Sound Quality Vs. Measurements

[Conrad Hoffman]

On the 627 thing, I used to use these for scanning tunneling microscopy; there was not much better out there for working with signals on the edge of existence. IMO, the input current and general behavior of the input stage is extraordinarily good.

That said, I have little opinion on their sound qualities one way or another for audio use, but my feeling is that people are paying a huge premium for characteristics that probably don't matter much for audio applications. It's another case of, "It's expensive and hard to get, so it must be better."

I still prefer the newer National (TI) parts because they're inexpensive, have lower distortion and are indistinguishable if the circuit is properly designed. If you're hearing differences between high performance opamps that don't show up with spectral analysis, differential or other methods, something is wrong.

[SY]

Originally Posted by a.wayne

Do tubes have more "effect's" than SS ..............?

Depends on the design. You can design either to be colored or either to be neutral.

[a.wayne]

Well considering that most tube amplifiers are power rated @1% thd and most SS at .01% from a pure technical position (taste's aside) it would appear tubes have more inherent distortion , more slewing, low damping and limited bandwidth (especially in the bass).


With all due respect, i find it interesting the cognitive dissonace of those building and designing tubes, where it does appear a lot of sound vs measurements is being practiced, especially when one consider their technical stance in other areas and the importance placed on such measurement for deciding good , better , best...


Just my Observance ....

[Wavebourn]

Originally Posted by a.wayne

Well considering that most tube amplifiers are power rated @1% thd and most SS at .01% from a pure technical position (taste's aside) it would appear tubes have more inherent distortion , more slewing, low damping and limited bandwidth (especially in the bass).

Absolutely not. The right answer is: tube amps even without heroic efforts to minimize THD and maximize DF can sound better.

However, high output resistance of tubes and low output resistance of dynamic speakers require output transformers that are tricky beasts. You can get wider bandwidth, better DF, lower THD, using much more expensive output transformers, but it does not worth it, since sound quality improvement from such heroic efforts is questionable.

I myself had such belief when was young, that absence of output transformers, availability of complementary devices, guarantees better results with transistor amps. No matter how good my complementary totally symmetric SS amps were measured, anyway that stubborn professional tube beast Tesla Mono-130 sounded better, cleaner, more transparent. Much later, when I returned back to audio design, and made tube amp that measures like best transistor amps in terms of THD, bandwidth, and DF, I finally realized how wrong I was thinking that tubes were worse devices than transistors.

[Conrad Hoffman]

Is "it" the tubes or the transformers that provide the magic? I'm thinking of the McIntosh solid state amps that still use transformers.

[Wavebourn]

Originally Posted by Conrad Hoffman

Is "it" the tubes or the transformers that provide the magic? I'm thinking of the McIntosh solid state amps that still use transformers.

Honestly, I don't hear any magic in McIntosh solid state amps. I've repaired recently one, it has just optimal design, unlike other amps that were made in order to get some specific measurements as best as possible without sound quality in mind.

[tvrgeek]

I wonder, with the basic tendency of a tube to act like a compressor more than a transistor does, maybe one raises the average level a little and the perception is more detail? Dependent on where the tube is biased along the load line of course. I don't recall much discussion about gain being non linear and its effect on subjective results. I remember back when our systems were full of peak unlimiters and various other boxes which all generated "impact" but in the long run were dismissed as not as musical. An LP at 65 dB range on a good day sure does not have the theoretical level of detail a CD does, but if you don't mind the other aspects, can be more, dare I use such a subjective term, involving? This should be easy to test. I think one of my DSP packages has a compressor.

Grasping at another straw, we typically measure amp distortion with a resistive load. Should we be measuring the difference to a captured sound from a reference speaker system? Are some of the subjective differences only measurable with the complex loads, or as Linkawitz describes, totally evil passive crossovers? Some far more evil than others. I might expect the full range driver camp to chime in here as that is the basis for their pursuits.

I quit playing with tubes after a few rounds of adding solid state rectification, bias control, and phase splitter. Each both measurable and sonicaly better. The end game would have to have been replacing the outputs with transistors. End of my tube experiments.

[SY]

Originally Posted by tvrgeek

I wonder, with the basic tendency of a tube to act like a compressor more than a transistor does...

Really?

[tvrgeek]

Er, yea. It is not linear either. Enter where the discussion splits to ccs vs cvs vs a resistor on the cathode.

[wahab]

Originally Posted by Wavebourn

tube amp that measures like best transistor amps in terms of THD, bandwidth, and DF

This , is unrealisticaly exagerated and at odd with all known
measurements/comparisons of best tube amps vs common SS amps,
let alone these latters best ones , unless you re talking about the
early transistorized amps , of course...