ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Muff Fuzz (Transistorized)

:

11/24/1999 3:45 PM

Muff Fuzz (Transistorized)

Anyone own an original electro-harmonix Muff Fuzz or ever built the Muff Fuzz shown in the upper right hand corner of the following link?

EH" target="_blank">http://www.ee.ualberta.ca/~charro/cookbook/audio/guitar/ehbsters.gif">EH Boosters

I know Mark Hammer has built one, since he warned me in advance that the clipping diodes should be connected to earth (ground), not the 9v+, as shown in the schematic. I built it last weekend and it actually sounds pretty decent with 1N34A diodes, however, it doesn't really get into the heavy clipping range that I expected it would, in fact it barely clips with 1N914s. Maybe I expected too much. Can anyone tell me how much distortion a known working unit puts out on full volume? I'm just wondering if I got it working up to standard or if I need to do some tweaking.

I'm planning to post the details (with a layout) if anyone else (beginner) is interested in building one.

JD

11/24/1999 4:50 PM
MKB	Hi, JD. I worked on a friend's original Muff Fuzz about two months ago. The schematic was the same, however the unit had the positive rail grounded, with NPN transistors. Imagine the positive rail as ground and the ground as the power supply rail, all hand wired. It works, but is really wierd. In any case, the unit did not fuzz a lot, even with humbuckers. This one had 1N4148's.

11/24/1999 8:44 PM
anonymous	MKB, Wait a minute, I a little confused. The schematic does use NPN transistors, did you mean to say the unit you worked on had PNP? I tried the 1N4148's, but it barely had any clipping with them in there. Does it make sense that the 1N34A germanium diodes would cause more distortion, or was I imagining that? Thanks, JD

11/26/1999 10:47 PM

Yes, this unit had NPN's. It just had the positive and ground rails switched, along with the battery polarity. I would guess someone was having a bad day (or had a hangover) at the EH plant that day, since the unit was basically sky wired by hand. BTW, the problem with the unit that I fixed was bad grounding. The grounds of the circuit were soldered on the back of the pot while the jacks had to ground on the case. Symptoms; very low output, and the neatest radio receiver I have heard in a while! Hard wiring the jack grounds to the pot fixed the problem.

The 1N34A's will give more fuzz, with less output voltage of the effect.

11/24/1999 5:19 PM

The Muff Fuzz... that brings back memories. Not counting a homemade booster I had that was built inside a cardboard cigar box, the Muff was my first fuzz box. My older sister gave me mine as a birthday present when I was 14. It seemed plenty "fuzzy" to me at the time, but this was in pre-Metallica days

I built it last weekend and it actually sounds pretty decent with 1N34A diodes, however, it doesn't really get into the heavy clipping range that I expected it would, in fact it barely clips with 1N914s.

Not surprising, since the 1N34As have a much lower forward voltage drop (clipping threshold) than the 1N914/1N4148 types.

Retain the 1N34As and try increasing the value of the collector load resistor on the second stage. That might help. Don't increase it too much, though, or else it might reduce the collector current enough to throw off the bias on the first stage. (Notice the "bootstrapped" biasing arrangement, which offers a higher input impedance than the typical voltage divider arrangement).

11/24/1999 8:46 PM
JD Sleep	Dave, Thanks for the reply, I'll try fiddling with that resistor. Thanks, JD

11/24/1999 9:57 PM

I had a functioning one long ago, yanked it apart, and squirreled the parts away. Stumbling onto the schematic (and *eventually* recognizing the errors contained), I rebuilt it (still had the 2N5133's sitting around, soldered to the original DPDT switch; it had NO board, just point to point wiring between jack switch and battery).

You're right, not a lot to recommend it (although I remember one hairy gig in a school gym in 1972 where I plugged two in series). The original just has one pre-set gain. You can stick a pot between the emitter and ground of the second transistor, and vary the gain in a manner than makes it a bit more flexible. The 2n5133'S aren't especially high gain units, so maybe using 2N5088's or higher hfe BC239's would help.

I use 1N914's. In the absence of anything after the diodes to add some gain, my own preference is to stay with silicon over germanium so as to maximize output level, and come closer to the clipping threshold by tweaking the gain of the circuit than by leaving the gain where it is and moving the threshold down with the diodes. This lets you push the amp hard enough to get some amp-based distortion along with FX-based distortion. But this is my taste, and doesn't have to be yours.

To its credit, a VERY easy circuit to make on perfboard.

Page 1 of 2