Help with DIY CMOY Build

[bmwpowere36m3]

*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.

[bmwpowere36m3]

Also can someone recommend a decent mini (3.5mm) plug from digikey to use to make a interconnect cable.

[meat01]

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.

[bmwpowere36m3]

Originally Posted by meat01

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.

[Pars]

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.

[bmwpowere36m3]

Originally Posted by Pars

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?

[kirtar]

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)

[bmwpowere36m3]

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.

[Pars]

Bad form, quoting myself...

Originally Posted by Pars

<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>

[bmwpowere36m3]

Originally Posted by uhcmos

good

???, trying to up your post count

[bmwpowere36m3]

Originally Posted by Pars

Bad form, quoting myself...

I'm assuming you mean, like this:

[Pars]

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.

[bmwpowere36m3]

Originally Posted by Pars

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

[bmwpowere36m3]

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.

[fortney]

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