[JaZZ]

Quote:

Originally Posted by milkweg /img/forum/go_quote.gif Sure, they make a difference but not to sound signature. They make a difference if they can drive your speakers/headphones to the sound level you like without clipping.

Don't put words in my mouth! You're interpreting my statement the way you would like it.
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[olblueyez]

Quote:

Originally Posted by milkweg /img/forum/go_quote.gif Sure, they make a difference but not to sound signature. They make a difference if they can drive your speakers/headphones to the sound level you like without clipping.

I wish someone had clued me in before I spent so much money on tubes.

 

[PhilS]

Quote:

Originally Posted by Pio2001 /img/forum/go_quote.gif For what it's worth, I've added the simulated frequency responce of a room in the FR topic : http://www.head-fi.org/forums/f133/m...5/#post5456598 We can see that an amp have response variations in the +/- 0.5 dB range, while a room is rather in the +/- 10 dB range, which is 20 times more. Also, the room has much more frequency peaks than the amplifier : 39 peaks between 20 and 1000 Hz, vs 2 peaks for the amplifier measured here : http://www.soundandvisionmag.com/ass...rInterface.pdf

Thanks. I figured there was support for the proposition that was previously advanced, and it makes sense. It just struck me as odd that an "objectivist" who relies on measurements or "science" to the exclusion of everything else would so casually toss out various statements subject to measurement or proof without any support. I guess what's good for the goose is not good for the gander.

 

[PhilS]

Quote:

Originally Posted by milkweg /img/forum/go_quote.gif Sure, [amps] make a difference but not to sound signature.

And your support for this is what again?

 

[Pio2001]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif I agree: metrologically room acoustics have much greater impact -- although you seem to think frequency response is all that matters, which is wrong.

Background noise is usually higher in the room than in the amplifier.

The reverberation time is much, much longer for a room than for an amplifier.

On the other hand, harmonic and intermodulation distorsion only become significant in the air over 120 dB.

 

[JaZZ]

Quote:

Originally Posted by Pio2001 /img/forum/go_quote.gif Background noise is usually higher in the room than in the amplifier. The reverberation time is much, much longer for a room than for an amplifier. On the other hand, harmonic and intermodulation distorsion only become significant in the air over 120 dB.

I understand that. My objection is directed to your limitation to frequency response as the sole measuring basis -- a discipline where all amps indeed are more or less identical, and rooms are not. Roughly spoken: amps have zero frequency-response distortion, whereas rooms have massive frequency-response distortion, so according to this logic the impact of a room is infinitely greater than that of an amp.

In turn the area where amps have the most obvious difference is the harmonic-distortion spectra -- whereas room acoustics generally have almost zero harmonic distortion (apart from a vibrating bookshelf and the like). So based on this premise the impact of amps is infinitely greater than that of room acoustics... Go figure!

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[Pio2001]

What's important is to quantify the problem. We could say that room acoustics have more wow and flutter than amplifiers, because according to the temperature, the eigen modes of the room can be moved a couple of Hertz away.
But wow and flutter are not important at all in room acoustics or in amplifiers.

I focus on frequency response because that is the only measurment that I have, and also because for me, this is the most interesting.
The next most interesting characteristics for an amplifier (after the frequency response with a real load) are the power, and the stability. Some designs overheat, clip, or even burn, when the load is too capacitive at low frequencies, or if there is a resonance in the speaker cable. Unfortunately, I found no clear technical characteristic that reflects this problem. I have been said that it was the "gain margin", or "phase margin", and i also read about the output inductance, that is supposed to prevent in-cable megahertz resonances.
It seems that distorsion and background noise come next.