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Old 15th January 2012, 10:09 PM   #1
Netdewt is offline Netdewt  United States
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Default CMOY newb

I'm interested in trying to build a Cmoy. Does this look right for a BOM. Am I missing anything?

2 - 4.75k Vishay metal film
3 - 10k Vishay metal film
2 - 100k Vishay metal film
2 - 1k Vishay metal film
2 - 2k Vishay metal film (for trying if the 1k are too much gain)
1 - OPA2132PA
2 - 220uF Nichicon electrolytic cap
2 - 0.1uF Vishay film cap ORANGE DROP
pot of some kind (ALPS?)
proto board
9V connector
enclosure (thinking a wood one a la Grado)
volume knob
power LED
1/4 phono output jack
RCA input jacks

Could anyone recommend an ALPS pot I could use for this?
RK09D113F25C0A104 ALPS Potentiometers
Would something like that work? There are a bunch of things I don't understand about these. How do i know if it's dual ganged? Is that for 2-channels? How do i know if it has a built in on/off switch? Otherwise I'll just get the recommended one from Radio Shack.

Parts list I'm looking at:
Part Lists and Suggestions

Thanks.

Last edited by Netdewt; 15th January 2012 at 10:21 PM.
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Old 15th January 2012, 10:21 PM   #2
GloBug is offline GloBug  Canada
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Yes dual gang is for 2 channels.
It will say if it has on/off.
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Old 15th January 2012, 10:57 PM   #3
Netdewt is offline Netdewt  United States
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Maybe I got the ALPS. This looks like the one I want. I don't see where it says it's an on/off, but I found something that says this is the one:
RK0971221Z05 ALPS Potentiometers

So, given that. Will this set up work for the Grados?
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Old 17th January 2012, 02:58 AM   #4
GloBug is offline GloBug  Canada
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It's been awhile since I built my cMoy, but I think you are well on your way.

I did not bother with a volume control on mine, in fact I don't like to use them unless they are needed.

It sounds slightly better without a volume control, plus I already have the volume control on the iPod etc.

The pot linked above looks like a nice one, but without an/off. You could always add a separate switch.
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Old 17th January 2012, 03:40 AM   #5
Netdewt is offline Netdewt  United States
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Actually, I just found here it says:

Quote:
Single-shaft with rotary switch type
RK097 Series - Basic information

I assume that means it has a switch. Omitting the Volume makes sense... I hadn't thought about the fact that anything I listen to with headphones has volume built in. Although I'd still need a switch... hmmm.
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Old 17th January 2012, 03:45 AM   #6
GloBug is offline GloBug  Canada
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That looks like the one you would need.
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Old 17th January 2012, 03:50 AM   #7
ddietz is offline ddietz  United States
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Basic CMoy is fun and a very rewarding first diy audio project. I bought my alps pot directly from tangent as a thank you for putting so much into the tutorials.

Your missing a resistor for the LED. Input RCA is nice but if you can add a 1/8 or 1/4" also it will be more versetal. Do your self a favor and order enough parts for a few. They addicting at first and you also might screw up. There electrical components cost only pennies so get extras.

You should use 5mm 1uf Wima caps on the inputs, much better sound.
You may also want to add a barrel power jack so you can use a DC wallwart. The device also has more dynamic range with more voltage. The common OPA chips can handle up to +- 18 vdc. It works good with a single 9v but better at higher voltages.
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Old 17th January 2012, 04:16 AM   #8
Netdewt is offline Netdewt  United States
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Quote:
Originally Posted by ddietz View Post
Your missing a resistor for the LED.
I think I put in 3 10k resistors. 2 are used in the amp and 1 is for the LED. I could be wrong...

Quote:
Input RCA is nice but if you can add a 1/8 or 1/4" also it will be more versetal.
I was just thinking of using a Y connector in case I need a 1/8 or 1/4" connection. Any DAC I'd buy would have RCA outs anyways.

Quote:
Do your self a favor and order enough parts for a few. They addicting at first and you also might screw up. There electrical components cost only pennies so get extras.

You should use 5mm 1uf Wima caps on the inputs, much better sound.
I'll consider that! 1uf or .1uf? The schematic says .1uf. I thought orange drops were supposed to be good stuff?

I can always order more... perhaps. The opamp is $6, and it's a $30 project!

Quote:
Basic CMoy is fun and a very rewarding first diy audio project.
I have all the parts to build a Shigaclone, and I want to build a DAC (or partially at least), but I really need to get my feet wet. I've been sitting on that stuff for a year now.
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Old 17th January 2012, 05:18 AM   #9
Netdewt is offline Netdewt  United States
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Score! I just rechecked over a bunch of free samples I got from TI a few months ago unsure if I'd ever use any of it.

Hmm. PCM1794ADBR, PCM2704DB, SRC4192IDB, DIR9001PW and... OPA2132PA.

I guess I plan better than I thought.

Last edited by Netdewt; 17th January 2012 at 05:22 AM.
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Old 17th January 2012, 05:43 AM   #10
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You can get the ALPS with switch for $3.25 from here......

AMB audio shop
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