Overdriving one channel with another - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 14th March 2013, 03:56 PM   #1
diyAudio Member
 
Join Date: Mar 2013
Default Overdriving one channel with another

I was wondering if I could overdrive the input of one of my amp channels with the output of the other channel. I have an Ampeg B25 (schematic linked) and I was thinking about removing the 270K resistor between the channel 1 pre-amp out and the power section input and connecting the output of that channel to the input of channel 2 so I can overdrive it. Do I run the risk of breaking something in the channel 2 pre-amp section if I do that?

Thanks for viewing! Below is the link to the schematic.

http://www.drtube.com/schematics/ampeg/b25-jp.gif
  Reply With Quote
Old 14th March 2013, 04:02 PM   #2
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Moved to I & A. Please post all music amplifier questions to the Instrument & Amps forum per forum policy. Make note of the sub-headers in the forum title.

Quote:
Instruments and Amps Everything that makes music, Especially including instrument amps.
and

Quote:
Tubes / Valves All about our sweet vacuum tubes Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 14th March 2013, 04:03 PM   #3
diyAudio Member
 
Join Date: Mar 2013
Quote:
Originally Posted by kevinkr View Post
Moved to I & A. Please post all music amplifier questions to the Instrument & Amps forum per forum policy. Make note of the sub-headers in the forum title.



and
Thanks!
  Reply With Quote
Old 19th March 2013, 02:42 PM   #4
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Yes you can, you'll break nothing, but the amp will probably hum/hiss/oscillate/whatever because of the tremendous gain boost.
It can be done, but be careful.
Good luck.
  Reply With Quote
Old 19th March 2013, 11:56 PM   #5
diyAudio Member
 
ArcticBreaze's Avatar
 
Join Date: Dec 2010
Location: Oamaru
yes it works well but you may have to put in a resistor to lower the max gain. this will fix the oscillationproblems and still give good overdrive. both my harmonica amps are done like this the first was a 5e3 fender clone that i moded to be like this.( see attached ) my new amp is based on the first one but with a few differences worked out latter. havn't drawn up the working schematic for it yet.
Attached Images
File Type: gif harp deluxe.GIF (25.8 KB, 43 views)
__________________
Fat Tubes For Fat Sounds
  Reply With Quote
Old 22nd March 2013, 01:40 AM   #6
diyAudio Member
 
Join Date: May 2010
Location: was Chicago IL, now Long Beach CA
I followed Jerry Garcia's approach, and put one channel of an Alembic preamp output into the input of the other channel (with a pot between, and another pot at the power amp input). 1 volume pot on guitar, 1 volume pot in 2-stage first channel, 1 volume pot between channels, 1 volume pot in 2-stage second channel, 1 master volume pot at power amp.

Not only does it have a wonderful overdrive, it also has a wonderful bright clean available if you twist a few knobs! Lots of 'bright' high-treble boost requires throwing away lots of gain in the tone stacks; this gives you two tone stacks in series. That's the real advantage! You can control the tone before and after the distortion is generated, so one of my favoite settings is very bright and treble in the first channel, then make some distortion, then cut the treble in the second channel. The guitar comes thru bright and articualte enough, while the harmonics are very complex and chords and bends sound great, meaty and beaty, yet the distortion is not all bright buzz and irritating.

Consider an on/off switched volume pot instead of the second input jack for the second channel. Lets you run thru just the second, or thru both. A relay and footswitch is even better.
  Reply With Quote
Old 22nd March 2013, 01:42 AM   #7
diyAudio Member
 
Join Date: May 2010
Location: was Chicago IL, now Long Beach CA
There's also something "special" about squasing the peaks of the waveform, then rotating the phase thru another stage and doing it again.
  Reply With Quote
Old 22nd March 2013, 03:17 AM   #8
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Well, that's nice.
  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
Removing gain channel preamp tube(s) Palomino V50 for better clean channel tone? tubeFrank Instruments and Amps 2 22nd March 2012 11:54 AM
Overdriving the grid of a triode MadDave12 Tubes / Valves 24 10th December 2011 08:40 PM
Confusion on home made buffer, one channel clear, two channel not? Destroyer OS. Digital Line Level 16 14th May 2010 07:27 PM
Overdriving (or overclocking) components Matttcattt Parts 9 8th July 2003 01:08 AM


New To Site? Need Help?

All times are GMT. The time now is 12:09 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