Fuzzrite recomendation

[nonost]

Hi! I'm going to build a box with a reverb (dub a dub) + fuzzrite. It's my first fuzzrite so I thought it was a good idea to post here and get good advices from experimented builders.

I want to build the silicon version. I've build lots of germanium fuzz faces but not silicon, so this goes silicon.   That way I don't have to deal with voltage inverters and some other stuff (remember: reverb + fuzzrite).

I've read a bit and there are a few discussions about: the 500k or 350k pots, the 22k and transistors hfe and model

The more I care about is the latter. What transistors do you recommend me? I have BC141 at 150 hfe that could be good I think. But I can't think of any low gain silicon around 90 hfe...Do you know any?

Thanks!

[induction]

2n2222 are usually somewhere between 35 and 300
293904 are pretty low gain (100-ish), 2n3903 are generally about half of that

If you can't find any low gain silicon, you can always piggyback bjts to dial in whatever hfe you prefer. See this and this.

[nonost]

Mmm...my 3904 are around 200 hfe.

I read that 150hfe is a good value for Q1 and that Q2 should be lower, like 90 hfe.

Thanks induction! I will get some 2222 and 3903 and measure them.

[induction]

nonost wrote

I read that 150hfe is a good value for Q1 and that Q2 should be lower, like 90 hfe.

That sounds backwards to me, unless you're referencing a schematic with non-traditional transistor numbering. Usually the advice for Q1:Q2 is in the range of 80:120 or 95:170. See here for example.

In any case, I would recommend experimenting with the hfe. The magic values you often read about do sound good, but so do other values. The Eric Johnson signature FF, for example is generally closer to 220:550. The Skreddy Legacy is in the range of 275:750.

When I built mine, I did a lot of testing, and found that keeping the ratio of Q1:Q2 somewhat close to 1:2 generally made for good sounds. Anywhere from 40:80 to 300:750 sounded good. The main differences I found were the character of the distortion at full gain and the cleanup. In addition to filthy fuzz, I like to turn my guitar volume down and get nearly clean, sparkly sounds with a FF, so I ultimately went with the classic 90:150. But 40:80 was a very interesting result that sounded both clean and dirty at the same time (sometimes I would even get that singing amp feedback sound with a nearly clean tone) but it had a lower SNR than other combinations, while the 300:750 was amazing at max drive, but didn't clean up quite well enough for me. This sort of thing is very easy to play with on a breadboard, especially with piggyback transistors because you can dial in any hfe you want with a trimpot. Piggybacking only reduces hfe, so you would want to start with fairly high gain Si transistors, which are ridiculously easy to find.

Of course the bias is important too. (The EJ fuzz, for example biases at about 3V, while the standard approach is to go for 4.5V.) I set mine up with an external bias control that ranges from 2.8V to 6.8V on Q2. Lower bias gives the splatty, velcro-ripping sound, while higher bias gets closer to a harde-edged distortion tone rather than a spongy fuzz.

In the end, go with what sounds best to you. I'm just recommending exploring a bit. On the breadboard if you have one.

[Travis]

I’m not sure how much is really known about the transistors in the Si Fuzzrite model. I can’t remember seeing one with discrete components, the one I have uses the fully encapsulated sprague module

The behavior of the depth pot is a little unusual in the original to begin with. I would recommend staying as close to the original specs as possible if it’s the original sound you’re after. I am inclined to recommend putting a resistor in parallel with a 500K pot to make it 350K. Although the taper will differ, that will still give you the original range of settings.

Do you have a breadboard? This is a simple enough circuit that it would be a great candidate for dialing in on the breadboard before soldering.

One thing I have noticed is that a lot of people like to use bigger value coupling caps for more bass. IMO if you’re after the original sound, don’t do this! The bass roll off is key to the “vintage” sound

[nonost]

 Ey induction! I read it on one of the big forum, but it might be the case they were talking about the Ge version. I will try low gains since the clean up is really important for me. What's the bias resistor? The 470k from +v to Q2 collector?

Great Travis! I'll follow the Mosrite Fuzzrite vero and I'll do the 350k pot thing. I'm after original sound so this sounds the more appropriate.

 Thank you both very much :)

 I have to build Tremulus Lune with 6 pots before the ReveRite (rub-a-dub reverb + fuzzrite), but I will let you know about it goes.

 I do have a breadboard but I don't get on well with it :) I will socket the transistors and let's see.

[Travis]

I think induction was mistakenly giving info for the Si Fuzz Face

IMO the Fuzzrites will clean up a bit with the guitar volume but don’t expect it to be like the fuzz face amount of cleanup

[nonost]

Ahh, ok! That would make sense, since the link he posted was about the fuzz face.

Any transistor or hfe you recommend, Travis? For the Fuzzrite I mean.

I'm thinking about a couple around 150hfe and 200hfe. In a few days we'll see!

Cheers :)

[induction]

Travis wrote

I think induction was mistakenly giving info for the Si Fuzz Face

True, sorry. Disregard.

[nonost]

Love this fuzz! :)

I tried different transistor and end up with BC141(150hfe) and BC108B(200hfe).

But it is too noisyyyyyy! Damn! Does the shielded input/output wires help? Any trick to reduce the noise? Fuzz faces are noisy but this one is even more.

Cheers!

[induction]

What are you powering it with?

[nonost]

Hi induction. With a 9v battery. And I put a 100uf cap from +9v to ground as well. It's not boxed though...

I also have another problem: I can't get enough volume from it. I know the stock circuit lacks of it so I put a booster at the output but it doesn't get more volume, it only adds gain. I get almost the same volume with or without the booster. I've checked all components and changed the transistor, but nothing...It's really annoying me. Such a tiny circuit it's giving me headache like no other.

Cheers!