Tube sound is not about warmth. It's about correct presentation.

Excellent article thanks golftime...😊

Back in the mid-80s Bob Carver challenged the writers of Stereophile Magazine that he could tweak his relatively inexpensive solid state amp to sound exactly the same as any tube amp of their choosing. The writers of Stereophile accepted the challenge and chose a highly respected and much more costly tube amp as the benchmark.  The challenge would utilize a null test where a third speaker was set up to produce only the difference in sound between the two amplifiers.

At first the third speaker produced a significant amount of distortion however after a couple days of tweaking Carver had reduced the audible difference between the two to zero, even getting the golden ears of the Stereophile writers to agree he had won the challenge.  Carver went on to market the new solid state amp.

This challenge has been discussed on this forum before but this thread made me think of it.  The article can be read here.

The challenge got the attention of the audio community not only because Carver seemed to prove his amp could duplicate the sound of a high end tube amp, but also because it seemed to show that any high end amplifier could be replicated exactly without too much effort.

In  the end, I believe there are great tube amps as well as great solid state amps and it's nice to enjoy whatever floats your boat.

Tubes can go a long way in revealing the strengths of the speakers. 

It’s a pity that these conversations always lead to food fights. But I prefer tubes. 

There is nothing academically superior about tube amp performance. It is less accurate than competently designed solid-state, full stop. If a solid state system sounds poor, lacking, irritating or incorrect, the most likely culprit is the speakers or the room. Tubes can go a long way in masking the weaknesses of many speakers. Most listeners would rather throw tubes at the system than address their speaker problem. 

asctim, this is a fascinating hypothesis. Interesting reading about photography too, though I didn't really understand everything.

Correct presentation is an interesting concept, and I can’t resist the temptation to make analogies to photography. If we’re going to print a photograph of a sunny beach scene, and we want it to look natural and realistic, are we just going to linearly map the light that hit the sensor on to the paper? That’s impossible without compressing everything, because the photographic paper has drastically less dynamic range capability than the real beach scene. A linear compression looks bad, so we use curves. The film in the camera develops with a curve, and the print film is also developed with a curve. If you shoot digital, curves are still used. There’s a mid-band of shades that actually track as steeply as they should, but the deeper blacks and brighter brights are compressed, so the curve typically has an "S" shape to it, flatter on both ends. This gives a "correct" presentation because of how our eye adjusts for contrast. It turns out we really don’t see that much contrast all at once. Our eyes are constantly adjusting in bright daylight, and even still we end up reaching for sunglasses because it’s more intensity than our eyes can comfortably handle. So the S curve makes the printed beach scene look realistic, with good, natural contrast. It doesn’t look compressed, even though it is. This works because our eyes automatically adjust their contrast sensitivity within limits.

With hifi it’s a little different, but there are similar limitations that have to be adjusted for to make things perceptually "correct." You could call the "S" curve in a photo distortion. Or you could call it a correction for perceptual purposes. If you don’t use the S curve in photos and just linearly compress across the entire range, the photos typically end up looking rather flat and lifeless, although detail in shadows and highlights can be excellent - at the expense of noise becoming very visible in shadows. Also if there’s any clipping in the highlights it’ll really show up and look bad. This sounds somewhat similar to the complaints people make about solid state amps. Maybe tube amps employ something similar to an S curve to make up for limits to how only two speakers can interact with our ears when trying to convey a realistic sound space, with proper tone, and also to compensate for limits inherent in recording techniques.

And above I wasn't being entirely facetious. The perceived "liquidity" of tubes is a certain something hard to technologically dissect apparently.

“Surfing to me is like playing music. You play different melodies with different boards.” – Skip Frye

"Tubular" Dudes

The surfers nailed it years ago

I have only owned two tubed components.  One was a Prima Luna integrated amp, and I hated it and returned it.  It sonically was the equivalent of pouring maple syrup over a steak.

  However, my favorite preamp for the past several years is Cary Audio SLP3.  This broadened the sound stage and fully fleshed out instrumental colors with sweetening everything 

In other words, good tube amp just sounds right, the way it should be. And that's kind of magic, yes.

@asctim “…good tube amps sound plain and natural, not exciting or magical.”

Let me change the gist of that a little. By being natural… and musical, they capture the magic of the music. I absolutely find good tube amps magical… they can send shivers down my back and goose bumps on my arms… it is the reality of the music, so exquisitely reproduced. Anyway… that is what I am talking about… nothing plain.

