 mains cables, connected to 4 mains outlets. Even then, it’ll be 400 watts short. If the T904 truly can generate 6400 watts from a 1500 watt mains outlet? Then this company is on to a winner. Over night they’ve solved the world’s energy crisis and helped to lower the carbon footprint by 75%! My car has a top speed of 135mph. If I drive it at full acceleration down a long steep hill, with a tail wind, it will reach much higher top speeds. But that is not sustainable, nor is the peak power of that thing!

[@DaveRat]

Yes in a very simple view, a watt is a watt but we live in a world where things change over time And the car analogy works. Your car can go 135 and may be rated at 135 but around turns and uphill and averaged over a drive, the speed will be lower, maybe 60 or 70 so should you car be rated at 70 mph? No, it is rated at the max speed just like newer amps. Older amps typically had a top speed that was equal to their average Newer amps now spec power similar to how loudspekears are rated. Power handling over a time frame with a crest factor. Usually 6 db, so a 400 watt speaker is really a 100 watt RMS speaker or less. The development of rating amps in the same way that the speakers they are connected to is a useful and wise development that is more in line with that music that are used to reproduce. That said, if you listen to sine waves rather than music, this does not work well And yes, I did this video to help people get their head around this logical and practical concept Because it may be useful for you and others to become aware of the newer way amps are rated.

[@howardskeivys4184]

@@DaveRat I’ve no issue with the format manufacturers use to verify their products measurements, but, a watt is still a watt. Whether it’s continuous or peak. My car’s maximum speed is honestly stated by the manufacturer at 135mph. It is capable of a lot more, but is restricted. The car’s average speed is incalculable. It is dictated by the driver and road conditions, not the car. One measurement you didn’t give on those amps, it the gain. My old 90 watt integrated amp had a gain of 29db. My new 520 watt monoblocks have a 26db gain. I normally listen to music at about 85db. To achieve this level with my old integrated I had to turn the volume control to 11 o’clock. To achieve that 85db with the monoblocks I have to set the volume control at 1 o’clock.

[@DaveRat]

So you missed the read between the lines aspect of new watts being "the way watts are spec'd now is diff than how they used to be spex'd?" Yes Gain is important and other aspects as well but in this video I was just covering the change of how manufacturers tend to spec their amps and the change in how professional amps are manufactured now versus how they used to be I'll post more videos on apps and I have a bunch of others up already

[@FreeAssRecords]

Impressive comparison test, Dave. Thanks, man. I also appreciate that you presented it in a way that I understood. There was a lot of information digested and I didn't get any brain gas. 👍😁

[@DaveRat]

👍🤙👍

[@AlexJoneses]

I miss my 60 pound qsc isa300ti's. They were a bitch to lug around to smaller gigs but frankly they outshone my 2kw peak power amps while retaining more quality from less distortion, and never ever broke, even though they were 15 years old and absolutely covered in dust rust and grime. This however is not to say all new amplifiers suck, I am particularly interested in the rise of the ultra tiny class D amplifiers as they seem to be doing some crazy stuff for the size, but as of now, and maybe wont be for too long, if you want that clean reliable power, the heavier that transformer the better it's been.

[@DaveRat]

I we saw the opposite. We had louds of issues with the Crest amps. We now deploy literally 100s of L-acoustics LA48 and LA12x amps with very low failure rates, improved sound quality and volume levels that make the Crests sound broken

[@Rhythmattica]

Incredibly insightfull..... or inearfull. Brilliant .

[@DaveRat]

👍🤙👍

[@meandmyarrow]

It would be interesting with your demo music to measure dB in the room at the edge of clipping with the 2 amps (with your dummy load setup, running into another amp/speaker).

[@DaveRat]

The dummy load was running directly into a speaker and there wasn't really a need for an amp. You can just put a speaker across part of the load and the speaker will play the voltage drop that's showing on that load. So that's pretty much what you heard in the video

[@meandmyarrow]

Ok I grabbed 2 sections of audio from the video with music playing through the 2 amps (not ideal with KZbin but worth a shot). Looks like about 7dB difference over the sections. Does that sound about right?

[@DaveRat]

Yes that sounds about right. The Crest amp puts out 400 watts and I was running it right near clip and the power soft amp puts out around 1600 Watts which is 4 times the power which is 60b.

