[balrog]

I built Tangent's version of the cmoy and got it working/cased thanks to the help of the forum!


I am using a Touch or nano with a Send Station line out. Right now I have Grado SR80 and Etymotic ER4S headphones. I am going to get either the Shure 530 or UE Triple fi 10 pros and a set of Yuin earbuds for work.

What gain setting should I reduce it to to be able to run all of the headphones above?

If I start changing the values of C1/C2, does that affect the gain ?

Thanks for your time. Now I have to decide on the UE or Shures.

 

[MisterX]

Quote:

What gain setting should I reduce it to to be able to run all of the headphones above?

Somewhere around three should do nicely.

Quote:

If I start changing the values of C1/C2, does that affect the gain ?

No.

 

[breakfastchef]

This post is a mistake. I do not know how to delete it. See following post.

 

[breakfastchef]

I just went through this myself. To change the gain, you need to change either R3 or R4. If you read deeper into Tangent's tutorials, he does go through the gain adjustments. I built a straight Cmoy with the gain of 11 and build another with a gain of 3. To get to three, I changed R3 from 1K ohm to 4.75 K ohm. For a bass boost (also mentioned in Tangent's site) I replaced the C1 caps with 470 microfarad caps. Hope this helps.

 

[FallenAngel]

Would have been a little smarter to change R4 instead, but it should work.

 

[balrog]

Thank you for the replies.

FallenAngel-
Why would it be better to change R4 vs R3?
To obtain a gain of 3, I would change R4 to 2k ohm. Is that correct?

 

[dgbiker1]

I've found a gain of 7-8 worked well with my Grado 225s, 11 was deadly when using the line-out.

 

[nikongod]

Quote:

Originally Posted by balrog /img/forum/go_quote.gif Why would it be better to change R4 vs R3?

a lower combined (r3+r4) will give lower noise.

Quote:

Originally Posted by dgbiker1 /img/forum/go_quote.gif I've found a gain of 7-8 worked well with my Grado 225s, 11 was deadly when using the line-out.

7-8 is masochistic, IMHO.

by FAR my favorite gain for grados is 3 or 4.

 

[dgbiker1]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif 7-8 is masochistic, IMHO. by FAR my favorite gain for grados is 3 or 4.

With a 7-8 gain my volume control was only turned up about 10% though for comfortable listening. I'm glad I set it that high since my K701's (purchased after the amp was built) need a lot more juice, now I'm even running into clipping problems with a 12VDC source.

 

[eruditass]

Quote:

Originally Posted by breakfastchef /img/forum/go_quote.gif I just went through this myself. To change the gain, you need to change either R3 or R4. If you read deeper into Tangent's tutorials, he does go through the gain adjustments. I built a straight Cmoy with the gain of 11 and build another with a gain of 3. To get to three, I changed R3 from 1K ohm to 4.75 K ohm. For a bass boost (also mentioned in Tangent's site) I replaced the C1 caps with 470 microfarad caps. Hope this helps.

iirc changing C1 and C2 don't add "bass boost". higher C1 simply adds more current reserve for low impedance headphones and drum hits, so it doesn't bottom out. higher C2 makes the bass rolloff less and bass phase shift less.

or am i wrong? buildling my cmoy tomorrow to real quick while i wait to find a 6680 for my soha...

i have a question with capacitor types for C1

i have the choice between a 0.1 metalized film, 0.22uF polyester film, and 1.0uF tantalum capacitor. higher cap seems better but the tantalum looks so small it has to be bad quality, right? these are for my mostly-radioshack cmoy.

edit: i received my soha kit and instead of 2 OPA2134's like i requested, i have one of those and a OPA134PA. does this mean i am short one opamp? both soha and cmoy need the dual version? the other is a single op amp?

did my order get messed up or am i confused?

 

[dgbiker1]

Quote:

Originally Posted by DoomzDayz /img/forum/go_quote.gif iirc changing C1 and C2 don't add "bass boost". higher C1 simply adds more current reserve for low impedance headphones and drum hits, so it doesn't bottom out. higher C2 makes the bass rolloff less and bass phase shift less. or am i wrong? buildling my cmoy tomorrow to real quick while i wait to find a 6680 for my soha... i have a question with capacitor types for C1 i have the choice between a 0.1 metalized film, 0.22uF polyester film, and 1.0uF tantalum capacitor. higher cap seems better but the tantalum looks so small it has to be bad quality, right? these are for my mostly-radioshack cmoy. edit: i received my soha kit and instead of 2 OPA2134's like i requested, i have one of those and a OPA134PA. does this mean i am short one opamp? both soha and cmoy need the dual version? the other is a single op amp? did my order get messed up or am i confused?

Yea that's right. The caps improve bass response, they don't give a bass boost.
IIRC the 2134 is the 2-channel version of the 134, so you shouldn't even need the 134, not for the output stage at least. Is the soha just a CMOY circuit kit? Maybe the opa134 is for some kind of power circuit???