@mahgister +1

putting all tube amps in one basket and comparing it to single basket wit all SS designs is a little bit “incorrect sound equipment design development” representation! :-)

there are plenty of good sounding, warm (meaning linear) SS amps, incl x-fet, v-fet, darlington, class A, G etc on market. typically “warmer” sounding SS amps cost more, because devices used for output stage perform better (less distortion with less fb) at lover current, thus require more of them, matched/selected, in parallel.

warmer sounding tube amp is “easier” to build, if you have high quality matched tubes, expensive transformers, capacitors etc., which cost plenty. tube amps require more often maintenance, tube replacement, bias/bal adj. etc. 

for 25 W range amp I prefer tubes, for higher power and low freq. content music I prefer SS (accuphase A, ML).

In this hobby anything opposing tubes in general and S.S. or digital and analog or turntables to dac, or music lovers versus audiophiles , is almost more annoying than informative ...😁

The reason is simple: the quality is more in the implemented design than in the parts choices and too many factors differentiate each customers journey, and needs , and ears, system coupling , room acoustic, psycho-acoustic biases , fetischism, and knowledge etc then imposing a choice once for all for all situation is preposterous ...😁

Psycho-acoustics and acoustics rule over gear, when synergy is reached ...And rightfull mechanical and electrical embeddings controls exceed many upgrades half of the time if not more in acoustic impact ...

These rules apply for most people with limited budget not for people with no limit for audio budget ... Then my rules apply for most people who must make CHOICES and who cannot afford 500,000 bucks system and acoustically professionnally designed room ...

For example the fact that on a very costly system a costly turntable can beat AT THE END a costly dac had no useful information for most of us and our more mundane low cost choices ... It is better to have a top dac in an optimized room than a top turntable in a living room ...Too much factors are at play , it is useless to claim anything superior once for all and for all needs ...

My experience with tube amps has not been better than solid state. I've liked some tube amps well enough, but I have yet to hear what it is that gets others so excited about them. In any case, I'll agree with the OP's assertion that proper presentation is what I'd want from a tube amp, and I've heard some do it just fine. 

ghdprentice's description suggests that good tube amps sound plain and natural, not exciting or magical. Maybe that's what I failed to understand while listening to them. I've read so many glowing reports of some captivating, mesmerizing, transcendent effect that I expected to be wowed, when that's the opposite of what they do.

ghdprentice, excellent post. Not only because I fully agree with what you said.

OP, “Tube sound is not about warmth. It’s about correct presentation.”

I absolutely agree. I suspect that the term warm came when solid state entered the picture as it was cold, steely, and harsh… with a compressed midrange. Warmth refers to a fully fleshed out midrange without the sound dominated by harsh trebly distortion.

Presentation. I could not agree more, well designed tube gear gets the presentation right. Solid state tends to over emphasize details, venue and bass slap. This brings up an unnatural presence of the mastering and venue. While it is exciting to hear some violinist move his foot during a performance or the London subway train rattle under the symphony hall… is this really enhancing the music? Or taking the focus off of the music.

Tubes tend to get the presentation right, get the gestalt… the core of the music right. Now some companies have pushed their tube designs to asymmetrical capture the details. But companies like Audio Research, Cary, VAC, and Conrad Johnson have remained true to getting better and better at capturing the music and keeping the presentation real. After ten years of attending all the symphony orchestra conserts in 7th row center seats I can attest to how well they do this. The violins are properly placed… not artificially dropped in my lap. Rock albums do not take the cymbals from the back… carefully integrated into the song and put them in my face. While, it can be exciting to hear this… over the musical spectrum it screws up far more music and the musical experience than it makes sound great.

You accuse me of what you did FIRST after my post to you which was acknowledging your post... "Nitpicking" my post with the word "bickering" ...😁

Discussing politely without using words as bickering or nitpicking in my first post answering someone is what i do ... Can you say the same ?

My best to you....

I will stop here with you ...

@mahgister Yes, I get all that. You seem to rather enjoy nitpicking, isn’t that what you’re doing?

Yes, it is, bpoletti. Voicing is another matter.

@mahgister Yes, I get all that. You seem to rather enjoy nitpicking, isn’t that what you’re doing?

My remark acknowledging your rightful claim in your post is not "bickering"...

But your answer accusing me of "bickering" dont please me...

I already answered above about tube versus S.S. and correct presentation ...

