Understanding Power Amplifier Measurements

[@AudioScienceReview]

Sorry about the audio quality. My external microphone got disconnected and video got recorded using internal camera mic. Hopefully you can still understand my voice.

[@KernelFault]

Not a good look when you are talking about low distortion. 😁

[@rlwings]

Ya, might want to invest in a proper mic. It will give you better dynamic range and frequency coverage. ie, you voice will be 'meatier' with better bass and mids modulation. Rounding out you voice in a very pleasant and full way. Much nicer to listen to. Think FM radio station .... I love your videos by the way. :)

[@AudioScienceReview]

@@rlwings As I noted, I do have a proper microphone. It is just that it got unplugged and the internal camera mic got used. I didn't catch it until I finished the video. It is fixed now and should be good for the next video.

[@NosEL34]

Listening to the video thru my phone without headphones I didn't notice anything wrong with the audio quality.

[@oscardziki4543]

You made me looking with suspicion at my genelec monitors :)

[@PiOhMy]

I learn more in an hour watch your vids than decades looking elsewhere. Thanks.

[@epi2045]

I love this channel and it keeps me in check with my addiction. I was at Apoxna ‘23 two weeks ago and drooled over many car & home priced gear.

[@zefrog7482]

Certainly makes you weary of all the KZbin reviewers that have raved about the Luxman for example.😂 Really is an industry full of crap and the majority of reviewers are actually just influencers.😂 Great work as usual, refreshing to see someone using actual science combined with honesty, no wonder a lot of those peddling high end gear really get annoyed by you. Nice to have somebody genuinely for the consumer.

[@gamerpaddy]

Amir & ASR is the "Project Farm" of HIFI, no bs, no marketing wank, only test results matter. thanks !

[@AudioScienceReview]

If there is one person I worry about taking my job is Project Farm! 😀 That man is far more dedicated than I am!!!

[@jeankazamer9166]

Also, Amir, usually tubes of 10 minutes are cut in like 20 segments. you are rolling straight through 1 hour plus long 😂😂 When someone is passionate and has mastered his passion this is what we get!! incredible sharing :) ❤❤

[@Projacked1]

Have to say this again; The whole point of listening to an expert, backed up by the science= > you lose all the myths very fast. And that is all humanity needs imho. Amir, you rock man.

[@alexYT87462]

Except that all of humanity’s progress is predicated on finding answers to difficult questions that can’t be answered. Not measuring things we already know. Or?

[@Projacked1]

@@alexYT87462 So how did Flat Earthers happen, again? 🧐 I have to admit, this planet is WEIRD...

[@annenominous7220]

Brilliant tutorial, must watch for folks that wish to learn the truth about amplifier performance. Not the full story, but certainly the easy to understand part of the story. Thank you!!

[@DaveJ6515]

The truth about amplifier performance is closely related to the system you put it in. Which includes source, speakers, cables, room, furniture, noise leve, and people in the room. The measurement of performance is done by ears and heart. Music is sound with emotions, not a Fourier transform (which, incidentally, is my profession as a mathematician)

[@TheLkdude]

Wow , the holy grail of amplifier measurements !!! , Many thanks for sharing this knowledge and for the fantastic presentation !

[@HeyYall398]

This lecture made my day. I thoroughly enjoyed it! Second time hearing it!

[@JesusMartinez-mk6fc]

Now a masterclass on amplifier measurements Aimr. Excellent! You're killing it with this "understanding measurements" series of videos Amir. Great idea to present three different levels of performance and what sets them apart, a SOTA design, a competent performer and an example of what to stay away from. Furthermore, it demonstrates very well how higher cost gear doesn't always correlate with higher performance in this shameless marketplace. You killed three birds with one stone Amir; OK the last one was already dead. 😂

[@motjones2341]

Nice job Amir. Very good idea to point out the top, middle and bottom of the specification spectrum. I thoroughly enjoyed your explanations and very good pace packed full of information. Thank You Sir.

[@eattoast6378]

this man is puttin out content. I love to see it.

