CMOY shootout! - Page 2 - 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 18th February 2010, 03:18 PM   #11
diyAudio Member
 
Join Date: Feb 2010
I've very recently bought one of these kits, had great fun building it, and have enjoyed listening to it as well! I haven't compared it to my proper headphone amp, but for making my portable CD player (and various MP3 players) usable with decent Sennheiser (HD565) and Grado (325i) headphones, it works!

Click the image to open in full size.
Click the image to open in full size.

Last edited by Johnny Blue; 18th February 2010 at 03:37 PM.
  Reply With Quote
Old 21st February 2010, 09:45 AM   #12
Beftus is offline Beftus  Netherlands
diyAudio Member
 
Beftus's Avatar
 
Join Date: Nov 2008
Location: Netherlands
Cool! Count me in as well. I have the cMoyBB PCB and the TLE2426. Still waiting on some parts (Alps pot, caps, .25W resistors). I have an OPA2134 and an AD8066 for it to start with. Soldering the AD8066 was a challenge!

I'm going for a red coloured theme: red PCB, red LED, red mint tin.
Attached Images
File Type: jpg Barkleys_Cinnamon.jpg (25.9 KB, 1028 views)
File Type: jpg DSC_0421.jpg (91.1 KB, 1039 views)

Last edited by Beftus; 21st February 2010 at 09:51 AM.
  Reply With Quote
Old 21st February 2010, 12:32 PM   #13
diyAudio Member
 
Join Date: Feb 2010
I was interested in the cMoyBB board, but wouldn't want the BB bit! I like the idea of using good quality components (ALPS pot, etc.) and 6.35mm jack sockets in a kit, though, and getting the PCB is the hardest bit...
  Reply With Quote
Old 21st February 2010, 02:00 PM   #14
Beftus is offline Beftus  Netherlands
diyAudio Member
 
Beftus's Avatar
 
Join Date: Nov 2008
Location: Netherlands
Quote:
Originally Posted by Johnny Blue View Post
I was interested in the cMoyBB board, but wouldn't want the BB bit!
The BB (bass boost) is switchable or can be eliminated entirely if you wish so. If you want a little less bass boost you can install two lower value resistors or opt for a bass boost potmeter. Try the simulator (Java!) at: JDS Labs - cMoyBB Calculator

Last edited by Beftus; 21st February 2010 at 02:23 PM.
  Reply With Quote
Old 21st February 2010, 02:28 PM   #15
diyAudio Member
 
Join Date: Feb 2010
Yes, I'd read on the JDS CMoyBB website that I could wire out the BB: my thinking is that the less junctions/resistors/pots/switches in the way of the sound, the better (coming from a purist, no-tone-control point of view)!
  Reply With Quote
Old 24th February 2010, 10:24 PM   #16
Beftus is offline Beftus  Netherlands
diyAudio Member
 
Beftus's Avatar
 
Join Date: Nov 2008
Location: Netherlands
Progress! Today some parts arrived, cMoyBB is now nearly finished. I'm still waiting for the Alps pot. A quick test showed that the rail splitter works. I tried a 33K and a 24K LED resistor but settled on the (default) 24K one.

Bass boost resistors are 16K for a lower gain. Bass boost caps are 0.1F instead of the default 0.068F. It decreases the bass boost bandwidth a bit.

Had a bit of a problem with one hole on the PCB: it was to small to accept a resistor lead. I successfully used a sewing pin as a reamer.

Lesson learned: such a small PCB requires a finer tip on my soldering iron.
Attached Images
File Type: jpg red-cMoyBB.jpg (150.5 KB, 1029 views)

Last edited by Beftus; 24th February 2010 at 10:45 PM.
  Reply With Quote
Old 24th February 2010, 11:51 PM   #17
Zigis is offline Zigis  Latvia
diyAudio Member
 
Join Date: May 2005
Location: Riga, Latvia
Quote:
Originally Posted by nad View Post
Howdy Mike!

I had the same idea last week so I purchased on of these New Portable Hi-Fi Stereo CMOY Headphone Amp Amplifier* on eBay (end time 17-Feb-10 22:05:34 GMT) Hasn't arrived yet but for only 12ish delivered, it's worth a shot.
This kit use dangerous schematic!

