In article , JustMe
wrote:
Some amps' frequency responses can alter during warm up. Whether
this is a reflection of poor design or the designer's intent is
another matter.

I'd be interested to know which models do this, and by how much, and
at what frequencies, this change occurs. Not something I have
encountered so far as I can recall.

It's an Alchemist Kraken integrated -
http://www.alchemisthifi.info/ranges...pd6_integrated
_amplifier.htm. It's a class A amp so runs hot (I don't know how much
the fact that the room temperature is 20 or 25 degrees effects an amp
that "idles" at about 55 degrees). I have noticed the same changes on
different examples of the same amp though, in different environments and
with different speakers. Recently I found an old review of the amp which
actually stated that the amp's frequency response fluctuated for several
hours before settling down -
http://www.alchemisthifi.info/ranges...integrated-rev
iew-hifichoice.jpg - I presume that this result was gathered through
measurement.

OK. Thanks for the above. The above does sound as if the operation of this
amp is, indeed, distinctly device-temperature dependent.

One of my favourite amps sounds *very* different when first powered
up, compared with when it's hot, to the degree that a demonstration
of it when cold would not impress me whilst, when warm, I love it.

Again, I'd be interested to hear the details.

See above. Like I say, I don't mind the fact that this happens, nor the
fact that, on paper the amp is noisy or gives "distortion", as I like
the amp more than the modest inconvenience of permenant power-up.

However, see the comment you make later on... :-)

I was at the hifi show in Manchester last week and overheard Eric
Kingdom from Sony talking about the digital Sony amps and talking about
the sound being "unusual" to some people because of the lack of
distortion introduced between source and speaker. He made the point
that, what a lot of people refer to as "musicality" was just colour and
distortion introduced by amps. I felt that this was probably right, but
it didn't make me prefer the Sony amp.

Not certain of his comments. For example, one reason the current 'digital'
amps may sound different is that they have to employ an LCL filter in their
output to stop the switching ultrasonics getting to the speaker at full
level. This filter then can alter the frequency response quite a lot in the
audio band with some speaker loads.

[snip]

There's no doubt that the Kraken amp is coloured, but that colour is one
of the things that I like about it - I enjoy the music more and so it
does what I've paid for. Even the amp's designer says that the frequency
response is deliberately rolled off early, so it strikes me that this is
by design and therefore not a flaw.

Again, see what you write later, though... :-)

[snip]

I'd be even happier if the amp sounded the same from the get go and was
silent when not in use.

This is the real point I was trying to make. If you prefer an amp with a
specific audible distortion or frequency response, etc, that's your
privilige. Similarly, the designer/maker can choose to offer that if they
also like it and feel some customers will do so. However if this *is*
your/their preference then I'd argue that it is their task to try and
ensure you get this *without* having an undue delay after switch-on.

To that extent, I'd say the design was 'flawed', although it may be a
'flaw' you are happy to live with, on balance.

Slainte,

Jim

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