And i can resume in a sentence my point : Acoustic matter more than the gear choices, if the chosen designs are relatively good to begin with , being tube or S. S. because the choice of gear is between design that can be good in the two case and at the end synergy matter more for acoustic experience than tubes or S.S. choices ...Nowadays it is already proven fact that some S.S. design are good others bad and the same is true for tubes... Audio is about trade-off all along the chain component from recording to room /ears acoustics...

And saying that is not "bickering"...

@mahgister Whatever. Not interested in bickering.

How about the subject at hand?

@mahgister Whatever. Not interested in bickering.

How about the subject at hand?

DSP room correction is very useful indeed...

It does not replace room acoustic no more than room acoustic can replace dsp tool...

@mahgister When you take into account that literally straight out of the box their Room Perfect software, which is easy peasy use and took me every bit of :20 to execute, completely tamed my difficult room situation.

@secretguy in regards to how tube technology actually works, I believe you are correct. And also according to traditional Class D design feedback is needed, correct? My understanding of electrical design is very rudimentary, please feel free to correct me where I’m wrong.

Given all of that … the design feature that attracted me the most to my Lyngdorf tdai 2170 is, in essence, what I understand to be the wire with gain concept. I’m sure someone can explain it better than I can, but my understanding is that that is a little more about correct presentation. Or shall we call it a true unadulterated signal.

My understanding is that the other electrical design element that makes the Lyngdorf approach to Class D design unique and also very high performance is what they call Intersample Clipping Correction.

The thing I like most about both the design and the sound is that because the signal is 100% digital and there is no need for digital to analog conversion.

The sound is so entirely pure. I’m not referring to the signal, I’m talking about the sound. We tend to overuse this word, but the term that actually describes the sound I’m getting the best is organic.

It would be interesting to start a thread on how different the quote Lyngdorf sound is … because, to my experience anyway, it was SO different when I first started listening to it that, tbh, it took some getting used to.

But I’ve had it long enough now, that I can now recognize the sound as being literally completely natural.

I know others will be familiar with the idea that a piece of equipment will sound so good that it will either expose your weakest link or confirm that you have synergy.

It would also be interesting to hear other peoples thoughts on the way Lyngdorf approaches tone control on their tdai amps. It seems to me that these guys are just doing things so uniquely differently than any of the other designers that it’s almost difficult for people to compare to other designs. Their voicings is what I’m referring to specifically.

I’m currently using a pair of Usher BE-718 bookshelf speakers that have an ability to go very low with a lot of accuracy. Like I’m not even using a subwoofer. So, to get the bass response I want out of them occasionally I will use the Bass 2 voicing. Instead of boosting! the bass on that voicing, they adjust the curve so that it’s reducing! the higher frequencies and middle frequencies to allow more of the lower frequencies to come thru proportionally. The example I’m illustrating is how that’s such a novel approach to, in essence, tone control.

What sounds best all the way around, even with these small speakers, as opposed to my Martin Logan Summits is the neutral voicing because it’s completely balanced. But under certain circumstances, ie: no subwoofer, it’s nice to be able to tailor my sound.

@mahgister When you take into account that literally straight out of the box their Room Perfect software, which is easy peasy use and took me every bit of :20 to execute, completely tamed my difficult room situation.

The thing that took the most getting used to, was losing the bass bloat effect that apparently I had gotten confused with having my bass truly grounded and rock solid. It is now and baby I’ve got the power to go along with it at 170 watts at 4 ohms.

All of this ^^^ and what nearly every single reviewer I’ve read has called the blackest background ever.

Would love to hear others compare and contrast all of that with the tube gear experience. Please feel free to correct me where I am wrong.

Would love to hear from the OP.

It's NOT tubes or solid state.  Its the designer's voicing of the component.  

I am of the opinion that Benchmarks class G amplification sounds to sterile, at least when I auditioned it some time back, but I am also a valve fan and enjoy my distortion like Nelson Pass. 

How much distortion is required for 'correct presentation'? 

It's about added distortion. The end.

@mrskeptic (What’s in a name?) To me ElL-34’s in most amps sound warm. Maybe warm means not fast. Other tubes like the KT-150’s are not as warm (at least in my amp).. There’s something in the micro timing or thier musicality (sound rendering). Last but not least tubes are time proven analog. And many love to see ‘em glow.

