Questions regarding building the CMoy

[Sipher 0]

maybe someone can start a potential sticky regarding where to get various brands of caps, resistors, pots, tubes available in SG?

 

i think it would really help DIY newbies on getting the parts especially those audio grade stuff

Edited November 21, 2003 by Sipher

[tropicalrips 0]

Just to check with you guys.

Just started on my Cmoy.

Resistors value giving me problems.

Looking at so many sites I still can't see what are the correct values for the resistors.

Can you guys like give me some ideas.

R1 - R5 use what values?

R5 is optional?

 

Thanks.

 

In addition I think should really make it into a sticky.But then again, is whether anyone(mods/admins ) going to clipped the thread or start a whole new one.

i think we were all confused by the r2 & r3 on the cmoy design

there are 2 sets of it, first set is for the power side to divide the voltage, it should be 4.7k for r2/r3 the original drawing labels them as r1

 

the second set is for the imput/output signal side, this is what i use :

r2 = 100k

r3 = 2k (original design is 1k, but i find the gain too high, and it cause a lot of hissing when use with low ohm headphones)

r4 = 10k

r5 = 43ohm (i tried values 43-47-50 with higher values the low ohm cans hav less hiss, but it makes the higher ohm cans sound softer)

 

hope this helps u

[tropicalrips 0]

finish my cha47 today

here are some pics

Edited November 21, 2003 by tropicalrips

[tropicalrips 0]

bought new caps in SLS, the lady said its audio grade "gold caps"

[tropicalrips 0]

the porn !!

[jtfoo 0]

You workmanship is getting better. Very neat, can see that you properly bent the resistors lead...

[N@Z 0]

Well done! You're churning them out very fast! Now all you need to do is to tidy up the wiring & I'll probably buy one from you!

 

I have so many questions to ask you:

1. That battery you have in the last photo, is it a rechargeable type?

2. How did you make the holes for the sockets & switch? How is the board fixed on to the enclosure?

3. If the board was made shorter & shifted closer to the left (or using a Grado RA-1 clone design), could you fit in 2x 9v batteries? As the tin looks long & tall enough to fit them if they we're laying upright on it's side.

[tropicalrips 0]

1.my batt is a GP rechargeable

 

2.as for the holes, i just use a cordless drill, u will need to drill it a few times starting with a smaller drill bit because the tin box is too thin, using a big drill bit will just bend the box

 

3.i tried laying the 9v on its side but its too high, can't cover.2 batts should be no problem in this box with a cmoy, for cha47 will need to re-layout the components, i'm thinking stacking the PCB or maybe hav the second op-amp at the bottom to reduce the space its taking up

 

i think once i figure out how to jumper the power to the second op-amp the wiring should be neater, u can see that the power has to cross each other it took me a hr to finally giv-up and use jumper wires

 

has anyone tried this design before? i can't really hear the difference in sound for this compare to the cmoy it still works when i take out the second op-amp rite? or did i get it wrong

[Sipher 0]

tropicalrips, is it troublesome to take a pic of the bottom of the board of your CHA47?

Thanks

[tropicalrips 0]

tropicalrips, is it troublesome to take a pic of the bottom of the board of your CHA47?

Thanks

i'll take it tonight, but theres nothing there all my jumpers are on top

[jasonhanjk 0]

Has anyone tried this design before? i can't really hear the difference in sound for this compare to the cmoy it still works when i take out the second op-amp rite? or did i get it wrong

Should sound the same. Try on HD600 or Grados, you may hear some difference.

[N@Z 0]

The CHA47 was originally designed with Grado headphones (or low impedance headphones) in mind.

[av98m 0]

Very nice! How long does the battery last?

[Sipher 0]

is there any one shop in SLT where i can get all the parts needed to build a cmoy??

or do i have to go "parts hunting"?

prefer to get all from one shop. easier for me. i guess i can leave out the casing for now. anyone?

Edited November 22, 2003 by Sipher

[jtfoo 0]

Try the Grados on the cmoy first, and crank up the volume. You'll notice lots of distortion. Now try the Grado on the CHA47 and crank up the volume, no more distortion. That's the main diff between the cmoy and your CHA47.