[@willmanJohn]

I use electrostatic speakers, which can have very demanding impedance loads, both high and low. Is there a difference between these amps with, let's say, a 2 Ohm load or a 60 Ohm load? (Yes, I have one pair of speakers that have these impedance extremes, depending upon frequency)

[@DaveRat]

It'd be interesting to try a class D app on those. I know the PowerSoft amps can run loads as low as 1/2 ohms and have the voltage swing to run high impedance loads and still deliver a good amount of power more so then class A B apps. It would seem the class D would be better suited for those complex loads but would we worth testing

[@duroxkilo]

i enjoyed this... they have these super small class D for under $50 that run on aprox 40Volts. the other weekend we powered a 400Watts Cerwin-Vega sub for our backyard darts games and it sounded just as loud as with the old and heavy Crown amp. now it makes sense :)

[@DaveRat]

🤙👍🤙

[@mprecht]

I know that you run into copyright issues but have you ever tried the sound difference with a song like Bjork's "Hyperballad" which keeps the power supply on constant stress?

[@sim82]

what would happen if you run the same signal through all four channels of the Powersoft amp? Would the highly correlated peaks in the signal hit the overall power limit quicker? I'd assume that part of the calculation with the modern amps is that the signals are not uniform (e.g. delays being used on some channels)

[@DaveRat]

Here is the data sheet. I trust PowerSoft to release accurate data as they have always tested to spec and I know the designer Claudio. Look at the symmetrical and asymmetrical power specs to see how it performs with multiple channels driven www.powersoft.com/wp-content/uploads/datasheet/PS_TSeries_DS_EN.pdf

[@sim82]

@@DaveRat Thanks for pointing out that detail!

[@DaveRat]

🤙👍🤙

[@ralmslb]

Could you share some more details regarding the load you are using? How did you achieve an 8Ohm load that can't handle all this power? Also, is the lamp just a standard AC LED lamp? Won't the lamp add also resistance to the output? Lastly, is it dangerous to measure the amp output voltage while driving a speaker if the speaker is rated for at least the same as the amp?

[@stevendenmon9557]

I understand the peak power and music duration. Question asking is how, dose the two work together? I’m thinking about a driver. The response of peak power handling. Is the powersoft continuous in control of the two or the driver?

[@DaveRat]

The signal tells the amp what to do, the amp then tries to send it and the speaker then tried to do it. All is good until the signal exceeds the amp's capability to deliver. And amp with more peak capability will deliver the peaks, and amp without the peak capability will clip/distort. Same thing sort of with continuos except the powersoft amp has built in protection so it will never clip or distort, it just turns down things that are too much to deliver

[@stevendenmon9557]

Thanks. Didn’t know the body of the 3 paragraphs. That’s an ah ha moment. 🔊😁

[@DaveRat]

Awesome!!

[@laszlosokolai2858]

I had to take out the IEC power connectors and hardwired cords of the proper guage into all my amplifiers. I haven't had an amplifier failure since then. The IEC power connectors are THE number one cause of amplifier failures as they are only meant to carry 10 amps. The 20 amp IEC only carries 15 amps. The power lights don't dim on my amplifiers any more. If you don't believe me, put a volt meter between one of the lines and the corresponding connector in the amplifier and drive it at full power - 20 to 30 volt difference and drop between wall receptacle and power switch inside the amplifier!. I have 3 dozen Cerwin Vega CV-5000 amplifiers rated for 5,000 watts each. They came with 20 amp IEC's - i could not get the amplifiers to put out anything past 2,925 watts bridged at 4 ohms. When I hardwired 8 guage power cords into each of them - 6,600 watts bridged at 4 ohms, pulling 60 amps peak each amplifier.

[@IswanjanaHariAdi]

Very cool demonstration as always. Thumbs up, keep up the goodwork Dave. Thanks for the knowledge.

[@DaveRat]

👍🤙👍

[@josiahberry8743]

One of the best demos I've seen online! Ironically, modern EDM music (trap, dubstep, and drum & bass especially) has much more sine wave content, especially in the subwoofer range, compared to a live band. Burst power ratings should be almost meaningless for that type of sine wave bass music. With sine waves having a 3db crest factor, I imagine modern DJ music has a crest factor closer to 6db at most whereas a live band is easily closer to 12db+... Getting the rights to play music on KZbin is not the easiest thing in the world, but I wonder how this exact experiment would look/sound with an actual EDM bass music song vs just a raw 50hz sine wave... I imagine the Powersoft amp may be a hair louder but I would expect the difference to be less than it was in this experiment using a track that was recorded with live musical instruments... So cool to see this either way!

