Building a symmetrical psu B1 buffer - Page 193 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 20th August 2010, 08:51 PM   #1921
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
If you have hum then realistically its a ground loop. The fact that when you disconnect the LS ground and still have music means that the ground part of the signal is still getting to the LS.

Think of 2 separate "grounds". One is the signal ground. the other is the safety ground or "earth". This earth is connected to the chassis and the ground pin of the IEC. The signal ground and earth are only connected at one junction, and separated by either a CL60 or 2 diodes (cheapy 1n4007 are AOK) wired 69 style, and then with a ~10R 5W resistor and 0.001-0.01uF >250V cap in parallel.

If you can configure it that way then you will have zero hum. But you must make sure signal ground doesn't contact the chassis anywhere.

Fran

Last edited by woodturner-fran; 20th August 2010 at 08:52 PM. Reason: spelling
  Reply With Quote
Old 20th August 2010, 09:30 PM   #1922
Malka07 is offline Malka07  England
diyAudio Member
 
Join Date: Mar 2009
Thanks for your help Woodturner-Fran...Ive been trying hard to think where the signal grounds could be in contact with the chassis...is it posible that the metal standoff's im using for the boards are somehow causing this? coz apart from that i really cant think of anything else

Is there anything i could check with my Mutimeter Continuity function?

Alon
  Reply With Quote
Old 21st August 2010, 11:04 AM   #1923
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
The signal lines coming in from the RCAs are not screened and not twisted.

This is one of the biggest problems with two channel amplifiers. How does one connect the source to the power amp and maintain an interference free connection from source to power amplifier through a pair of spaced apart RCAs?
Those two loops that are visible would be excellent aerials for transformer hum and EMI.

But the buzz is also a clue. It may be a PSU grounding error. Where is your main Audio Star Ground?
__________________
regards Andrew T.
  Reply With Quote
Old 21st August 2010, 11:21 AM   #1924
Marra is offline Marra  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Near Lincoln
Does anyone know of a supplier other than Selectronique for R core transformers. I was going to order 2 because they seem to be the transformer of choice for the DCB1 but selectronique want payment by bank transfer which means an extra 30% on the bill! Thanks in advance.
Marra
  Reply With Quote
Old 21st August 2010, 11:38 AM   #1925
Reality first!
diyAudio Member
 
ClaveFremen's Avatar
 
Join Date: May 2005
Location: Milan, Italy
Quote:
Originally Posted by Marra View Post
Does anyone know of a supplier other than Selectronique for R core transformers. I was going to order 2 because they seem to be the transformer of choice for the DCB1 but selectronique want payment by bank transfer which means an extra 30% on the bill! Thanks in advance.
Marra
I've buyed from Selectronic with Credit Card, I don't remember if via PayPal but I'm sure of it...
__________________
Dario
ClaveFremen "Bailando Salsa en el Sietch"
  Reply With Quote
Old 21st August 2010, 01:00 PM   #1926
Malka07 is offline Malka07  England
diyAudio Member
 
Join Date: Mar 2009
Quote:
Originally Posted by AndrewT View Post
The signal lines coming in from the RCAs are not screened and not twisted.

This is one of the biggest problems with two channel amplifiers. How does one connect the source to the power amp and maintain an interference free connection from source to power amplifier through a pair of spaced apart RCAs?
Those two loops that are visible would be excellent aerials for transformer hum and EMI.

But the buzz is also a clue. It may be a PSU grounding error. Where is your main Audio Star Ground?
Hi Andrew, thanks for your help. The signal lines are a twisted pair, the only ones that ar'nt are the dcb1 output to output rca's as the wire are very short.

I have attached a labeled picture of my build, hopefully it will be more clearer as to whats happening with my build.

Click the image to open in full size.

I also found out that on my optivol board, all the signal grounds are connected to each other...Input L/R and Output L/R all connected together.
Is this maybe why when i disconnected the Input grounds(doing this got rid of a loud hum, when chassis ground is connected) i still got sound, because the output grounds are still connected and they are connected to the input grounds on the board??? Have a look at the attached pic...

Click the image to open in full size.

Also i dont have a main audio star ground?? i thought that this would be done on the boards...how would i do this??

Thanks for your help.

Alon
  Reply With Quote
Old 21st August 2010, 01:24 PM   #1927
diyAudio Member
 
regiregi22's Avatar
 
Join Date: May 2009
Location: Madrid (Spain)
Quote:
Originally Posted by Malka07 View Post
I wasn't expecting an improvement in SQ, i only did it because (1) I had a spare Shunt Reg and (2) I read somewhere that a clean power supply can help keep a fan quiet...so i thought id give it a go...
I would try to change a the fan for a better one. That is a really improvement, audible for any person, even if they don't know anything of HIFI they will be able to discern a clearly decrease in enviromental noise around the equipment.
And a very important thing, run it below 12v. 9v is ok but you can go lower. This bring the most important improvement in noise. Try it with a pot to control it.

Connect the CL-60 between the earth ground that comes from the IEC and the central ground of the DCB1 power supply, that's between the two big filter capacitors. The connect the ground from the IEC to the chassis. The rest of the audio input or output or Optivol grounds should be disconnected and isolated from the chassis. This point is very important.
Check with the DMM in continuity mode if there is a short between the RCA connectors and the chassis. It should have nearly the same resistance than measuring the CL-60 alone.
Yoour main star gorund should be between both big capacitors of the DCB1

Regards,
Regi
__________________
diyAudio, doing it as big as you can, JUST BECAUSE WE CAN!
  Reply With Quote
Old 21st August 2010, 01:27 PM   #1928
Marra is offline Marra  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Near Lincoln
Quote:
Originally Posted by ClaveFremen View Post
I've buyed from Selectronic with Credit Card, I don't remember if via PayPal but I'm sure of it...
Thanks for that. I emailed them because I don't sepak or read french and they got back to me saying payment to be by bank transfer. I've sent them another mail so hopefully they'll let me pay by paypal.
  Reply With Quote
Old 21st August 2010, 01:57 PM   #1929
Tea-Bag is offline Tea-Bag  United States
not politcally affiliated
diyAudio Member
 
Tea-Bag's Avatar
 
Join Date: Feb 2006
Location: Kennebunk
Blog Entries: 7
Alon, what kinda 220R's you got? They look like Z-foils. Yum.
  Reply With Quote
Old 21st August 2010, 01:58 PM   #1930
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by AndrewT View Post
But the buzz is also a clue. It may be a PSU grounding error. Where is your main Audio Star Ground?
Quote:
Originally Posted by regiregi22 View Post
..............Your main star ground should be between both big capacitors of the DCB1
no.
That puts the charging currents in with the audio currents.
The main star audio ground MUST NOT be between the the main smoothing caps.
The Main Audio Star Ground can be after a short link from the main smoothing cap Zero Volts. Even 1mm of short link would do the job properly. MyRefC v1.3 uses the length of the plated through hole on the PCB as this separating link. It's just like Sugden have used, 1.6mm long and perfect separation.
__________________
regards Andrew T.
  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
New-building of my B1 buffer Babowana Pass Labs 328 20th February 2010 01:14 AM


New To Site? Need Help?

All times are GMT. The time now is 09:34 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