[[email protected]]

I just got a Van Alstine Model 1 preamp on Ebay. I wanted a simple
preamp to go with my MC225 and this seems to be it, except that the
power switch wiring has been buggered up. The "switched" outlet on the
back and the preamp are on all the time and the ON/OFF switch only
turns on the indicator light (why do people do this?). I want to put
this thing back the way it's supposed to be. Even though it was hacked
pretty badly, I think I can figure most of the intended wiring out, but
the part that has me confused is that my guess about the original
wiring would still have the preamp remaining powered all the time and
the on/off switch only switching the switched outlet. I should say that
my guess about the correct wiring comes only from staring at what's
left and trying to create a schematic from cut wire ends, etc. It's
seems weird that a commercial preamp would always be powered so I'd
like to look at a real schematic if anyone has one, or info on how to
get one. Also if anyone owns one of these I'd like to know what your
power switch does.

[Peter Larsen]

wrote:

back and the preamp are on all the time and the ON/OFF switch only
turns on the indicator light (why do people do this?).

They feel - or hear - that the sound is better after a few hours of
equipment warm up, and preamps usually have a small mains current
demand. It could also be a simple fix for a turn on/off thump behaviour.

I want to put this thing back the way it's supposed to be. Even
though it was hacked pretty badly, I think I can figure most of
the intended wiring out, but the part that has me confused is
that my guess about the original wiring would still have the preamp
remaining powered all the time and the on/off switch only switching
the switched outlet.

Makes perfect sense. My RIAA pre's are never powered down, my main pre
and cross-over are powered down if expected to be off for more than 4
hours. My amps are powered down if expected to be off for more than 2
hours, as are computers and monitors.

I should say that my guess about the correct wiring comes only
from staring at what's left and trying to create a schematic
from cut wire ends, etc. It's seems weird that a commercial
preamp would always be powered

No. Go to the local electronics all-mart and check out the number of
appliances that toggle between standby and on. Today it is so that if
you want something to be off and not contribute CO2 you have to
disconnect it or turn the wall socket switch, if any, off. Much simpler
anyway.

so I'd like to look at a real schematic if anyone has one, or
info on how to get one. Also if anyone owns one of these I'd
like to know what your power switch does.

I am not familiar with the product, I had probably given it a mains
switch if I had diy'ed it, and hardly ever used it, not even for turning
it off. One reason for the Van Alstine design choice could, as said
above, be that it thumps at turn on/off operations .... you might want
to add say a 12 to 18 dB fixed attenuator in front of your poweramp in
case it does, mostly doing just that is an advantage anyway.

Preamps traditionally have 22 dB gain in their line amp after the main
volume potentiometer, and CD-players output 6 dB more than what is
needed to clip household type poweramps. Such an attenuator also reduces
the risk of loudspeaker damage in case of unwise plug-in or out
behaviour.

Devices that go on stand by instead of powering down when the mains
switch is operated can be major wasters of your money ....

Peter Larsen

[[email protected]]

I have done that. No reply so far.

Regarding waste of power from always-on supplies, the worst offenders
are products with wall warts. A wall wart almost guarantees that it
will be left powered all the time. I must have at least a dozen plugged
in my house right now.

François Yves Le Gal wrote:
On 29 Nov 2006 01:24:46 -0800, wrote:

I'd
like to look at a real schematic if anyone has one, or info on how to
get one.

Why don't you contact Audio by Van Alstine, the manufacturer?

http://www.avahifi.com/