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

[esldude]

Tubes are better because they do a better of passing the details of real music in real space.Dealing with the problems is just easier. DHT is the holy gmail of audio. Now other goals may be better served by other devices. Overall
there is no contest.

Well actually tubes color the sound to seem as if they have more details or more real music. Those differences you hear, are generated by the tube equipment. The input signal actually didn't have it to start with. The tube equipment added it in.

DHT may be the holy g(r)mail of audio, if so we need to get the signal transfer figured out so we can add it with DSP to all of our equipment. Unless Monty Python is doing an updated movie called Monty Python and the Holy Gmail.

 

[DonH50]

The Maggies, other than impedance, seem to be pretty easy to drive. There is a conversation here about the difference between efficiency and sensitivity though. Both are a measure of energy being placed in the speaker. One is a Power Paradigm measurement and the other is the Voltage Paradigm measurement (see http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php). If the speaker is 8 Ohms they are the same thing. If the speaker is 4 ohms, the efficiency will be 3 db less than the sensitivity rating. So a 4 Ohm loudspeaker that is rated at 90 db Sensitivity (2.83Volts/1 meter) is really 87 db efficient (1 watt/1 meter). This is because 2.83 volts into 4 Ohms is 2 watts, not 1.

So when two woofers are put in parallel, they have the same efficiency as a single woofer, but the sensitivity figure will be 3 db higher as the impedance is cut in half. I do find that people are confused by this, but it relates to something called Kirchoff's Law, which says that there can't be any more energy in an electrical system than the energy put into it. So if you have 2 woofers in parallel, and put 1 watt into the array, each woofer will dissipate 1/2 watt. A single woofer with the same 1 watt will dissipate the entire thing.

Understood. I routinely convert Magnepan's voltage-based number to power to compare dB/W/m since that used everywhere. I do have a passing understanding of Kirchoff's Laws and how parallel/series circuits work... I realize you probably know that.

To add a bit, if the woofers in question are in two separate boxes, then their placement also matters and influences the effective SPL gain.

Aside: Is your OTL circuit patented (i.e. is there a schematic I could see?) Curious...

 

[MylesBAstor]

Well actually tubes color the sound to seem as if they have more details or more real music. Those differences you hear, are generated by the tube equipment. The input signal actually didn't have it to start with. The tube equipment added it in.

DHT may be the holy g(r)mail of audio, if so we need to get the signal transfer figured out so we can add it with DSP to all of our equipment. Unless Monty Python is doing an updated movie called Monty Python and the Holy Gmail.

In your opinion. Which is no more valid than Greg's opinion.

 

[esldude]

In your opinion. Which is no more valid than Greg's opinion.

In your opinion.

 

[Phelonious Ponk]

In your opinion. Which is no more valid than Greg's opinion.

In your opinion.

Let's break this down (quotes from esldude):

Not just opinion:

Well actually tubes color the sound

Opinion, everywhere except in the scientific relativist world of the high end:

to seem as if they have more details or more real music.

Not, etc.:

Those differences you hear, are generated by the tube equipment. The input signal actually didn't have it to start with. The tube equipment added it in.

Opinion:

DHT may be the holy g(r)mail of audio, if so we need to get the signal transfer figured out so we can add it

Not etc.:

Unless Monty Python is doing an updated movie called Monty Python and the Holy Gmail.

Tim

 

[MylesBAstor]

Let's break this down (quotes from esldude):

Not just opinion:



Opinion, everywhere except in the scientific relativist world of the high end:



Not, etc.:



Opinion:



Not etc.:



Tim

Tim perhaps you can supply us with the reference (s) to the peer reviewed scientific paper (s). Otherwise it's just speculation and conjecture that has no more validity than anything else posted. Hell ESL couldn't even explain why OTL amps (and I might add other topologies-not to mention the original recording) didn't fit into his *theory*. That ambience isn't created by tubes; it's there on the master tape not to mention the hard drive. No it's lost during the production and recovery process.

At least Ralph provided some scientific studies.

 

[Mark (Basspig) Weiss]

So how do you explain my findings about a Spectral SS amp sounding in my system very similar to my tube amp in post #22 (page 3 of thread)?

There's really too little information to go on. Are you comparing a 2A3 amplifier to a SS amplifier? They are vastly different creatures and I know of no SS amplifiers in manufacture today that boast 10% THD figures at 4 watts output.

 

[microstrip]

(...) More magic from you Micro? (...)

No Tom, the "magic" comes from the well known audio designers that I have referred in this thread. But if someone only knows about very simple things everything else looks like "magic". However, as I told you - you have won - I can not explain it better than the original authors and specially keep it "simple" - your word for very basic electronics.

