"Des" <des@oregon.nOSPamPlz.org.uk> wrote in message
news:7ub3hv4up31o6avjqs5hf3k2racnh2grku@4ax.com...
> Reviewers often comment that it takes about 100 hours before a new amp
> settles down and start to sound like it 'should'.
>
> In this case, what constitutes 'burning-in'? Is it sufficient to just
> leaving the power on for a week? Or does it have to be driving a load
> (the neighbours are going to just love that)?

IMHO yes leaving the power on helps, but it would be better if you listened
to music 'from cold' to find out if you can hear any differences as things
warm up. If not, then save some electricity and leave it off when not in
use!

I can think of some areas where changes occur in an amplifier over time.
These may be minor and in most amps inaudible, but it depends on the design
and the listener.

1. Electrolytic caps in PSUs. These 'form' over a very long time (weeks).
Would lead to better performance (ie better smoothing, more DC like
voltages) over time.

2. Temperature effect on electrolytic caps. In switched mode supplies too
much heat dries them out and they lose effectiveness. If you look at specs.
they quote life of say 10,000 hours. Most supplies last a lot longer than
that!

3. For coupling capacitors between stages (ie in the analogue audio path)
effects 1. & 2. would effect slightly the characteristics of the capacitor
to how well if passes signals of different frequencies. May or may not be
audible.

4. Transistors warm-up. Again for analogue stages the transfer function of a
transistor will vary with temperature, depends on the design how well this
is compensated for.

HTH, no 'rules', just listen with open ears.

Regards,
John