[@DaveRat]

If you do the math there a 6DB crest factor would mean that a 500 watt amp would need a 2000 w peak because 6dB is four times the power. The apps that I measured show the class D having more continuous power and more peak power and fully capable of meeting the specs you propose

[@josiahberry8743]

@@DaveRat Yes, I use all Class D. The weight savings and efficiency is a must in the modern era. I remember when I had boat anchor QSC RMX and Crown CE2000s amps as a kid when first getting into audio. My how time flies when you're having fun! Thanks as always, Dave!

[@DaveRat]

Awesome thank you Josiah!

[@kyle_neuron]

Funny thing about crest factor is that it's affected by bandpass filtering. Guess what every loudspeaker on earth is, even before you add extra processing? A simple sealed box is a second order high pass filter, and that alone can make your 6 dB CF content suddenly look like 9 dB... What actually hits the speaker is rarely quite so dense. That is of course, unless you've not brought enough rig for the gig or don't have amps with sufficient peak voltage swing to handle the 12 dB CF side-chained kickdrums that sit on top of the rolling sub...

[@DaveRat]

Interesting

[@pirateradioFPV]

PMPO 🤭 Personally I'm just glad of how far the D-class has come. The first gen wasn't all that great but nowadays used properly for and in application, they're good. Like, really good.

[@DaveRat]

Agreed

[@Audio_Simon]

Cool experiment! I'd love to know what internal voltage these amps are running. I.E. is the powersoft/crown voltage or current limited? Id guess the powersoft is running very high voltage internally but relies on capacitors to provide the current. When the capacitors empty out after a second the amp clips.

[@DaveRat]

The powersoft has built in processing that is set to protect the amp and prevent clipping from ever occuring

[@izaakgray1718]

The biggest issue with class D, isn't the peakyness of the power, but the quality of the sound of their output. Up loud on a decent enough mid band device it's heinous.

[@DaveRat]

Interesting I think that some additional exposure to top quality Class D amplifiers maybe in order. The usage of Class D amp maybe a lot more widespread than you realize. I know I was skeptical in the transitions and also I own and deploy over a million Watts of Class D amplifiers at large festivals, world tours and shows. We have actually seen improvements in sound across the board when switching out of the older amps into the modern Class D versions

[@izaakgray1718]

​@@DaveRat How can I possibly compare my skillset or experience to yours? Alas I cannot sir. But I must say that I've actively removed class D amplifiers from venues, and replaces with class TDs or class Hs, and the venue owners have always thanked me. Which as you'll know, is unusual, given that venue owners rarely care about much other than putting out the raging financial fires that consistently threaten their businesses. Class Ds removed: FFA Powersoft Linear Research Most generic designs Class Ds: I found 'ok' D&B D20 (only through their own kit, which basically has no mid) And some mall lower power units in some modern hifi/monitors. I've read that the lower power units have less dead time. When you say you switched out to the newer units, did you A/B against your trusty crests? Practically speaking, class D has them kicked. It's not like you can even BUY class H designs very easily any more. :)

[@DaveRat]

Yes, I did compare. When I swapped out the old crown and Yamaha amps at the Roxy in Hollywood for PowerSoft, that old Clair piston system lit up. Even to the point where when U2 played there, a Clair account, I got a call from their asking what I did, he has never heard a piston rig sound so good, even when new. When we swapped out crests on our Rat subs to lab gruppen we saw an improvement and when we run them from the L'acoustics class D amps, it pumps them up even more. One thing that is important is that with older amps, class ab and such, running low impedances like 4 and 2 ohms is advantageous but you get loss in the speaker wires. With modern class D, they are better at higher voltages and while they can drive low impedances, using higher power amps and then using them at higher impedances like 8 ohms when possible tends to be advantageous, less loss in the speaker lines, more control over individual speakers, and faster cleaner sound relying on more power sources.

[@izaakgray1718]

@@DaveRat Ok! Maybe it has to do with my design philosophy. I pretty much always have a discreet mid range unit 300-4.5khz and I like my systems mid range forward. Whats the mid range on those Clairs? I ran that t604 on some KV2 units, which sounded very aggressive indeed. Meanwhile some old school mosfets and she sounded great. Funny that you prefer lab and the l'acoustic units (they're re badges from powersoft I think?) I've literally gone the other way and ended up favouring the crest pro 9200. I've even got 3 in a rack at home for my hifi. I generally avoid anything lower than 4 ohms. Voltage is awesome, if a bit terrifying on an amp with terminals.

[@DaveRat]

Lab made the LA48, PowerSoft made the LA4x but when they bought Camco, all the amps are made in house. L-acoustics is good at finding or making the best

[@JeyGifford]

Thanks for the video Dave. So, since it takes 10dB to double volume, but you only get 3dB per doubling of watts, then it’s sort of a logarithmic scale? 3 1/3 X watts is 2X volume?

