VTA ST-70 Tube Stereo Amplifier Review

[@NeverTalkToCops1]

My rig: 4 Klystron tubes, 4 Eimac tubes, 2 traveling wave tubes, some stuff from an MRI machine. All powered by a utility pole transformer run in reverse. Visually stunning! Hidden in all this are 2 class d chip amplifiers producing the actual sound.

[@peterlarkin762]

Lol.

[@mb-electricalservices]

So a Class D Amp body-kit ..... Nice.. 👍

[@MickeyMishra]

I always needed a night light that doubles as an ionizer.

[@rlwings]

These daily videos have become my "good book" before bed! - Thank you so much... I'm such a geek. :)

[@twentythreeeightyeight5260]

Thank you mr. Amir for releasing so many videos recently. It’s a real treat. It may sound strange, but I personally get two very important things from those: objective knowledge, of course, but also a great example of how an intelligent person should talk. The are not many people who talks like this left in former ussr, where I live. Thank you!

[@AudioScienceReview]

That's very kind observation for you!

[@frankgeeraerts6243]

Nothing in your life is objective..........all perception is subjective....that's the precieved reality ...

[@skip1835]

I appreciated the subjective "listening" vs the objective measurements in this vid - it's interesting to have the parallels between the two pointed out and I'm personally fine with your subjective listening and resulting descriptions whether they offend or not. Thanks Amir.

[@veniceog]

Fair, straight shooting, and matter of factly. It addressed in a respectful way those that might like the amp and but was clear in his own opinion. It felt that it led the viewer to an informed point to make up their own mind. Great review.

[@scottspencer4018]

I think you're nucking futs! A pair of these absolutely sings in my system...clear as a bell, musical, lively, holographic from 60hz up (bass isn't great, but everything else is). They simply sound beyond wonderful. I used a pair of stock Dyna 70s for over 20 years, and find the VTA mods to improve (subjectively ) on the Dyna 70s in just about every category you can mention. The Dyna 70 is one of the best selling amps of all time....for good reason. Either something's amiss with the rig you evaluated, or there's something wrong with the evaluation process itself, because my experience with VTA has been stellar. Having owned many receivers, two Hafler amps, New York Audio Labs, and Discrete Technology amps (modded B&K), IME the VTA 70 represents among the best values on the market.

[@frankgeeraerts6243]

Inded Scott........strange comments from someone who claims that digitalprocessing a natural sound make it better !.........he must b elieve also that processed food is more healthier than natural real unprocessed food.... I lived and worked with tubes for over six decades .......in every technology there are bad and good designs......to my experience tubes ( nos ) are better preserving the soul of music than solid state ......solid state means half or semi conducting ...... Yes I have and love some of my solid state amplifiers and some of them come close to a good tube amplifier but my heart beats with tubes .

[@julesl6910]

Completely agree, whatever data this guy thinks he's generated doesn't equate to the listening experience. This is really the defining line between audiophiles. Do you like what you're hearing or do you like what you're reading? I listen to an amp and decide. Fine tube amps sound far more enjoyable than any solid state amp. I don't care about imaging and where the tambourine player is located. I want it to sound pleasant.

[@frankgeeraerts6243]

@@julesl6910 I totaly agree with you ...........i watch his videos to better catch the mindset of these ( deaf )" experts "..............just like telling other people that cables don't make a difference , maybe he's right they don't make a difference in HIS own system !?

[@ridirefain6606]

Very informative. I appreciate you looking into tube amps and checking their performance. There is not a lot of info out there and glad to see someone shedding some light on their drawbacks. Being a tube-head I love the technology. Nonetheless, I like it when someone points out that they are not the end all be all, and there are compromises performance wise that one should consider.

[@Mikexception]

I see there are two "scools" in containing obvious differences in results of ear results vice measurements by electronic systems. One says that ear is not perfect but measurements are perfect because shown results are so easy to describe It looks liks paradox because measurements are developed to show the ear impression . But they don't. And other that measurements have deficiences comparing to ear sensations . And I stand for that second because electronic measuring gear works in too much different way

[@AudioScienceReview]

You are very enlightened but unfortunately way too few people like you exist in the other camp!

[@orangejjay]

Hi, Amir. As many others have said: Thanks for doing what you do. I'm sure you've helped THOUSANDS to make better decisions and it's something long overdue in the music lovers community. When you can, would you make a video showing us your equipment and testing in action? Would love to see how this is all done and I'm sure others would as well.

[@larsv6144]

Better decisions are made by listening and choosing personal sound preferences.... that is what music is about. Measuring a few parameters without being able to correlate them to human hearing and how the human brain translates the incoming signals (perceived sound) is futile and thinking your can come to "conclusions" without listening, is just arrogant and ignorant. Where is the "science"in that approach?

[@chefsteve8381]

Love your review's always a highlight of my day. Could you do a video of you showing us how you use your anerlizer thanks.

[@AudioScienceReview]

Sure, can do.

[@CyberBeep_kenshi]

Never owned one, but these things look like pure art to me, gorgeous

[@ramencurry6672]

Tube amps actually do sound amazing even if a lot of accuracy type audiophiles don’t like them

[@juanmillaruelo7647]

My audio jurney began with Mk3 Dyna amps (60w per block). When I switched to solid state in 1971, the reactions were "this sounds so transparent!, crystal clear" Tubes are nostalgia. And I enjoyed music with tubes AND with modern amps. But to use tubes today is like using a 1940's car as a daily driver. It's fun, enjoyable, lots of looks, but a reasonably priced modern box will wipe the floor with it.

[@ramencurry6672]

That’s true but not always. I have a modern made 300 B tube amp and it sounds smooth and gorgeous especially with some of the vocals. I love state amps too but there’s definitely times when a good tube amp is preferable.

[@ramencurry6672]

I also have a 1970s Marantz solid state amp. They were considered better than tube amps. The Marantz is good amp but it sounds harsh, somewhat grating and clinical compared to my modern made post 2000s tube amps.

[@julesl6910]

What are you talking about? Just because you like how transistors sound you're making a conclusive statement about amplifiers and that's just ridiculous. Tube amps operate in a fundamentally different way than solid state amps and produce a harmonically different output. I find people like you are threatened by the fact that the path you've decided upon isn't conclusively "the way" and solid state amps are lacking many of the qualities that obviously many people prefer. I prefer tube amps both to work on and repair and specifically the way they sound. Millions of audiophiles do too.

[@thomasstanfel7589]

Great review..its nice actually seeing how tube amps compare to solid state.thank you.

[@michael1326]

Really appreciate all the time and effort you put into these reviews Amir!

[@Seiskid]

I love tubes. Magical how they work. But no, they are not hifi and are in fact nothing like it. The high impedance output is very dependent on the speakers you connect to them, since the speaker has more freedom to do its own thing to a certain extent. Especially in the lower frequencies where the limited feedback is further reduced by transformer frequency rolloff and phase shifts. With the right speakers I'm sure these really can sound nice. And I suspect with the right music too. At the height of the valve era music didn't have deep tight pumping bass. Back in the day the gentle warmth tubes and flabby speakers add to the bottom end never needed to be especially tight. Thanks for doing this review.

[@Lauren080508]

I guess is about taste and previous experiences, some people like some distortion and harmonics in their music, also many like the scratching sound of vinyl in their music, nothing wrong having a taste preference, but I do prefer perfect fidelity.

