Guide to fix up a Cmoy 2

[Kube 0]

Ermm...sorry, noob question, but the cmoy 2 is basically a portable amp, right? Anyways, could you PM me too? Thanks.

[dbwinger 0]

I finally got around to finishing my CMOY2 that I have had the parts for what seems like forever. I was really nervous when I put it together, but it worked on the first try!

 

So far it doesn't sound too bad. I'm impressed. This is my first headphone amp so I have nothing to compare it to.

 

I don't have a digital camera, but I will try to post pics soon.

 

Thanks go out to tropicalrips and Jason for all of your help.

[dbwinger 0]

How would I go about wiring a closed circuit DC jack?

 

Tangent's directions

 

Go down a ways until the pic of the jack. I understand the battery V- and Wall V-. Where do I hook up the two positive wires?

Edited July 25, 2005 by dbwinger

[jasonhanjk 0]

Oh, this something new.

 

The 2 positive are short together.

[dbwinger 0]

The 2 positive are short together.

So I solder both of the positives to the same lug on the switch?

 

Also, would there be any advantage to using polypropylene caps (I know they will be a little bigger) instead of the Wimas?

[dbwinger 0]

Has anyone built this using the LM6171?

 

If so, what are your impressions of the amp?

 

I am wondering if this amp sounds better with the LM6171 or additional Wima caps?

[jasonhanjk 0]

The cap at the signal or power supply.

 

My ear is not that good so I won't comment on the sound...

[Kippei 0]

Can plug the ad8620 directly into the amp after converting to DIP?

 

Also OPA2107. Is there any changes needed?

 

Which opamp are good for ms-1

Edited August 15, 2005 by Kippei

[johanjr 0]

Got mine up to go on the first try!!

But there's too much bass...roll off the cliff

soundstage sounds narrow

resistor i change the value abit

10 = r1/r5

100k = r2/r6

20k = r3/r7

20k = r4/r8

20k = r9/r10

are these the problems?

anyway i can improve it?

thanks

 

[Kippei 0]

Can try changing opamps....

 

I got a couple just to test it out

[Kippei 0]

Can use this? It is a single unit pots... The rest are all out of stock

 

Whats is the difference between single and dual pots

[heady 0]

Single unit pot will control volume for only one channel, ie left or right and not both. So definitely not usable for a stereo amp. For controlling volume on both right and left, you need a dual unit pot. If you are in SG, the only place selling dual unit pots is Farnell (as far as I know).

 

You also need the dual log to be audio taper or also known as logarithmic. The linear pot which is more common is not advisable for audio use.

 

But you can order from Tangentsoft, only problem is, you need to order more than 1 pot to make the order cost effective. You can always order PCBs.

 

[jasonhanjk 0]

Got mine up to go on the first try!!

But there's too much bass...roll off the cliff

soundstage sounds narrow

resistor i change the value abit

10 = r1/r5

100k = r2/r6

20k = r3/r7

20k = r4/r8

20k = r9/r10

are these the problems?

anyway i can improve it?

thanks

Hi.

 

You should try these value to reduce the bass rolloff.

 

R1: 10

R2: 20k

R3: 20k

R4: 20k

R5: 10

R6: 20k

R7: 20k

R8: 20k

 

[johanjr 0]

Got mine up to go on the first try!!

But there's too much bass...roll off the cliff

soundstage sounds narrow

resistor i change the value abit

10 = r1/r5

100k = r2/r6

20k = r3/r7

20k = r4/r8

20k = r9/r10

are these the problems?

anyway i can improve it?

thanks

Hi.

 

You should try these value to reduce the bass rolloff.

 

R1: 10

R2: 20k

R3: 20k

R4: 20k

R5: 10

R6: 20k

R7: 20k

R8: 20k

hi jason

 

tried it but it sounded funny....i get weezing sound when i touch any of the resistor.the resistor is mounted on the socket so i can play around with gain and such.

going to resolder the wires with those multi strand wires. was using the single core type and it seem to come off 1 by 1. progress abit slow though

[jasonhanjk 0]

Ok, change them back to the original and short the 2 input cap. That should give no bass roll-off.