[@jesuschrist2284]

It sounds even better through my new platinum oxygen free active cables

[@Untilitpases]

You've done it again! Thank your for providing so much x-ray vision to a "compromised" community (paradoxically claiming to chase high fidelity while lacking integrity/fidelity and debasing the discussion level 😁) As a zen saying goes, a talk with a knowledgeable person is worth many a book. Even your passing comments are insightful. (Like when an amp might sound bright, likely separation to soundstage correlation etc.) Thank you Amir, you already knows this but it bares repeating: you *are* making the world a better place in your way, and making lots of manufacturers angry 😂 in the process. May you be blessed!

[@jcrollman]

This is phenomenal- thank you Amir! With the hot marketplace today for vintage 1970's amplifiers, I'd be curious to do a comparison between an aged vintage amp and the same amp today with replaced capacitors and compare and analyze the difference.

[@masterxyr]

Brilliant walk-through all these graphs and steps, and even though I've been on the block for a bit, it's still helpful and elucidating to have such an exposition on the subject. thanks a bunch

[@narmar]

Great video - very informative and thorough. Could you share the list of equipment and software you use to test and measure power amplifiers? Thank you.

[@phpn99]

If you didn't exist, Amir, we'd have to invent you. Each time you speak, my faith in humanity is restored. There is so much quackery in audio circles, it's disheartening.

[@MasterofPlay7]

I'm new so for eg what?

[@masterxyr]

wow the luxman sq-n150 is such a gorgeous piece of hifi gear and its finishing is sweet, and yet it measures 🤮 And just like you said, if there is so much objective noise and distortion, _nobody_ is listening to most of the detail, let alone *more* detail. Thanks for such great work, Amir! I enjoyed this long feature :D

[@leekumiega9268]

Amir I am grateful you are testing and confirming or debunking manufacturers claims. One issue though when you tested vintage and newer Carver amplifiers you just showed that it measured poorly but did not listen to them to see if your above average listening skills could detect slight distortions . In order to keep relative costs down and provide the most power for the money with the ability to drive difficult speakers Bob feels that as long as you can not hear the THD+N then why spend the money to improve a measurement. I have a 1981 Kenwood monster receiver the Super Eleven that has fantastic specs for it's day but my Carver MXR 130 receiver brings out a lot more micro detail that I did not hear before. Same goes for my Sunfire AV receiver that I use mostly in stereo mode for music, friends that have much more expensive systems never said they could hear that it has a low THD+N rating when asked for an honest opinion. In the future please listen to equipment that measures poorly to see if the deficiencies are audible.

[@zergbong]

Amir, you are Internet's uncle that knows audio.

[@jeankazamer9166]

I cant keep up !!! crazy! masterclass ongoing 😂 ❤❤❤❤❤❤

[@KevinLaffey]

Another brilliant, informative video. Thanks Amir.

[@skip1835]

Excellent - continuing along with these measurement details & explanations in this series is so welcomed - personally, I didn't notice the time length at all, the content, from my perspective, was completely immersive. The Luxman was a perfect candidate for poor performance comparisons and I appreciated the subjective insight too, couldn't help but wonder if that performance is indicative of that model in general even though I wouldn't expect anything in a night and day sort of way with multiple samples given that's it's a low or no NFB Class AB (apparently) design - it performed so poorly that I couldn't help but wonder why, especially given that it sounded terrible too - I did wonder about the condition of the tube set and whether or not there could be any problems involving those or if there was some other "out of spec" issue - - but no matter, for the sake of the explanations of the measurements, which of course is the point of the video, the Luxman was the perfect candidate. I'm (again) very impressed and appreciate the effort of bringing this video to us - and yeah, I do feel like at least have a bit more understanding. Thank you Amir.

[@veniceog]

A decibel is used to express an absolute value or a change in value (+1 dB or -1 dB). If it’s used in the former case, it signifies the ratio of a value to a reference value. You can’t remove the reference tone measurement and say the distortion measured is inaudible at -125db. It doesnt work that way. The distortion can be -125db to the reference tone but still be audible. In absolute values, the threshold of hearing is around 0db.

[@tomb375]

Awesome Video again. I'm looking at either a Anthem STR or a Parasound JC1+ Your thoughts? Thank you again for all your Incredible Video's! Keep up the GREAT WORK!

[@queenssmith9438]

Thanks Amir for the explanation and great work. I am wondering whether you used static resistive loads for all your measurements? Wondering whether speaker loads (may have more complex impedance and backemf) will deteriorate your measurement results? Also is damping factor an important measurement index for amplifiers?