[@Mikexception]

@@Lauren080508 My reel recorder has noise level at 55 dB and in normal listening I can't hear that noise hidden deeply under usefull sound . To be clear I listen to symphony and prog rock where average level is often very low. So it is not clear to me why is that talk about THD and second raw distortion of around 1% at full power. Surely with required for my normal listening power of 1 watt it may range 0,1% which means 60dB below sound level. At that level I cannot spot anything . . At other side I would not dare to qualify amlplifier alone as hi fi or no hi fi . To achieve hi fi counts everything including positioning of spaekers and surely their construction, also phase distortioons everywhere which cannot be avoided in more than one speaker cabinet . With old tube ampliifier I enjoy so total mimic of reality that it is even frighetning when perceived without preparation Speaker in studio is talking like sitting 2 meters from me but he is not there which is hard to feel comfortable There are no signs of "warm" sound or "nice distortions" To make more confuse I use parralell solid amplifier and it is very hard to recognize by sound from tube amplifier

[@armandorancano6415]

The dictionary defines high fidelity as the reproduction of sound with little distortion, giving a result very similar to the original. But, what if what is objectively described as distortion is perceived by however many people as being close to the original? I greatly value objective measurements, but they do not override my judgment when I hear gear that brings me closest to the memories of 50 years of listening to amplified and acoustic music in live venues and recording studios.

[@Mikexception]

@@armandorancano6415 I agree. Only I would discuss the dictionary - it is not accurate to say that High Fidelity in general means "reproduction" "with distortion" - setting low level to them does not cover that fault . High Fidelity is top level of reality perceived by hearing from electronic system (in compare to original) Unfortunately that original reality simply vanishes after session . So I would prefer the "human sensation of presence of sounds" or "availability of perfectly understanding all sounds existing in recorded material " No mentioning about scientificly developed and measured distortions which is only one of many necessary tools in production of gear.

[@Lauren080508]

@@armandorancano6415 distortion will not get you closer to the original sound, the less the closer you get, it is just common sense; now about your own perceptions...our brains are something special, but subjective to so many biases, preconceptions are strong in our minds, I work in medical science, i can tell you, i have seen crazy stuff regarding biases. Blind testing is the only way, I do not trust my own perceptions or opinions unless corroborated by a blind test.

[@markphilpot8734]

I’ve had one tube amp in my whole life and it was a Roger Majeski RM9. It was a very dynamic amp with 2 6DJ8s and 4 EL34 tubes per side. 100W per side of output. It was completely rewired with silver plated high strand copper wire with Teflon insulation. The wire on some circuits was quite small before the change. You can’t change the wire from the transformers. It was left alone. A soft start circuit was added to extend the life of the tubes. I also changed out the power cable which was 14 gauge with a 10 gauge SJO cord and a hospital grade plug. It will not be current starved with that. There was little changed in it’s presentation except for clarity, openness and the ease that it had driving my speakers. It was worth the time and effort I spent on it. It was a lovely amp while I owned it. Everyone has an opinion on tube gear, but my experience was a very pleasant one. I wouldn’t hesitate to buy another RM9. Best tube amp made in my experience. Well made and very gorgeous sound. Stay safe my mates!😊👍🏻😁 Enjoyed this review very much Amir.

[@peniku8]

How does a 14AWG power cable current-starve a 200W amp? How long is it? 2 miles?

[@markphilpot8734]

@@peniku8, I can’t make you see an advantage of a larger gauge power wire if you don’t want to. To each their own. It may be adequate, but I saw it as not so. The way I see it, if you have an easier flow of electricity to your equipment, it certainly can’t hurt it. You can believe what you want and that’s your right. I chose to because I believe it matters. You do as you please and we’ll all be happier. The power cord supplied got warmer than I liked. Safety first is never a bad policy.

[@peniku8]

@@markphilpot8734 Leaving the senseless religion discussion aside, your power cord got warm on a 200W amp? I'd be concerned about that too. Sounds like something isn't quite right here and that's not the fault of a 14AWG cord. I'd suggest having an electrician check on your setup, like you said, safety first. Don't burn your house down with defective equipment!

[@markphilpot8734]

@@peniku8, the electrical wiring in that house was faulted. I found out out after I left. The house was demolished. No loss. The cord I replaced the smaller gauge cord with never got warm so I figure from that, it was a smart move. You were right about the electrical problem. It was over 30 years ago this happened. Good for you! I have a new amp now, no worries.

[@Mikexception]

@@markphilpot8734 If that cord had earth wire and was connected to "zero" then could be leakage to "zero" and then it prevented user from voltage on chassis. Good for you but be carefull about that amplifier - i would measure AC voltage between chassis and any "ground" around When not grounded it may not heat up wires just because not conneceted

[@markfischer3626]

In 1968 I said goodbye to tubes forever and never looked back.

[@matthewtaylor7355]

In 1986 I purchased my first valve amp and never looked back

[@markfischer3626]

@@matthewtaylor7355 to each his own. I liked the greater clarity and I could afford a much more powerful amplifier. Funny, my tube amplifier was Harman Kardon A500 that used 7355 tubes. I still have it, never use it. Needs to be recapped. Should have built the Dynaco Stereo 70 and PAS3X instead.

[@richardmelville5973]

I still have the Stereo 70 that I built in 1962. So -- it has been around for at least 60 years.

[@Mikexception]

My purchased 3 years ago Bell is made in 1963 and it lives it's youth again. Replaced bad capacitors and left in place all good one and adjusted one resistor (not accurate), replaced one damaged pot in tone circiut and replaced volume pot for doubled reistance - just found it works a bit better Adjusted bias , added volume indicators, modified external case to more modern look, new knobs And modified "tape head" input to have high senitivity but with switched off it''s head correction. The phono inputs are working perfect and amplifier in modest listening is competitive to high class solid

[@geoff37s38]

Very interesting Amir. I am very ancient and remember my schooldays building Mullard design valve/tube amps. They were very good for the day but no match for todays SS amps. I can understand the attraction of vintage stuff like this for some people but I see no practical use in a modern hi-fi system.

[@user-xg6zz8qs3q]

I'm approaching this from a non-"Hi-fi" perspective. I am not seeking the most neutral sound. Low power tube amps sound marvelous with high efficiency (95 db SPL) single-driver full range speakers.

[@jimfarrell4635]

@@user-xg6zz8qs3q Yep. I agree. I run a Korean Allnic 300b SET amp at 12.5 watts with Zingali 93dB speakers. For acoustic music and jazz it sounds sublime but doesn't do well with rock and orchestral music. For that I have a Kinki Studio EX-M1 Class AB amp with 215 watts per. Channel. The combination works for me. The Allnic has pre outs and I would love to try it with a Purifi Eigentakt power amp.

[@user-xg6zz8qs3q]

@@jimfarrell4635 I'm saving some cash to buy a pair of Audax AM21 speakers and a Unison Research simply Italy amp (EL34). I sampled this combo in a shop in Paris and I was floored. I know it will measure worse than a pair of cheap studio monitors. I don't care.

[@MichaelBeeny]

@@user-xg6zz8qs3q it really doesn't matter. If you like it, that's fine.if we all had the same hearing and requirements, one amplifier would suit everyone.

