"Stewart Pinkerton" wrote in message
...
On Mon, 13 Dec 2004 23:27:18 +0200, "Iain M Churches"
wrote:

It obviously depends on the bandwidth of the amp, which doesn't have
much to do with 'high end' credentials.

Understood:-)
But I assumed the better the amp the better the performance.


A Naim amp for instance is
specifically designed to have limited bandwidth, and will have phase
angles of around 10-20 degrees at 20Hz and 20-30 degrees at 20kHz. At
the other extreme, a Spectral will have phase angles of less than five
degrees at these frequencies. My own Audiolab 8000P measures about 5-7
degrees at 20Hz and 8-10 degrees at 20kHz (approximated due to being
measured on a 'scope, since I don't have a vector voltmeter). The
Krell is about the same. Some SS amps are DC coupled, which will give
them zero phase angle at 20Hz.

Hmm! Thanks for the info. These are pretty impressive figs.
I have access to a phase shift generator/meter combination (digital of
course:-) made by Feedback Electronics in the UK.
That's why I was interested to obtain some kind of a yardstick.

An initial investigation of my 50W amplifier which has the first and second
stages DC coupled, shows -3 degrees at 10Hz, and -8 degrees at 50kHz.
So about the same as the Audiolab 8000P, and very close to the Spectral?
Not too shabby:-))

This amp has custom-designed Sowter transformers. A similar amp with
Hammond iron may not perform so well.

Iain