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Old July 9th 07, 10:15 PM posted to uk.rec.audio
Eiron
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Posts: 782
Default (Spam) It's clearout time again!

Keith G wrote:
"Serge Auckland" wrote

If you're selling your Technics amp and the Dynacos, what will you
drive your TLS80s with, not a SET?


I certainly can, but right this minute I have my little (50 Watt?)
Denon PMA-655R on them - I doubt many could stand the *loudness* of a
CD at half volume on that setup!


Half volume is typically -20dB on most volume pots. CD players output
2 volts, and amplifiers typically have an input sensitivity of 100-500
mV so your CD at half-volume is outputting somewhere near the maximum
of the amplifier which is 50 W into 8 ohms, in practice probably more.
Consequently, I'm not surprised it's loud. However, if my experience
with IMF is anything to go by, you are probably clipping the little
Denon, which will also increase the apparent loudness. I wouldn't use
less than 100 watts on the IMFs, more if I had it.



Just off out, so a *quickie*:

The amp is fine 'til the 2 o'clock mark and then audibly distorting well
by the 3 o'clock mark. (The IMF 'manual' says 'Power Driving
Requirements: 40 - 100 Watts'...??)



It's generally better to know what the amp is doing rather than guess,
especially if you have a DVM and an oscilloscope.
I would disconnect the speakers, put on a test CD with a sinewave at 0dB
and adjust the volume control for 20v rms or 28v peak (50w into 8ohm),
then treat that as a maximum for the volume knob.
Or better still, make up an attenuated interconnect so that with the
volume turned up to 11, it gives 20v.

This won't stop the amp clipping with both the bass and volume turned up
but you could leave the 'scope connected to watch that.

--
Eiron.