[@user-xg6zz8qs3q]

@@MichaelBeeny You're describing the dream. Find the best speakers. Find the best amplifiers. Use them as a benchmark for sound production etc... Mass produce them. Lower the prices. And then Amir would be out of a job LOL

[@GodmanchesterGoblin]

You mentioned the interdependency in the bias adjustment... I took a look at the normal ST-70 schematic (assuming that this is probably quite similar in that area). The output tubes in each channel (EL34) are arranged as a long-tailed pair with a single resistor (originally 15.6 ohms) connecting the two cathodes to ground. The marking for the bias voltage of 1.56 volts would therefore imply a steady state bias current of 50mA for each tube assuming they are well matched. However, the circuit board appears to have one adjustment pot for each tube. The shared cathode resistor means that when you increase the bias for one tube, the current in its counterpart in the same channel will automatically reduce to compensate. That is expected behaviour for a long-tailed pair. You would need to modify the bias on both tubes up or down equally (assuming matched tubes and an equally matched initial bias setting). Without additional measurements, so that the current in each tube can be monitored, there is no way of knowing whether the tubes on one channel are sharing the current equally or whether they are perhaps taking 40% and 60%, or even 30% and 70%. The bias voltage reading across that resistor would be the same in all three cases, and if the current sharing was not equal, this would be adding significant harmonic distortion (possibly second harmonic). To me, this is therefore a flawed design. I would want to know with greater certainty that the bias was balanced between the two tubes on the same channel. There could be some small degree of interdependency in the bias between the left and right channels, but that would be a function of the HT voltage stability with varying loads and would be much less of a concern generally..

[@EskWIRED]

What effect would this condition have on the measured results?

[@GodmanchesterGoblin]

@@EskWIRED Imbalance between a pair of output tubes in any push-pull amplifier would adversely affect the harmonic distortion with one tube driving more than half the signal and the other tube driving less than half (for a sine wave, for example). The other significant issue is that this creates a flux offset in the output transformer. When the currents in each of the two tubes are equal there is no flux in the core under quiescent conditions since the flux generated by each winding cancels that from the other winding. Push-pull output transformers are not air-gapped and so a current imbalance could also cause one half of the signal to potentially cause the transformer core to saturate prematurely when driving large signals. That would also add significant distortion.

[@AudioScienceReview]

Thanks for the comment. They make sense. FYI I went back and forth and got both tubes in each channel with the same bias voltage and hence current (subject to accuracy of the resistors they used). So while it was some work, the test was with equal bias for each tube.

[@GodmanchesterGoblin]

@@AudioScienceReview Cool. I also just found a schematic that claims to be for the VTA ST70. That shows separate cathode resistors, so that would certainly help. But while it makes bias setting easier, it requires the two tubes in a channel to be more evenly matched in terms of their slope characteristics than would be the case with the long-tailed pair arrangement. Just one of those trade-offs that designers make - gain a bit here, lose a bit there... Keep up the good work.

[@cletusberkeley9441]

Just love my VTA ST-120

[@nigelpearson6664]

The speaker that suited the ST70 was the Quad ESL57. Most modern speakers prefer transistor amplifiers that have very low output impedance. I did notice the 3rd harmonic higher than second ( theory of PP amps says it would ), I like it the other way. The original Dynaco sounds a bit soft to me. The Marantz 9 is much more like a transistor amp with valve virtues. Original Dynaco's overload the rectifier a bit, don't throw out your other valves without checking ( GZ32 ? ). The 7199 should last a long time. Good news as it is hard to get. The ST70 is a great example of minimal design. A very high gain pentode DC coupled to a high current phase splitter ( 7199 derived from a TV valve ). UL outputs. Hafler, Walker and Blumlein designed variations of UL. Hafler is Dynaco. There is global feedback to lower the output impedance. It also lowers THD. I say it that way as local feedback lowers THD if required. In the day global was prefered. 1930s amps might prefer local feedback ( Schade RCA 807, 1938 ). UL can ring. People design so called Zobel circuits to cure that. The 1972 GEC book mentioned it ( KT88 ). Triode should be less troubled.

[@WoodSmartUSA]

I find going full Solid State, especially with most of the “New” power amps tends to be too bright for my liking. Maybe it’s just my age, but tubes somewhere in the chain of things allows me to listen to music closer to how I learned to love listening to music in my younger days. Although I never had tubes back then, the sound I became accustomed to probably was more that the speakers back then played with a much softer sound than many of the ear drills of today… Heck back then the speakers even looked soft, I still remember being able to see the fiber weave of the woofers… LOL. 91db + speakers, Digital Signal, Bright SS Amp & Pre… Ugh. Sure a set up like that is accurate but fatiguing no matter how much room treatment. Keep in mind this is just me and your milage may vary. I had the Carver 275 for just shy of 2 years and I have to admit it sounded really good. Had it hooked up to a Parasound P5 Preamp at 1st running Triangle Comete’ EZ Bookshelves, then switching over to Maggi .7’s. Sounded great with the high efficient Triangles but on the Maggi’s would hear it’s low power affect the Maggi’s ability to deal with mid to high frequencies once you tried to turn it up, low volume though sounded pretty good but I could always hear there was a headroom issue…. the speakers always sounded they wanted more. I Purchased the carver thinking I’d be getting 75w x 2 knowing I’d be moving into a set of Maggi’s. I Really felt mislead by the marketing and even though it sounded pretty good at lower levels, felt it’s power limitations and the thought of having to lay out big bucks at some point to replace (4) KT-120 tubes was just too much so away it went… Replaced it with a SS Oddessy Khartago Extreme Amp & Tubes4hifi / VTA, SP-13 Tube Preamp allowing me to continue having the tube sound I love and have been experiencing Audio Nirvana ever since. It’s not always about accuracy but rather if you enjoy what’s coming out of your rig or not. It’s not that controlled distortion is wrong, it’s just a different flavor. Tubes and the distortion they introduce can be quite pleasing if you’re seeking a more relaxing listening experience.

[@rainier939]

The beauty of tube amps is that you can build something that makes decent sound with simple circuits and upgrade your design over time. When you buy a benchmark of purifi amp it's done. If you are really really good at designing you might be able to build a pre amp stage for you purifi module but most wouldn't even dare to do so.

[@McgarickWAstate]

Had one of these, fantastic sounding unit with rolling in good tubes.

[@johngutmanis3580]

Hi Amir, many thanks for what you are doing on your channel! I do have a question about quality control, if a company tests one unit out of hundred produced, can the results be reliable to conclude that all units are the same? What I’m getting at is can you say with certainty that every (CC275) Carver Crimson 275 amp is as bad as the one you tested! I purchased a CC275 and have been generally happy with its performance. My other amp is a McIntosh mc352 which in the day was $7000. When I listen to each amp using my Klipsch La Scala’s I prefer the McIntosh. More detailed in the mids and highs. I can here more voices and pick out more instruments and details. When I switch to Magnepan LRS speakers the two amps are equal to my ears, maybe the mids on the CC275 are a bit more lush. My CC275 is very quiet, no hum what so ever, as compared to an St 70 I owned years ago that I sold because the hum was so annoying. My point here is perhaps you should ad a note on your reviews that you are testing single units and they could be an a outlier when the review is particularly bad as it was with the CC275. I have to say again thanks for what you do! We need more science in the audio world to combat the snake oil aspect of this hobby! I remember sitting through an hour long demo from Audioquest on power cords, along with 40 other Audiophiles. Watching some of them nodding their heads saying they heard a difference, and myself thinking no all the same. Again thanks!

