Cmoy Headphone amp - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems

Headphone Systems Everything to do with Headphones

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th May 2009, 03:04 PM   #1
Puffin is offline Puffin  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: U.K
Default Cmoy Headphone amp

I have built one of these using a schematic. I am having some problems getting a stereo output. If I join one of the input channels to the headphone socket ground I get stereo. If not I only get mono.

I also have an issue with the volume pot. At low volumes it is mono, bit louder, stereo, bit louder, mostly in right ear.

I have a DC reading mis-match at the headphone out of 23mv on one channel and 182mv on the other.

Can anyone help?
  Reply With Quote
Old 11th May 2009, 03:55 PM   #2
Atilla is offline Atilla  Norway
diyAudio Member
 
Join Date: Jul 2008
Ok, all of this sounds wrong, so you'd better start posting the exact schematic you used, some photos if possible, and a little more detail on what you have connected where.
  Reply With Quote
Old 11th May 2009, 06:48 PM   #3
Puffin is offline Puffin  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: U.K
Schematic/layout here

http://bp2.blogger.com/_0URxOBSyTPQ/...b_standard.jpg
  Reply With Quote
Old 11th May 2009, 07:26 PM   #4
Atilla is offline Atilla  Norway
diyAudio Member
 
Join Date: Jul 2008
I think this schematic can be very confusing. For one, it can lead you to believe that a single 10k potentiometer is enough for both channels, which is wrong. For stereo, you obviously need a dual potentiometer, one that controls both inputs with the same knob.


What kind of potentiometer are you using?
  Reply With Quote
Old 11th May 2009, 07:32 PM   #5
Puffin is offline Puffin  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: U.K
I am using a dual pot.
  Reply With Quote
Old 12th May 2009, 09:05 AM   #6
Artie is offline Artie  United States
diyAudio Member
 
Join Date: Jul 2007
Hey Puffin. Your first paragraph suggests that perhaps two different problems may exist. It sounds like maybe you have one input reverse-phase. Probably in the wiring of the input volume control. The source device will use a common ground, so when you touch one input to ground, you get both channels.

An out-of-phase condition is much easier to identify with speakers, because the bass cancels. But not so with headphones.

It also sounds like you may have greater gain in one channel than the other. But then again, this may just be a quirk of the mis-wiring.

So . . . I'd double check the pot wiring real close first. (Input wiring too.) See what that does, then recheck your resistor values if there's still a problem.

Hope this helps.
Artie
  Reply With Quote
Old 12th May 2009, 09:49 AM   #7
mjf is offline mjf  Austria
diyAudio Member
 
Join Date: Jan 2009
Location: Austria
hello.
ground connection between the two 9v batteries?
greetings............
  Reply With Quote
Old 12th May 2009, 10:10 AM   #8
Atilla is offline Atilla  Norway
diyAudio Member
 
Join Date: Jul 2008
There is a virtual ground, based on the resistor dividers and the caps. The schematic looks fine, I guess it's only the wiring that is mistaken. Check carefully how the inputs and outputs are wired.
  Reply With Quote
Old 12th May 2009, 02:02 PM   #9
Puffin is offline Puffin  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: U.K
Thanks for all your replies. I have been looking at the thing and trying various wiring combinations for the last 2 nights. I may have to start from scratch again.

I'll let you know how I get on.
  Reply With Quote
Old 15th May 2009, 04:55 AM   #10
lgreen is offline lgreen  United States
diyAudio Member
 
lgreen's Avatar
 
Join Date: May 2003
Location: San Diego, USA
Default connectors

Puffin, sometimes those minijack and 1/4" connectors are funny and don't conduct consistently. I have a miniplug that is new from digikey and does not conduct on the left channel unless bent a certain amount but it looks perfect.

You may want to check you connectors if your wiring looks ok. Or post a pic of your wiring and people here will look at it.
__________________
Retired from DIY (2010) but still lurking now and again. My DIY audio projects- PartTimeProjects.com.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cmoy headphone amp sammydee Headphone Systems 2 20th May 2009 11:47 PM
CMoy Headphone Amp ... I'm Back! lgreen Headphone Systems 4 23rd January 2009 04:37 PM
CMOY headphone amp, can it be used as a mic preamp? internecine Headphone Systems 3 25th September 2007 05:39 PM
new cmoy amp inox Solid State 7 11th December 2005 10:15 PM
CMOY Help? sbelyo Chip Amps 2 3rd July 2004 10:14 AM


New To Site? Need Help?

All times are GMT. The time now is 05:12 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2