Why Tube Amps Sound Different (and better) Than SS Amps

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Exactly Mark. The differences between tubes and solid state are well known, understood fully, and simple to quantify using the standard metrics of fidelity. In every case competent SS has higher fidelity than tubes, even if some people prefer the sound of tubes (which is fine). So why are there still arguments? Tim said it very well:

--Ethan

Sheesh. This statement is simply false. Solid state has its own set of colorations, ones caused by odd ordered harmonics which are much more irritating to the human ear. This has been well understood since the 1960s.
 
Fairly obvious in this thread that those who love tubes, love tubes-- and those that love ss, love ss. Never the two shall mix, LOL:D.
This is a topic that has worn thin years ago....kind of like those who defend analog and those who defend digital!
However, this does bring up a question....isn't this hobby about reproducing MUSIC?? Since I would say that it is, who really cares
which topology is the more "accurate"...( a term that is debatable in regards to one's perception of what music sounds like) BUT more about what we PERSONALLY perceive as more musical and hence the old term: enjoyable to our selves.
 
Fairly obvious in this thread that those who love tubes, love tubes-- and those that love ss, love ss. Never the two shall mix, LOL:D.
This is a topic that has worn thin years ago....kind of like those who defend analog and those who defend digital!
However, this does bring up a question....isn't this hobby about reproducing MUSIC?? Since I would say that it is, who really cares
which topology is the more "accurate"...( a term that is debatable in regards to one's perception of what music sounds like) BUT more about what we PERSONALLY perceive as more musical and hence the old term: enjoyable to our selves.

I care, and I like tubes. Why do I care? Because if you think tubes do some magic we can't measure, and you search for more magic you are on a ghost chase. The results are chaotic, expensive and don't really progress toward anything. Plus others attempt to 'fix' SS products that don't do what tubes do.

What tubes do is a psycho-acoustic trick. That is fine, I like those and they can work. Would make more sense to investigate how the trick works and optimize processing the signal for that purpose rather than a sure to fail search for the holy grail of what makes tubes magic.
 
I care, and I like tubes. Why do I care? Because if you think tubes do some magic we can't measure, and you search for more magic you are on a ghost chase. The results are chaotic, expensive and don't really progress toward anything. Plus others attempt to 'fix' SS products that don't do what tubes do.

What tubes do is a psycho-acoustic trick. That is fine, I like those and they can work. Would make more sense to investigate how the trick works and optimize processing the signal for that purpose rather than a sure to fail search for the holy grail of what makes tubes magic.

We both like tubes, however, I also like ss. Both have a "flavor" and IMO neither is absolutely "better" than the other. I happen to believe that there is room for both topologies and that that scenario should continue.
 
I care, and I like tubes. Why do I care? Because if you think tubes do some magic we can't measure, and you search for more magic you are on a ghost chase. The results are chaotic, expensive and don't really progress toward anything. Plus others attempt to 'fix' SS products that don't do what tubes do.

What tubes do is a psycho-acoustic trick. That is fine, I like those and they can work. Would make more sense to investigate how the trick works and optimize processing the signal for that purpose rather than a sure to fail search for the holy grail of what makes tubes magic.

It's done. You can walk into any Guitar Center in your town and buy a solid-state powered digital modeling amp packed with models of classic tube amps. I played nothing but meticulously maintained vintage Fender Deluxe Reverbs full of NOS tubes and vintage or vintage repro speakers for years. I now cary an amp on stage that weighs a little more than half my Deluxe, has 5 times the power and has models for 50 amps in it. I don't use them all, of course, but I carry that one amp up there, turn it on and virtually play through a vintage Deluxe, Twin and Vox AC-30 Top boost. Just step on a button; I can play rhythm through the Twin, solo through the Vox. All three of those models are absolutely convincing. Could tube hifi amps be modeled as successfully? It would probably be easier. Hifi doesn't come close to pushing the capabilities of tubes the way guitar amps do. Why don't they model them? I suspect there's no market for it. Most of the people who love tube hifi sound would never believe in it, no matter how good it sounded.