[@craigmyers6449]

I think what may be missing here is that tube are low power and not meant to drive lower efficiency speakers. I own a valve amp (Elekit 8200R - 8W) that I built myself from a kit - as well as several solid state amps. When I first fired up my valve amp with my 87db speakers - I was disappointed - insufficient volume and distortion. So after some complaining and research I invested in some high efficiency 100db full range speaker (Lii Audio - silver 10 and their Lii Audio matched cabinets ) - so 1 watt of power should give me 100Decibels at 1 metre - so now I get no distortion - decent volume and what I think is a wonderful sound. Rarely go over 1/3 on the volume knob. Bottom line you can't just buy a valve amp and attach normal low efficiency modern speakers to it and expect good results. The whole flea watt power is the concept - with matched high efficiency speakers . The characteristics of the system are stunning sound stage and centre image - the most beautiful midrange - and surprisingly respectful bass with the cabinets. I listening to all music from classical to Jazz to punk rock and metal - all sound good in my opinion.

[@TheAppleExperience]

How dos it sounds? How big is the soundstage, how accurate is imaging, is the presentation realistic.

[@watchnut]

I have the higher power version of this amp the ST-120, it is absolutely amazing with Klipsch Heritage speakers. Super detailed, transparent, and plenty of grunt.

[@veniceog]

You made a point that is highly relevant. A tube amp will sound flabby on a speaker whose impedance dips dramatically at lower frequencies. A flatter load within the range of the amp wont produce the same result.

[@jeankazamer9166]

Taking over the interwebs are we ?? Let's learn together again :)

[@epi2045]

In my main system I switch between a solid state Mark Levinson power amp and a custom tube amp. I listen to my tube amp nearly 80% of the time. I’m sure it measures terribly compared to my solid state but man it just sounds better at only 4-5 WPC.

[@Lauren080508]

Very interesting experience, have you do a blind test? not that I don't believe you, but our brains are so easily fooled by biases, if your preference stands a blind test, I'll tell you, I will finally consider to buy a tube amp.

[@Mikexception]

I also keep system of two amplifiers - solid and tube and have possibility to switch between them in seconds. And I see some adventages in both but not clear winner because both sound almost identical I switch to tube amplifier for turntable and cassettte and reels because then I sit in place and listen and choose solid when I listen to TV and PC. Just to spare tubes. Stopped since about 3 years to listen to CDs because they show too much not defined differences in mastring. Anyway I have one too and CDs. Also I use digital Korg recorder for recording my preformances but again last time I switched to old reels as more practical while it's quality is to degree challenging Korg

[@epi2045]

@@Lauren080508 Absolutely blind tested, including level matching within 1-2db. Is the difference significant? No but it’s enough to keep the tube amp around. I have tried using a tube preamp with my solid state and it’s still not the same compared to a full tube amp.

[@armandorancano6415]

I have both SS and tube gear and use them interchangeably because any differences are negligible. Perhaps ignorance, in the sense that I don't necessarily hear measured distortions, is truly bliss.

[@epi2045]

@@Mikexception One day I’m going to get a reel to reel 😃

[@martinbaron2921]

Another excellent video! Mechanically-induced noise in tube amps is an issue, so vibration isolation becomes important. This makes me question: why do audiophiles protect solid-state equipment from vibration? Have you ever tested expensive vibration-isolation racks or stands to see if they offer any performance benefit to solid-state gear?

[@drde4010]

Infinity speakers was all that was stated. How would anyone expect tight bass with inefficient speakers? What speaker does infinity produce efficient enough for this amp to drive properly? How could you do a review this extensive and not express that enough? You briefly mention it. This amp is speaker dependent. I’ve used mine for several years and it’s not like this video describes. I notice you only respond to people who like what you say.

[@tommyd777]

Amir "On this thing" Majidimehr! 😍

[@AudriusN]

My cat loved the tube amp, he found it very comfy to sit with his butt pointed at the warm glowing tubes.

[@harisjaved1379]

Wow Amir you are on a roll! But I will be honest. I do enjoy lame product reviews more like speaker wires, power cables etc…could you please test the nano fluid and NCF Clear Line By Furutech. They absolutely look like snake oil garbage but I would love if you could test those! Thanks Amir.

[@AudioScienceReview]

Sure, I will see if I can get the Clear Line to test. I have their AC outlet which I plan to test at some point.

[@johnsmith1474]

Why, if you know a product is lousy, would you want it tested?

[@AudioScienceReview]

Found the NCF Clear Line on Amazon so just purchased it. :)

[@AudioScienceReview]

@@johnsmith1474 People search for reviews of these products and make buying decisions that way. There are a ton of fluff reviews of these products right now. If they perform, then my data adds backing to them. If not, potential customers need to be informed of true performance of these devices. But sure, after I have tested products from many companies and people learn what they all do, then I can slow down.

[@harisjaved1379]

@@AudioScienceReview awesome Amir thank you so so much! Can I support the channel via patreon? Thanks !

[@mikede2464]

I would *LOVE* to see how bad my Airtight ATM-300b amp measures. I treasure it and could never afford to replace it if it got damaged in shipment. But if I lived closer....man would love to see the measurements.

[@kelvinjinxd]

That’s why I like the original circuit of dynaco st-70.

[@julesl6910]

The Dyanco ST-70 Mark II was really the proper step up. It used solid state rectification so bass is much tighter, and replaced the 7199 tubes. Also has automatic bias meter led's. The ultimate ST-70 in my opinion.

[@Thoughtflux]

Hi Amir, can you please test a tube buffer device please? It's very popular and is around $100 on Amazon. These are only 12V 1A devices which are not the usual push pull but are only used to add "tube sound". Do such devices add odd or even harmonics in reality?

[@MODAC]

That Dynaco (not Dyne Audio) design is from 1959. Vintage tube gear is an entirely different universe than the modern linear Chinese made DACs and headphone amps you evaluate. I own that same, newer unit and it is very engaging and glorious sounding. You don’t appear to know much about synergy between components. I could have told you that Infinity tower speakers would not be a great combo. Stick to solid state. Coincidentally, I’m currently shooting a review of mine for my channel.

[@sergeysmelnik]

Im really looking forward to all the measurements youre gonna take of your tube amp

[@AudioScienceReview]

I explained in the video that much more efficient speaker may pair better with it. And given its high output impedance, a more careful analysis may have to be performed to know how the frequency response changes with the speaker. Outside of that, the word "synergy" as no meaning. It is a made-up concept by audiophiles to escape logic of something not performing well.

[@MODAC]

@@sergeysmelnik Obviously no measurements.

[@MODAC]

@@AudioScienceReview Synergy is not a made up term. It’s actually part of the fun of being an enthusiast. Mixing and matching gear can lead to some surprising combos and audible results. It’s not measurable however…but you know it when you hear it.

[@sergeysmelnik]

@@MODAC with no measurements your review means nothing. Synergy in hifi is just a bunch of mumbo jumbo. If the amp and dac measure clean and there is enough power for the speakers it will sound like any other brand amp and dac that measure clean and have enough power. If different combos yielded audible results then yes it can be measured. There is no such thing as something being heard but not being able to be measured. This is how companies sell overpriced cables and power conditioners to the audiophools.

[@giriprasadkotte9876]

Tubes add distortion but some of it can be "musical". Like compression ( at low frequencies) and adding harmonics (at high frequencies). But all this can now be added through software.