[@AudioScienceReview]

Thanks for the kind words. Most of the tests use resistive load. However, if you look at the Topping LA90, you will see at the end measurements with reactive loads. A better example is in this review with 3-D plot ("Powercube"): www.audiosciencereview.com/forum/index.php?threads/buckeye-3-channel-purifi-amplifier-review-2nd.43834/ This is a new load that I am experimenting and hence the reason I did not drill into it in the video. On damping factor, it is not an issue in anything but high impedance tube amps. That effect is then seen in the frequency response measurements.

[@marcb8874]

hello and thank you, looking for information on this luxman SQ-N 150 I am very disappointed with the results, to find it second to last on your list, although we cannot tell the difference between a 10w and a 150w? Especially in power with these r453 speakers given for amps recommended power of 20-200W, so it is normal that at 10w the amp crashes. otherwise I appreciate the test and would like to know with a video the measuring devices you use. marc from France

[@iggyzep7576]

Спасибо, Амир! Шикарные обзоры! Вот я теперь захотел себе Топпинг!🙂

[@iosifderecichei3743]

Hello, I saw your review and measurements of the Schiit Lokius EQ. I was thinking of buying one, but after your review, kind of changed my mind. Do you think a vintage model would be a better option? I definitely want one, so your advice on a specific model would be highly appreciated. Thank you very much!

[@AudioScienceReview]

Unfortunately without testing them, it is hard to say. I do have a new Schiit EQ that I will be testing. As a rule, you can do so much better with software EQ/DSP than any of these boxes. These are only good to make dynamic changes as you listen.

[@iosifderecichei3743]

@@AudioScienceReview Thanks for your answer, really appreciate it! Do you think something like this could be an option?TKL T531 Digital Equalizer Noise Reduction Spectrum Display 31 Bands for KTV I can't use EQ software because it's between a Classe prepro and the power amp. Some concert DVD's must be corrected. Thanks a lot!

[@Jim33142]

I learned so much from this video. Thank you Amir! Peace….Jim

[@jamesmay1322]

Could you please point to the citation for the -115db "threshold of hearing" claim.

[@AdamsBrew78]

Hi Amir; I was very disappointed to learn about your measurements of the Cambridge CXA81 just days after I picked one up. I love it so far, I’m just a bit confused about the exact scenarios that cause ground loop. Is it correct that it’ll only occur when USB and balanced inputs are connected? Will I be in the clear if I stick with USB and unbalanced analog ins, or use external dac connected to balanced or unbalanced and avoid using the usb port? I only use USB and optical so far, but planning on getting a couple unbalanced analog sources. (TT/CD) and potentially a topping dac.

[@34332]

That was excellent. Thank you again for all the hard work and bringing some sense into noobs like me ;)

[@VQR420]

Thank you for the great video, Amir! Out of curiosity, what would you say is the ideal amount of wattage for a given speaker sensitivity? I know that question is dependent on frequency and how loud you want to play, but figured it worth asking. Suppose we go for peaks up to 105, 110, 115, or 120 dB?

[@AudioScienceReview]

I would say you need hundreds of watts in "far field" listening with today's modern speakers which as a rule are not very sensitive. For near-field (e.g. desktop) you can get away with less than 100.

[@Adam.NavyVet]

Preaching the Truth. One measurement is worth more than thousands of opinions. Anyone has an opinion. Engineers and Scientists have measurements and prof of performance. Follow the data and you will find Amir behind the curtain!

[@markallen2536]

Measurements are also meaningless. Ever measure a 10k dollar Pass Labs power amp? If not you need to!!

[@Adam.NavyVet]

@@markallen2536 Well that’s One. One opinion 999 to go…

[@markallen2536]

@@Adam.NavyVet Actually, I've been working in Audio since 1972! I have pretty much heard, seen, and done it all...

[@lfazio9690]

Nice video. Am I to understand that in your subjective listening tests you enjoyed the sound of the Topping and Fosi more than the Luxman tube amp?

[@davidcarr2216]

Another great one Amir. I have to say though I was a bit disappointed 🙁. I was expectantly awaiting the point where the reviewer says well you put this on and it does this and sounds like this and makes Nora Jones sound like she's sitting in your lap, or some such 😀.

