[intlplby]

where can i buy cmoy pcbs?

i want to buy like 5-10 of them to make as gifts to go with a pair of grado sr-60s.... i don't want to go through all the trouble of the breadboard if possible.

if no one sells one, does anyone have a layout for one that accepts regular parts or smd parts? and can you suggest a place where i can get 10 of them printed for cheap?


thanks for the help

 

[picklgreen]

You can send a PM to jasonhanjk. He sells the CMOY2 PCB.

 

[fordgtlover]

I haven't yet made the CMOY2 to vouch for its quality, but I ordered 2 boards from Jason. I paid through Paypal and the boards arrived at my door in Australia two weeks later (a bit slow because of Christmas).

The CMOY2 board is about 48mm x 43mm. While not tiny, it's only about 25% larger than the section of breadboard I used for my standard CMOY, but much neater.

The following thread over at sgheadphones.net describes the CMOY2.
http://www.sgheadphones.net/index.ph...ded&show=&st=&

 

[picklgreen]

I built my CMOY2 and I really like it. Im using 2 OPA2227 and 1 LM6171BIN for the ground. Wima 1uF caps, Panasonic 1000uF output caps and vishay/dale resistors and a pink LED make that little Hammond 1593PBK sound very nice indeed! Now if I had only ordered enough switches....it wouldnt be glowing so pinkly all day long

 

[intlplby]

what was the cost of parts... i'm trying to make these on the cheap to go along with grado sr-60s as gifts

 

[picklgreen]

about $25 or so

 

[Uncle Erik]

I bought a couple of them from Guzzler several months back. He calls them the "GMOY." You might want to see if he has any more for sale. Very nice guy, as well.

 

[fordgtlover]

The GMOY looks quite different to the CMOY2. It seems that the GMOY is a development by a member called Guzzler and some others. While the CMOY2 appears to be a development coordinated by a member called jasonhanjk over at www.sgheadphones.net.



Picklegreen: Did you build the CMOY2 as recommended and running it of 9v?

I was hoping to build it up to be able to run it off 24v (for when I build an external Steps), but the Panasonic caps are too big. At 25v, 1000uf cap is 12.5mm x 20mm (diameter too large to fit the board and too tall for the hammond).

 

[MASantos]

Quote:

Originally Posted by picklgreen /img/forum/go_quote.gif I built my CMOY2 and I really like it. Im using 2 OPA2227 and 1 LM6171BIN for the ground. Wima 1uF caps, Panasonic 1000uF output caps and vishay/dale resistors and a pink LED make that little Hammond 1593PBK sound very nice indeed! Now if I had only ordered enough switches....it wouldnt be glowing so pinkly all day long

The 1000uf Panasonic caps are not output caps, they're the power supply reservoir caps.

Quote:

Originally Posted by fordgtlover /img/forum/go_quote.gif Picklegreen: Did you build the CMOY2 as recommended and running it of 9v? I was hoping to build it up to be able to run it off 24v (for when I build an external Steps), but the Panasonic caps are too big. At 25v, 1000uf cap is 12.5mm x 20mm (diameter too large to fit the board and too tall for the hammond).

You don't necesseraly need 1000uf. A normal cmoy uses around 220-470uf.

----------------------------

This Cmoy2 is not a cmoy, if I remember correctly it is based in the A47 design. This design uses two double opamps per channel. One does the voltage amplification and the other does the current amplification, similar to a opamp+buffer design. This design also employs a buffered ground channel, so it is very different from a standard cmoy. I never built one, but it should have better sound than a "normal" breadboard cmoy. Will certainly drive current hungry cans(such as grados) better because of the added current capability.

I would advise to replace the OPA2134 with a OPA2227. In my cmoys and Pimeta I have always prefered the 2227.

 

[Xakepa]

Not sure about GMOY, but if it's A47 with buffered ground, that would be a substantial improvement over CMoy. I built A47, and I also have a Cmoy with buffered ground, both running with 24 ohms cans. While A47 (dual 2132) wasn't a big improvement over CMoy, BUF634T-buffered ground in CMoy is definitely better.

IMHO, if you have buffered ground you don't gain much by having dual amps (voltage gain+buffer). Eighter get A47 or buffered ground CMoy, or go for a PIMETA.

On a sidenote, I don't like 2227 - it trades resolution and top-end for bass impact. Could be a good thing for Grado, but for a neutral cans you might try AD823 or BB2107 first

 

[MASantos]

Quote:

Originally Posted by Xakepa /img/forum/go_quote.gif Not sure about GMOY, but if it's A47 with buffered ground, that would be a substantial improvement over CMoy. I built A47, and I also have a Cmoy with buffered ground, both running with 24 ohms cans. While A47 (dual 2132) wasn't a big improvement over CMoy, BUF634T-buffered ground in CMoy is definitely better. IMHO, if you have buffered ground you don't gain much by having dual amps (voltage gain+buffer). Eighter get A47 or buffered ground CMoy, or go for a PIMETA. On a sidenote, I don't like 2227 - it trades resolution and top-end for bass impact. Could be a good thing for Grado, but for a neutral cans you might try AD823 or BB2107 first

A PIMETA will be at least 2-3 times the price of building this cmoy2. It is certainly a better design, but not an inexpensive project( at least for me)

 

[picklgreen]

Actually I would be interested in knowing if anybody has some PCB for the original CMOY design they made and are willing to sell? I know you are out there because Ive seen your amps on EBAY!......

 

[MASantos]

Quote:

Originally Posted by picklgreen /img/forum/go_quote.gif Actually I would be interested in knowing if anybody has some PCB for the original CMOY design they made and are willing to sell? I know you are out there because Ive seen your amps on EBAY!......

The thing is, it is so easy to improve the original design by Chu Moy, that when most people design a PCB, they add improvements such as a TLE2426 railsplitter or bigger power supply caps with bipass film caps, different gain, etc.

There is not standard cmoy configuration, so people build pcb taking their need into consideration.

 

[picklgreen]

Yes i agree! My most interest would be if someone has a PCB that utilizes all SMD components to make it nice and small...

 

[IEATTEFLON]

I don't see the point of a small cmoy/etc pcb when the size of the battery, jacks and volume controller will be relatively huge. Also, does anyone know of a suitable case for said small pcb? Other than candy tins the smallest case that I know of is the hammonds.