[@Lauren080508]

probably it can be done by software , potentially even better and customable

[@Mikexception]

@@Lauren080508 But it will be noticeable by ear damaging of sound. Tube amplifier can deliver perfect sound which by definition is forbidden to carry noticeable damagesI Am not hopeless lover of tubes but comparing my 15W tube amplifier to high class solid 70W amplifier in the same system and the same material I can't find any reasons to set any of them above other Only solid upbeats in some cases lowest frequencies while tube shows more details in low tones. No winner. For sopranos they work exact , anyway I use for tube amplifier additional electrostatic "supplement" to speakers just to compensate capacities of wires which obviously for tubes are many times more dangerous

[@giriprasadkotte9876]

@@Mikexception You're describing tube compression and limiting. Obviously, both can be easily implemented in software code. Several free programs exist.

[@giriprasadkotte9876]

@@Lauren080508 Yes, Izotope Ozone is a good commercial example.

[@Mikexception]

@@giriprasadkotte9876 There is no practical explanation for what you say about tube compression and limiting . Look that most winyl recordings in 50- 60 ties (copied later to digital steraming) were originally recorded with valve technology. Now are admired with best SS technology and today some say that they do not recognize in them original tube compression and limiting. Only using tube amplifiers. How come?

[@nlewis559]

Awesome content as usual! Do you plan to measure more tube gear?

[@AudioScienceReview]

It all depends on what people send me. Right now this is all I have to test as far as tube gear.

[@bigjay1970]

Amir is sure cranking them out lately.😬

[@phpn99]

To me, amplifying sound using a tube design is at best like printing a photo on coloured paper. Some people love sepia tone ; makes them feel nostalgic, and in many ways, they deliberately love the 'instant patina' that such electronics impart to their music. When they are intellectually honest, they have next to no arguments to promote the linearity and distortion performance of a tube amp in the burden of sound amplification, but when they are being truthful, all they can say is "I like it". There's a reason tube stages are still used in electric guitar amps, specifically for their saturation and distortion characteristics. I also see it like driving a 1961 Pontiac : It looks the part, there's something about the user experience... but when the times comes to park the damn thing, or to slam the brakes, you're quickly reminded you're not driving a modern Audi. At least the tube crowd assumes its bias (no pun intended), contrary to the snake oil producers and consumers whose modern electronics are mostly pure foolery.

[@p_mouse8676]

Good analogy. The biggest difference about photos/art and cars is that people are honest about the fact that it's the experience. Without many fancy theories and such (well, there are always a few ofcourse). I am an engineer myself and I like working with tubes exactly for the nostalgia feeling. They also look mechanically fascinating. But audio-wise I would never tell they are the best in the world, because they are not. It's also a very interesting contrast with the Class-D power amps I design as well.

[@jimfarrell4635]

"all they can say is "I like it"" Absolutely. But isn't that the whole point of the hobby ? Essentially it's about what conveys the music to the listener in a way they appreciate and enjoy ? Ultimately that's all that counts. If you enjoy tubes, great. If you love the clean, excellently measuring power of a well designed Class D amp, great. Neither position is less valid than the other and there are people like me who have the capacity to enjoy both depending on music type. It's all good.

[@wescurtis1961]

This is not great new discovery. Tube amps have never measured perfectly, probably never will. But what they lack in the specs, they more than make up for in the sound. I’ve had several solid state and tube amps. Currently I’ve got a Hegel solid state, and a Primaluna tube amp. As good as the Hegel is - and it’s my favorite SS amp - I much prefer listening to the Primaluna. Don’t let the specs keep you from trying out a good tube amp. Let your ears be the judge, and you won’t be sorry. You’ll find the numbers aren’t everything. For many of us, tubes will always sound much more natural than solid state. So don’t make the mistake of dismissing tube amps based on the measurements of a single antique model that Amir was able to get his hands on. Tube bliss is worth exploring.

[@AudioScienceReview]

Maybe. I listen to them and have yet to find a tube amp that sounds better than solid state. At best, the distortion is not audible. At worst, it is as was the case here. People though are not sensitive to such impairments so I can see them not hearing the issues. As long as they arrive at their conclusions in a blind test, I am not going to complain. But if it is sighted test, then there are so many biases here that no outcome is reliable.

[@ze_german2921]

AS a newbie, is the ST-70 worth investing or does it have to much distortion?

[@edwardhaynes8857]

This amp does not exhibit normal characteristics for a St-70 type amp; it must be defective perhaps in the kit wiring. You should have tested a pre-wired STA-70 from the factory.

[@vaejoviscarolinanus]

I built one of the Sound Valves VTA ST 70ii yesterday . It was alot different as far as the board goes and mine is SS rectified. It sounds sweet but I have a faint hum in left channel if I put my ear to the speaker. I guess I made a cold solder somewhere.

[@LeeBergerMediaProd]

Transformer coupled outputs should always deliver the same wattage on the 4 or 8 ohm taps. McIntosh autoformers do that for solid state amps. My MC2150 is 100 watts at 4 or 8 ohms.

[@jean-paulschweitzer6211]

Some guys liking tube amps, knowing that they perform bad regarding THD and efficiency, but they´re loving the sound. Others linking SS amps, knowing that they perform good and have good efficiency. Other liking Class D. That´s really nice. Il faut de tout pour faire un monde!

[@Mikexception]

You are right but the goal for amplifiers is pleasure

[@AudioScienceReview]

I would love to do a blind test on them to see if they really can hear that "tube amp sound." And inversely, they are this insensitive to the distortions it adds to music. Personally with tens of millions of music tracks out there, I get variation in tonality through those recordings. Don't need an amp to overlay the same distortion on everything.

[@WDeranged]

Hey Amir. Would you consider testing something a bit more niche? Many users of the SweetVinyl SugarCube would be curious to know how well their DAC design works, given the huge asking price. A user recently reported seeing spectrogram spikes in vinyl rips from the SC-2.

[@AudioScienceReview]

Hi there. The demos I have heard at shows have been quite effective. That said, the signal processing to detect a true pop/tick is non-trivial and is bound to misfire sometimes. If you make the algorithm too strong, it can confuse music for such interference. But sure, if I can get one to test, it would be great. Do you mind contacting the company and asking them to send a sample to me for testing?

[@WDeranged]

@@AudioScienceReview The processing is very impressive. I hear a slight dip in treble detail on certain records. At least I think I do... Otherwise it sounds perfect. There is a small issue where the left channel starts spontaneously clicking until you reboot. It's got some of us worried. Sure I'll sent Sweetvinyl an email. I don't expect much to come of it, but it's worth asking.

[@ukspawn666]

Amir, Do you have any way to test Mission speakers? i want to buy the ZX-5 and cant find any measurments or even reviews online but it looks like a decent speaker for the money. Thanks for the work you do!

[@AudioScienceReview]

I just took a quick look but it doesn't look like ZX-5 is sold in US. How about contacting them and asking if they would send a sample to me for testing. I love to test more products that are available in Europe for people to buy locally there.

[@ukspawn666]

@@AudioScienceReview I will see what I can do, thank you I appreciate the offer to test them.

[@h0ll0wm9n]

Thx Amir! I had the orig Dynaco St-70 and ST-35, which I purch'd used, listened stock, then DIY updated via VanAlstine kits and plans. Tubes (valves) have a charac. sound that is DIFFERENT than solid state. You can also go hybrid (tube-trans) and mos-fet topologies that will balance SS and tube benefits. One day physicists will discover the test metric that correlates to subjective experience.