[@jeantrivelly]

Hi Amir, Thanks a lot for your video and explanation ! One question: could you add damping factor to your measurement ? I think it is important to know how the amp can control the speaker cone mainly for bass ones. Thanks Jean

[@dangerzone007]

It would be interesting to see a review of a tube amp. Many people love tube amps even though they have more distortion.

[@AudioScienceReview]

I showed one in the video! :) I have done some others: VTA ST-70 Review: www.audiosciencereview.com/forum/index.php?threads/vta-st-70-review-stereo-tube-amplifier.32353/ Dynaco ST 70 Review: www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-dynaco-st-70.7224/

[@dangerzone007]

@@AudioScienceReview thanks I commented before watching the full video.

[@pnaubry]

.another great video...thank you...all the best

[@robertopedrazzini1735]

One quick question: when you measure an amp power into 8 or 4 ohm load besides thd, you mean you test it on a resistive load, right?

[@martinbaron2921]

Can your amazing bar charts of all products tested be viewed on the ASR forum? I can't find them. There's a "neighbourhood" snapshot in your reviews, but these charts are such an impressive amount of work that I'd love to be able to explore them in their entirety.

[@AudioScienceReview]

Currently no. We hope the next version of our review database software can produce them.

[@amanieux]

great data collection work and putting it all in perspective in such video is paramount. there is a huge difference in performance between $800 a90 and $100 bt20 pro but will this difference be audible on cheap ($200 a pair) speakers when playing 256k mp3 ? thanks

[@amanieux]

@Douglas Blake agree, the law of diminishing return surely hit hard for a $800 amp vs a $100 where it is not 8x better but what about a $200 amp vs a $100 amp, where is the sweet spot for amps ?

[@amanieux]

@Douglas Blake ok then i am good to on the amp side with my a07 but where is the sweet spot for speakers now ?

[@alexYT87462]

Did you try another Luxman unit or a new set of tubes to make sure everything was working properly. Some of what you described hearing may reflect tubes nearing end of life ( a valid reason why many choose not to own this type of amp). Would hate for a viewer to watch this great video and not bother giving the Luxman a listen for themselves because the measurement results are so damning. Have seen other reviewers state upfront that they have done thorough checks/tests to make sure everything is in good working order when results are very bad. Keep up the good work. Am learning a lot from your channel.

[@tomaseriksson4533]

Seams like we back in the same situation as in the 8ts when Japanese amps started to use high feedback and bad sounding IC/OPA instead of discrete components. Everything for low THD but they sounded crap. Topping LA90 measure good and I think it is better than the high feedback 8ts amps. Testing a 10W tube amp at 5W is just crazy. You don't buy a tube amp with EL84 tubes if you don't have a speaker that can deliver close to 100 dB/W.

[@AbsoluteFidelity]

Amir, please do a deep dive into pre amps because that is the section where most of the audio fuckery is going on.

[@AudioScienceReview]

Sure, I can do that. Let me cover major categories first and then circle back there.

[@AbsoluteFidelity]

@@AudioScienceReview awesome, it would be great to know in depth for example what causes a larger soundstage / deeper soundstage besides phase/noise/distortion and all the innaccuracies that can be manipulated by the ome designing the amp.

[@sonicsaviouryouwillnotgetm6678]

What does actually happen when amps get driven into distortion for the power measurements. Do the components take a hit? I mean transistors and such. Obviously tubes can burn up.

[@IsmaelMartinezPR]

Do we know what was the achievement in the LA90 that made it perform so well at that price point?

[@AudioScienceReview]

I don't know specifically. The company is razor focused on low noise and distortion and has really refined its skills in this front. They first did it with headphone amps and then power amps.

[@lyndonheiss5812]

Wonderful presentation, Amir. Appreciate your efforts. I do have a question. You mention a coupon for the Fosi on Amazon, and I don't see it on your website, nor in this video. I am a member of both. Am I missing something? Again, thank you for all the reviews.

[@AudioScienceReview]

Thank you for kind words. Here is the link to the coupon: www.audiosciencereview.com/forum/index.php?threads/fosi-audio-bt20a-pro-amplifier-review.43751/post-1552740 I am not sure where it is good though.