Virtual ground here is simple split of two batterys. It is good, until one battery discharge little faster than other, or you connect slightly used batterys with different voltages. In this case you can get few Volt DC offset, and even burn phones.

To fix it, just add to schematic standard CMoy virtual ground with two resistors or TLE2426, and disconnect battery split from ground.
  Reply With Quote
Old 25th February 2010, 08:56 AM   #18
diyAudio Member
 
Join Date: Feb 2010
Quote:
Originally Posted by Zigis View Post
This kit use dangerous schematic!

Virtual ground here is simple split of two batterys. It is good, until one battery discharge little faster than other, or you connect slightly used batterys with different voltages. In this case you can get few Volt DC offset, and even burn phones.

To fix it, just add to schematic standard CMoy virtual ground with two resistors or TLE2426, and disconnect battery split from ground.
Quote:
Originally Posted by Johnny Blue View Post
I've very recently bought one of these kits, had great fun building it, and have enjoyed listening to it as well! I haven't compared it to my proper headphone amp, but for making my portable CD player (and various MP3 players) usable with decent Sennheiser (HD565) and Grado (325i) headphones, it works!

Click the image to open in full size.
Click the image to open in full size.
As I've written above, I have recently completed this kit, and am using cheap NiMH batteries (see the photo above!), which could well discharge at different rates. Is this circuit really likely to damage my precious headphones, and how do I prevent it? (Zigis statement is OK for all you DIY experts out there, but means nothing to me: can anyone explain simply exactly what I need to do?)
  Reply With Quote
Old 25th February 2010, 09:17 AM   #19
diyAudio Member
 
Join Date: Jan 2008
OK. Your two 9V batteries are connected in series, via some point on the PCB where a lead from each battery is connected by a track on the PCB.

You should disconnect the leads from this point. Now reconnect them (off the board, just to each other).

Now take two 4700 ohm (4k7) resistors. Solder one end of each into the holes vacated by the two leads you removed earlier. The other end of each needs to go to the other connection from each battery (that is, the leads from the batteries that are still connected to the board).

Is that clearer?

EDIT: Looking at the diagram you've posted, it appears that the common point to which I referred may actually be on some kind of terminal block, not on the PCB itself.

Last edited by TheSeekerr; 25th February 2010 at 09:21 AM.
  Reply With Quote
Old 25th February 2010, 09:27 AM   #20
diyAudio Member
 
Join Date: Jan 2008
OK, here's another way of explaining it, taking into account the diagram.

Going to the terminal block, you have two wires from the battery, and two wires leading to the board. Remove the two wires that lead to the board.

Now, on the board itself, you have two blue capacitors. In parallel with each capacitor, solder a 4700 ohm resistor. That is, solder one leg of resistor to one of the capacitors, then the other leg of the resistor to the other leg of the same capacitor. Now do the same thing, but with the other capacitor.

EDIT: now that I look again, I see that it's not a terminal block, but the power switch. This is a fairly stupid way of switching power.

OK, so if you do what I say above, it won't work, thanks to the power switch thing. What you'll need to do is move one of the wires that remains on the switch, so that instead of being in the same column as the other (looking at the diagram for reference), it's next to the other, but in the same row. That will restore function to the power switch, although it's still a bit dumb. It should now work.

If you have more questions, feel free to ask - perhaps some-one more patient than myself will go to the trouble of modifying the diagram to show you the right way.

Last edited by TheSeekerr; 25th February 2010 at 09:35 AM.
  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
DHT drivers - shootout andyjevans Tubes / Valves 28 14th April 2010 06:47 PM
Tripath chips shootout oon_the_kid Class D 10 31st May 2009 01:53 AM
Shootout: ZBM4 vs. ZMV5 (?) diesel_88 Multi-Way 1 29th March 2009 01:00 AM
6J5 Shootout - which one's best? Rodango Tubes / Valves 7 6th May 2008 08:03 PM
300B shootout aldovan Tubes / Valves 25 21st January 2008 03:56 PM


New To Site? Need Help?

All times are GMT. The time now is 07:02 AM.


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