Questions for experienced Fuzz Face builders

[Vallhagen]

When i change to components as in the Hipster schematic (including trimpot, and go for Q2c==4.5V ), i get:

Q1:
C 1.42
B 0.63
E 0

Q2:
C 4.57
B 1.42
E 0.75

Sorry if im almost flooding this thread and even quote myself... But i browsed around and found some reference voltages for SI NPN at GGG (as a comparison for the GE values earlier in this thread). Maybe its old news for you guys, but someone hopefully finds it useful. Fairly close to my measurements above.

Supply: 9V

Q1:
C 1.4V
B 0.6V
E 0.0V

Q2:
C 4.5V
B 1.4V
E 0.8V

***

I just orderred a few different transistors to play around with. Hopefully ill come up with one of those nice boxes when im done.

Cheers

[9Lives]

I just finished a buzzaround (by far my fav) and what I'm noticing is, that the leakage matters more than the gain. I'm not stating anything universal here but to MY ears the lower leakage transistors sound better. The fuzz face being picky-er  than buzzaround (by a landslide). I've played with 20 or so transistors pluging them in and switching and matching and the best results are lower leakage. I have a few 2n1309 which I find are badass Q2's. Super low leakage >100 <25 and Q1's I've used ac188. Looks cool and sounds good to me. Gains 80-120 leakage 100 on all mine. If you keep in the gain ranges everyone post they'll be ok. Just find the low leakers and use them in the right places. Don't use them for the helluvit. And I haven't built these circuits with si  but I would think  the voltages would be way diff since the hfe so high. But I'm not sure

[midwayfair]

Yes, the voltage on Q1 in a silicon will almost always be above 1, mostly due to the gain of the transistors coupled with the extremely low (almost nonexistent) leakage. Leakage is a pretty big factor in fuzzes, like Grant says. (Though a lot of experts on the Buzzaround say that a leaky tranny is a little better better in Q3, same deal in a lot of 3-transistor fuzzes like the Screwdriver.)

This is part of the reason a silicon fuzz doesn't react to the guitar volume the same way. Normally, you distort the first stage when your guitar's input signal exceeds the headroom of the first stage. Since there's only half a volt, this can start happening fairly early on the dial and then reach saturation even with low-output single coils.

There are ways to build the bias network will be a little closer on Q1 with silicons. Another easy way to get it to react more like a Ge is to use a very low-gain transistor. hfe of 60-70 is good. Something around 40-60 is even better (my favorite Q1 for the Hipster was a weird metal can with an hfe of about 55). The reason to use the lower gain transistors rather than changing the bias network is that you'll get less "transistor sound."

[9Lives]

Hey J, on my buzzaround I accidentally used a 500K pot for the sustain control. It's a lil non-responsive. Kinda seems like it's wide open all the way down to nothing.. The nothing. Is it worth changing the pot back to 100K you think?

[midwayfair]

Hey J, on my buzzaround I accidentally used a 500K pot for the sustain control. It's a lil non-responsive. Kinda seems like it's wide open all the way down to nothing. The nothing. Is it worth changing the pot back to 100K you think?

The Sustain pot is essentially a volume control between the two-transistor input stage and the "zomg fuzz" stage. It works a lot like a pre-gain control on a fuzz face, except in that case, the signal you're reducing is coming from the guitar, which is the right call there given that so much distortion is created on the first transistor. In the Buzzaround, a lot of the distortion is created at the third stage. Reducing it will certainly help some with what you're experiencing -- it will also probably brighten up the effect considerably. Q1 and Q2 actually have a fair bit of voltage to play with (so I don't think it's something like hot pickups affecting it much), and they pass on a fairly clean and very LOUD signal to the third transistor. Slamming that first transistor, creates a lot of the distortion.

The Buzzaround also has a hard clipping diode, and this is the reason it doesn't clean up quite as linearly with the guitar volume as a Fuzz Face design. Normally turning down our guitar volume would result in less signal slamming the third stage, but with diode distortion it's notoriously hard to reduce the input volume enough to change it. On my build, even with three Russian trannies below 80hfe, I get quite a bit of fuzz anywhere past 10:00 with the 100K pot, and there aren't really any completely clean settings to be found in the pedal. You could try lifting the diode if you want more clean and more volume, but it can be a real trap to tune every fuzz in your arsenal to sound similar ... I fell into that and figured out that there was no reason to reach for fuzz numbers 2 and 3 if I kept making them sound like fuzz #1. That diode is part of what gives the Buzzaround its overall sound (more compressed but still punchy), in addition to the Balance and Timbre controls.

[9Lives]

I used 2 ac188 for darlington setup and a hi gain 2n1309 SUPER LOW leakage for q3. Somthing above 25 less than 100. Also reduced input cap to 10n. The input cap really affects the total fuzz imo bc the low freq give it that messy sound. I was going for a Ge OD sound and I got pretty close.

[Vallhagen]

Some great info here. Thanx guys. I just received a bunch of different transistors (as recommended above and on other places), and i am about to re-start my breadboard experiments as i type.