Tim
 
Tim, I recently had the opportunity to play my Strat through a Vox modeler and a Black face Super Reverb...really there was little similarity between the two sounds. The black face was just leagues ahead in the tone dept. While I admire what the modeler's bring to the table, I do think that they have some way to go to get near what the real thing sounds like. A small facsimile, yes...BUT at the moment that's all.
 
If the only thing that matters is measurements, why do none of the same folks own QSC or Crown amps? There would be no reason to spend more than 750 bucks.
 
Until the day that somebody can build an amp that can satisfy all parameters, for all listeners, for all circumstances, a true universal amplifier, accept that none, NONE, are perfect.
 
I don't know where you got the 10 % THD number from, it appears it's more like 5 % THD at max output:

http://www.hifitubes.nl/weblog/wp-content/rca-2a3.pdf

But I doubt my amps ever come anywhere near max. output. They have four 2A3 tubes per channel and drive a minimonitor with no deep bass output (linear only down to 50-60 Hz, from there an active subwoofer takes over) and a benign impedance load at 90 dB sensitivity. Max. listening SPL levels are 95-97 dB (only at rare occasions, mostly max. SPL is not more than 92-93 dB at orchestral peaks) at about 2 meters distance from the center between the speakers.

I honestly don't care if the two amps are vastly different creatures; if they sound similar then they sound similar.


Even 5% is still a lot. The sum of all the harmonics must be more than -32dB below fundamentals in order to fall below the masking effect of human perception. That happens around 1-2% for most people. I, myself, am sensitive to much smaller amounts of distortion. Your amp sounds like a parallel push-pull arrangment, not an SET, so it's distortion (especially even order) is probably much lower than 5%. Probably more like .5% or better. In such a case, and assuming solid state (not tube) rectifier, and a stiff, low impedance power supply, the amp can sound a lot like solid state.

One of the most dramatic modifications I've done to a customer's amplifier was to change the tube rectifier to solid state. Granted, these Altec amplifiers had some of the best output transformers in existence, so I had a great platform to work with. With stock rectifier, measured distortion was 1.2%. Altec claims "less than 2%" so the amp was well within spec. After my rectifier mod, distortion at full power dropped to .15% and was as low as .034% at normal listening levels of 1-5 watts, while max power output went from 40W to 55W. The source impedance dropped immensely. The customer said this about the modification:

"They sound great! I have so far used them for ~6 hours on Sunday listening to a wide variety of music. My impressions are below:(1) Much lower noise level. I hear nothing in the background.
(2) Hissy tones that occurred with loud passages are gone. I do not know if they were due to the limited power or pasasitics, but the dynamic range is now much, much bigger and all notes (especially high ones) vibrate more cleanly.
(3) Muddy-sounding vocals in orchestra now sound clearer. I also can raise the volume without reaching that point of "compressed" feel.
(4) Bass is tight. Very tight. I did not know my 15 inch can be this tight. Contrabass and bass drums sound very sharp now. It does not sound like a vacuum amp driven system!

I am so excited that I will have to keep my audio bug in check going forward. I have been good for the last decade or so, not changing much at all, but I feel like I can use a new pair of speakers now. No, says Ichiko. I know...


Thank you very much Bass Pig!"


Tube amps can have the tightness of solid state, given a low source impedance. Granted, the output transformers on the Altec 1568A will pass a near perfect square wave at frequencies down to 40 Hz--very few transformer amps can do this, with exception of McIntosh MC30 and a few other Mc amps. Modern amps with transformers of recent manufacture ring like a bell with square waves and have extremely limited bandwidth. Some Carver amplifiers that I tested recently suffered slew rate limiting at frequencies as low as 4KHz! Transformer winding is really an art, and a lost art at that. Much of that knowledge was lost with the engineers at UTC, Stancor and Thordarson, decades ago.

For reference, a 70 piece classical orchestra that I regularly record is capable of 105dB peaks when the tympani section is playing. Low 90s would be chamber music.
 
A perfect amp probably would be considered sterile sounding by many on this forum....dont ya think..

Actually I don't think so. I would if I thought most recordings are sterile to begin with.
 
Sheesh. This statement is simply false. Solid state has its own set of colorations, ones caused by odd ordered harmonics which are much more irritating to the human ear. This has been well understood since the 1960s.

