Wiring Attenuator for dual channel Balanced - Page 2 - 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 11th December 2012, 11:36 AM   #11
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
Quote:
Originally Posted by AndrewT View Post
With a balanced interconnection, the impedance on both the hot and cold are identical. If they are not identical then the interconnection is not balanced.

The attenuator must insert identical resistances into both the hot and the cold poles of the signal connection.
Yes that is true, and that is the nice thing about this balanced attenuator. It only switches one restistor between hot and cold (after the two series restistors) so it is always balanced perfectly.

William
__________________
een ooievaar is geen konijn want zijn oren zijn te klein!
  Reply With Quote
Old 11th December 2012, 11:39 AM   #12
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by wuffwaff View Post
...............so it is always balanced perfectly..................
Is it?
What is the channel matching tolerance?
__________________
regards Andrew T.
  Reply With Quote
Old 11th December 2012, 11:51 AM   #13
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
the chanel as such is balanced perfectly (you can match the two series resistors if you think 1% isnīt enough or use 0,1% as I did).

Between left and right channels you can get 1% when using 1% resistors. In dB that would not be very much.....

cheers,

William
__________________
een ooievaar is geen konijn want zijn oren zijn te klein!
  Reply With Quote
Old 11th December 2012, 11:55 AM   #14
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
between hot and cold.

0.1% is usually the biggest acceptable tolerance. That is half the tolerance of using +-1% resistors. Some would say you should be aiming for better than 0.01% for hot to cold channel matching.

I don't care if it's -30.02dB or -30.09dB
__________________
regards Andrew T.
  Reply With Quote
Old 11th December 2012, 12:17 PM   #15
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
Andrew,

Iīm not sure we are talking about the same thing.

Iīll try to say it more precisely:

The attenuation by changing only one resistor (between hot and cold) wonīt change the balance (between hot and cold) of this channel. It will stay as it is.

If the balance between hot and cold needs to be better than 0,01% I donīt know. This would mean using only precision resistors to set the gain and attenuation. Most preapms using 4-way pots and 1% resistors (at best) will never get near this value.

william
__________________
een ooievaar is geen konijn want zijn oren zijn te klein!
  Reply With Quote
Old 11th December 2012, 12:29 PM   #16
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
yes you have identified the problem.
Balanced requires precision matching of impedances.

Throw away precision and you throw away all the advantage that balanced brings.
__________________
regards Andrew T.
  Reply With Quote
Old 7th May 2013, 04:22 AM   #17
diyAudio Member
 
Join Date: Aug 2012
Location: Singapore
Hi all... Thank you for all ur precious advices . The attenuator now works fabulously. I used a 50k pot instead of 10k as recommended. I would also like to find out with this configuration can I use a 100k pot ? Also for both the 5K resistors is there any power rating or requirement? (I.e 1/4 watts or something with bigger values? Thank you once again you had been a fabulous people.!!!
  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
In-line attenuator for headphones (wiring)? Norfox Everything Else 6 19th March 2010 02:38 PM
H Type Balanced Attenuator. GeeVee Pass Labs 24 17th July 2008 06:39 PM
Looking for Balanced attenuator ideas cartman Analog Line Level 11 30th May 2008 02:11 PM
DIY Fidelity attenuator wiring - help please tfowler Class D 10 3rd December 2006 05:33 PM
I'm wiring my 4 channel 8 parallel LM4780 boards... check my wiring :) Audiophilenoob Chip Amps 9 16th August 2005 04:37 AM


New To Site? Need Help?

All times are GMT. The time now is 01:11 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2