[@DaveRat]

3db double watts, 6db 4x watts 10 db is 10 x the watts and 20 db is 100x the watts 10db is said to 2x the perceived volume level. Or 10x the watts to double the perceived Volume

[@JeyGifford]

@@DaveRat ohhhhh. I missed that detail. I would be really interested to learn how we measure perceived volume.

[@DaveRat]

Yeah, I am not convinced it is as simple as they say. Adding 3 db to a system running 115db sounds significant and adding 3 db to a system running 90 db sounds irrelevant

[@TimpBizkit]

@@DaveRat also frequency. Going from background dinner levels to cleaning levels I notice a significant increase in bass, so at least initially the bass grows louder first, though it levels off at very high volumes and is overtaken by the rest of the sound. Perhaps it's the level of tactile feel increases faster than the loudness of the tone due to the increased energy beyond the rate of increasing loudness. Although I tend to think those frequencies around 3kHz get louder the fastest. Adding 10dB to a 3kHz note sounds a much bigger change than adding it to 150Hz. The fletcher munson loudness curves are an interesting look up.

[@scottw5253]

Honest question: Why examine and compare the wave forms of frequencies humans can not hear?

[@DaveRat]

Maybe similar so testing a car above the speeds anyone will travel in it. It shows capability. Does the car barely get to 80mph or can easily travel above the speed it will be used? If it can barely reach the upper limit,at what point is is degrading? Is the degradation audible? Humans are all vastly different in ever aspect yet we all hear to exactly 20k? Or lower? What's the maximum age a human lives? Or max speed one can run? Or max time we can hold our breath? Is 20k the one and only firm limit that no humans exceed but dogs do? These are all questions to ponder

[@scottw5253]

@@DaveRat Gotcha. The car analogy makes sense totally. Right on man. Also - your method of recording so as to provide the youtube listener with, as close as possible, the same signal as what you hear through your speakers is FAAWKING genius dude. When you mentioned that I was like, "OH shit, YES! That makes so much sense!" That's a clever solution/alternative to recording sound from speakers with a mic, to then put that through the KZbin compression/degradation upload process that invariably ends up sounding like canned asshole for the end listener. You're good man, love it!

[@DaveRat]

Awesome and thank you!

[@rbrown2925]

Audio amps are supposed to roll off at very low freq to avoid frying low freq drivers with inaudible tones. The roll off is a good thing and a sign of a proper design and not (necessarily) a tech limitation. In comparison, lab amps may be flat down to DC-or you may have a dangerous old “audio” amp like a Crown DC150. I fear some folks may get the wrong impression from your subsonic tests.

[@DaveRat]

Yes and no. Having the capabilities to extend beyond the usable range can be useful both in the upper and lower limits. Then imposing filtering as needed to limit the response There is a false perception that class D amps tend to lack the ability to reproduce lower freqs. In my opinion, the most desirable amp and audio gear in general is capable of a full octave above and below the range to be used and we the limit it as needed. Yes, I want a car that can go 120 to go 60, not a car that can't go 61 so I can travel at 60 Did they make a DC-150? I thought it was a DC 300 and a d150. One of the cool things you could do with the DC 300 is use it as a variable DC power supply. When I worked at Hughes aircraft we had McIntosh 2300s we used for variable AC voltage power supplies that we could vary the frequency and level on. Also did you know that KZbin will record low frequencies down to about 1 Hz? I did a video on it and got a great comment from someone dealing with seismic measurements and data and he was excited to know that he could use KZbin's audio to transmit and store seismic data information they needed down to those low frequencies.

[@basspig]

The modern amplifiers use a principle similar to a photo flash where in the store of a tremendous amount of power and capacitors and then they can release enormous amount of power for a very short duration. Not much good though if you need continuous sine wave for several seconds. You're going to be limited by the wall socket.

[@DaveRat]

Also modern amps can recycle back EMF from the speaker as well as they are significantly more efficient than older amps. These factors combine to offer quite a bit more usable energy delivered to the loud speaker from the same wall outlet than older amps.

[@sambaker7255]

DAVE !!!! Why are you not measuring Total Harmonic Distortion ... Freq response is 1 thing.. THD is another ... I'm disappointed that your experiments did NOT take distortion into account, other than clipping, Which is audible. ... THD will impact the 'listenability" and ear fatigue over time.