...and ignored by the measurement fanatics.

You bring up an important point, however.

I find the simplistic thinking of those addicted to their digits and meter needles touching and heartwarming. Elsewhere I have pointed out the measurement problem, that we often don't know what the most important measurements are and how to make them, a problem which as a scientist I am acutely aware of. It has been countered by the assertion that we do know which the most important measurements are, at least in digital (which was the topic then). Right. Nice try.
 
...and ignored by the measurement fanatics.

You bring up an important point, however.

I find the simplistic thinking of those addicted to their digits and meter needles touching and heartwarming. Elsewhere I have pointed out the measurement problem, that we often don't know what the most important measurements are and how to make them, a problem which as a scientist I am acutely aware of. It has been countered by the assertion that we do know which the most important measurements are, at least in digital (which was the topic then). Right. Nice try.

Well we do know what to measure for the most part. The old "we don't know what to measure" canard is God of the Gaps type thinking in the audiophile context. Metaphysical thinking. Something, something not measurable, something we just don't know, something you can't capture with measurements etc. etc.
 
Even 5% is still a lot. The sum of all the harmonics must be more than -32dB below fundamentals in order to fall below the masking effect of human perception. That happens around 1-2% for most people. I, myself, am sensitive to much smaller amounts of distortion. Your amp sounds like a parallel push-pull arrangment, not an SET, so it's distortion (especially even order) is probably much lower than 5%. Probably more like .5% or better. In such a case, and assuming solid state (not tube) rectifier, and a stiff, low impedance power supply, the amp can sound a lot like solid state.

Yes, it is push-pull. At the time of comparison, the amp also had solid state rectification (beefed up over stock). In the meantime I have gone to tube rectification, but my observations are quite opposite of yours with tube vs. solid state rectification. They can be read in my review here:

http://www.whatsbestforum.com/showt...trol-MB-external-power-supplies-for-tube-amps


One of the most dramatic modifications I've done to a customer's amplifier was to change the tube rectifier to solid state. Granted, these Altec amplifiers had some of the best output transformers in existence, so I had a great platform to work with. With stock rectifier, measured distortion was 1.2%. Altec claims "less than 2%" so the amp was well within spec. After my rectifier mod, distortion at full power dropped to .15% and was as low as .034% at normal listening levels of 1-5 watts, while max power output went from 40W to 55W. The source impedance dropped immensely. The customer said this about the modification:

"They sound great! I have so far used them for ~6 hours on Sunday listening to a wide variety of music. My impressions are below:(1) Much lower noise level. I hear nothing in the background.
(2) Hissy tones that occurred with loud passages are gone. I do not know if they were due to the limited power or pasasitics, but the dynamic range is now much, much bigger and all notes (especially high ones) vibrate more cleanly.
(3) Muddy-sounding vocals in orchestra now sound clearer. I also can raise the volume without reaching that point of "compressed" feel.
(4) Bass is tight. Very tight. I did not know my 15 inch can be this tight. Contrabass and bass drums sound very sharp now. It does not sound like a vacuum amp driven system!
I am so excited that I will have to keep my audio bug in check going forward. I have been good for the last decade or so, not changing much at all, but I feel like I can use a new pair of speakers now. No, says Ichiko. I know...


Thank you very much Bass Pig!"

In my case with tube rectification the noise floor has dropped, resulting in much greater resolution (I still hear nothing in the background, which is a slightly different topic). Dynamics are more effortless than before. Bass is powerful and even more controlled. Everything sounds cleaner (you can read it all in detail in my review).

While lowering the level of electronic noise, the external power supply with tube rectification apparently also has stabilized the HT (B+ rail) supply, as advertised. Yet as has been pointed out in a discussion, this is only possible because a) the new external power supplies are truly massive (they would never fit in my amps) and b) my amps are low power output -- I guess the scenario simply would not work with an amp the type of which you modified for your customer.

How massive the power supplies are you can see from images here (there is a rack where you see four of them below a BorderPatrol amp; the last picture on the page shows the inside of a power supply):

http://parttimeaudiophile.com/2012/10/24/rmaf12-borderpatrol-take-me-away-to-the-living-voice/

With tube rectification as regularly implemented I might indeed have all the problems that usually are solved with solid-state rectification.