There is no "warm" tube sound. Tubes get warm or even hot and some dimwit reviewer probably used the term "warm" or "warmth" and it went from there. If you believe a sound can be warm or cold, you're like Ralph Wiggum when he said, "It tastes like burning."

In my experience both can be stellar or lousy. Obviously it’s the whole system and room.
Given my youthful sixty seven years I recently invited in a few younger women (supervised with feet on the floor) to also listen when changing from a tube intergrated to a SS. We all picked the SS. The youger ears can hear more.
I had been using a tiptop KT 170 AMP. The SS amp has a bit more power.
Certinally this isn’t any sort of proof but what’s in the whole stew adds up to the final result. I wonder if fellow folks here take into account that their gear’s synergy, especially thier speakers coloring thier preferences. Every one tends to tout thier stuff untill they get other equipment. So there’s that too.

I own a pair of Legacy Audio Focus XD speakers Ijust got in August 2023, they have an internal 750 WPC Icepower amp, you can run them fully internally amped or bi amped. I tried them both ways, first internally amped. Then I hooked up my VAC Renaissance 70/70 amp that is 30 years old. (Fully updated in Feb 2023) When i got the VAC on the top the soundstage was much wider, deeper and layered immediately. Midrange timbre and spatial information was more real. It is still a very good amp.

@mahgister + 1 - as soon as I see 'all' or 'no' in regards to some category of items like 'tube amps' or 'ss amps', I dunno - just doesn't make sense to me.  

Besides Carver's work, also read David Manly and how increasing the grid isolation resister can make a tube sound more solid state.  

I think Benchmark might disagree with SS "missing" something. :)

Now as far as that "metallic" sound, I did find this as one of my easy showroom "NOs" when auditioning amps. A great test is a good classical guitar recording and if the bass strings sound metallic.  Very clear on some Julian Bream.  A Vocal like Joan Baez can show it up.   My MOSFET passed. Modified Hafler and B&K passed. Atoll and Hegel integrated passed. So does my new Rekkr and Vidar.   I thought it was more Bi-polar vs MOSFET, but some bi-polars' sail through too.  Some failing costing well into the ego bragging range so none of that "not expensive enough stuff". A $150 Schiit passes.  Speakers have a bigger influence and for some reason, I have never heard a hard dome I liked.  By measurements, they should be better, but I keep going back to paper woofers and silk domes. 

Chasing "live" is pointless as you are dealing with the last link of the chain and the sources we have are no where near live. No one has ever succeeded in recording a piano half way believable I have found. ( if anyone knows one, let me know)  If not in the source, we are not going to reproduce it.  Pleasurable is a better goal. 

 The closest to "live" I have ever heard was a solo bass being bowed, 2 mics, right into a Revox half-track. Not even any Dolby.  Played back in the same room through some Levenson and first generation B&W 801's.   Close.   The best we can do is hope not to screw up what the recording,  mixing, and mastering engineers did to it.

I was about to try another tube amp. Last time I listened to some and then built a few, my MOSFET was better in all respects. Things progress though. My desk I could easily use a 6 to 10W amp and those are "reachable"   Jumping to 50 or so on my main stereo is out of my price point. Then I got the Rekkr on the desk and darn is it good. 

What each of think is pleasurable varies.  Sound is real, hearing is our brain deciding what we think. It is not objective no matter how fervently some seem to think it is.  It is personal and neither I nor you can tell anyone what they like. 

I’ve had mostly good tube equipment over many years w/ some good solid state mixed in between & what I’ve noticed generally is that tube electronics do a better job of giving each instrument or vocal more space & air around it creating a better 3 dimensional illusion. With tubed equipment, The frequency extremes probably aren’t as extended, dynamics may not be as good ( although easily ameliorated) w/ an efficient speaker), tubes die & can be noisy, tubes get hot etc but w/ the right system, generally sound to me closer to live music & are more enjoyable.  

I don't pretend to know anything anymore.... BUT I have heard great sounding SS amps and horrible sounding Tube amps.  So many other things to consider (source, speakers, room, desired tone, genre of music etc.).  There doesn't always have to be a "one or the other".  Keep in mind, the quest for "live" music feel is chasing tone.  All PA systems are SS reproducing "some" tone amplifiers (guitar,bass,keys etc") and presented on loudspeakers.  Of course if you are chasing the sound of an acoustic guitar, horns or vocals that are standing in your living room, that is another desire.  
 