[@RennieAsh]

Perhaps the measured stuff here is exactly that, and people just prefer that kind of sound?

[@willbrink]

Tubes are like LP, etc, the longing for nostalgia leads to confirmation bias they actually sound better than digital sources, solid state etc. They don't.

[@johnnytoobad7785]

I was thinking of building one of these (the original Dynaco ST 70) back in the 70's but I ended up buying a Dynaco 120 instead. I sold that amp. (Big Mistake!) It's was one of two amps that got me through college. I would love to see a test of that amp. There's are re-build mods for that one too.

[@AudioScienceReview]

Yes, it would be nice to test a SD-120. Hopefully someone sends one in.

[@nathan7265]

Topping has a new $900 power amp. I would be interested in your current power amp recommendations.

[@AudioScienceReview]

In general if you can afford it, I recommend high power amps from Hypex and Purifi (modules). Running out of power is a sure way to get bad/distorted sound.

[@nathan7265]

@@AudioScienceReview Thank you.

[@nathan7265]

@@AudioScienceReview Can you recommend any analog amps?

[@viperracing2889]

Tube amps are nice for electric guitar, but I would never use one for high fidelity sound reproduction.

[@daeejon3100]

Thanks for For your Awesome reviews and testings I just got my MC901 macintosh Sounds wonderful in compare with the previous amp I would really want to know what science says I wanna hear your thought thank you so much

[@AudioScienceReview]

I have nothing to say about it until I test it. If by chance you live in US, it would be great to test it.

[@daeejon3100]

@@AudioScienceReview I am in los Angeles area That would be great thank you

[@johnsmith1474]

As I gleaned from a recent vid you have a home audio installation company, so I wonder if you have something to say about music access tools. I use a PC running Winamp for a few thousand lossless albums on hard drive, to two channel hifi. The software allows me to search & find every version of a song, or get to any album or band in seconds, see covers and discographies, and just really dig in & use my collection effortlessly A to Z. A favorite feature in Winamp is, "play random album" which ends the hassle of trying to pick what to play. With clunky access (albums on high shelves that need cleaning) some areas of a collection become overplayed, others are neglected. I find that if you have a large collection, fast & flexible access to the library is a difference maker for listening.

[@AudioScienceReview]

Winamp used to be great 20 years ago. But now, my favorite and what I use every day is Roon.

[@sergeysmelnik]

@@AudioScienceReview I used to use winamp too about 10 years ago. Have been using Foobar

[@johnsmith1474]

@@sergeysmelnik - Foobar runs nicely and I use it for some tasks like format conversion. It's Library display is too weak for large collections of albums, and it's not as flexible generally for perusing.

[@sergeysmelnik]

@@johnsmith1474 I dont know if 408 albums is a lot but thats how many I have on there. I have it to where I see the artists in alphabetical order. Ill click on the artist I want to play then the album and listen to the whole album. On the bottom Ive got the album cover visible. Its enough for me. Maybe there are some features Roon has that I dont know I want.

[@johnsmith1474]

@@AudioScienceReview - Winamp still is great, if a bit geeky. Thanks for the direction, Roon looks like a fine product. But it's a subscription, which makes no sense to play music you own. And it collects data and makes suggestions, I don't want a data sharing relationship with a corporation. And, the whole shebang is a morass of dubious claims and slick advertising, just a turnoff. Looks perfect for controlling music on an estate, where ironically (for sound) the speakers are usually in the ceiling. I don't have that problem, I just have a small place on a beach.

[@erics.4113]

So it's fuller sound because it's 'fuller' of distorted noisy shhh. .?

[@darrylduck6356]

Any designer speccing EL34 output valves was never intending to get anything clean coming out of the amp. It is basically a guitar amp designef to produce satuation

[@Mikexception]

EL34 as I read was modification of 6V6 in direction to more power As for me starting from 5W more power means less chances for any ideal speaker system/cabinet which can handle it. For guitar we do not even want ideal speaker so no problem

[@armandorancano6415]

Wow, you need to expand your reading.

[@darrylduck6356]

@@armandorancano6415 If they wanted to do a clean amp then a 6L6 would have been a much better choice. They would also have had a sensible amount of negative feedback. They were simply designing for the so called warm sound which is a amp with heaps of harmonics. And the EL34 is very good at that, hence it's popularity in the guitar market where distortion is wanted to give more timbre to the sound.

[@kyron42]

I saw a review that claimed that the Schiit Asgard 3 sounded warmer than another amplifier with lower distortion. The Asgard 3 is claimed to have less than 0.002% THD and less than 0.002% IMD. Can this level of distortion actually make a noticeable difference when considering the distortion in headphones? Could there be another reason for one amplifier sounding warmer than another when they both have a flat frequency response?

[@sergeysmelnik]

Youre assuming the reviewer wasnt full of shit

[@kyron42]

@@sergeysmelnik I'm giving him the benefit of the doubt.

[@kyron42]

@@sergeysmelnik judge for yourself kzbin.info/www/bejne/f2LMnJuCo5airsU

[@AudioScienceReview]

Those are the reviews you want to ignore. :) I have yet to find an amp that sounds "warm" or "cord." Or analytical. Or "detail king." These are all imagined characteristics these poets write. Please ignore them. There is no science or engineering that back them. The warmth or lack thereof come from your speakers/headphones and content you play. You can also get some brightness if the amp runs out of power and distorts.

[@JimLongCO]

In my experience I find my tube amps (Dynaco ST-70 and ASL AQ1004) to be less fatiguing than my SS amps (Sprout and GAS Son of Ampzilla). The SS amps definitely offer better bass and definition but I just can't listen as long.

[@Mikexception]

SS tends to sound "hard" but reason is in design of speaker system. Only with resitance at terminals all is nice and flat for tube and solid .

[@jesuschrist2284]

Only $1400 earth dollars? I need a New audiophile distortion pedal for my guitar ;) your videos and website are fantastic btw

[@Biefstukje]

I have hypex Ncore dual monos and smsl su 9. Both measure excellent but my willsenton r8 tube amp is so much better. It is not a small difference. Voices sound full and thick, pianos sound huge and in the room, the sound is so much more wide instead of narrow with the hypex. I like the hypex, bass is faster, treble is a bit smoother and maybe a tiny bit more detail, although I'm not sure. But still, the sound of the willsenton for me is better. Hypex sounds a bit Fake in comparison willsenton is more like live music. Speakers used are audio physic classic, combined with Cambridge cxc CD transport.

[@KUDJU]

Please do more tube gear

[@MichaelBeeny]

These valve amplifiers were the best sound available in the 50/60s but things move on. A modern amplifier (mostly) wipe the floor with power, detail, dynamics, distortion etc. I think people look at a valve amp, looks great, costs as much as a small car or even a big car in some cases! so it's got to be good. It's a case of the placebo effect mixed with a bit of snake oil. But, if it sounds good to you, buy it, we all have a choose.

[@Mikexception]

Why so many people discuss about other people and changing times instead of their own experience?

[@MichaelBeeny]

@@Mikexception Experience, lets see. Started work after leaving collage in the lab at Quad, Head of test at Cambridge Audio, Development of 3 way cinema loudspeakers with UCI. Retail Audio T. Founder member of Monitor Audio. I think I know a little about audio!