For reference, a 70 piece classical orchestra that I regularly record is capable of 105dB peaks when the tympani section is playing. Low 90s would be chamber music.

Yes, but those peak levels are rarely reached. And for normal listening, 95 dB is really loud (not for you I guess, from posts of yours I read elsewhere on this forum). After two minutes of the final brass chorale of Bruckner's Fifth Symphony at 95-97 dB my ears feel the pressure, even though there is hardly any perceived distortion in playback. Chamber music typically does not go beyond 85-90 dB (mostly the lower value), but if you put the microphone closer than the usual listening positions in the hall you may exceed those levels at that position handily of course. It also depends which chamber music. If it includes percussion it may be a different story.
 
It's done. You can walk into any Guitar Center in your town and buy a solid-state powered digital modeling amp packed with models of classic tube amps. I played nothing but meticulously maintained vintage Fender Deluxe Reverbs full of NOS tubes and vintage or vintage repro speakers for years. I now cary an amp on stage that weighs a little more than half my Deluxe, has 5 times the power and has models for 50 amps in it. I don't use them all, of course, but I carry that one amp up there, turn it on and virtually play through a vintage Deluxe, Twin and Vox AC-30 Top boost. Just step on a button; I can play rhythm through the Twin, solo through the Vox. All three of those models are absolutely convincing. Could tube hifi amps be modeled as successfully? It would probably be easier. Hifi doesn't come close to pushing the capabilities of tubes the way guitar amps do. Why don't they model them? I suspect there's no market for it. Most of the people who love tube hifi sound would never believe in it, no matter how good it sounded.

Tim

C'mon Tim. Is the point of plugging an electric guitar into an amp ever to achieve the closest possible fidelity to the original electrical signal from the pickups? Seldom ever. What you and I both love about Blackface Fenders, Vox AC30s, Matchless Chieftans, Marshall JCM800s or HiWatts is that they depart from the original signal. Some more so than others, but no one wants a "straightwire-with-gain" guitar amp, although maybe a Roland JC120 might qualify. Guitar amps are designed to take the signal from the strings, pickups, volume and tone pots and amplify it into distortion, not away from it, even if only by the slightest or most trivial amount. It's why we love boutique, hand-wired amps in the first place, be they EL34, EL84, KT88, or 6L6-powered. Did you ever swap rectifier tubes in a quest for "higher fidelity" to the original signal? Probably not. I'm imagining you did so in a quest for ultimate tone, irrespective of whether that was closer to the sound of your guitar (which is inherently problematic due to the fact that the "sound" of an electric guitar can be whatever you want it to be depending on pickup selection, volume setting, etc). Amp modelling works because the signal from a guitar is fairly predictable compared to the signal originating from a recording which is timbrally and dynamically far more complex. And hi-fi amps are seldom ever connected to a steady state predictable load that any given loudspeaker may represent.

Personally, I think the Fractal is an amazing tool, and of course, much more practical than carrying around a load of finicky amps and heavy mitre-jointed Finnish Birch cabs. I think it sounds truly excellent, and I know many guitarists have given up on their racks for the Fractal. But digital modelling has yet to convincingly recreate a concert grand to my satisfaction, and I've heard no digital drum kit that even comes halfway close to recreating the touch, spread and texture of a 7A wood tip stick on a burnished and smoke-covered cymbal. At least, not yet.

Having said that, the Devialet fascinates me, both from a design and technological point-of-view. I hope to hear one this year.
 
