My ST70 is located on a fairly high shelf for safety. I have a couple of curious grandkids that think the tubes are pretty lights. The power switch is difficult to get to, but I always find a way. The unused mono/stereo switch is a convenient location, but I'm skeptical of running AC from the back of the chassis to the front. Recommendations are welcome.....
5 posters
Power switch (re)location
GreggW- Posts : 80
Join date : 2015-07-16
peterh
peterh- Posts : 1869
Join date : 2012-12-25
Location : gothenburg, sweden
My recommendation for powerswitch :
Install an SSR ( solid state relay) inside, connect it in paralell with the existing power switch,
and install a rca connector that is used for the 3-32V control circuit.
Then tap your preamp for a DC withing the range ( PAS3 already has a suitable DC), on anything else
if no DC available, rectify filament and use as control.
This will give a convenient remote power control.
An alernative ( not as fun) is to purchase a AC distribution panel where one outlet
will control the others, connecting the preamp to the controlling outlet will
enable the other outlets that may be used for the ST-70.
Don't rewire AC to the front switch !!
Install an SSR ( solid state relay) inside, connect it in paralell with the existing power switch,
and install a rca connector that is used for the 3-32V control circuit.
Then tap your preamp for a DC withing the range ( PAS3 already has a suitable DC), on anything else
if no DC available, rectify filament and use as control.
This will give a convenient remote power control.
An alernative ( not as fun) is to purchase a AC distribution panel where one outlet
will control the others, connecting the preamp to the controlling outlet will
enable the other outlets that may be used for the ST-70.
Don't rewire AC to the front switch !!
audiobill- Posts : 425
Join date : 2014-03-13
Location : Albany, NY
How about a switched outlet strip of sufficient current?
sKiZo- Posts : 1530
Join date : 2013-04-02
Location : Michigan USA
I'm still kinda partial to my power switch ... ;-}
Not sure what your issue is with just rerouting the power switch to the spot used by the mono switch? Kinda tight, but seems to me I've seen it done. Wires for mine go a whole lot farther than yours would in a stock chassis, and I've not had any noise issues or such.
Plan B - reroute all the bias connections to just one of the bias sockets to make room for a power switch there?
Or just drill a hole in the side of the chassis for a toggle.
Or just add an inline switch to the power cord and bring that to the front under the chassis?
Lotsa options, eh. Some that might even work!
Not sure what your issue is with just rerouting the power switch to the spot used by the mono switch? Kinda tight, but seems to me I've seen it done. Wires for mine go a whole lot farther than yours would in a stock chassis, and I've not had any noise issues or such.
Plan B - reroute all the bias connections to just one of the bias sockets to make room for a power switch there?
Or just drill a hole in the side of the chassis for a toggle.
Or just add an inline switch to the power cord and bring that to the front under the chassis?
Lotsa options, eh. Some that might even work!
GreggW- Posts : 80
Join date : 2015-07-16
I read the replies and decided to take another look at my amp. Seems like there are a lot of extra parts in it like a second choke and some extra capacitors. The power transformer has the same height as the one on the 120. The ST70 is a ST120! Never looked at the ST120 on the Tubes4HiFi page as I "assumed" it was a 70. No wonder my electric bill is a little high. Anyway, I'm going to move the power switch to the front and see what happens. If I get negative (60-cycle) waves, it will get moved back. Thanks for the good tips.
peterh- Posts : 1869
Join date : 2012-12-25
Location : gothenburg, sweden
GreggW wrote:I read the replies and decided to take another look at my amp. Seems like there are a lot of extra parts in it like a second choke and some extra capacitors. The power transformer has the same height as the one on the 120. The ST70 is a ST120! Never looked at the ST120 on the Tubes4HiFi page as I "assumed" it was a 70. No wonder my electric bill is a little high. Anyway, I'm going to move the power switch to the front and see what happens. If I get negative (60-cycle) waves, it will get moved back. Thanks for the good tips.
You don't really listen ehh ?
Luddite- Posts : 233
Join date : 2009-02-04
Age : 74
Location : Texas
audiobill wrote:How about a switched outlet strip of sufficient current?
IMHO this would be the best option (K.I.S.S. principle). You probably just need a temporary solution until your grandchildren are old enough to have learned not to touch hot objects. At that point you could rearrange your hi-fi components so that the amplifier is more easily accessible. FYI, I built an ST70 in the early 90's from NOS Dynaco parts, obtained from Sound Values. Not only did I locate the power switch on the front, I also located the fuse holder on the front. Furthermore, the audio inputs were relocated to the rear of the chassis. These modifications caused no problems whatsoever. Thanks and...
Best Regards,
Charlie