Like I said, I don't pretend to know anything anymore.  But I know what I like. 😁✌🏻

Well, there’s Bob Carver’s take, here’s Nelson Pass’ thoughts on the topic (and somewhere here, or another forum, someone shared the actual schematic for the project should someone feel like building a do-it-yourself distortion unit to a SS amp):

https://www.stereophile.com/content/gramophone-dreams-26-nelson-pass-harmonic-distortion

Not here to disparage the SS camp,  perhaps our ears and perceptions allow us different avenues to the gratification  of well produced musical reproduction. The Bob Carver interview was enlightening. Never knew of his depth of knowledge as to the auditory process and ability to create amplification that our ears would find appealing. 

Correct presentation ? Presentation of music that touches your spirit ? Of course, this would be worked out in individual systems of particular design, physical materials used, and component synergy -- inside eqpt. as well as unit to unit-- as suggested by others here.

With very good SS and tube amp designs we are surely in the realm of subtlety, but I find this to be crucial.

Listening to LP’s with fast, transparent Decca cartridges, Transformer Volume Control and 104dB single driver horns, I hear the very slightly greater separation of instruments and information of SS with a First Watt J2, yet the large bottle glass AD1 tubes in my Yamamoto 4w + 4w SET give very nearly this level of abundant detail, equal or greater soundstage, and fully natural and organic sound. This effects what I seek which is to be immersed in and deeply connected to music.

It seems too obvious to state that the different physical materials of glass and metals of tubes, and the materials of SS devices, will inevitably sound different. Of course, preference for one or the other (or each, for different moods, or programme material) seems in the realm of taste, as for different wines, beers, and all the rest.

@wolf_garcia ...Like that....👍 "Bi-Polar" might be better, but starts a whole different disc-cussion....

...Bi-spherical, we can certainly assume....*L*

(Some researchers have posited that the universe may be an inside-out black hole, which 'splains a lot to me....but I've always thought it's all in ones' head anyhow...)

...but I'm just bent that way....

...for those of us with 'aged' hearing, 'organic high frequency roll-off', one can have all the warmth one can stand and then some...

Adding my aids adds an interesting conundrum:

Would the digital items in my ears effect my realization of 'warmth' from a totally A system, represented front to drivers considered to be 'A friendly'?

Since I'm SS from front to amp, and of no pretense of whether or not my choice of speakers would have any....'preference' in their presentation....?

I occasionally think 'warmth' is the F temperature of the studio or hall of the recording.....but I'm just kidding about that....*s*

I can relate to @mahgister's comment of prejudice, but feel it's more of a 'preference'...🤷‍♂️

Re 'hybrids'....tube pre>ss amp v. ss pre>tube amp....what would seem to occur?

Curious minds out on the limb....😏

Tubes are simply more interesting maybe. They glow...if a transistor amp glows start looking for traces of smoke and try to remember where the fire extinguisher is. Tube guitar amps still rule that roost, but hey...my Pass XA-25 is in a constant battle with a single ended Had tube amp my earball's attention. Swap them whenever I feel like it and I'm somehow always in the fun zone. Bi-tubular? 

Of course. More organic, more natural, closer to reality.

It always upsets me when I hear that some speakers are intentionally made to sound their best with SS. In my book this is a very wrong approach and I will never consider such speakers.

SS is kind of digital, in a manner of speaking. Tape and vinyl are not perfectly quiet yet they are superior.

I feel that “warmth” is an over used term.  My experience is that tube amplification sounds more organic.  The sound stage is more of what you may expect to hear with live music.  This organic quality comes with imperfections like hum and pops and little odd twinges. Some may find these imperfections to be too distracting and so SS is a better fit for their tastes since it feels cleaner.

Hybrid amps are SS amps.

Love that simplicity Curious Jim.

I started with tubes, then went to SS, went back to tubes and then a couple of years ago I bought my first integrated amp.  The Hegel H390 sounds pretty darn good to me. Maybe in a couple more years I’ll go back tube separates.  Or maybe Hybrid amps like the PS Audio BHK 300’s that use a couple of 6822’s in each mono block to give the user more of a tube sound.

Disagreed.

Also assuming tubes provide “warmth” then that’s a problem because warmth might be nice but it’s definitely not “correct”.

So the logic of the assertion proposed is flawed to start with and that kind of puts a damper on things right out of the gate.

Modern tube amps and hybrids are the the my preference. 

Softer metallic sound is still the same metallic sound.