SmallBear Fuzz Face resistor reference?

[k.rock!]

Hey guys!

I got a pair of matched OC140s (Q1:Hfe 95, L: 15)(Q2:Hfe 160, L: 43) from SB and he provided the resistors used to match them, however I have no idea which are the resistors mentioned in the provided piece of paper:

R3: 33k
R4: 680
R5: 10K
R6: 100K

In the Mangler, where would these resistors fit?

Thanks!

-Kaleb

[k.rock!]

I think I'm just gonna go with R4 as 680 ohms instead of 470 like the mangler schematic calls for? And I assume the 10k would be the bias resistor which I'm building as a pot anyways so I'll leave the 220R in there and use the 20k pot.

Comments?


-Kaleb

[JakeFuzz]

100K = R1
10K = use thetrimmer for this (leave out)
33K = R2
680R = R4

Should be right. Man you are going to love those  I am excited for you!

[k.rock!]

100K = R1
10K = use thetrimmer for this (leave out)
33K = R2
680R = R4

Should be right. Man you are going to love those  I am excited for you!

haha thanks dude! I am too!  I really can't wait to put it all together...They only concern I have right now is stuffing it into a 1590B enclosure I have prepared for it. Problem is that I couldn't use it for a compressor build because where the jacks on the sides where drilled, and I think I'll be having a similar issue with this one

I'm already using the dremel to file stuff down a bit haha so let's see how that goes.

Thanks!

-Kaleb

[cjkbug]

yeah I hate getting predrilled enclosures. there is always an interference with a part fitting properly.

[k.rock!]

yeah I hate getting predrilled enclosures. there is always an interference with a part fitting properly.

I know...I usually don't have problems with predrilled enclosures since I like to use custom drilling and I'm very careful to choose all the holes exactly where I need them. This enclosure was one of the standard predrilled enclosures in PPP which happens to have the side jacks on the sides but closer to the pots than to the switch and that tiny difference (probably .25") makes a HUGE difference when building it up

I might be able to make it work still but it'll take some patience for sure

[bigmufffuzzwizz]

yeah I hate getting predrilled enclosures. there is always an interference with a part fitting properly.

That was always the hardest part of the BYOC kits. I just finished one yesterday for a buddy and i was reminded how hard it can be when the board fits the whole box and everything needs to fit a certain way. I have to follow the instructions in order, I just don't like it. The total diy stuff is where its at. You have the freedom to do almost anything.

[k.rock!]

The total diy stuff is where its at. You have the freedom to do almost anything.

I agree...I feel like I'm going into "phases" with this DIY fever haha it hasn't even been a year since I started doing this. Step 1, kits. Step 2, predrilled/prepainted enclosures and source parts. Step 3, add graphics and improve build quality. Step 4, drill/paint my own enclosures and etch my own boards. Step 5, world domination. haha 

I'm on Step 3 and this is one of the reasons why I'm recently leaning over the next step (besides wanting to learn how to etch my boards). I just need to spend some money on tools for all of that which is definitely going to be an investment, but a good one I'm sure

[bigmufffuzzwizz]

Etching really isn't that scary. I just completed my first batch and it was fun and something I'm eager to continue to do. I'll post some pictures soon to show you all.

[jball85]

Any good links that will inform me on matching transistors for fuzz pedals (why and how its done to be specific)

[bigmufffuzzwizz]

Any good links that will inform me on matching transistors for fuzz pedals (why and how its done to be specific)

Check out RG Keens The Technology of the Fuzz Face if you haven't yet. He has a few paragraphs in their explaining how to pick the right transitors.

[BoxOfSnoo]

I just got my set of Germaniums, but for the Zygote instead of Mangler.  Does this sound right?

His References vs Zygote Schematic
-----------------------------------
R3 = R3
R4 = (R4 + Tweak) [220R + Tweak] or
       (R4 + R5) [220R + 1k (in parallel with tweak)]
R5 = (R6 + 25k bias pot) [220R + 25k bias pot]
R6 = R2

The values he gave me are rather close, and in anticipation of my germaniums arriving I went and soldered in the Zygote values.  I'm wondering if they're close enough.  Here are the differences:

R3 = 27k (vs. 33k)
R4 = 680R (this is tweakable I guess)
R5 = 12k (somewhere midway on the bias pot)
R6 = 91K (vs 100K)

Is it worth pulling the 33K and 100K for these values or will the pots make those differences negligible?

Thanks

[Haberdasher]

well r3 and r6 are within about 10% of the ones he recommended for your transistors, so as long as your resistors aren't too far off from their own ratings it's probably not a big deal.  I'd probably leave those in and only change them out if something doesn't sound right.

out of curiosity, what are the hfe's of the transistors he sent you?

[cjkbug]

Any good links that will inform me on matching transistors for fuzz pedals (why and how its done to be specific)

TRY THIS ONE! http://www.diystompboxes.com/biascalc/bmbias.html

EDIT: My bad, I thought you said matching resistors! oh well. it's a useful tool anyway.

[BoxOfSnoo]

well r3 and r6 are within about 10% of the ones he recommended for your transistors, so as long as your resistors aren't too far off from their own ratings it's probably not a big deal.  I'd probably leave those in and only change them out if something doesn't sound right.

out of curiosity, what are the hfe's of the transistors he sent you?

Q1 is marked 102 (L=125) and Q2 is 178 (L=174).  Not 100% sure what that means, sounds like the gains are on the high side?

I'm tempted to put his values in, just because.  R6 is within 10% but R3 is a little farther out of that range.  I was kinda wondering if my logic was sound in matching them up, and I think so.