Power supply resistor matching - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 30th December 2012, 07:03 PM   #1
MGH is offline MGH  United States
diyAudio Member
 
Join Date: Jul 2004
Location: Texas
Default Power supply resistor matching

A newbie question here. I've seen people getting matching left and right channel resistors (<1% tolerance) in low level signal section of preamp or amp. I suppose this is even more important in balanced differential preamp/amp. But how important is matching left and right channel power supply resistors in an amp? Seems 1% resistor tolerance is excessive in power supply.
  Reply With Quote
Old 30th December 2012, 07:09 PM   #2
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
1% is more than enough in most cases but some people like to have 15.000 volts but it is not important.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread || Diamond buffer |Thread for the group buy | Wiki
  Reply With Quote
Old 30th December 2012, 07:19 PM   #3
MGH is offline MGH  United States
diyAudio Member
 
Join Date: Jul 2004
Location: Texas
Thanks. What type of resistors are typically used in power supply...wire wound, metal film, metal oxide, carbon film...?
  Reply With Quote
Old 30th December 2012, 07:33 PM   #4
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Resistor types (and tolerances) are chosen for the purpose of the
resistor in the circuit, there is no carte blanche simple answer.

Power supplies are are varied as the circuits they feed.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 30th December 2012, 08:02 PM   #5
diyAudio Member
 
Join Date: Feb 2012
Quote:
Originally Posted by MGH View Post
Thanks. What type of resistors are typically used in power supply...wire wound, metal film, metal oxide, carbon film...?

The ones that are flame proof and non-inductive. Not sure if both options will fit your needs due to sizes, ratings, etc... This is due to me not wanting to start an inferno in my basement due to a failure, while not wanting to couple any stray magnetic flux from the XFMR and large currents into any stray inductance from a cheap wirewound resistor. I had an ANTEC 1000W PC PSU unit start smoldering in my media server PC (located in my 72" tall rack with all other stuff, xbox, xbox 360, cable box, reciever, etc..). It was smoldering/burning for at least 3-4 days. the wife kept smelling something while i was away. The only reason I am writing this is due to the flameproof components and coatings. If it was a ebay cheapo supply, my house might be missing. PC still continued to run until I pulled the cord, despite the PSU board melting down, smoldering and unsoldering itself. I was damn lucky.

It is a shame to place such precision and materials in the amp section and forget about the PSU. Remember...garbage in is garbage out. If it was me and I was doing a one-off for myself, I would spend the extra $5-10 USD for better components. If it is a mass produced product there will always be the bean counters to throttle the components back to basics.

Last edited by NissanSR20Man; 30th December 2012 at 08:10 PM.
  Reply With Quote
Old 30th December 2012, 08:41 PM   #6
MGH is offline MGH  United States
diyAudio Member
 
Join Date: Jul 2004
Location: Texas
Yes, I agree good reliable resistors that are overrated should be used. I was thinking high quality noninductive wire wounds from Mills or the like. Any reason not to use them in certain parts of the power supply?
  Reply With Quote
Old 30th December 2012, 09:34 PM   #7
diyAudio Member
 
Join Date: Feb 2012
A good writeup from here...Resistor Types--Does It Matter?

Read through it, pretty good. I would have chosen incorrectly. There are several articles like this.

"Wirewound resistors are the best choice for noise, followed by metal film, metal oxide, carbon film, and lastly, carbon composition. However, wirewound resistors are not readily available in large resistance values, and are usually inductive, which can cause instability problems in some cases. Bear in mind, however, that many people prefer the "sound" of carbon comps, claiming they sound warmer than film or wirewound types. This is possibly due to distortions generated by the modulation of the contact noise current by the AC signal. Since this noise has a 1/f frequency characteristic (similar to pink noise), it is more pleasing to the ear than white noise. However, pleasing noise is still noise, and in my opinion, it should be reduced to the lowest possible level. The signal distortion is a different topic altogether."

Last edited by NissanSR20Man; 30th December 2012 at 09:40 PM.
  Reply With Quote
Old 31st December 2012, 08:17 PM   #8
MGH is offline MGH  United States
diyAudio Member
 
Join Date: Jul 2004
Location: Texas
Quote:
Originally Posted by NissanSR20Man View Post
A good writeup from here...Resistor Types--Does It Matter?

Read through it, pretty good. I would have chosen incorrectly. There are several articles like this.

"Wirewound resistors are the best choice for noise, followed by metal film, metal oxide, carbon film, and lastly, carbon composition. However, wirewound resistors are not readily available in large resistance values, and are usually inductive, which can cause instability problems in some cases. Bear in mind, however, that many people prefer the "sound" of carbon comps, claiming they sound warmer than film or wirewound types. This is possibly due to distortions generated by the modulation of the contact noise current by the AC signal. Since this noise has a 1/f frequency characteristic (similar to pink noise), it is more pleasing to the ear than white noise. However, pleasing noise is still noise, and in my opinion, it should be reduced to the lowest possible level. The signal distortion is a different topic altogether."
Thanks, I read that article. Seems wire wounds are suited and are favored for most applications if you can find the right value. If you get the noninductively wound WW resistors, you shouldn't have any instability problems, which I assume are high frequency oscillations that can be induced (eg, grid stopper) by inductive resistors.
  Reply With Quote
Old 1st January 2013, 08:30 AM   #9
diyAudio Member
 
Join Date: Sep 2010
Location: Melbourne
There is no blanket rule each type has it's advantages, The noisy carbon composition resistor works very well in pulse power or RF circuits also there are many places in an amplifier where a noisy resistor is of no consequence or the noise is heavily filtered by a decoupling capacitor, same goes for instability, a bypass capacitor may move any resonances so far outside the region where the amplifier produces any gain that oscillation is impossible.
  Reply With Quote
Old 1st January 2013, 02:06 PM   #10
MGH is offline MGH  United States
diyAudio Member
 
Join Date: Jul 2004
Location: Texas
Quote:
Originally Posted by metalsculptor View Post
There is no blanket rule each type has it's advantages, The noisy carbon composition resistor works very well in pulse power or RF circuits also there are many places in an amplifier where a noisy resistor is of no consequence or the noise is heavily filtered by a decoupling capacitor, same goes for instability, a bypass capacitor may move any resonances so far outside the region where the amplifier produces any gain that oscillation is impossible.
Hi, thanks for your input. So what part of the power supply is a particular type of resistor critical or more important?
  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
Help finding matching power supply for Ivchikx Power Supplies 2 6th March 2011 04:59 AM
Audio note M2 power supply resistor value drobert Tubes / Valves 0 20th November 2007 10:01 AM
Resistor matching tip Nordic Parts 5 13th January 2007 05:19 PM
bleeder resistor for ZenV4 power supply; and ancllary matters Zapped Pass Labs 13 24th September 2003 04:02 AM
power supply for Mosfet matching russbryant Pass Labs 3 12th November 2002 08:04 PM


New To Site? Need Help?

All times are GMT. The time now is 08:15 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