[@mahasidha9]

Hello Amir, My wife and I own the Marantz PM-11S3 Reference integrated amplifier; your test results of the Marantz PM-11S1 Reference 0.0016% 96 230 were favorable; I also saw the following: McIntosh Laboratory MC501 0.0012% 98 1,000 and McIntosh Laboratory MC462 0.00050% 106 720 We do not want separates;; Is it safe to assume their newest integrated the MC-9500 with built in phono stage will yield the same measurements as the MC 462? I hope in the future you will review integrated amplifiers that have outstanding phono stages meanig great S/N for both their MM and MC sections. They do exist. Thank you in advance..

[@mahasidha9]

It should say the MA-9500 integrated thanks again.

[@amantiwari9822]

Hi sir I have a question What is the makes the sound of Pill different from Bill (or of Kill different from Gill) I know that it is not pitch neither loudness of sound so what is it

[@j-mo3129]

Amplifiers are generally rated at 4 and 8 ohm. Many have double the wattage at 4 ohm as 8 ohm. A speaker varies its impendence over the frequency range. How does this impact the quality of the sound from any particular amplifier, speaker combination? Seems like it would degrade the sound.

[@craigenputtock]

Amir, would you agree, or disagree, with the notion that even though a cheap amp has good specs, more expensive amplifiers with the same or worse specs can put out better, somehow richer and fuller sound?

[@AudioScienceReview]

In general disagree. More distortion and noise is never pleasant. Exception is high impedance amplifiers like tubes which can modify the frequency response of the speaker. And in doing so, could boost or reduce certain frequency ranges. If that is liked, you should use EQ to much more precisely and intently make those modifications.

[@craigenputtock]

Thanks!

[@ubacow7109]

I enjoy using my topping gear but one thing that does seem to grow more and more as I accumulate their gear is that they have pretty poor quality control and software like had a few w/ broken power bricks now, firmware errors now and then. Had one unit break completely on me, sent it back got a new one (paid for shipping tho). They make good gear but they really need to do more stress testing on their gear and bug fix before they put them on market.

[@mauanderuk]

That Topping what a piece of engineering! well done Fosi too I feel kind of sad about the luxman they were such a good company looks like the Chinese are taking over.

[@you2ber252]

Hi Amir. You're not testing how the amplifier reacts to non-purely resistive loads, or do you? Ok sorry... I've just watched the part in which you mention testing with capacitive and inductive loads.

[@dragonstone6594]

How much is the dumping factor of this amp?

[@jamapaza]

What I don‘t understand is, why bad measured amps sound often better than good measured amps. I‘ve got a Buchardt I150 and a Nord NC500. The NC500 is measured very good or excellent and the I150 with NCore NC250 modules is measuring not as good as the NC500 but it sound much better. Same pre amp and the NC500 sounds harsh above lets say 1kh and the Buchardt I150 with NC250 modules sounds smooth. I‘ve tested a lot of class D amps because I am a fan of class D but the I150 sounds just the best. How can it be if it measures not as good as other class D amps? And I am not the only one that thinks the I150 sound great and not like a typical class D amp.

[@zefrog7482]

Can come down to specific voicing, or the way in which certain frequencies are presented. You can have 2 ruler flat response amplifier's sound very different in the way they can project the frequencies sonically such as how cohesive or ability to show details. Measurements aren't the be all and end all, but it's certainly a good place to start in many ways, the Luxman example is really proof that a lot of that products perceived quality and sound is likely psychological, possibly because it looks stunning and is heavy, would naturally lead to the idea of perceived quality. Regarding your amplifier, I wouldn't worry if it sounds good to you, and I'm sure the measurements aren't near as bad as an amplifier costing far more. The fact it sounds good to you means it's obviously presenting a sound that is pleasing. I've heard the Topping featured in this video, I wasn't a fan despite the impressive measurements, despite being flat and overall impressive measurements wise it just didn't present a sound I liked, it's ability to present certain sonics really didn't impress as much as say a Hypex NC500 based amplifier. My next amplifier is going to be Hypex Linai500 Monoblocks I think, has the sound signature I like. Just remember, measurements tell you how well engineered a product is, not the sound signature attributes, unless of course it measures ridiculously bad like the Luxman in which case there is no arguing that any perceived degree of excellence from it is based upon other factors influencing the perception.

