Natural Sound

[Atmasphere]

He defines "sound floor" as "The "lower limit" of an audio component's capability to reproduce (or pass) softer and softer sounds".

There are class D amps that are much better at that than SETs due to a lower noise floor (class D amps are immune to 0V crossing distortions). He sounds (if your translation is correct) as if he thinks other amps have a characteristic that 'gates' the signal, as if signals below a certain level are not amplified. Its utter rubbish, purified bunk. There are amps that aren't as good at low level detail since distortion is masking it. This is all about a good first Watt.

2. Atmasphere, who argues that to sound Natural equipment must be accurate so accuracy and sounding natural are the same thing, doubts SET’s can be “accurate” because of high second and third harmonic distortion. Then tells us that the OTL’s and class D amplifiers, that he sells, have much less distortion (so must be more accurate, thus sound more natural). But then, he owns a business that competes directly with Lamm for market share, so go figure.

This statement is highly misleading since its incomplete about my claims.I outlined far more than just 2nd and 3rd harmonic distortion. Since that is being ignored here I'm going to repeat myself and add more content.

SETs can't sound natural because of their high distortion (causing the sound to be warmer than the actual signal) but also because higher ordered harmonics causes them to sound more 'dynamic' than the actual signal itself which is unnatural. In addition, bandwidth is unavoidably limited causing them to sound anemic in the bass which is unnatural. Phase shift caused by limited bandwidth with no feedback to correct it causes colorations at the bandwidth extremes. The rise time is very slow (often less than 10V/usec), causing the amp to actually sound slow compared to the actual signal. Speed is important as the brain has tipping points, so when its too slow the music processing moves to the cerebral cortex rather than being processed by the limbic centers as in real life. Hum and noise is a problem since you need high efficiency speakers to really take advantage of what SETs do right. Output impedance is high, so most speakers simply cannot be used with them not only because they might lack the efficiency but also because tonal aberrations will result.

SETs are Power Paradigm technology like any zero feedback tube amplifier and so will attempt to make constant power with respect to the load impedance rather than constant Voltage (IME no zero feedback tube amp succeeds in this). This isn't a fault so much as something you have to be aware of when choosing a speaker as this limits the speaker choices enormously. As a general rule of thumb its a good idea to ask the designer of the speaker what sort of amp is recommended for the speaker. Fortunately the brain pays more attention to tonality generated by distortion rather than that caused by actual FR errors but this still crops up! Many modern speakers are rated '8 Ohm compatible' but are really 4 Ohms in the bass. Zero feedback tube amps will sound bass shy on such speakers; move the speaker cable to the four Ohm tap and it gets better but now the mids and highs aren't right. A proper Power Paradigm loudspeaker will thus have controls on the back for the midrange and high frequency drivers to allow you to set the speaker to match the Voltage response of the amplifier. If you have a vintage JBL, Altec, EV and the like you've seen these controls. IOW Zero feedback tube amps are not plug and play with respect to speakers.

What SETs do right: the lower ordered harmonics very easily mask higher orders which is important as they make more higher ordered harmonic distortion than any other kind of topology. That's why they sound nice and smooth despite the large amount of higher ordered harmonic distortion compared to other kinds of amps. Distortion vs frequency is a ruler flat line across the audio band and this is IMO is far more important than THD, which I think we all agree is highly misleading if stated by itself (since it tells you nothing about how the amp will sound). Quite literally this is why SETs are around, why tubes are still around; solid state amps have been terrible at this since their inception. Fortunatly there's a way out of that problem for solid state, but it appears that right now there aren't that many solid state designers that understand how important distortion vs frequency really is, so most solid state amps today still sound lifeless, boring and/or bright.

I read your second paragraph to say when you play a record of a recording, accuracy and natural "are effectively one and the same" because we don't have access to the performance that was recorded. I read that as (in your words) a proposition, but I don't read it as a conclusion. I believe you see it as true, but to me it is simply a statement without means to convince.

Maybe we have a different understanding of 'accuracy'. I accept a standard dictionary definition viz:
"the condition or quality of being true, correct, or exact; freedom from error or defect; precision or exactness; correctness." Or accurate "free from error or defect; consistent with a standard, rule, or model." Are those your meanings?

