[Pyroburner69]

I am trying to build the cmoy amp and gathering all the parts. I mostly picked up things from radio shack since its down the street and I don't have to pay for shipping. I still need to order the Op amp and I was looking for the Panasonic EVJ-C20 10 kΩ. I have been unable to find it at mouser or digi-key. I am not really sure what I could use for a good replacement and was hoping for a little help. I have a good deal of experience working with small components (going to use smd resistors) but I dont really know much about how the electrons work or what good replacement parts would be. I would like something about the same size so I would be able to put it into an altoids tin.
 
Thanks in advance.
This sites been pretty useful so far. Just picked up a set of A151 earbuds.

 

[OJNeg]

In case you haven't seen this:
 
http://tangentsoft.net/audio/cmoy-tutorial/
http://tangentsoft.net/audio/opamps.html
 
There are quite a few op-amps to choose from. I built my Cmoy with a BurrBrown OPA2227P. To be honest, you can use anything that is up to spec and it will sound fine.

 

[shake]

I got an email from digikey a few weeks ago saying that panasonic has discontinued their EVJ line of pots.  The next best thing would probably be the ALPS RK097, which you can get from tangent's part shop.  His prices are very fair and he packages his things like a baus.
 
I agree that the opa2227 is a good starter opamp.  It's a dual part which simplifies the design.

 

[Pyroburner69]

Cool I will have to check out the site then. I didn't even think to look at it for parts. Thanks I will probably look for that chip then. I was thinking of grabbing a few different kinds and seeing what the difference was if any at all. I am hoping that one of the electronics shops around here has some of these parts but I think I may be out of luck so Thank you for the links.

 

[tangent]

Quote:

I got an email from digikey a few weeks ago saying that panasonic has discontinued their EVJ line of pots.

 
Sadly, this appears to be the case. Digi-Key still seems to have quite a few models in stock, though they're now out of stock of many, too.
 
The closest remaining to the EVJ-C20 is the EVJ-CC1F02651. It may be that the only difference is a flatted shaft instead of a round shaft, but since the part number doesn't follow the old part number scheme, I can't verify that without buying one and tying it.
 
I'm particularly uncertain that the "logarithmic" taper is actually the "A" or "audio" taper. If it were, the third from last position in the part number would be an "A", but the fact that it is not doesn't prove it's wrong, since that position is supposed to hold a letter in any case. My guess is that this is a special-purpose EVJ-C variant Panasonic created outside their normal process to serve the needs of a large customer to help them bridge to a replacement product.
 
Anyway, I've removed the EVJ-C20 line item from the CMoy part table.
 
 
Quote:

The next best thing would probably be the ALPS RK097, which you can get from tangent's part shop.  His prices are very fair

 
Thanks for the recommendation!
 
 
Quote:

he packages his things like a baus.

 
Translation, please? Google Translate guesses it is German for "construction", but that can't be exactly right for grammar reasons.

 

[shake]

Quote:

 
Translation, please? Google Translate guesses it is German for "construction", but that can't be exactly right for grammar reasons.

http://www.youtube.com/watch?v=NisCkxU544c
 
 
Quote:

Cool I will have to check out the site then. I didn't even think to look at it for parts. Thanks I will probably look for that chip then. I was thinking of grabbing a few different kinds and seeing what the difference was if any at all. I am hoping that one of the electronics shops around here has some of these parts but I think I may be out of luck so Thank you for the links.

If I were you, I'd just go ahead and buy a really nice opamp, such as 2xOPA627 or 2xAD825, that ways you won't itch as hard to upgrade so soon XD.

 

[ostewart]

I Always liked LME49720 NA

 

[shake]

The LME49720/49710 look interesting, and they're cheap so it would be worth it to try them.  Only ~26mA/channel, so a buffer would be required.

 

[Pyroburner69]

I was going to ask what I would have to do in order to try one of the other chips listed here. I am still unsure of what I will need to do for most of the tweaking once I get it up and running. I just wanted to get the base set up working and figured I could go from there. The only plan I have at the moment is replacing the led with a clear blue one instead of a tented red one.

 

[shake]

I know some are going to snap at me for saying this, but since opamps are all pin-compatible, you can just switch them out with each other.  The issue is that some designs that work fine for one opamp might not work well with another. 
Also, I would suggest not using the stock cmoy gain of 11 with your IEMs.  5 would be a better number.  It is still high enough to be stable, but low enough so you can turn the pot most of the way.
The 2227 is a fine opamp though.

 

[Pyroburner69]

Thanks for all of the tips ill have parts on order very shortly. I picked up a TL082CP in the mean time. Figure I can get it put together and then slip in a 2227 or something.

 

[Pyroburner69]

Got everything together and it works. I used the radioshack chip and it sounds a bit off but it works so I am happy. I still have to get it into the enclosure but I didn't have time yet. There is a bit of static on when I move the switch but I think it is a poor connection that I will clean up once I have the box set up. I see why people configure the altoids tin they way they do. I wish there was a little more room so I could have the audio in on the bottem and the out on the top but its a little tight with the two batteries in it. Ill post up some pix once everything is squared away.
 
thank you guys for all of your help.