Gain Clarification

[einolu]

If I want to set the gain of my CMoy to 5, I should have 100k ohm resistors in the place of R2 and a 2.5K ohm resistor in the place of R3. Also, in the powersupply both R2 and R3 are 4.7K ohm?

Lastly, I have a faulty Panasonic pot (10K), and need a toggle switch. I was wondering if anybody out there has any extras? I dont know how much you would want me to pay, but I think shipping should be cheap since the stuff would probably fit in an envelope. Didnt post this in the Sale Forum because I thought it was too small a request.

Thanks,

~EO

 

[tangent]

Quote:

If I want to set the gain of my CMoy to 5, I should have 100k ohm resistors in the place of R2 and a 2.5K ohm resistor in the place of R3. Also, in the powersupply both R2 and R3 are 4.7K ohm?

The values are all correct, but only R3 in the amp circuit has any relevance to gain.

 

[einolu]

oh, i thought they all had to change or something like that.

For grados, should I put a resistor in the place of R5?

~EO

 

[Megaptera]

Quote:

Originally Posted by einolu Lastly, I have a faulty Panasonic pot (10K), and need a toggle switch. I was wondering if anybody out there has any extras?

If you're in Boston, there's no need to go through the hassle of buying/shipping one from a Head-Fier. Find your local Radio Shack (I go to the one in Cooledge Corner) and pick one up there for cheap.

 

[einolu]

do you happened to know the product number? should I get any 10k pot?

 

[Megaptera]

I don't have a part number off the top of my head, no. Just look for a 10K stereo (not mono) pot and whatever type of switch you need. I haven't tried Radio Shack's pots, but I've heard they're not the best at tracking -- I somehow read your post as just needing a decent switch, which the Shack can provide.

 

[einolu]

yeah, maybe I should just post on the sale forum since radioshack pots arent supposed to be the greatest.

Just want to make sure again, for grados, should I put something in the R5 place?

 

[Megaptera]

Edit: Double post

 

[Megaptera]

I would try it without R5 first. If there's a lot of hiss that you can't attribute to the source, recording, interference, or grounding, then I'd try R5. Adding it probably wouldn't hurt anything in any event, but I'm of the philosophy that if you don't need to add it, you shouldn't add it.

Regarding the pot, if you buy one from Mouser and go with Priority Mail, shipping will be real cheap, and you'll get it within a few days. Probably much easier than coordinating a sale with someone.

 

[tangent]

Quote:

i thought they all had to change or something like that.

Only if you're using a bipolar-input chip. And you shouldn't be, as a newbie.

Quote:

should I put a resistor in the place of R5?

Not until you know for a fact that you need it.

Quote:

should I get any 10k pot?

Radio Shack only offers 100K stereo audio taper pots. That's what you need to look for. Also, you'll need to replace R2 in the amp section with 1M resistors. You'll probably have to use carbon resistors, but that's okay for a CMoy's input resistors.

Quote:

radioshack pots arent supposed to be the greatest.

CMoy amps aren't the greatest either. So you're set.