petereugenefoley
Member
- Joined
- Sep 12, 2016
- Messages
- 10
Hello all. I got some Fairchild 662 preamps complete with input and output transformers for a steal. I hooked em up to my bench supply and they sound very nice; however, I would like to add an output trim so you can crank the input. Attached is the schematic -- the only thing that was cutoff was a zener diode between the -18VDC and R21, a 1W 56r resistor. I have questions:
1. The input control is a little 150r trimpot. If I want a more accessible input pot, would I simply replace this with a similar value and mount it to the faceplate of the rack unit it will go in? How might I add a stepped attenuator instead of a pot?
2. Where would I attach an output trim pot, and what would be an appropriate value?
Thanks.
Edit: after looking at the schematic more closely, would it be more correct to say the 150r trimpot is actually the output trim and I would in fact need to add an input pot?
1. The input control is a little 150r trimpot. If I want a more accessible input pot, would I simply replace this with a similar value and mount it to the faceplate of the rack unit it will go in? How might I add a stepped attenuator instead of a pot?
2. Where would I attach an output trim pot, and what would be an appropriate value?
Thanks.
Edit: after looking at the schematic more closely, would it be more correct to say the 150r trimpot is actually the output trim and I would in fact need to add an input pot?
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