Dual star ground wiring in mono power supply - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 11th December 2011, 04:30 PM   #11
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Originally Posted by gabdx View Post
Hi , thanks for pointing this to me. I thought using only the + signal would work, the - signal would not connected.
It will work, but substantially degrades the performance of the DAC. The benefit of balanced operation is that even harmonics and noise appear as common mode signals on the output cancel when combined.

This design seems needlessly complex, a high quality 1:1 transformer will do your balanced to unbalanced conversion, giving you great common mode rejection and a single amplifier stage after that ought to be all that is required.
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 23rd December 2011, 12:15 AM   #12
gabdx is offline gabdx  Canada
diyAudio Member
Join Date: Jan 2008
I build it and of course it was quite a challenge... First, do not build the circuit as shown; ill remove it, because the headphone section has all the wrong values calculated by lampizator website. (srpp correct voltage 165V, Headphone section : Ra=7500 Rk1= 200, Rk2 = 6500 V=165)
There is some parasitic noise in the volume control metal casings and the signal wires from the dac to the headphone amplifier. One tube diode socket makes the ez81 noisy, I can’t figure why yet.

The biggest problem is the dac output going to the srpp tube. The dac signal seems over-amplified and the dac is clipping badly when music is louder. I will try to load the input with 10K instead of 240K or 75K (made no difference). I will also try to put a 1k resistor in serie to normalise the output impedance of the dac.
  Reply With Quote
Old 31st December 2011, 11:10 PM   #13
gabdx is offline gabdx  Canada
diyAudio Member
Join Date: Jan 2008
Project : completed !
I used a wolfson dac with build-in opamp, similar to tda1543
The circuit is simple, volume control shunt 100k input.
- cathode follower 1/2 tube left and right , 150uf output capacitor
CLCRC filter, AC heaters, EZ81 rectifier.
Sound ? Awesome ! no hum, no noise, perfect amplification, just a bit loud , I recommend lot of volume control attenuation !
  Reply With Quote
Old 1st January 2012, 07:50 PM   #14
gootee is offline gootee  United States
diyAudio Member
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Maybe you should post a photo of the circuit and a final schematic.
  Reply With Quote
Old 2nd January 2012, 03:54 AM   #15
gabdx is offline gabdx  Canada
diyAudio Member
Join Date: Jan 2008
Yes ! It is not very pretty after 3 rebuilds, just a prototype. Of course it will help others who would like to go beyond the opamp and the discrete transistors solutions without making a mess.
  Reply With Quote
Old 2nd January 2012, 04:15 PM   #16
gabdx is offline gabdx  Canada
diyAudio Member
Join Date: Jan 2008
Click the image to open in full size.

Important Parts : Hammond 369EX, Choke Hammond 181R 20H, EZ81, 6n6p,
Specifications : tube bias 8.8 ma on 1/2 6n6p, grid current 0.0005ma 1/2 6n6p
Grid bias resistors : grid-HT : 355k, Grid-Ground : 145k.
Power rating : 0.1W , 300R Headphones recommended.
  Reply With Quote


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
Power transformer star ground AmpBuilder225 Tubes / Valves 4 1st March 2009 04:13 PM
Dual Mono vs Stereo Power Supply Question bluegti Chip Amps 4 2nd January 2007 03:26 PM
Dual mono amp star grounding questions HiFiNutNut Solid State 10 8th August 2005 09:24 PM
Star ground w/ Dual capacitor banks Killjoy99 Solid State 23 29th September 2004 10:23 PM
Dual Mono - Anti Mono Power Supplies pmkap Everything Else 3 16th February 2002 05:10 AM

New To Site? Need Help?

All times are GMT. The time now is 09:46 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2