Further questions; the positive/negative ground dilemma; IF i choose to go the PNP way, but still want to feed my FF with the "common" negative ground supply, do i really need to do an internal conversion to -9VDC with a 1044 circuit (or similar)?

The tonepad version of FF; http://tonepad.com/getFile.asp?id=82  have the option of keeping the negative ground. Is there any disadvantage in that solution? At least i am pretty happy to run across it, it looks clever.

Cheers
Bengt

[midwayfair]

Further questions; the positive/negative ground dilemma; IF i choose to go the PNP way, but still want to feed my FF with the "common" negative ground supply, do i really need to do an internal conversion to -9VDC with a 1044 circuit (or similar)?

If you want to daisy chain it with other negative ground pedals, yes. If you want to go battery only there's no issue. And if you will be using an isolated power supply for this one pedal, you can just swap the negative and positive wires at the DC jack. However, I really recommend going the road rage route if you're going to be using a power supply. That way you'll never forget, and if it goes to someone else THEY won't forget.

[Vallhagen]

Further questions; the positive/negative ground dilemma; IF i choose to go the PNP way, but still want to feed my FF with the "common" negative ground supply, do i really need to do an internal conversion to -9VDC with a 1044 circuit (or similar)?

If you want to daisy chain it with other negative ground pedals, yes. If you want to go battery only there's no issue. And if you will be using an isolated power supply for this one pedal, you can just swap the negative and positive wires at the DC jack. However, I really recommend going the road rage route if you're going to be using a power supply. That way you'll never forget, and if it goes to someone else THEY won't forget.

Thanx for replying:) And to make it clear: Yes i fully understand what you are telling me. And i have actually a few 1044s here, ordered specifically for this task, if needed

But...: I was more asking for a different approach. I think it should be possible to - from a DC point of view - isolate in-and outputs from the rest of the circuit. Basically keep the negative ground (enclosure etc), but let the PNP-s "think" that they have positive ground. A workaround without the need of a 1044.

Words oh words... im not sure if i make myself understandable; but did you check the Tonepad document in my previous post? It looks like they have solved it, and it looks... just fine to me.

***

...besides that, i have a wellworking sweetsounding circuit right here. I ended up with two AC128 transistors, and with some tweaking i am pretty much exactly on the recommended voltages.

***

Cheers!

[Vallhagen]

Words oh words... im not sure if i make myself understandable; but did you check the Tonepad document in my previous post? It looks like they have solved it, and it looks... just fine to me.

... and here i am again, quoting myself ...

I mean - something like this, should work just fine. If i havent missed something obvious?:


...ill give it a try.

Cheers

[9Lives]

looks great to me , how did it come out?

[Vallhagen]

looks great to me , how did it come out?

Hey. Thanx. Yes it looks fine but...

WARNING WARNING WARNING ...

I breadboarded it. Really some easy changes from the usual FF schematic. Result: It oscillates in many settings and it sounds... a little different, in a bad way. Hard to explain how, but i should say more "broken" and thrashy sound. Maybe the word "harsh" is correct. I guess the bad sound is caused by added oscillations too.

And why this happens is beyond my knowledge.  i think - as you say - that it looks just fine.

Maybe it is a cause of "happens now and then"; if you try it with slightly different components it may work? Or maybe, if i put it on a pcb and box it, it will be better? I havent done further investigations at that point. As i found "my" transistors and "my" resistor network, i like to go on with them for this FF.

so...  i will box it with a 1044 for voltage conversion. This time:)

***

Cheers!

[9Lives]

I know from my own experiments that sometimes on a breadboard the Ge transistors a prone to picking up radio freq and  amplifing  them if not shielded properly. I usually use the remains of a wire after I strip it. Just slip it over the leads and ground your pedal well. Also try a different transistor.. I'm sure you did that, same results?

[Vallhagen]

I know from my own experiments that sometimes on a breadboard the Ge transistors a prone to picking up radio freq and  amplifing  them if not shielded properly. I usually use the remains of a wire after I strip it. Just slip it over the leads and ground your pedal well. Also try a different transistor.. I'm sure you did that, same results?

Thanx for your time.

This time, i dont think it is radio freq. Rather self-oscillating. The circuit also react to the pot-setting on the guitar. when i adjust the guitar volume pot it goes wooiiiwwoooowiiiwoo. Which might be fun ... but not in this project

And no, i really didnt spend much time faultfinding or investigation. I just doublechecked my couplings, and I swapped the transistors to another pair of same model, but that made no - as suspected - difference. And, when i go back to positive ground everything is just fine again.

Again, maybe it will make a difference when really proper boxed/grounded, but ... nope i didnt go all the way to find out:)

Cheers

[9Lives]

I'm willing to bet my bottom dollar that it's a biasing issue. The gain of both transistors DOES matter. Bc one transistor is "humping" the other transistor it might be effecting your over all current/voltage. I'm not very scientificly knowledgeable with this tho . I just pick and poke around w these circuits