[@Mikexception]

​@@MichaelBeeny I mean experience as something unknown discovered in audio which could be help for those who would be gratefull for it . Audio is mostly unknown land of beliefs.

[@armandorancano6415]

@@Mikexception Darn, "an unknown land of beliefs sounds so good and wise" but I have no idea what it actually means.

[@Mikexception]

@@armandorancano6415 It means that no objective judgement above doubt is possible .Subjective are the only ones because too much differences of details are mixed together We all trusted that there wiill be at end available ideal gear with ideal acoustic output. But even every room will modify it in other way not mentioning faults applicated by unaware milions of users

[@EddyTeetree]

All vacuum valve amps aren’t the same. You get the good bad and ugly like any product. Also synergy between source amp and speakers is crucial. For certain a well engineered valve amp with golden era speakers will deliver plenty of tight full bass.

[@joesshows6793]

Another question…what’s the deal with low wattage amps and people claiming ‘5watts is all you need’ type nonsense??? Is 5watts all you need or is this for maybe a single full range driver type setup? Maybe we are just being sold garbage?

[@sergeysmelnik]

It just depends on the sensitivity of the speakers. Klipschhorns for example will probably make you deaf at 5 watts

[@joesshows6793]

@@sergeysmelnik interesting.

[@Mikexception]

I use speakers 3W and do not feel need for more because I livie in block appartment with neighbours. They deliver full from 45Hz to 18 kHz Measuring at my normal full comfort level I see max 1,5W but with "silent listening" it measures 0,1W

[@joesshows6793]

@@Mikexception nice

[@AudioScienceReview]

You get reasonable volume at 5 watts. But to get more, the power required goes up exponentially. 4X more power is 20 watts. But 4X of that is 80! Our perception of loudness also gets worse and worse with volume. As a result, I am able to bottom out all but the highest powered amps. Now if you have a 100+ dBSPL speaker sensitivity, maybe you are OK without it.

[@resistorstudios]

I restored a ST70. It has original 7199s and transformers. Honestly, its ok. I think its very overrated. I started out with tubes and I am a fan of the way they look. However, The bass is slow, and muddy. there is an air to them, but yea it distorts when cranked. Why they used EL 34 and tube rectifier is probably a technological reason as there are better tubes for this such as 6l6gc and SS rectifiers. Marantz 2235b i have also restored and its much more clear, the bass is much tighter.

[@jesuschrist2284]

Surely you can measure this with your buttery audio detector? ;)

[@jozefserf2024]

Hi-Fi is odd in that sometimes less detail and more distortion can actually sound more pleasing. Accuracy is something else entirely.

[@AudioScienceReview]

I hear you but per my listening test, this is just degradation and not any kind of improvement. But I agree some may not hear them as distortion and think there is something good there.

[@MisterAMG12]

Thanks !

[@pauldavies6037]

A great review and listening tests hooray please test some Linn and Naim pre and power amps it's time somebody did some real testing

[@volpedo2000]

True. Would love to see a Linn Klimax amp go through your review Amir. Maybe not as easy to get hands on in the USA.

[@jesuschrist2284]

Not that complicated to do :) have you seen my attempts at soldering? Ouch

[@sammccaig6684]

You should plug this in to the P12 ;)

[@AudioScienceReview]

Would have been fun to do it to see if any of that distortion and noise is reduced!

[@joesshows6793]

Ahhhh so when someone says the amp sounds ‘warm’ it’s really just the higher noise produced by the amp. Are there any tube amps that have low distortion?

[@p_mouse8676]

If an amplifier sounds at all, with "warm" people mean in general more distortion with even harmonics. Although it also does come with some other issues as described in the video.

[@Mikexception]

All made by experienced producer have enough low distortions to be ommitted . Just see - with average 1W amplifier uses 3-10% its nominal power and then even less then proportionaly are heard it's 1% nominal distortions. How say 0,1% distortion in tube can impact sounding and at the same time 0,005% in solid is noticable better? . Isn't a Snake oil?

[@joesshows6793]

@@Mikexception I don’t get it either. That’s why I think tubes are ‘warm’ cause you are hearing the actual device give off noise.

[@Mikexception]

@@joesshows6793 Before one say sometnhing sounds "warm" he should think what is the definition (or condition) of such "warmth". if it is bad foogy impression than it cannot be any good. Unfortunately some would accept. I have my idea, which matches my experiments and has nothing to do with nolinear distortions but with frequency chracteristic which is not represented by standard measurements of frequency curve. It is rooted in cooperation beteween amplifier and real speaker mess of dependencies for which solid is more vournerable. Such dependencies are dramatically smaller in one cone speaker and using such speaker solid has also this "warmer" sound - solid on 1 cone speaker additionally with germnanium transistors can sound no any worse than tube. I have amplifier from B&O with grermanium and it is with my construction one cone speakers like paradise

[@hugobloemers4425]

It just shows that there are also bad tube amps. Probably it would be better to stick with the original ST70 design, also because that it the point of vintage sound, to recreate sound as it was back in the day. And to be honest, I love vintage sound. My set up is from the 80's (OK, solid state obviously) and I have no desire to take it to 2020's.

[@sergeysmelnik]

Lots of awesome speakers from the 80s especially if the caps are replaced. I love my '86 Klipsch Forte I with replaced caps of course. Still a better design than the later versions which all measure worse

[@sonicsaviouryouwillnotgetm6678]

really cool view.

[@jimshaw899]

Welcome back to 1960. What could be better with all those glowing bottles and a chrome chassis making garbage sound? The real fun is listening to the garbage sound-lovers rave about the romance of pop-rock played on distortion machines. Maybe it brings aged memories of a Wurlitzer jukebox? Every roadhouse in America had one. Dreamy. Beauty is in the eyes of the fantasizer. "High Fantasy"? [Uh-oh... ducking for cover...]

[@AudioScienceReview]

I think there is something to be said about listening to music produced in 1960s which likely was monitored on amps like this. Indeed, there are audiophiles that listen over and over to old recordings as their entire audiophile life.

[@jimshaw899]

@@AudioScienceReview Well, if they do, I have an ancient record changer around here someplace with a Ronette ceramic stereo cartridge that I'll part with for no more than $1900. Vintage sound, if I can find it. The Salvation Army wouldn't take it. But, yeah, it'd be a good match for a 60's design tube amp.

[@JC.LC.]

Replace the tube rectifier with a solid state one and you'll notice the performance of the Amp go up a few notches.

[@MichaelBeeny]

You will of course have to add a resister to lower the voltage due to a diodes lower internal resistance.

[@armandorancano6415]

It depends on the tube rectifier used. My experience is opposite to yours.

[@JC.LC.]

@@MichaelBeeny if you are doing yourself yes, but there are companies out there that sell plug and play solutions. Just remove your rectifier tube and plug in the new solid state.

[@iimv]

Hello Amir. Can you test some naim amplifiers :)

[@AudioScienceReview]

Their PR person was going to contact me about me testing them but I did not hear back. I will see if I can ping them.

[@henriksrensen3220]

Why not listen to some Naim amps instead of these useless meauserments?

[@iimv]

@@henriksrensen3220 If I was thinking is useless, I wouldn’t ask for measurements. I own a nait xs 3, but thinking maybe to go to a purify amp. So will be very interested in how it measures.

