I am not quite sure which forum this belongs in, but I would like for someone to look over my passive pre-amp design that I may build for an innaugural electronics project.
I will use a linear pot/high quality resistor bridge for attenuation. I will use a DPDT with a center off to switch between two inputs, and the center for mute.
There will be two of the attenuators, so that I have both balance and volume control. (Turn both for volume increase/decrease, turn one for balance adjustment) This will keep the signal paths the simplest, one fo my goals.
Let me know what you think.
-Paul Hilgeman
I will use a linear pot/high quality resistor bridge for attenuation. I will use a DPDT with a center off to switch between two inputs, and the center for mute.
There will be two of the attenuators, so that I have both balance and volume control. (Turn both for volume increase/decrease, turn one for balance adjustment) This will keep the signal paths the simplest, one fo my goals.
Let me know what you think.
-Paul Hilgeman
Passive Preamp
Sounds like a good project, can you post the schematic on line?
Also, you might want to look at Goldpoints website for some ideas on resistance values
http://www.goldpt.com/vcb.html
My first preamp had ganged pots with individual concentric controls. I found that it was a pain to keep everything tracking. I decided that I did not really need a balance control so I substituted a dual alps pot.
PaulyG
Sounds like a good project, can you post the schematic on line?
Also, you might want to look at Goldpoints website for some ideas on resistance values
http://www.goldpt.com/vcb.html
My first preamp had ganged pots with individual concentric controls. I found that it was a pain to keep everything tracking. I decided that I did not really need a balance control so I substituted a dual alps pot.
PaulyG
Those are a little too expensive for me, I was looking at about 75 for the whole project. I will expirament with how much of a PITA it is to use both separately, but as is, I am always messing with the balance controll since many recordings seem to be out of wack. Usually about 1dB, but sometimes much more.
-Paul
-Paul
Passive Preamp
Looks pretty good to me. As long as your sources have enough oomph to drive 13k ohms (100K at max volume in parallel with 15K) and your amp is loud enough with the outputs from your sources, then it looks like you should be in business with the values shown on the website. (most solid state equipment should have no problem).
Good luck!
Paul
Looks pretty good to me. As long as your sources have enough oomph to drive 13k ohms (100K at max volume in parallel with 15K) and your amp is loud enough with the outputs from your sources, then it looks like you should be in business with the values shown on the website. (most solid state equipment should have no problem).
Good luck!
Paul
BTW, also make sure there is a coupling capacitor somewhere (or have equipment with no DC in the signal lines). Otherwise you will be blowing fuses or worse, loudspeakers. (BTDT)
My suggestion is a 10uf polypro capacitor before the pot as DC can make pots scratchy in the long-term. The loudspeaker guys (Madisound and Parts Express) seem to have the best prices for these components.
PaulyG
My suggestion is a 10uf polypro capacitor before the pot as DC can make pots scratchy in the long-term. The loudspeaker guys (Madisound and Parts Express) seem to have the best prices for these components.
PaulyG
Thanks! Got that covered. BTW, this will all be part of an integrated amplifier using the LM3875 Thor type amplifier.
-Paul
-Paul
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