Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Stereomour => Topic started by: Dobs on December 14, 2013, 03:44:18 PM
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Is it possible to easily install a variable preamp out on the Stereomour?
Thanks
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You can hack all kinds of stuff into or alongside most of our products, including Stereomour - but it was not designed with a small-signal output in mind, so whatever you do will be a hack, not just a parts substitution.
That said, what exactly do you mean by "variable preamp output"?
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Preamp signal that will follow the volume control
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You can, but it will potentially have pretty high output impedance, which is very undesirable.
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Yeah, what PB said. There are two choices which I believe I've posted before, but the posts may be hard to find:
1) If all your sources will work with a 10K ohm load, you can swap the volume control for a 10K potentiometer, and take the output of the pot to a set of output RCA jacks as well as to the driver grids.
2) You can put a small resistor in series with the 249K grid resistor of the 2A3 or 45 output tube, at the ground end, and take the signal across this resistor to a set of output RCA jacks. A value of 4K or less is desirable.
In both cases, you should still keep the output interconnects as short as possible, no more than 2 meters and of low capacitance. Also in both cases, you will have to either give up one of the three inputs, or find another place to put the output RCA jacks. Not having tried either one, I can't guarantee their performance. These are the reasons I call these changes "hacks".
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Option 2 looks better, i think i will try this way.
Thanks a lot,