How can we tell that experiencing natural sound from a system is accurate, that it is 'true', 'correct' etc.?

I answered the above question (higlighted) earlier but again: You need a recording you made so you know. You don't have to produce an LP or CD, the master (especially if digital) is all you need. Contact a local group that plays in a decent venue that you know (for me this was O'Shaunnassy Auditorium on the campus of St. Catherine's College in St. Paul) and see if they will let you record. Recording equipment these days isn't expensive relative to the kind of money people shell out for a decent SET. When I started doing on-location recordings really good mics required me to take out a bank loan. Now you can get into good large diaphragm condensor mics for a few hundred dollars! To me this is a no-brainer.

The dictionary definition is the one I use. To your first paragraph, I regard the italics of the statement above as requires no conclusion as it is a conclusion and not a proposition. The means to convince is that you have to understand that no-one uses a direct microphone feed to play music; everyone uses recordings. So being accurate, being true to the recording is the only access to the system sounding natural. If the system somehow sounds natural and the recording is not, that's just wrong!

Did not this discussion get started because Ralph claimed that my system could not sound natural precisely because a signal at my Lamm ML2 SET amplifier’s output does not match the signal at the input? He determined this by measuring the two and concluding they are not the same so the amp is not accurate so the sound is not accurate which is the same as the sound is not natural.

No. It started because I said that SETs don't work because they are incapable of sounding natural because they are not accurate; explaination repeated above.

Ralph further stated that speakers that do not accurately convey the bottom octave cannot be considered accurate or able to produce accurate sound and because of his equivalency, that means that they cannot sound natural. That sounds like an absolute statement to me.

It is- you are correct! I may have spent too much time playing in an orchestra. I can enjoy systems that lack the bottom octave but that isn't the same as saying that they sound natural as they are not accurate. I want it to be convincing.

In case its not clear, I don't regard a solid state amp that has 0.001% distortion but sounds 'boring and sometimes offensive' as being either accurate or natural. Unless the recording itself is 'boring and sometimes offensive' then the amp is simply wrong, probably because the designer didn't understand the importance of preventing distortion rising with frequency- something that any SET owner understands innately if not conciously.

I don’t keep changing the conditions of the argument.

Neither do I, just for the record.

 

[Atmasphere]

As an example: have you spent time with a very low distortion amp? Those that say thd 0.001% @ 500W, but forget to say that last bit is all high order, even at 1W? That's a very close to zero figure, so we should be good. It is also a very boring and sometimes offensive experience. Not all distortion is created or perceived equal. Very few things are linear and simple. Details matter.

+1 Emphasis added

I just said Class A amplification are more linear and never compared SET vs Push Pull.

No worries! FWIW please do not attach meaning to my statements where it does not exist. I tend to be very literal and get in trouble for that a lot (as here). So to best interpret my comments (and I hope my ability to convey my thoughts is sufficient, although its obvious it often falls short) its best to read only what I wrote and nothing beyond that. I beleive Pater A and I are going 'round and 'round a bit due to the specific and literal nature of how I convey myself.

It seems matching of amplifier/speaker is very important in this area.

Yes- especially if the tube amp (whether SET or not) is zero feedback! You might want to read the article I linked above.

 

[hopkins]

There are class D amps that are much better at that than SETs due to a lower noise floor (class D amps are immune to 0V crossing distortions). He sounds (if your translation is correct) as if he thinks other amps have a characteristic that 'gates' the signal, as if signals below a certain level are not amplified. Its utter rubbish, purified bunk. There are amps that aren't as good at low level detail since distortion is masking it. This is all about a good first Watt.

The proof is in the listening. Send him one of your amps!

 

[Al M.]

Did not this discussion get started because Ralph claimed that my system could not sound natural precisely because a signal at my Lamm ML2 SET amplifier’s output does not match the signal at the input? He determined this by measuring the two and concluding they are not the same so the amp is not accurate so the sound is not accurate which is the same as the sound is not natural.

"Accuracy" is not that simple. What does that even mean in practice, that a signal at the output does not match the signal at the input?

