fuzz face with low pass

[Austrian]

Hello guys,

I'm new here and I have a question.

How can I implement a low pass filter with a fuzz face?

You have a schematic?

[patrick398]

This is a pretty nifty tool for calculating the corner frequency of either low pass or highpass RC filters.
http://www.muzique.com/schem/filter.htm

I'm pretty new to this too so not sure exactly where you'd put it...my guess would be near the input...but then all the bass frequencies would go through the gain stage and it might sound muddy/wooly. How about splitting the signal so certain frequencies go through the gain stages. With low pass avoiding the gain stages and then blend at the output? I don't really know what i'm talking about i'm just thinking out loud ha.

[antonis]

Hi & Wellcome...

Of course you can do that but WHY..??
(do you have RF interference..??)

P.S.
Whatever you implement, take care of PS polarity.. 

[Austrian]

because I want to recreate the Fuzz O)))

https://www.youtube.com/watch?v=uaHmegtyOpE

[patrick398]

Here's what i'd do(om). Make the input cap bigger, say 10u, then try a loss pass just before the volume. Stick it on a breadboard and fiddle with RC combinations until you get something you like

[GibsonGM]

It'll make your level lower due to insertion loss.    There isn't much different about an R-C at the output of the fuzz (anything at all, actually) than rolling back the tone knob on your guitar, which is also just an R-C filter...

What I would do if I wanted this functionality would be to try a tilt control (a Big Muff tone control), followed by a recovery stage just like in the Big Muff, then your volume pot (just like the Muff, again).  Might as well go for the gold, right?   Then you can set one side to be very bass heavy/no treble, and the other total treble - with one tone knob.     

Just my 2 cents...

[pinkjimiphoton]

try faking a variable cap between b and c of q2.

put a 10p cap to pin 1 of a 250k pot, put a 2.2n cap to pin 3. tie the ends of the two caps together. connect to c of q2. connect the wiper to b of q2..
then you can sweep from 10p to 2.2n and dial out practically no treble, to quite a bit without losing much gain or your mids.

you could do it on either stage really.
try it. you may like it.

[GibsonGM]

^  Yup.    There are several fuzz variations that use this, 'panning' between 2 caps.  Good compromise.

[pinkjimiphoton]

the dif is this is in the feedback path, not the audio path

[PRR]

[pinkjimiphoton]

that will work paul, but thats gonna be a severe treble cut and VERY lossy.

putting it in the feedback loop of the q isn't as lossy and its for all intents and active circuit.

it doesn't kill all your volume, and it doesn't mudd the fuzz out. it just lets ya shave off the high end. you can go as low as 4.7n for the "big cap" but after that, you start to lose mids.

nobody wants to try this control as i describe, lol. too bad. it works great, can be put in almost anything, and doesn't suck up all your tone and volume.

[Gus]

This was posted recently  http://www.diystompboxes.com/smfforum/index.php?topic=118576.0
another form the past http://www.diystompboxes.com/smfforum/index.php?topic=112341.msg1036524#msg1036524

IIRC MAC posted a nice RC across the top Q2 collector resistor I have not found the thread.

I often use a cap across the top Q2 collector resistor

Do a search for fuzz, fuzz face etc. you will find some good information.

[italianguy63]

My contribution...

Replace the 470R resistor with this:

As Jimi says-- better in the oscillator circuit.  Superior to a "treble bleed"-- I have had great luck with this.

I don't take credit for this-- it is from an old thread from in here in DIY some time back!

MC

[pinkjimiphoton]

those are all different, but mark's isn't as lossy as some.
putting a cap across the c resistor is different. that's a treble peaker.

what i am suggesting varies the treble content from full treble to cut treble without losing volume and gain.

its just a variable snubber cap. nothing special, until ya try it. it works better than all the other treble cut things i've tried out there. ya don't lose a bunch of signal, and it doesn't change the tone. just cuts the ice off the top.

[PRR]

> gonna be a severe treble cut and VERY lossy.

Bass loss is insignificant: 10K into 500K.

Top-cut can be shifted from 16KHz (full guitar treble) to 800Hz (appropriate for making heavy fuzz mellow); and can be further shifted with different cap values.

Not trying to detract from your tested plan. Mine is untested (but will meet spec).

Cutting in the NFB loop is another standard trick in linear amps. In fuzzes, the NFB isn't happening while the signal is being fuzzed. Results are too hard to predict. Your observations are useful here.

There's many ways to shave a moose. With the question on the table, it is good to have several paths.

[Gus]

My contribution...

Replace the 470R resistor with this:

As Jimi says-- better in the oscillator circuit.  Superior to a "treble bleed"-- I have had great luck with this.

I don't take credit for this-- it is from an old thread from in here in DIY some time back!

MC

I think MACs post was  like that. If you cap bypass the "top" collector resistor at Q2 you form a lowpass at the center node of the two collector resistors.
The 500 ohm potentiometer is close to a 470 ohm fixed.

[Austrian]

try faking a variable cap between b and c of q2.

put a 10p cap to pin 1 of a 250k pot, put a 2.2n cap to pin 3. tie the ends of the two caps together. connect to c of q2. connect the wiper to b of q2..
then you can sweep from 10p to 2.2n and dial out practically no treble, to quite a bit without losing much gain or your mids.

you could do it on either stage really.
try it. you may like it.

yes, so I do it

[antonis]

In fuzzes, the NFB isn't happening while the signal is being fuzzed.

Quoted it just to have more attention...
(it deserves it, 'cause it expilcates many weird/unpredictable behaviors ..)