gus muff fuzz mods soundclips?

[Marcos - Munky]

Anybody have soundclips of Gus Muff Fuz mods 1 and 2? I built a Muff Fuzz (opamp), and I'm curious to hear how the mods sounds.

[WGTP]

I don't have sound clips, but a variation of Gus' mods is my favorite op amp distortion.  The main improvement is putting a 470K/1meg in parallel with the diodes.  I also like increasing the input resistor to 220k.  My personal favorite mod is to change one of the diodes to an LED and let it rip.

[Marcos - Munky]

What did you tried? And how the 220K input resistor changes the sound?

[WGTP]

The 220k resistor increases input impedance and seems to increase the treble/reduce bass and increase clarity.  If you drop it to 10k you get lots more mid-range.  Check the Mockman at ROG.  A 250k pot there is good for gain/tone adjustments as Gary said.  Also a 1meg pot in the feedback loop of the first op amp is better for gain admustments.

The Led/SI (might try 2 SI's or a Jfet) combination raises the output which helps the signal to noise ratio, produces a nice thick/rich asymmetrical distortion and is cool to watch in the dark.  

Some small caps in the feedback loops 33-100pf can help with noise and smooth out the highs, but 1 - 100pf in the first stage is all I use.

You can also try diodes to ground at the output for additional distortion/volume/tone variations.  

I also use a 2.2k resistor between stages.

I think it really rocks and I haven't been able to build a better op amp circuit yet.  Good Luck.  

[brian wenz]

Hello Hello-
      I'm having trouble reading Gus' Muff Fuzz mods [from the 'Schematics" section].  Is there another place I can get them from??
Thanks-
Brian.

[Gus]

the 220k and .01 was found with experiments to be a good starting point.  In this circuit the opamp used number and brasnd makes more of a difference because of how it is used.  I like a NS 353 but change to taste.  For bass use a .0047uf yes a .0047uf and a 220k or 470k first opamp feedback R.  With guitars adust the ist section feedback R for pickup type use hot humbuckers 220K to 330K lower output singles 470K.

The schematics Aron has posted of mine are starting points for average guitars and bass.  I like to tune voice whatever you call it on a ceramic single coil Ibanez roadstar for the 80's

Have Fun

[WGTP]

Hey Gus, glad you here and thanks for the cool mods.  As I said my favorite Op amp design.  Didn't think they could sound this good.

How does the resistor/cap between stages effect things.  Does it just alter gain, or does the impedance change effect frequency response.

[brian wenz]

Hello Hello--
   eerrmmmmm.......so I guess the answer to my question is "NO"   ??
Brian.

[petemoore]

Hey Gus, glad you here and thanks for the cool mods.  As I said my favorite Op amp design.  Didn't think they could sound this good.

How does the resistor/cap between stages effect things.  Does it just alter gain, or does the impedance change effect frequency response.

I decided to try it again, I think the first one had a unique 'issue'.
 I wired one up just now,
 two 220k's and a 100uf for the divider,
 4k7 between stages,
 .056uf [socketted] input capacitor
 EZ change Si's for asymetric clipping, thinking of adding a diode switch
 220k + 500k pot for second gain stage [no 1Meg handy], seems to distorto' plenty...and nice...more tests before I start raving...quite promising !!!
 1Meg for 1rst stage gainset has EZ access leads for adding parallel resistor or replaceing with V/R pot.
 Should be interesting to try this thing out out on the Big Amps !!!
 Thanks To Gustav C. Smalley !!!! [and others...]

[brian wenz]

Hello Hello Pete--
   Are those all the mods??
Thanks-
Brian.

[petemoore]

I copied the standard Muff Fuzz schematic from GGG.
 Then I went to the Gus's MF File, saved the picture, then opened the picture [both of these functions [saving and opening can be accessed] should show at the top left of the schematic [save], after you run your cursor over 'back' and see it move, then run the cursor around the left top of the schemtic till the four buttons pop up, the left button is save].
 Then when you open it in another program hopefully you can Zoom In on it, it then becomes more legible. It is rather faint.
 If not, it's just a few component values away from the Muff Fuzz Schematic, and I can identify these, thoough I think WGTP has typed them out above.

[brian wenz]

Hello Pete--
    Yeah, I've got a copy of Gus' drawing....it's just dificult to make everything out properly.
Thanks-
Brian.

[petemoore]

Voltage divider uses two 100k's / and two 100uf one from Gnd to 1/2 one from Gnd to V+. Both Opamp + inputs are tied to 1/2v.
> .01uf input capacitor {I used .047uf..too Whoophy Bass with HB's tho]
 >Input R is 220k instead of 100k
 >Feedback loop #1 gets a Resistance up to 1M. Lower this resistance, [I used V/R pot] and Fuzz decreases.
 >insert .1uf Capaciter between 1rst stage and the 10k.
 >Use another pot for second feedback loop: 1Meg.
 >.1uf output cap I think is the same.
 Oh don't forget to let yourself easily change diodes types etc..

[WGTP]

Be sure and try just 1 diode SI or LED in the loop.  

[petemoore]

WOW, I'm glad I tried this one again. I think I tried the one without the mods last time. What a difference some mods can make!!!
  I rounded up the right pots and did found a slight error...I had the diodes only on the 500kpot I was using and they were 'missing' the added 220k...long story short works Fantastic !!!
 This is a Fabulous sounding circuit, I was surprized that a feedback clipper could be so rough ! It's closer sounding to the DIST+ than a TS... :shock:
 Does the excellent FUzz !!!

[brian wenz]

Hello Hello--
    Pete and WG-- Thanks!  I've had trouble with this circuit before, so now I can rebuild.
Brian.

[WGTP]

I guess it's a little different since it uses the inverting inputs, but it was the first op amp design I messed with, so all the others seem different.

I just noticed that the Blues Breaker uses both types.  The first stage is non-inverting, like the TS, SD1, etc. and the 2nd is like a MF.  

I think that means the input and output are out of phase which reduces feed back.

[Marcos - Munky]

Thanks. I will build it again in a few days and I will try some mods.