Which Fuzzes sound good after a buffer?

[mr.adambeck]

Hi, a friend of mine asked me to build a fuzz for him to replace his Boss Fuzz (I don't know what number it is).
Te problem is that he uses this pedal at the END of his signal chain, after a bunch of buffered pedals, and all the fuzzes I've built in the past don't sound right after a buffer.  So, I'm wondering if anyone could tell me which ones DO sound the same after a buffer?
I've heard that the Boss Fuzz is based off of The Univox Superfuzz, however that pedal seems like it might be a little too complicated for my level.  So, also if anyone knows of any heavy, bassy fuzzes that would be a simpler replacement, please let me know!

[oliphaunt]

I built a fuzz based on the Axis Face that works just fine after buffered effects.  You will need to mod it a bit to make it "heavy and bassy" though.  You can get a lot more low end out of it with a larger output cap. 

[jacobyjd]

check out the 'pickup simulator'. That will let you use any fuzz anywhere.

[edvard]

http://www.muzique.com/lab/pickups.htm

and some discussion that happened here:
http://www.diystompboxes.com/smfforum/index.php?topic=77832.0

[mr.adambeck]

I've seen those links, and if nothing else I will definitely go that route, but I guess I'm wondering what fuzzes still sound good even without something like that.

[mth5044]

I've always found BMP's to sound good anywhere in the chain.

[edvard]

I've seen those links, and if nothing else I will definitely go that route, but I guess I'm wondering what fuzzes still sound good even without something like that.

*facepalm*

I really need to pay attention to the title of the thread more than the replies...
Sorry; it's a solution, but not an answer to your question.

I've always found BMP's to sound good anywhere in the chain.

I second that.
Generally, a low impedance input loading your pickup is essential for many fuzz pedals to produce the desired tone.
Buffers totally change all that, which you probably already know.
So pretty much any fuzz that uses a jfet, op-amp or emitter follower as an input buffer should be good anywhere you stick it.
A direct-to-transistor-input circuit that has a higher input impedance worked into the design would work as well.
The Big Muff falls under both categories. There was an op-amp version and the transistor versions all have a reasonably high input impedance.
(link once more for good measure...)http://www.pisotones.com/BigMuffPi/psst/BMP_versions.htm
Compare those to other fuzz schematics you're interested in.

[mr.adambeck]

Thanks!  That makes more sense.

[Gus]

Think about the FF and other gain stages that use collector to base DC bias/feedback resistors (the FF buffers Q1 C by taking the feedback from Q2s emitter this is in The tech of the FF at geofex).

Thinking the input of the FF loads down the guitar might not be the right way to understand what is going on.  Think of a FF, C to B bias stage etc as an IMPERFECT summing node kind of like a inverting opamp circuit.  The guitar when direct connected to the input is a part of the feedback equation.  Think of the guitar as a voltage source driving the passive parts (pickups, resistors, caps).

In the schematics link at the top of this page look for the 3 tran the 10K after the EF is a simple crude guitar sim.  I control the open loop gain of the transistor with the 10K C and 100 ohm E (work out the gain at 1.5VDC at the collector) that and the 47K / (10K, input cap and EF small signal output resistance) set the first FF type stages gain.  It does not sound like a direct connect FF but it is OK if you need a buffer before a FF type

Remember the gain of the first stage of a FF type circuit is the combination of the open loop gain of the transistor(one reason people select by hfe) and the feedback resistor(100k, 47K etc.) / source Z (the passive guitar RLC).  

What happens with frequency with the source Z and the gain of the first stage?