[@DaveRat]

Total harmonic distortion is useful and important for low volume and mid volume and anything that isn't driving an amp really hard. Once you get into clipping your total harmonic distortion goes through the roof. This test is all about seeing which amp can deliver more power before it goes into massive distortion IE clipping. As far as Fidelity and listenability and other aspects those will vary greatly for manufacture to manufacture as well. This test was more answering the question " doesn't app need to be big or heavy in order to be loud and deliver more power?" Kind of like taking two different cars to the drag strip to see which one has better acceleration and top speed is what this test is about. A total harmonic distortion test is more like a test of which amp has a smoother ride.

[@sambaker7255]

@@DaveRat Hi Dave.. I would suggest that THD is very important especially at high volumes. Yes clipping is overdriving the amp (well the power supply) but If THD is high then all you are doing is amplifying the distortion along with the signal. BUT..... of course speaker distortion will eclipse THD from any amp so perhaps it's an academic discussion at best. As you know I am old school... for me an amplifier should be rated at rated RMS, 8 ohms 20-20K and as low THD as possible. Now i know current music as a much higher sub 20cps component which is the domain of Subs. The issue of "head room" or peak output is really a function of Power supply to the output chip set. Not enough power and the system will clip and loose frequency response. Your demonstrations and testing are always right on, so don't take my comments as discounting your methods...Just looking to have the conversation.. Thanks

[@DaveRat]

I try and test the things that are not readily available in the spec sheets. I believe the THD of the amps I tested is spec'ed either the same or nearly the same. And since they are trusted manufacturers we don't have any reason to believe their specs are not accurate or close to accurate. THD is a widely used and pretty universally standardized spec. For those kinds of tests there are other people out there, My adventures are about finding the hidden things and misunderstood aspects and audio Gremlins that people tend to overlook

[@sambaker7255]

@@DaveRat and you do a great job !

[@DaveRat]

And thank you! I appreciate your input and perspective. Very important to me. Please always let me know what cha think

[@haldorasgirson9463]

Class D amps are amazing. Especially for subs where you really need the power.

[@DaveRat]

🤙👍🤙

[@amsb4dafunk558]

If You have ever had to repeatedly load/offload A A rack full of QSC RMX5050(s) And Not suffered long lasting quality of life altering ouchies Hit That like, and subscribe button.

[@DaveRat]

Thank you!!

[@wilcandou]

You would think with the Powersoft Amp that what was represented as a bit of fuzz on the scope would be heard when the music was played, but apart from the output volume changing, it sounded ok. If anything is to be "considered", would it be a fair call to say that the Powersoft Amp would be a better choice (according to the scope) for bottom end sound? As the Crest Amp was far cleaner at the top end? Thanks Dave.

[@DaveRat]

That high frequency fuzz is in the 50 kilohertz region I believe so it's neither audible nor can speakers reproduce it

[@bobert4522]

Could it be the powersoft amp has an RC/LC filter to roll off anything over 20k? Seems too much of a coincidence that it starts right around 20kHz. There's nothing really to limit that frequency response on the amplifier design. Versus the old, the newer amp would have more responsive components by nature of their evolution.

[@DaveRat]

Yes and sort of. As far as a low-pass filter there is digital processing in the power soft amp and that I believe is 48K based so that sharp cut off was the Nyquist filter for the processing. But also we heard the power soft amp fan ramping up when I ran high frequencies continuous at a high level. And normal usage this is not an issue as high frequencies tend to be short-term and peaky but also it demonstrates the amp does struggle with higher frequencies when driven at high levels. But yes the amp should not have that steep of a cut off for anything other than the digital processing

[@andygibson8143]

The powersoft t904 is a class D type amp. They do not have any heatsinks on the transistors because they are switched on and off entirely. Therefore don't need much space, and make more use of the power coming from the supply. If you put 1000 watts in you get 998 watts out !

[@DaveRat]

👍🤙👍

[@ladjkaoz]

🤘😉👍great video... I love my old crowns power base 1 and 2 but I rather use the digital ones still crown. K2 Itech and Mtech.

[@DaveRat]

👍👍🤙

[@bms13]

Thanks for this great A/B comparison. Can you comment how the different amps handle the load of a real crossover + modern drivers vs the resistive voltage divider for this video? Maybe no one uses passive crossovers in pro audio anymore 😂

[@peniku8]

Powersoft can do energy recycling from reactive loads (idk if all amps but the only I ordered does), so you'll get more power out of the amp than on a purely resistive load. Keep in mind that real power delivered to the speakers will be lower than apparent power (V*I). Some amps might get unstable at various low impedance/weird angle loads, but idk much about that since nobody really tests that and I haven't seen much data on that.

[@DaveRat]

Yes, I will ponder a test for that

[@RWL2012]

A/B comparison lol