R vs. RC on secondaries - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 28th March 2005, 10:57 AM   #1
diyAudio Member
 
Join Date: Nov 2001
Location: Sweden
Default R vs. RC on secondaries

For a WOT preamp ive seen people using both R and RC in order to get better square waves on the output.

What is the difference between the 2 methods?




The transformer is a 4.5:1 LL1660.
Recommended RC: 2k+3nF
Recommended R: 2k
  Reply With Quote
Old 28th March 2005, 04:10 PM   #2
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Default Re: R vs. RC on secondaries

Quote:
Originally posted by kasra
For a WOT preamp ive seen people using both R and RC in order to get better square waves on the output.

What is the difference between the 2 methods?
I don't know that it's so much about two different methods.

A realworld transformer has parasitic inductance, capacitcance and resistance that combine to give the trnasformer a high frequency resonance which can result in response peaking and ringing in the time domain.

For a given transformer there will be a resistive load value that will result in a well-damped high frequency resonance without peaking or ringing. However since transformers reflect the secondary load to the primary, that resistive load may not be ideal in terms of what's driving the transformer's primary.

You may want the driving component to see a much higher impedance. However if you keep the load resistive and inrease its value, then you're going to start running into problems with high frequency resonance.

So usually what's done is the resistive load is increased in order to get the primary impedance in the passband that you want and an RC network is then paralleled with it in order to provide proper damping of the high frequency resonance.

se
  Reply With Quote
Old 28th March 2005, 09:11 PM   #3
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: USA
R loads down everything.

R+C only loads the supersonics.
  Reply With Quote
Old 28th March 2005, 11:31 PM   #4
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally posted by PRR
R+C only loads the supersonics.
I'll try and remember that the next time the Kings play Seattle.

se
  Reply With Quote
Old 29th March 2005, 01:56 AM   #5
diyAudio Member
 
Join Date: Mar 2001
Location: Auburn, WA (somewhere between Seattle and Tacoma)
Blog Entries: 1
Send a message via ICQ to Damon Hill
Quote:
Originally posted by Steve Eddy


I'll try and remember that the next time the Kings play Seattle.

se

Mental note: warn the 'Sonics that the RC has been spiked.

--Damon, who RCs his power supply secondaries
  Reply With Quote
Old 29th March 2005, 04:24 AM   #6
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Pffbt... lucky for you I'm not drinking or eating anything right now!

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 29th March 2005, 10:43 AM   #7
diyAudio Member
 
Join Date: Nov 2001
Location: Sweden
Thanks guys for clearing things out for me
  Reply With Quote
Old 29th March 2005, 04:04 PM   #8
diyAudio Member
 
Join Date: Nov 2001
Location: Sweden
Anyone that could point out somewhere were I can read about this issue - and how to calculate appropriate R load for secondaries?

The setup is like Euridice with 417a tubes biased @20mA, 2200uF cathode bypass, 20kohm input impedance. Trafos are LL1660 4.5:1 wired.
  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
One transformer with 4 secondaries or two transformers with dual secondaries Baka Chip Amps 5 28th November 2008 06:39 AM
Unused secondaries pilli Parts 8 7th October 2007 10:14 AM
14v AC from 15v Secondaries Jarno Parts 17 31st August 2005 10:58 AM
Aleph L PSU and 50V secondaries Stabist Pass Labs 20 28th June 2005 09:59 AM
? on secondaries of a tranny JazzzSpazzz Parts 13 21st April 2004 05:58 AM


New To Site? Need Help?

All times are GMT. The time now is 11:40 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