A component and even a whole system do not live in the abstract. They live in the room and with speaker/room interactions.

Let's take an example, speaker toe-in:

1. I like the least possible toe-in that I can get away with, under three conditions:
a) Vocals still need to be transparent
b) the sound still needs to pass the "triangle test"
c) the speaker/room interactions must not turn for the worse with toe-out of speakers

I prefer more toe-out because it sounds more realistic (or natural) to me, i.e., what best matches, on average, concert experiences of unamplified live music. Now, is it "accurate"?

In the sense of ruler-flat, linear frequency response when it comes to reproducing the recording, probably not. The signal at the output may not match the signal at the input. But then, as far as I am aware, it is known that most listeners prefer some in-room treble roll-off, rather than a ruler-flat frequency response.

2. Different amplifiers give different treble responses on my speakers, but this can be compensated by slight variations on toe-in (which are of a small enough magnitude where other aspects of the sound are not significantly affected).

Now, even if one amplifier shows a rolled-off frequency response compared to another which may be more linear (and thus, in a traditional sense, more accurate), what does it matter if it can be compensated for by changes in speaker toe-in? What matters is the "accuracy" of the whole system, no?

Now let's take bass as another example:

If I move either my speakers or my listening chair the bass changes. Obviously, I am trying to find the best position for both where, on average, I get what I personally perceive as the most realistic (or natural) bass response. Also, I dial in the volume of subwoofers so that they support the bass in the best (most effective while still unobtrusive) manner, to my perceptions and taste.

Is this the most ruler-flat, "accurate", bass response? Maybe not. Why should I care? If it sounds the best to me, isn't that what gives me the most "accurate" window into recordings across a wide palette of them?

Given all the above, which "accuracy" are we really talking about? As I argue, "technical accuracy" of a component is a *relative* concept in the context of an entire system, and on a broader scale, of a system with its speaker/room interactions.

If the signal at the output (i.e., the sound in the room) matches the signal at the input, and if this even matters, must be judged in the system/room context.

 

[Amir]

There are class D amps that are much better at that than SETs due to a lower noise floor (class D amps are immune to 0V crossing distortions).

SETs can't sound natural because of their high distortion (causing the sound to be warmer than the actual signal) but also because higher ordered harmonics causes them to sound more 'dynamic' than the actual signal itself which is unnatural. In addition, bandwidth is unavoidably limited causing them to sound anemic in the bass which is unnatural. Phase shift caused by limited bandwidth with no feedback to correct it causes colorations at the bandwidth extremes. The rise time is very slow (often less than 10V/usec), causing the amp to actually sound slow compared to the actual signal. Speed is important as the brain has tipping points, so when its too slow the music processing moves to the cerebral cortex rather than being processed by the limbic centers as in real life. Hum and noise is a problem since you need high efficiency speakers to really take advantage of what SETs do right. Output impedance is high, so most speakers simply cannot be used with them not only because they might lack the efficiency but also because tonal aberrations will result.

No. It started because I said that SETs don't work because they are incapable of sounding natural because they are not accurate; explaination repeated above.

“Natural sound” (like warm, sweet, emitional, cold, …) is a subjective term not about objective measurements. You can not say SET is not natural because it’s distortion is high.
Let me share an example: Silver cables are very very similar to copper cables in objective term (measurements) but copper cables sounds more natural more warm less bright.

No amplifier is perfect, if SET has high distortion and I exactly know why you do not like it then Push Pull amplifiers are not pefect to my ears.
I do not say SET is better than push pull but my limited experience shows I like SET more than push pull .

 

[wil]

“Natural sound” (like warm, sweet, emitional, cold, …) is a subjective term not about objective measurements. You can not say SET is not natural because it’s distortion is high.
Let me share an example: Silver cables are very very similar to copper cables in objective term (measurements) but copper cables sounds more natural more warm less bright.

No amplifier is perfect, if SET has high distortion and I exactly know why you do not like it then Push Pull amplifiers are not pefect to my ears.
I do not say SET is better than push pull but my limited experience shows I like SET more than push pull .

It sounds like you’re describing “natural” as more of a coloration rather than a true (as possible) representation of the recording.