C'mon Tim. Is the point of plugging an electric guitar into an amp ever to achieve the closest possible fidelity to the original electrical signal from the pickups? Seldom ever. What you and I both love about Blackface Fenders, Vox AC30s, Matchless Chieftans, Marshall JCM800s or HiWatts is that they depart from the original signal. Some more so than others, but no one wants a "straightwire-with-gain" guitar amp, although maybe a Roland JC120 might qualify. Guitar amps are designed to take the signal from the strings, pickups, volume and tone pots and amplify it into distortion, not away from it, even if only by the slightest or most trivial amount. It's why we love boutique, hand-wired amps in the first place, be they EL34, EL84, KT88, or 6L6-powered. Did you ever swap rectifier tubes in a quest for "higher fidelity" to the original signal? Probably not. I'm imagining you did so in a quest for ultimate tone, irrespective of whether that was closer to the sound of your guitar (which is inherently problematic due to the fact that the "sound" of an electric guitar can be whatever you want it to be depending on pickup selection, volume setting, etc). Amp modelling works because the signal from a guitar is fairly predictable compared to the signal originating from a recording which is timbrally and dynamically far more complex. And hi-fi amps are seldom ever connected to a steady state predictable load that any given loudspeaker may represent.

Personally, I think the Fractal is an amazing tool, and of course, much more practical than carrying around a load of finicky amps and heavy mitre-jointed Finnish Birch cabs. I think it sounds truly excellent, and I know many guitarists have given up on their racks for the Fractal. But digital modelling has yet to convincingly recreate a concert grand to my satisfaction, and I've heard no digital drum kit that even comes halfway close to recreating the touch, spread and texture of a 7A wood tip stick on a burnished and smoke-covered cymbal. At least, not yet.

Having said that, the Devialet fascinates me, both from a design and technological point-of-view. I hope to hear one this year.

Of course electric guitar amps are not about fidelity to the Strat. They are a good half the tone of a Strat, and sensitive to the attack of your hands on the strings to boot. That's why I'd guess that the technology that can sound like my Deluxe (and a Twin and a Vox and frankly that's where I stop caring), should be able to model the relatively minor effects of a Lamm without breaking sweat.

I've never heard a digital drum kit, or a model of a concert grand through a system that could recreate the sound, but I've auditioned several of the modeling amps and own one of the Fenders. I have my issues with the thing, but the authenticity of the vintage, low-gain models isn't on the list. In my hands, through my G&Ls, in my bedroom or onstage, it performs as advertised. But thats a very different challenge from modeling acoustic instruments. The instrument is still there, all the amp has to do is model the tube amp's response to, and processing of that instrument. Modeling a tube hifi amp would be a similar challenge, maybe even a lesser one. It wouldn't have to model the amp's response to the organic dynamics of string attack, which was probably the hardest thing for them to get.

Boutique guitar amps? I had an original 65 Deluxe with NOS Visseaux 6v6s and a Weber. Never saw the point in boutique amps.

Tim
 
Of course electric guitar amps are not about fidelity to the Strat. They are a good half the tone of a Strat, and sensitive to the attack of your hands on the strings to boot. That's why I'd guess that the technology that can sound like my Deluxe (and a Twin and a Vox and frankly that's where I stop caring), should be able to model the relatively minor effects of a Lamm without breaking sweat.

I've never heard a digital drum kit, or a model of a concert grand through a system that could recreate the sound, but I've auditioned several of the modeling amps and own one of the Fenders. I have my issues with the thing, but the authenticity of the vintage, low-gain models isn't on the list. In my hands, through my G&Ls, in my bedroom or onstage, it performs as advertised. But thats a very different challenge from modeling acoustic instruments. The instrument is still there, all the amp has to do is model the tube amp's response to, and processing of that instrument. Modeling a tube hifi amp would be a similar challenge, maybe even a lesser one. It wouldn't have to model the amp's response to the organic dynamics of string attack, which was probably the hardest thing for them to get.

Boutique guitar amps? I had an original 65 Deluxe with NOS Visseaux 6v6s and a Weber. Never saw the point in boutique amps.

Tim

Tim, Tim, Tim,

Your problem is you just don't want to believe in the magic. What is wrong with you? Believe in the magic and it will become real for you. You know you cannot 'copy' magic.
 
Of course electric guitar amps are not about fidelity to the Strat. They are a good half the tone of a Strat, and sensitive to the attack of your hands on the strings to boot. That's why I'd guess that the technology that can sound like my Deluxe (and a Twin and a Vox and frankly that's where I stop caring), should be able to model the relatively minor effects of a Lamm without breaking sweat.

