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Help with DIY CMOY Build

post #1 of 17
Thread Starter 
*BUILD DONE*

I completed my build of the CMoY, it took a few hours since it was my first DIY amp build and I strayed from the original plans. All in all I'm happy with the build, after using it for a while on 2x 9V, I switch over to a DC wall-wart and to accompany it I added a THREAD.

Here are the parts:



Here's the completed amp:









I initially wanted to build the amp into an Altoids tin. With future possibilities of running in on battery power and plugged-in @ home to conserve power. I made one huge oversight during the build, when I chose to use larger caps (both the PS 470uf and coupling .47uF ones) I didn't account for their size. There was no way they would fit in the Altoids tin and upon initial build w/ the dual 9V batteries I realized I never use this as a portable amp... so I switched over to a THREAD and added a wall-wart.

*Initial Proposition*

After some more research and decision making I've finally come up with my game plan for my CMoY build. Here's my list of parts ordered thru Newark:



Parts in salmon are the "original" components based on tangentsoft.net and the yellow ones are my own choice.

Here's the schematic:





All that's left is to get some protoboards and an altoids tin...

I got the itch to build a headphone amplifier and decided a cmoy is a nice first start. I will only be powering IEM's with this amp, (Shure E2's, RE2, and YUIN PK3). I've decided to use this tutorial: How to Build the CMoy Pocket Amplifier

I've decided to go with a gain of 2 due to IEM usage. Now my question is does this look good (i'll be getting the protoboard and 3.5mm jacks @ RS unless there one's on Digikey as well?).

I was thinking of adding a buffer virtual ground, the "TLE2426-Based Virtual Ground (Noise Reduction Version), now my question is what the additional capacitor (CNR 1uF), is it actually 1uF? Is this virtual ground improvement even worth it?

Finally can I run on 1x 9V battery or should I go with 2x? Any other tips and hints would be appreciated, thanks.
post #2 of 17
Thread Starter 
Also can someone recommend a decent mini (3.5mm) plug from digikey to use to make a interconnect cable.
post #3 of 17
The virtual ground takes the place of 2 resistors. I prefer using the virtual ground.

I believe you want a .1uF capacitor rather than the .47.

You can run it with 1 or 2 9 volts. It can be tricky fitting 2 9 volts in a mint tin. It can be done, but you have to plan ahead and make the board a little smaller.
post #4 of 17
Thread Starter 
Quote:
Originally Posted by meat01 View Post
The virtual ground takes the place of 2 resistors. I prefer using the virtual ground.

I believe you want a .1uF capacitor rather than the .47.

You can run it with 1 or 2 9 volts. It can be tricky fitting 2 9 volts in a mint tin. It can be done, but you have to plan ahead and make the board a little smaller.
Well, the "original" circuit has a virtual ground as well (2 resistors & 2 caps), I guess your saying you prefer the "buffered virtual ground"?

I'm using .47 as the input caps based on this: "As for the input caps (C2), a larger cap will improve bass handling, but it's by a different mechanism than with larger power caps. See the companion article, Input Capacitors for Headphone Amps for a full discussion. Bottom line, the default 0.1 µF is a bit on the low side. Try 0.22 µF, 0.47 µF, or even 1.0 µF instead."

Cool, I was thinking that 2x 9V might be hard to fit as well.
post #5 of 17
Yes, 2x9V is hard to fit in a mint tin... I've seen it done, but never tried it myself.

If you use the "TLE2426-Based Virtual Ground (Noise Reduction Version)", you might want another DIP-8 socket since the TLE2426 that has the noise reduction pin on it is a DIP-8 package instead of a TO92. I personally just replace the two stock virtual ground resistors in the stock Cmoy build with a TO92 TLE2426 and go with that (you would need another 470uf cap to do this).

One other thing I would consider is using the Alps 097 pot that Tangent sells with the switch. This cleans things up a bit, as you don't need a separate power switch, and the pot is somewhat smaller and to me works better than the Panasonic pot does.
post #6 of 17
Thread Starter 
Quote:
Originally Posted by Pars View Post
Yes, 2x9V is hard to fit in a mint tin... I've seen it done, but never tried it myself.

If you use the "TLE2426-Based Virtual Ground (Noise Reduction Version)", you might want another DIP-8 socket since the TLE2426 that has the noise reduction pin on it is a DIP-8 package instead of a TO92. I personally just replace the two stock virtual ground resistors in the stock Cmoy build with a TO92 TLE2426 and go with that (you would need another 470uf cap to do this).

One other thing I would consider is using the Alps 097 pot that Tangent sells with the switch. This cleans things up a bit, as you don't need a separate power switch, and the pot is somewhat smaller and to me works better than the Panasonic pot does.
So the "extra" noise reduction isn't really worth it I'm guessing?
post #7 of 17
is it worth it to have a cap before the splitter and 2 after?
(as in http://www.head-fi.org/forums/attach...-check-psu.jpg)
post #8 of 17
Thread Starter 
So here's my schematic of the PS, a combination of the "original" cmoy and with a "improved virtual ground TLE-2426" circuit:



So my question is, for C1 does it hold true to make it a larger capacitor (vs. 220uF) for improved bass response?

Second what is the capacitance of CNR is it actually 1uF? Based from this drawing (original):



Also is there any benefit to running pin 8, so called the "noise reduction pin"? Since I could get away with a three pin 2426 (TO92-3).

Or is there an improved circuit, that is fairly simple and can fit in the confines of a mint tin? Any tips would be helpful.
post #9 of 17
Bad form, quoting myself...

Quote:
Originally Posted by Pars View Post
<snip>
I personally just replace the two stock virtual ground resistors in the stock Cmoy build with a TO92 TLE2426 and go with that (you would need another 470uf cap to do this).
<snip>
post #10 of 17
Thread Starter 
Quote:
Originally Posted by uhcmos View Post
good
???, trying to up your post count
post #11 of 17
Thread Starter 
Quote:
Originally Posted by Pars View Post
Bad form, quoting myself...
I'm assuming you mean, like this:

post #12 of 17
Yes, that is how I have done them. The TLE (TO92 case) drops right in (at an angle) in place of the two resistors in Tangent's diagrams. MisterX posted a picture of it at one time that you might be able to find.
post #13 of 17
Thread Starter 
Quote:
Originally Posted by Pars View Post
Yes, that is how I have done them. The TLE (TO92 case) drops right in (at an angle) in place of the two resistors in Tangent's diagrams. MisterX posted a picture of it at one time that you might be able to find.
Thanks, now my build is underway
post #14 of 17
Thread Starter 
Well I've soldered up the PS so far and I think I have a problem, when apply a 9V (~8.4V) battery to the PS... for one the TLE2426 gets really hot (not sure if thats normal). Second when I measure the voltage at each leg, I getting 4.95V and 2.57V which added is the same as the battery V when its connected to the PS. However each leg is far off....

Even when I attached an external 12V DC PS, I was getting ~10V & 2V on the legs. Is the TLE damaged? Should I have the Caps before the TLE in the circuit. I've wired it just like the schematic in my first post.
post #15 of 17
Check all your solder joints with a magnifier looking for shorts and be sure none of the capacitors are in reversed position.

Note: I used the 2 resistor voltage divider as in CMoy 's original schematic and have no issue with noise in the amplified signal.

F
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