ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

 
Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

MXR Envelope for Bass


 
1/6/2003 12:36 PM
jogi
email
MXR Envelope for Bass
How can I modify my MXR Envelope for bass guitar?
 
1/6/2003 2:47 PM
Mark Hammer
email

There are two ways you can do so. (I am assuming this is either an original or clone of the MXR Envelope Filter)  
 
1) Basses put out a pretty hot signal so you may find there is not enough control over the threshold/sensitivity. Just switch the pot from 500k to 1M and that will help you to be able to dial in just the right amont of sensitivity even when your thumb gets possessed by the spirit of Larry Graham.  
 
2) The filter range is set by two .001 (1nf) caps. In the original board, they are positioned one on each side of the 4069. On the Tonepad A-Gua board, these are the caps that link pins 2 + 3, and 12 + 13 on IC1. Increasing these caps will lower the filter range. Since the stock values are already pretty high (i.e., a low filter range, in comparison to things like the DR. Q, etc.), try changing them for 1500-1800pf. That should provide a range that is suitable for bass.  
 
You can either do this by removing the existing ones from your unit and replacing them, or by soldering in some 510-820pf caps in parallel with the existing ones on the copper side of the board.  
 
3) If you have not done so, the variable resonance/emphasis mod is great for bass. Low resonance, slow attack time, and a bit of chorus gets a VERY nice "Jaco" style fretless drone sound where the brightness just sort of creeps up on you.  
 
NOTE: On the A-Gua project, Francisco initially misunderstood my mods and thought that you only had to change *one* cap to get the filter shift, so that's all he designed the board for. He now knows better but I guess hasn't gotten around to redrawing the board to accommmodate two cap changes. The filter is a 2-pole filter so you'll need to change BOTH of the indicated caps to get the desired range shift.
 
1/12/2003 6:03 AM
Rob
To me it sounded OK on Bass as is.  
 
Regards  
Rob
 
   Page 1 of 1