What makes an amplifier "bright", "warm", or "neutral"?

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There's no simple answer.

Sound quality is affected by frequency response and various
distortion mechanisms, which are themselves mostly a function
of basic design. I'd guess the biggest variable is loudspeakers
and room acoustics.

Tube electronics have traditionally had a reputation for a 'warm'
sound, and semiconductors for a 'harder' and 'brighter' sound,
which appears to be mainly a function of the distortion products.
Tubes generally have a higher percentage of distortion, but their
proponents claim they still sound better. It's almost impossible
for me to say as I don't own any tube equipment and rarely
get a chance to listen to such.

One can substitute premium components for existing parts, but
the effect is almost always marginal; basic design counts for a
lot more, in my opinion.

It's a complex subject; everything depends on everything else.
 
Just as I feared. I must continue buying amps, stockpiling, trading in until I find just the right one!!! They always seem to auditon so much differently than they sound at home, and I have a VERY neutral listening room, my walls are all covered in MDF and then covered in sheetrock. One large, dead speaker box.
 
Yes JohnS,what is sheet rock?
You can use something like plastic foam (dont know if is right word).That stuff use drum players to isolate rooms,it have characteristic sine wave form.

"bright", "warm", or "neutral"?

That are well used words in audio,even more wierd words use in magazines and audio salesman when trying to sell you components.Even now i dont know why buy expensive audio rack that is built like a speaker? I mean with spikes and filled with some kind of sand...whatever.

I heard MOS fets have 'metal' sound :confused:
 
what is sheet rock?
Pressed Gypson that is sandwitch between 2 to 3 mm thick card boards.



Its MOSFET not MOS fet. MOSFET are mainly used in digital circuits. MOSFET may look good on graphs but they a far from being linear. They waste to much energy to produce the given wattage. Transistors on the other hand are linear and very predictable.


Sound cards these days can re-create just about anything. Cards with EAX has infinite possiblities.


An equalizer should be used if the speakers can not be position optimally in the room. Many rooms make different frequencies louder than other frequencies.
 
JohnS said:
Just as I feared. I must continue buying amps, stockpiling, trading in until I find just the right one!!! They always seem to auditon so much differently than they sound at home, and I have a VERY neutral listening room, my walls are all covered in MDF and then covered in sheetrock. One large, dead speaker box.

Maybe, after all, it's not the amps but the room is the problem. Dead boxes create dead sounds.
And who makes good equalisers?
 
Re: What makes an amplifier "bright", "warm", or "neutral"?

JohnS said:
Which component, components, or circuits make an amplifier "bright", "warm", or "neutral"?
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bright - lightly biased Class B/AB stages; some opamps; cheap metal film resistors; some metallised pp caps; most cheap lytics; hf noise or oscillations in circuit adds brittleness

warm - polyester caps; oil filled ones; some class A stages.

Just a few descriptors from experience
 
adding harmonics

Koy said:
Reading the first post an indea struck me. People say the tonality can depend on amout of upper harmonics ( prevailing even or odd harmonics). Does anybody know any software which can add some harmonics to the signal ( 2nd or so) to perform the test?

I am of the opinion, from my own experience, that it is not as simple as 2nd v's 3rd harmonic. Rather it is the relative distribution of harmonics that is important. Also, there seems to be a strong similarity between the distribution of harmonics in valve amps and class A transistor amps, class B being quite different to these two. This might help to explain why class A are reputed to have a warm "valve sound".

I have done subjective experiments in audio in the past and they are very difficult to design so that they give you unbiased results. The best way to go about it would be to capture some suitable music samples from a CD and then pre-process them using something like Octave running on your PC (free Matlab clone found at www.ocatave.org). If you are not familiar with DSP there is a steep learning curve to using programs like this but they are hugely powerful. You then would need to perform double blind tests using processed and unprocessed versions of the same track and analyse your results later. You have to be very meticulous to avoid biasing the results but if you go for it, I'd love to hear your results.


DocP
 
The Nature Of The Noise

Distortions spectrums and tiny abberations in static and dynamic frequency response, and source and load dependance, and slew rate limitation.
0.1 dB frequency response ripple is audible and apparent.
Also reaction to noise input.
Noise spectrum input and load noise spectrum can both be modified and substantially alter the percieved sonic character of a system.

Regards, Eric.
 
What makes an amplifier

Way to go Brett! Maybe the only honest rational answer possible to such a broad question. All one has to do is design amplifiers for about 10 to 20 years for the real answers to this question. I would not even dare to propose an answer and I don't think anyone else in his right mind would either as there are thousands of things that can effect this highly subjective classification.
 
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