[@henriksrensen3220]

@@iimv Great meauserments don't always equal good sound

[@henriksrensen3220]

@@iimv before I got my Gryphon amplifier i tried the Benchmark AHB2 power amp, great meausuring amp but sterile sounding

[@chriswright5016]

With great respect, you need to review something modern like a Primaluna. Totally different ball game compared to this modded antique.

[@AudioScienceReview]

I can only review what has been sent to me. I have listened to a Prima Luna and found it also to distort but would like to do a formal test/review.

[@scottwheeler2679]

Why would you bother with a sighted listening evaluation?

[@AudioScienceReview]

This was a special case in that distortion was so high that it is readily within audible range. Many people take that and say it is "euphonic" distortion. I wanted to see if there was such but there wasn't.

[@scottwheeler2679]

How do you know? Your biases were in play. How is that any different than speaker evaluations where we know there are audible differences? Isn’t that a cornerstone of scientific subjective evaluation?

[@audiohertz2341]

Amir , May I suggest you listen before measuring ..! Regards

[@IgorSPopovich]

Dynaco ST70 is one of the modification & improvement case studies in my book "Audiophile Vacuum Tube Amplifiers". Most commercial mods like the one in the video are fairly superficial and don't improve the performance much or at all. The power supply is the weakest point of this amp and most improvements should be not in the audio circuit but in the power supply! For instance, just look at that joke of a choke under the chassis.

[@Trev9]

I always thought that there was something wrong with me for not liking the sound of tube amps

[@thomothomo1078]

More likely you have just never heard them with suitable speakers.

[@Trev9]

@@thomothomo1078Ive heard solid state sound better with suitable speakers

[@thomothomo1078]

@@Trev9 Suitable speakers would be overdamped and have a slightly domed shaped frequency response with typical SS amps.That might suit your room I suppose.

[@lwrs10]

I use a version of this amp I built myself with Bob's stuff. Kinda in-between an ST-70 and ST-120. It's been my main amp for 8+ years now. I've had/have a lot of nice amps, but the 'ol ST-70 keeps making its way back into my rack. I am using some upgraded Forte II's with it. It measures exactly like I thought it would. The one test I've ran between SS and tube amps is phase difference, at freq, between input/output. Have you ever thought about running a test like this? It's interesting.

[@Mikexception]

I think real test would be with pair of speakers connected to output which are the ones used for listening. Then results probably will be no comparable to those with resistance 4 Ohms but that is what we get

[@AudioScienceReview]

It is a good point. Let me see if I can organize that before the amp gets shipped to its owner.

[@armandorancano6415]

I, too, still have the ST-70 I built five decades ago. I disagree that it is sonically inferior to new designs and builds.

[@edwardbalboa5528]

With easy to drive 8 ohm speakers , a clean tube amp is magical ..... Don't bother with 4 ohm speakers , sound will be very mushy on the bass

[@davidlong1786]

Tube amps are only good for use in playing electric guitars for the overload grunge effect and other distortions. Even in that situation , digital plugins can mimic those sounds now using solid state amps. They do make nice heaters during the winter months though. Some "audiophiles" like the snob appeal and how much money they cost I suppose. I find it amusing that this amps "tweaks" resulted in it having worse distortions than the original version. I'm guessing no measurements were performed in making these "tweaks". A waste of money spent.

[@armandorancano6415]

I find it amusing that you dismiss tube amps as heaters, tube amp fans for being snobbish and bragging about their cost, and tweaks as a waste of money. Such universal certainty.

[@zyghom]

here in UK, when the first sign of the spring comes, people are taking out of their garages their vintage cars. Made in 50' 60' some even 30' probably. And they have fun. Can they speed up as modern cars? NO. Do they look better? IDK. Fact is: they enjoy it. And others are looking at these cars ;-) Is tube amp better than modern amp? Numbers show that not but people still use them. I am saying: let them enjoy but that is not my taste. ;-)

[@dagnisnierlins188]

The problem is not letting people enjoy tubes, but claims about tubes how they somehow make music more real etc.

[@zyghom]

@@dagnisnierlins188 wrong, when someone is 50+ and he got used to listen to the vinyls and tubes, today's music is unknown for him, strange and maybe even worse - far from what he got used to. So for such person the real one is the one he used to listen to 30, 40 years ago.

[@dagnisnierlins188]

@@zyghom are we talking about recording quality itself? I listen to 70s and 80s music and they all sound much better on moder gear.

[@rawsonte]

Ya, think person thinking to send a tube amp for ASR review insane and asking for punishment

[@keepingupwiththejones2933]

Classic traits of narcissistic personality disorder Have an exaggerated sense of self-importance Have a sense of entitlement and require constant, excessive admiration Expect to be recognized as superior even without achievements that warrant it Exaggerate achievements and talents Be preoccupied with fantasies about success, power, brilliance, beauty or the perfect mate Believe they are superior and can only associate with equally special people Monopolize conversations and belittle or look down on people they perceive as inferior Expect special favors and unquestioning compliance with their expectations Take advantage of others to get what they want Have an inability or unwillingness to recognize the needs and feelings of others Be envious of others and believe others envy them Behave in an arrogant or haughty manner, coming across as conceited, boastful and pretentious Insist on having the best of everything - for instance, the best car or office

[@Lesterandsons]

👍

[@frankgeeraerts6243]

A modified ST70 is not an ST70.........

[@inkedbuddhist5220]

Is this a joke? You took a used & unverified piece of equipment and "reviewed" it, lol. Can you verify it was up to spec? There is a nice little write up by Bob. He gives you test points & voltage ranges. Very simple. Very basic rule; don't test the unknown. Then, you compare a 120W tube amp to a new 400W ss amp?! LoL...that's not going to give results favored by the larger amp w/greater headroom is it? Have a 120W used SS amp to make it at least fair? Something of the same value +/- $100; also for science as more $$ usually gives better results. So, apples to onions and should not be mentioned. Sounds like you also failed to match speakers to amp in your ''listening session" too. This is a big no-no and you know this but obviously can't have the tube gear actually sound good, now can you?! A complete ingenuine review. We need less of ppl like you & tube heads who are like you, but w/tubes. I have a nice mix of tube & SS, depends on my mood. Happens when you stop hating.

[@wookchang8852]

I miss the Carver!

[@jonthompson8807]

i may have to order a deckware and have it sent to amir hahahha

[@AudioScienceReview]

If you do, I am ready to test it! :)

[@jonthompson8807]

@@AudioScienceReview the turn around time is like 8 months. ill follow up with you.

[@sergeysmelnik]

This is why I will never own any tube gear of any kind

[@kyron42]

Why would an amplifier have a pathetic sounding bass? I guess it's because it can't produce enough current quickly enough?

[@tubemaze270]

Tube amps have a low damping factor and must be match with speaker that have lighter drivers. In that setup, bass will be as good as ss amp

[@kyron42]

@@tubemaze270 what's the output impedance of this amp?

[@kyron42]

@@tubemaze270 I find tube amps work best for mids and highs in active speaker configurations.

[@Mikexception]

Pathetic sounding bass is created with that pathettic sounding speaker cabinets which create bass with acoustic resonance When this "see saw" is moving in resonance then controll of it's masive heavy membrane + mass of air in cabinet by amplifier is too hard. Crazy phase shifts make humps in low tones characteristic It can't be nivelated by amplifier

[@heathwirt8919]

Sixty years ago the ST-70 was considered a good amp, by today's standards this overpriced version is junk.