 

[Phelonious Ponk]

Tim perhaps you can supply us with the reference (s) to the peer reviewed scientific paper (s). Otherwise it's just speculation and conjecture that has no more validity than anything else posted. Hell ESL couldn't even explain why OTL amps (and I might add other topologies-not to mention the original recording) didn't fit into his *theory*. That ambience isn't created by tubes; it's there on the master tape not to mention the hard drive. No it's lost during the production and recovery process.

At least Ralph provided some scientific studies.

Miles, you don't need a study to know that it's not just an opinion that tubes color the sound, or to know that the color comes from the tube equipment itself. All you need are some fairly banal measurements of the source signal and the output of the tube gear. Or if you don't believe in simple FR and distortion measurements, you can do a null and hear the difference for yourself. This is not to say that it's bad or good, just to say that it is. And I can't point you to peer-reviewed and verified studies on the subject, because no one would put in that kind of effort to confirm the obvious.

This is also not to say that there isn't some as of yet unmeasured and immeasurable ingredient in tubes that raises their fidelity beyond current measurements and reveals detail from the source material that would be obscured by any other technology with the same distortion, compression and noise. Sure...it could happen.

Tim

 

[microstrip]

(...) This is also not to say that there isn't some as of yet unmeasured and immeasurable ingredient in tubes that raises their fidelity beyond current measurements and reveals detail from the source material that would be obscured by any other technology with the same distortion, compression and noise. Sure...it could happen.

Tim

Tim,

What is your opinion about the studies about thermal distortion and thermal memory in semiconductors? Their author carried and published lots of measurements ...

 

[DonH50]

Note tubes also have thermal modulation and distortion effects. Feedback solves a host of ills, for either technology. Personally I think the transformer dominates tube amplifier characteristics and discussions of electron flow in semiconductors vs. vacuum and plates/grids/etc. is somewhat moot. The added harmonics from tube amps often leads to a "fuller" sound people enjoy, and I am not immune to that, but it is not as accurate.

I have never heard Atma-Sphere OTL amps so cannot comment on them.

Edit: Sorry, I see this is devolving, I shall bow out. Enjoy your day, unless you've made other plans. - Don

 

[Al M.]

There's really too little information to go on. Are you comparing a 2A3 amplifier to a SS amplifier? They are vastly different creatures and I know of no SS amplifiers in manufacture today that boast 10% THD figures at 4 watts output.

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.

 

[Al M.]

No Tom, the "magic" comes from the well known audio designers that I have referred in this thread. But if someone only knows about very simple things everything else looks like "magic".

That about covers it.

 

[microstrip]

Note tubes also have thermal modulation and distortion effects. Feedback solves a host of ills, for either technology. Personally I think the transformer dominates tube amplifier characteristics and discussions of electron flow in semiconductors vs. vacuum and plates/grids/etc. is somewhat moot. The added harmonics from tube amps often leads to a "fuller" sound people enjoy, and I am not immune to that, but it is not as accurate.

I have never heard Atma-Sphere OTL amps so cannot comment on them.

Edit: Sorry, I see this is devolving, I shall bow out. Enjoy your day, unless you've made other plans. - Don

Don ,

How can you then explain that most of the sound characteristics people often associate with tubes also come from tube preamplifiers with excellent distortion measurements? Or that some recent SS amplifiers with excellent measurements sound like tubes in many people opinion, most of those preferring the classic SS sound?

The discussion on the thermal distortion was not started by the tube people, but by audio designers who were studying semiconductors. Curiously it was told that some semiconductors they preferred emulated very well some tube characteristics. If you are addressing just the "fuller" sound as the main characteristic of excellent tube designs, IMHO you are missing the more important positive aspects - you are just looking at the main negative aspect. IMHO transformer has an important contribution to avoid degrading the characteristics of the amplifier. However it is often excessively used as a main characteristic by marketing, as it is an unique feature of each design.

IMHO no system is perfect - even SS amplifiers. As some technical people can not explain the sound differences between solid state designs correlating them with measurements - surely these differences are due to faults in their performance, they focus their attention in tubes, although they are not their preference and they have little positive experience with them. But provoking audiophiles, specially tubephiles is so tempting ... Although yes, the OP openly regretted it, but this time the initial provocation comes from an unfortunately chosen thread tittle and mislead first post.

BTW, Don, no one is wanting to discuss the electron flow, just the consequences of using devices based in different physical principles.

 

[MylesBAstor]

Don ,

How can you then explain that most of the sound characteristics people often associate with tubes also come from tube preamplifiers with excellent distortion measurements? Or that some recent SS amplifiers with excellent measurements sound like tubes in many people opinion, most of those preferring the classic SS sound?

The discussion on the thermal distortion was not started by the tube people, but by audio designers who were studying semiconductors. Curiously it was told that some semiconductors they preferred emulated very well some tube characteristics. If you are addressing just the "fuller" sound as the main characteristic of excellent tube designs, IMHO you are missing the more important positive aspects - you are just looking at the main negative aspect. IMHO transformer has an important contribution to avoid degrading the characteristics of the amplifier. However it is often excessively used as a main characteristic by marketing, as it is an unique feature of each design.

