[spanks]

I am slightly confused about the parts list located on this site

http://tangentsoft.net/audio/cmoy-tutorial/parts.html

It has required parts, and optional parts. I can somewhat pick out the parts that would make it a wall powered amp, but what of the optional parts list do I need for the volume control and power switch?

Power switch (mini SPDT* toggle)

Volume control, Panasonic 10K, horizontal mount (EVJ-C20)

so far I have those two...I am trying to create the cmoy that he made in the "assembling the amp" section. I have read through it, but cannot figure out what of the optional list he used

The main things I am curious about are these two things.

DIP-8 IC sockets, gold contacts

R5, 47 Ω 1/4W metal film resistor --figured this one out

Thanks for the help

after looking at the schematics some more the R5 is just plain optional, the gold contacts though...not sure what they're for.

 

[fortney]

The socket which is gold lined will permit you to change op amps if you want and also permit you to do all your soldering without having the op amp in place. This will protect it from heat damage if you are not an excellent solderer.

R5 is used if the completed and functioning amp has hiss. The value of this may vary and I think you want to use the smallest value that stops the hiss. I did not have this problem. Initially the R5 should not be used, but a plain wire used in its place to permit the circuit to be complete.

Many people use 470 instead of 220 uF electrolytic caps for C1 (in the power supply section) and 0.22 or 0.47 uF for C2 (the input coupling caps). Both maneuvers improve bass response. My 220 uF CMoy sounds good out of my i-MAC, but the i-MAC audio is too bassy when using the 470 uF CMoy. Using my SONY Discman as a source, the 470 sounds fine and the 220 lacks some bass. At minimum I would increase the value of the input coupling cap.

What gain you want to use will depend in part upon your choice of source and its output.

Look upon it as a learning project. CMoys are well worth building and using--have fun!!

F

 

[spanks]

Thanks for your response, that helped me a lot! I will most likely wind up using the socket because my soldering experience is decent, but I've never had to be in such confined quarters before.

I'm definitely looking for a learning experience! I'm trying to work my way up to a pemeta, but atm just going to take my 2.1 speakers out of the way with a cmoy.

also, they look really cool in mint tins when they're finished

 

[pkshiu]

Quote:

Originally Posted by spanks /img/forum/go_quote.gif Power switch (mini SPDT* toggle) Volume control, Panasonic 10K, horizontal mount (EVJ-C20)

You can either have the switch to switch the power on/off, or use one of the "optional" volume pot that has a built in "switch" to turn the power on/off, very much like most portable device, the volume knob will turn to min then click to off.



Quote:

Originally Posted by spanks /img/forum/go_quote.gif DIP-8 IC sockets, gold contacts

If you want to try different op-amps later, you want to socket the op-amp. In fact, you probably should use the IC socket either way to make it less likely to fry the op-amp via direct soldering.

P.K.

 

[d0td0t]

IMO its still a better idea to had sockets, so that you can try op-amp rolling.
And decide on the sound sig U enjoy more with the different op-amps. They are dirt cheap anyway

Cheers

Quote:

Originally Posted by spanks /img/forum/go_quote.gif Thanks for your response, that helped me a lot! I will most likely wind up using the socket because my soldering experience is decent, but I've never had to be in such confined quarters before.

 

[Joshatdot]

Here's a Digi-Key parts list of 99% of every thing you'll need for a standard design CMoy:

Code:

[left]Number Description Customer Reference -------------------------------------------------------------------------- P12388-NDCAP 470UF 25V ELECT FM RADIALCMoy Kit - C1 470 uF EF1105-ND1.0UF/100VDC METAL POLY CAP CMoy Kit - C2 1.0 uF 4.75KXBK-NDRES 4.75K OHM 1/4W 1% METAL FILMCMoy Kit - R1 4.7k Ohm 100KXBK-NDRES 100K OHM 1/4W 1% METAL FILM CMoy Kit - R2 100k Ohm 1.00KXBK-NDRES 1.00K OHM 1/4W 1% METAL FILM CMoy Kit - R3 1k Ohm (Gain 11) 2.00KXBK-NDRES 1.00K OHM 1/4W 1% METAL FILM CMoy Kit - R3 2k Ohm (Gain 6) 10.0KXBK-NDRES 10.0K OHM 1/4W 1% METAL FILM CMoy Kit - R4 10k Ohm 49.9XBK-NDRES 49.9 OHM 1/4W 1% METAL FILM CMoy Kit - R5 50 Ohm (Optional) ED90032-NDIC SOCKET 8 PIN .300 GOLD CMoy Kit - 8-DIP Socket OPA2227PA-NDIC DUAL PRECISION OPAMP 8-DIP CMoy Kit - Op-Amp 232K-NDSTRAP BATT ECON 9V I STYLE 4"LD CMoy Kit - 9v Batt Straps CP-43502PM-NDCONN JACK AUDIO 3.5MM 4COND CMoy Kit - IN/OUT Jacks 350-1560-NDLED 3MM BLUE DIFF CMoy Kit - LED Blue 226-3104-NDKNOB CLR/MATTE .50"DIA 6MM SHAFT CMoy Kit - Knob P2U4103-NDPOT 10K OHM 12MM HORZ MET BUSHINCMoy Kit - Volume Pot EG2361-NDSWITCH TOGGLE SPDT 5A PC MNT 5PCCMoy Kit - SPDT Switch[/left]

 

[spanks]

Josh that was really helpful, thanks

Has anyone tried making a cmoy usb powered? I foresee the 5v supply not being enough, but possibly there is a way around that? Seeing as this would be a desktop item I'd be interested in trying to make it usb powered. I'm probably gonna get my parts tomorrow, or atleast see what the local computer surplus has in stock

Thank you

 

[Soymilk]

if you have enough powered usb ports on your computer, you could just have a bunch of plugs powering the cmoy wired in series. that'd be pretty ugly / bulky though with two cables coming from your computer to the cmoy.

 

[spanks]

hah, didn't think about using two ports...might give that a try

I have pleanty of ports, and I could deal with a bulky cable instead of having to replace/charge some 9v's all the time

 

[balou]

the opa2132 will definitely not work with 5v - the ad8066 will. but please keep in mind that most usb power supplies are very noisy, especially so in laptops. but hey, your computer has 12v rails! just grab the power off a molex connector (those harddisk power connectors). adding a regulator to it could be a wise idea - the lm317 has 2v voltage drop, that would give you a nice, clean 10v of power. look here for a simple lm317 circuit: http://tangentsoft.net/elec/tread/ . you can leave out all the rectifier stuff if you directly use dc voltage from your computer

 

[THESANTINI]

Sorry to bump an old thread. This seems like as good a place as any to ask a question concerning parts for the CMOY build. I'm going to build 4-5 of these CMOYs for friends. My concern is what parts should I be purchasing extra assuming I break/fry/etc? I don't want to pay to have different parts shipped constantly and stuff. Thanks!

 

[Reintz]

I'd suggest you to take some extra resistors so you can find matching pairs for left and right channels. And also if you're going to use resistors and capacitors for rail splitter.

 

[Fred_fred2004]

If you are building a basic cmoy, you'll proberbly be getting 100K, 10K, and 4.7K resistors
with 1K for the gain of 11, if I were you I'd get some other values like 1.5K 2.2K, 4.7K so you can play with different gains to suit different head/earphones
 
cheers
FRED