I've never heard a digital drum kit, or a model of a concert grand through a system that could recreate the sound, but I've auditioned several of the modeling amps and own one of the Fenders. I have my issues with the thing, but the authenticity of the vintage, low-gain models isn't on the list. In my hands, through my G&Ls, in my bedroom or onstage, it performs as advertised. But thats a very different challenge from modeling acoustic instruments. The instrument is still there, all the amp has to do is model the tube amp's response to, and processing of that instrument. Modeling a tube hifi amp would be a similar challenge, maybe even a lesser one. It wouldn't have to model the amp's response to the organic dynamics of string attack, which was probably the hardest thing for them to get.

Boutique guitar amps? I had an original 65 Deluxe with NOS Visseaux 6v6s and a Weber. Never saw the point in boutique amps.

Tim

It remains to be seen how difficult it is for digital modelling to recreate more timbrally and dynamically complex signals, which is why digital drum kits still can't quite capture the essence and response of the real thing. But technology advances, and in most cases the consumer continues to benefit. Who knows, maybe someone will release a 1U box that contains Lamm, Wavac, Shindo, Kondo, Atmasphere, Wavelength, WE, Altec, Marantz, ARC and lesser-known exotica available via virtually modelled algorithms - I suppose it's not outside of the realms of possibility. I admit it would be kinda cool being able to take something with the inherent efficiency and compactness of a Devialet and have $500K worth of tube amplification at your beck and call. And I imagine if one is only interested in the objective measurements of the FR, THD, IMD, crosstalk, slew rate, output impedence, etc, of those amps then maybe it's more possible than I think.

Whether or not it's possible to telegraph the more as-yet-unmeasurable subjectively-experienced characteristics inherent in they way those amps recreate musically significant signifiers - the portrayal of intention, touch, volition and emotion - not to mention its meaning, is anyone's guess.

G&Ls...? Had an ASAT Special with the MFD jumbo single coils in Cherryburst. Loved that guitar, loved it. Miss it too.
 
Tim, Tim, Tim,

Your problem is you just don't want to believe in the magic. What is wrong with you? Believe in the magic and it will become real for you. You know you cannot 'copy' magic.

The assumption that everything that needs to be known is known always amazes me. Heck it amazes me more than magic.
 
It remains to be seen how difficult it is for digital modelling to recreate more timbrally and dynamically complex signals, which is why digital drum kits still can't quite capture the essence and response of the real thing. But technology advances, and in most cases the consumer continues to benefit. Who knows, maybe someone will release a 1U box that contains Lamm, Wavac, Shindo, Kondo, Atmasphere, Wavelength, WE, Altec, Marantz, ARC and lesser-known exotica available via virtually modelled algorithms - I suppose it's not outside of the realms of possibility. I admit it would be kinda cool being able to take something with the inherent efficiency and compactness of a Devialet and have $500K worth of tube amplification at your beck and call. And I imagine if one is only interested in the objective measurements of the FR, THD, IMD, crosstalk, slew rate, output impedence, etc, of those amps then maybe it's more possible than I think.

Whether or not it's possible to telegraph the more as-yet-unmeasurable subjectively-experienced characteristics inherent in they way those amps recreate musically significant signifiers - the portrayal of intention, touch, volition and emotion - not to mention its meaning, is anyone's guess.

G&Ls...? Had an ASAT Special with the MFD jumbo single coils in Cherryburst. Loved that guitar, loved it. Miss it too.

You bring up drums again. I've never heard a reproduction system that got a drum kit right, so I don't think there's any way I can know if a model gets it right or not. Same goes for pianos. The advantage of guitar amp modeling is you play the model back through a guitar amp. That seems to get it. Take a line out, and play it through a very good PA, or even a studio monitoring system, and it loses something.

I don't think well ever know about modeling of tube hifi. I just don't think the market for it would ever believe in it.

G&Ls are the bomb. I've owned a bunch of them over the years, still have two.

Tim
 
The assumption that everything that needs to be known is known always amazes me. Heck it amazes me more than magic.

I would find that amazing as well, but what we're talking about here, as often as not, is reaching, stretching precariously for the unlikely in a desperate effort to deny the obvious.

Tim
 
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