IMHO no system is perfect - even SS amplifiers. As some technical people can not explain the sound differences between solid state designs correlating them with measurements - surely these differences are due to faults in their performance, they focus their attention in tubes, although they are not their preference and they have little positive experience with them. But provoking audiophiles, specially tubephiles is so tempting ...

BTW, Don, no one is wanting to discuss the electron flow, just the consequences of using devices based in different physical principles.

Once again design execution, not topology.

Or you belong to the flat earth school where all amplifiers sound alike. Solved the problem very nicely don't you think?

 

[DonH50]

I really don't want to get into a big debate nobody is going to win. Yes, my last few posts focused more on the bad, typically in response to other posts. I have stated the good elsewhere on WBF and other fora, will toss out a couple below.

The transformer argument only applies to power amps. And SS amps can also exhibit FR variations (etc.), just typically less than transformer-coupled tube amps.

IME the best tube and solid-state preamps sound very similar. Tube preamps tend to have a little more noise but much greater headroom, something I find especially good for handling the glitches from some DACs and ticks/pops from most all phono cartridge/records. That said, tube preamps with very low distortion seem to often garner the dreaded "sounds like SS" label, as I mentioned in an earlier post talking about the differential tube preamp I designed and reviews of some of the commercial tube preamps.

The distortion characteristics of tube and SS devices, and preamps, are well-known and can be readily measured. Not by me now as I don't have access to good audio-range test equipment at my current workplace, but I have done it in the past. My old SP3a-1 had <0.001% THD at modest (~1 Vrms) output, at my measurement floor and certainly as good as SS. 2HD tends to dominate the output of tube preamps, 3HD (and related IMD products) for SS. And of course many (most?) tube preamps still have much higher output impedance than SS preamps. Even with cathode-follower outputs my ARC was pretty load-sensitive; it did not like the ~10k load of several SS amps nearly as well as the ~100k load of my tube amps and higher distortion resulted with low loads. I did try using a FET buffer for a while but my final system had amps high enough in impedance it wasn't needed.

IIRC, in the audio range tubes tend to have less flicker and popcorn noise than most SS devices, though I am not certain of that (long, long time since I tried to compare noise characteristics). Using a microwave transistor at audio is usually a very bad idea.

Of course no system is perfect, and I suspect most of the problem measuring differences lies in the difficulty of recreating real-world test scenarios (test loads, signals). It is a lot of effort, and after you do all that a bunch of people will jump in and say it does not apply to their system. They'd be technically right but by and large I think the differences are overstated. My perception of the music changes much more with my mood, time of day, weather etc. than by rotating through several components in my system. That said, load (and other) interaction among components is one of the areas I feel most promising for explaining differences, and one of the very hardest to measure and correlate.

There was a discussion of electron flow earlier in this thread.

 

[microstrip]

(...) Of course no system is perfect, and I suspect most of the problem measuring differences lies in the difficulty of recreating real-world test scenarios (test loads, signals). It is a lot of effort, and after you do all that a bunch of people will jump in and say it does not apply to their system. They'd be technically right but by and large I think the differences are overstated. My perception of the music changes much more with my mood, time of day, weather etc. than by rotating through several components in my system. That said, load (and other) interaction among components is one of the areas I feel most promising for explaining differences, and one of the very hardest to measure and correlate.

There was a discussion of electron flow earlier in this thread.

Don,

I think that we agree on most of the technical aspects and difficulty of measuring and correlating, we have a different valuation of the importance of the differences and perceptual aspects.

And I have to say I do not consider the provocative flow of a few posts between two of our members as a "discussion of electron flow"!

 

[Phelonious Ponk]

Tim,

What is your opinion about the studies about thermal distortion and thermal memory in semiconductors? Their author carried and published lots of measurements ...

Haven't read it. Does it conclude with measurements of the output that show that semiconductors alter the signal audibly? Comparably to tubes?

Tim

 

[microstrip]

Haven't read it. Does it conclude with measurements of the output that show that semiconductors alter the signal audibly? Comparably to tubes?

Tim

No.

 

[DonH50]

Don,

I think that we agree on most of the technical aspects and difficulty of measuring and correlating, we have a different valuation of the importance of the differences and perceptual aspects.

Agreed.

And I have to say I do not consider the provocative flow of a few posts between two of our members as a "discussion of electron flow"!

Someone brought up differences in electron flow in tubes vs. transistors, I don't feel like trying to find the posts about that. Nor trying to debate drift currents, voltage fields, and quantum mechanics in this thread... I survived my college classes and delved deeply years ago when I started working with heterojunctions but have not looked at device physics for a long time.