[@AudioScienceReview]

It is easy to perceive differences that are not really there. Match levels and then perform blind AB tests and see if you can confirm the results. Once you have that, then we can dig into reasons why. Right now, there are countless people who have bought NC500 and are very happy with them.

[@jamapaza]

@@AudioScienceReview I don‘t nee d a blindtest. I can here it right away. I can‘t hear cables, powercords or even to hear the differences between DACs but I can hear a difference between my I150 and my Nord NC500. Right now I‘ve got also a Hifi Rose RA 180 at home and I sounds like a NC500. The highs are very, very clear or some would say harsh and the Buchardt I150 Ncore 250 sounds more relax and smooth and yes, the I150 was always the preamp. The difference was the DAC. For the RA 180 and NC 500 I‘ve used the DAC of the Node 2 but I don‘t think the DAC would make such a big difference.

[@YuengsNwings]

@@jamapaza What are you using as a preamp for the Nord?

[@jamapaza]

@@YuengsNwings I am using the Buchardt I150 as a preamp.

[@erichill5328]

Hey guys I got a new build question…. Option 1: Two Hypex Ncore NC400 mono blocks and using my pioneer head unit for my DAC and pre-amp..? Option 2: Two Crown amps model 1502 bridged to mono blocks and also purchase the Topping D90SE flagship DAC / Pre-amp. I would sell off my pioneer head unit Both options work out to be about the same price. The Topping D90se is a fantastic DAC for $899. Let me know and thanks 👍🏻.

[@MichaelBeeny]

I'm so pleased I'm not the only one that thinks valve amplifiers don't sound that good. Very nice in 1950 in fact most circuits ARE from 1950. All that's been added is lots of $$, chrome and other shiny stuff, sounds the same. I notice you don't show square waves. May I ask why?? I appreciate other tests do tell all.

[@AudioScienceReview]

Squarewaves were poor man's audio analyzer. You could read the tea leaves from it as far as frequency roll off and such. Today we have proper audio analyzers so we don't need that. In addition, square waves are illegal audio signals. To have them you need to heave infinite bandwidth. Certainly no digital audio sampled at 44.1 kHz is going to produce anything remotely resembling squarewave unless you use a very low frequency. For these reasons, I don't use them unless there is a special need.

[@borlach321]

Amir, do you think Tube amps will eventually become extinct? It seems there are only 2 countries where tubes are made (China & Russia) and neither are friendly or stable places. What do you think?

[@AudioScienceReview]

I don't keep track of availability of tubes. I would think it would get harder and hardet to get supplies.

[@Mrsteve4761]

Tube demand is driven largely by their presence in musical instrument amplification (e.g. guitar amps, etc.)

[@paulpaulzadeh6172]

THD change with reactive load , capacitive load has higher THD compare to resistive.

[@ShortwaveLog]

Interesting video. Not trying to despute anything here. I’m sure Amur knows the following. There are a few videos here on KZbin which describe via experiments how electricity flows through cables and the paths it takes through a circuit that can never be picked up via scopes due to their limitations. So measurements should not be used as any factor of sound quality - there are too many variables.

[@krunofilipovic7213]

This is very welcome.

[@bradleydbusse]

I just found you. Where have I been?!?!?

[@Cmdaddy88]

Why do eg Revel speakers measure around 4Ohm but advertised as nominal 8Ohm?

[@paulb4661]

Probably to manipulate sensitivity figure by quoting the value obtained at 2.83Vrms

[@AudioScienceReview]

They try to keep up with their competitors which fudge those numbers just the same.

