MESA STRATEGY BIAS MOD - 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 15th November 2012, 07:13 AM   #1
diyAudio Member
 
Join Date: Dec 2011
Default MESA STRATEGY BIAS MOD

LOOKING FOR SOME HELP WITH ADDING TRIMPOTS AND RESISTOR TO THIS AMP ,NEED TO KNOW IF I NEED 1 OR TWO TRIMPOTS ,VALUES ETC MANY THANKS.
  Reply With Quote
Old 15th November 2012, 07:22 AM   #2
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
How about post or link a schematic for this model?
  Reply With Quote
Old 15th November 2012, 09:31 AM   #3
diyAudio Member
 
Join Date: Dec 2011
Default mesa strategy

Hi Enzo thanks for your reply enclose a copy of the schemetic for you ,many thanks.Click the image to open in full size.
  Reply With Quote
Old 15th November 2012, 12:51 PM   #4
Simon B is offline Simon B  United Kingdom
diyAudio Member
 
Join Date: Dec 2011
Location: North-East England
The url given for the schematic is correct, but it won't play nicely unless you've opened the page that references it:

The Free Information Society - Mesa Boogie Strategy 400 Electronic Circuit Schematic

My sprawling collection of schematics inclues the one below.
Attached Images
File Type: gif Strategy_400.gif (30.1 KB, 32 views)
__________________
Engineer: One who can do for 10 shillings what any fool can do for 10 pounds.
  Reply With Quote
Old 15th November 2012, 01:10 PM   #5
diyAudio Member
 
Join Date: Dec 2011
MESA STRATEGY 400 SCHMETATICClick the image to open in full size.
  Reply With Quote
Old 15th November 2012, 08:55 PM   #6
diyAudio Member
 
Join Date: Oct 2012
Location: Seattle
I assume you want to add an adjustable bias circuit. The two resistors in the schematic are not labeled; one between the two caps, and another to ground- form a voltage divider. The bias voltage is determined by the ratio of these two resistors. Look at the resistor going to ground. Replace it with a pot and a resistor, the resistor on the ground side to prevent the bias from being adjusted too low. You will have to figure out the value of the pot and resistor based on the current value of what's in there now.
  Reply With Quote
Old 16th November 2012, 06:31 AM   #7
diyAudio Member
 
Join Date: Dec 2011
Thanks for your reply Snaggletooth ,the resistor to ground might possibly be 22 k does that sound about right would be the one to change ,looking at the schematic to 100k resistors the ground one to be changed is this what you are saying?
  Reply With Quote
Old 19th November 2012, 06:37 PM   #8
diyAudio Member
 
Join Date: Oct 2012
Location: Seattle
Yes, replace that with maybe 10k to ground connected to maybe 50k pot with wiper connected to one side. You may also have to reduce the value of the resistor in the pi filter.
  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
MartinLogan Bias Mod tyu Planars & Exotics 24 23rd November 2013 11:42 PM
MESA STRATEGY 400 blackarab Tubes / Valves 7 15th November 2012 03:14 PM
Mesa boogie strategy 110 to 230 volt conversion blackarab Power Supplies 0 20th August 2012 08:36 AM
mesa boogie strategy 400 amp blackarab Swap Meet 0 12th August 2012 03:44 PM
Mesa/Boogie Bass 400+ mod question fenderjazz Tubes / Valves 5 10th October 2011 08:50 AM


New To Site? Need Help?

All times are GMT. The time now is 12:20 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