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Big Muff DIY


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11/9/1998 4:25 AM
Chris
Big Muff DIY
I'm keen to build a transistor Big Muff Pi (based on a design found thru' Aaron's stombox page). Two questions: Can I use transistors other than those he mentions (2N5088, I think!) and still get the same characteristics ? Secondly, the EQ on the original seems very limited. Would adding a Marshall tone stack work well in this design? Any help, much appreciated  
 
Chris
 
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11/9/1998 9:13 AM
R.G.


quote:
"Two questions: Can I use transistors other than those he mentions (2N5088, I think!) and still get the same characteristics ? "
 
The transistor characteristics are not critical in this application. You can use BC549 or other high gain (300-800) low noise NPN silicon devices.  
quote:
"Secondly, the EQ on the original seems very limited. Would adding a Marshall tone stack work well in this design?"
 
It's not as limiting as you might think. Try the stock one first and then modify. Guitar amp tone stacks are designed for the amp application and may or may not give good results to your ears when used in applications without the frequency shaping that goes on in the other stages of the amp. It's a game of trust your own ears.  
 
By the way, GEO" target="_blank">http://www.eden.com/~keen">GEO has etched and drilled PCB's for the BMP, although it is not hard to hand wire.
 
11/9/1998 2:43 PM
Mark Hammer

You want tonal flexibility? Get two 3-position toggle switches (SPDT, centre-off), and wire in some caps in parallel with the caps in the tone circuit. Make the original caps in the tone circuit (the treble cap in series with one lug of the tone control, and the bass cap going between the lug on the other end and ground) half of their original value. Now use the two outer positions of each toggle switch to add in another cap to provide the original spec value, or another to double the spec value. For example, for the treble cap, replace the .004 cap with a .002 (probably .0022), and wire in another .0022 and a .0039 in parallel, using the switch.  
 
I guarantee that the 3 x 3 combinations of the switch settings, in tandem with the variable control, will give you far more tonal variety than you have ever likely experienced before.  
 
Bear in mind that the same mods apply to all circuits with the same essential tone control design (Jumbo Tone Bender, FET Muff, Hot Tubes, etc.).
 
11/11/1998 6:45 AM
Chris
Thanks to Mark and R.G. for your useful advice.  
Chris
 

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