[@phpn99]

You haven't measured Nelson Pass' FirstWatt series of minimalist Class A amps. I'm curious to see how they fare because by their own specs, they have relatively high THD. What's of interest is how audiophiles revere these kinds of designs which clearly aren't "straight wire with gain", as they tend to claim, along with the claim the minimalist approach ensures some level of "transparency" (whatever this means that would be unrelated to distortion and noise). The same folks who'd rave about triode and pentode designs, for the same reasons, as if they're living in 1949. Has anyone ever tried to find the rationale as to why these types of designs are claimed to 'sound great' (and hence, have a sonic character) while at the same time are claimed to be 'musical' and 'transparent' at the same time ? Even mastering engineers like Bob Ludwig are on this sort of bandwagon, for instance with vinyl, while the engineers who engrave the original matrices at, say, Abbey Road Studos, know and say that the equipment they use to engrave has relatively low fidelity performance. What are we talking about here ? Surely not all of these people can be delusional. If you eliminate the lunatic fringe, is there *something* to these minimalistic designs that is appreciated and may indeed sound "good" as opposed to "transparent" ? My own hunch (I have owned some of these types of devices) is that what people tend to love is the band-limited nature of these designs, which along their even order distortion, tends to conceal potential aliasing artifacts or other defects in recordings ? If this is the case, couldn't we simply implement such characteristics with a DSP and fool those ears in a double-blind test ?

[@AudioScienceReview]

No one has shown any benefit to these designs. All expression of sound from these amps is anecdotal and not in controlled situation. They can easily disprove this by performing a reliable blind test but they won't go there sadly. I have tested the Netson Pass' ACA amplifier kit and I found it awful (www.audiosciencereview.com/forum/index.php?threads/pass-aca-class-a-power-amplifier-review.9741/). Yet people rave about it. Power of marketing and perception over reality!

[@gioponti6359]

@@AudioScienceReviewClass A amps have no benefit? None of them? Vs what? Now, I do not have tons of experience with comparisons across the board of different amp designs, but I would imagine with certain music, appropriately selected speakers etc, they excel over other concepts ..

[@gregmatula9749]

This is the same question that I had. Many years ago I compared three amplifiers that I had a Sony ES receiver a bi-amp commercial amplifier and a Dyna kit Mark 3 Gold Lion tubes, mono signal through a single speaker and the same vocal recording. I heard a small upper treble level difference with the two transistor amps. The tube amp sounded more real to me I didn't know how else to describe it. Maybe it was a masking of microphone/recording distortions I don't know.

[@qddk9545]

@@AudioScienceReview I haven´t listened to that one, but that is a very low cost Pass design. I own a First Watt F5, and that sounds very good. Did you listen with your ears or just with your test equipment??. Everybody knows (or should know) that you still cannot measure sound quality. If amps really only had distortion figures of 0,00x %, they would all sound the same, and for sure they don´t. The human ear would not be able to detect that small differences. We/you are not measuring things the right way, amps still have distortion of in excess of 1%. That is the way it is, and has always been. With a lot of things we have come a long way the last 50 years, with sound quality tests we have come nowhere at all. By the way I like your videos, but Sinad and low distortion figures is just helpful side notes, it does not tell you anything about how a device sounds. There is a long way to go, and it seems that nobody is trying to think out of the box. A lot of good measuring amps sounds like crap. .

[@mikemullenix6956]

just use a higher db speaker, like 100db or better, problem solved with this topping la90 with 70 watt

[@lucaslee6637]

👍🙏

[@frederf69]

i like that you don't mind kicking the expensive/overpriced gear in the nuts, but why is Topping always the star of the show?; there are other great audio makers.

[@AudioScienceReview]

Partly. But there are other superb amplifiers such as Benchmark AHB2, Purif and various Hypex based amps. Ironically there are also some vintage amplifiers that run circles around what ships today. See this NAD 2200: www.audiosciencereview.com/forum/index.php?threads/nad-2200-vintage-amplifier-review.13960/

[@kyron42]

Some reviewers claim one amplifier sounds warmer than another even though they have the same frequency response. Are these reviewers taking too many illicit substances?

[@AudioScienceReview]

It is easy to imagine those characteristics. Brain is wonderful in the way it can fill in things. But yes, I have seen no evidence of any kind of tonality in amplifiers other than tube amps with high impedance interacting with speakers. Ask those reviewers to perform a blind test to prove what they say is there really is.

[@oysteinsoreide4323]

If you actually could do it properly, then you could make a video about it. The way you treated the Hegel H95 when it came to measurements really made me never trust you ever again. You measured it in a clipping condition. And the faulty test result is still out long after you actually know that you did a mistake. If you really had some spine, you would actually say that you have made a mistake, and take it down. Or do the measurements again with better method.