Zvex - Fuzz Factory

Beedoola · Post by **Beedoola** » 16 Mar 2009, 20:53

Barcode wrote:
trad3mark wrote:hey all,
i've just read through the 15 odd pages of this thread, and i have a few questions. I did read right through, so apologies if i missed these being answered before:

firstly, has the circuit on matsumin's Japanese site been 100% confirmed and verified? I know there's a couple of slight variations, particularly between that and the french site (which is now taken down??) but is there one circuit that people generally stick to?

secondly, the transistors. I have loads of 2n3904's, they're fairly common. But the AC128's are proving to be a difficulty. I know some people opt for 2N404's, or if they're lucky enough, the AC128a's with the tasty little radiator, but on mouser.com, there's 2 transistors given as cross-reference matches to the AC128 and 2N404's. they're NTE158's and NTE102's respectively. Anyone care to share some insight on these??

I'm planning to build this pretty soon, and i'd like to get it right...
the ac128 is germanium, the 2n3904 silicon. this is an important distinction to make in stompbox circuits, though some have reported equally good results with no regard to silicon or germanium in this circuit.

from a functional standpoint, the nte158 will work fine, in fact any pnp germanium in the right gain range will work fine. however, tonal characteristics are likely not the same.

What are the gain ranges of the trannies used in the FF?

bumblebee · Post by **bumblebee** » 16 Mar 2009, 21:06

From actual trannies removed from my zvex unit:
Q1>200 Q2>90 Q3>120

Q1 can be 200 or 800 it doesnt make a lot of difference.

sebruzda · Post by **sebruzda** » 18 Mar 2009, 21:52

Hi all. I built myself two versions of the fuzz factory based off two different schematics and i am having trouble making them oscillate. i searched for topics that have to do with oscillation in this forum and i could not find a concrete answer as to why my ff wont oscillate. If someone could help me i would be forever grateful. thank you

Beedoola · Post by **Beedoola** » 19 Mar 2009, 15:28

bumblebee wrote:From actual trannies removed from my zvex unit:
Q1>200 Q2>90 Q3>120

Q1 can be 200 or 800 it doesnt make a lot of difference.

Is Q1 the Germanium or the 2n3904? The "Factory de Fuzz" Vero shows q1 being a germanium. Where can I find germaniums with that high of a HFE? I've been searching for AC128s - checked ebay, and their HFEs range from like 60-120...

Thanks

bumblebee · Post by **bumblebee** » 19 Mar 2009, 22:15

Q1 is silicon Q2 is the lowest gain Germanium.
LINK

Scruffie · Post by **Scruffie** » 21 Mar 2009, 01:17

Hey everyone, i'm fairly new to pedal building ( in the technical sense ) but have a basic understanding of electronics but please excuse my ignorance, i've cloned a fuzz factory that works great with BC558B Silicon Transistors however i was given a batch of 10 AC128's for free ( i have tested them and 7 of them definitley work so its not an issue of there ability ) and i assume ( and for a fact know they dont work in the circuit ) there not going to work without being properly biased and wondered which resistors needed to be replaced on the general fuzz factory schematics, veroboard etc layouts with trim pots to resolve this situation, sorry for the ignorance but i hope to learn more.

bumblebee · Post by **bumblebee** » 21 Mar 2009, 21:08

The pots bias the transistors in the fuzzfactory so you shouldnt need to change anything.

Scruffie · Post by **Scruffie** » 21 Mar 2009, 21:12

Well thats what i thought, but they just dont seem to produce any fuzz, suppose they must be broken but they are giving an hfe reading on my multi meter.

bumblebee · Post by **bumblebee** » 21 Mar 2009, 21:39

Have you got them in the right way?

Scruffie · Post by **Scruffie** » 21 Mar 2009, 21:41

Yea, the Red dot is the collector as far as i know and i tried them the other way round just in case but didnt seem to do anything.

bumblebee · Post by **bumblebee** » 21 Mar 2009, 21:57

And it works fine with the silicon trannies yeah?

Scruffie · Post by **Scruffie** » 21 Mar 2009, 21:59

Yea perfectly, i think to be honest il just keep them in there and maybe try the AC's in something else later on.

TheLemon · Post by **TheLemon** » 22 Mar 2009, 00:23

Scruffie wrote:Yea perfectly, i think to be honest il just keep them in there and maybe try the AC's in something else later on.

AC128s are PNP which might be causing the problem?

Scruffie · Post by **Scruffie** » 22 Mar 2009, 00:28

Yea so are the BC558B's, i think the circuit is based on the fuzz face circuit which used PNP's aswell and i've read comments from people that have used AC128's without issue, good thinking though i'd probably have overlooked something like that.

hamster · Post by **hamster** » 22 Mar 2009, 15:31

Sounds more like your Ge's are too leaky. A DMM wont give a correct gain reading as it doesnt take leakage into account. Try them on RGs FF selector cct and check leakage values.

Scruffie · Post by **Scruffie** » 22 Mar 2009, 17:28

I was afraid of that and hoping i could dance round it and that it was something i'd done wrong but doesn't sound like it, cheers for all the help everyone.

trad3mark · Post by **trad3mark** » 22 Mar 2009, 20:27

well, i'm FINALLY getting started on this project. This is my FIRST pedal build, but i've built a guitar, and re-wired 2 others, so i'm confident!

I'm sure i'll be asking a few REALLY noobish questions along the way, but i'll make sure i search first. I'll post my progress anyway.

So day 1, I bought stripboard, and made an order list for Mouser. I'll have to order them tomorrow, cos i'm broke till 4pm tomorrow... still, tús maith leath na hoibre.

I'm thinking i'm going to go with the matsumin's schematic, and build it on stripboard. I also have a big breadboard for testing it. and now i'm just going back through this thread to see if there's an image i missed of matsumin's schematic on stripboard. I think i'll go for that schematic cos it has the 9v DC adaptor option too. I had a bad experience with a pedal dying on stage, so i'm pretty picky about pedals for that reason.

if someone has a schematic drawn up for stripboard WITH THE 9V DC ADAPTOR BIT TOO, posting it here would cut at least 2 days work off....

Scruffie · Post by **Scruffie** » 22 Mar 2009, 20:30

I have a working layout for the fuzz factory on strip board, if you go to the torchy veroboard not working link its in my megaupload... upload collection, verified by me.

https://www.freestompboxes.org/viewtopic ... 7&start=20 Bottom Post

And as for Switch Wiring with a DC Jack:

http://www.generalguitargadgets.com/ind ... &Itemid=27

trad3mark · Post by **trad3mark** » 22 Mar 2009, 22:06

aah! fantastic. So if i draw matsumin's one in Storm, could someone give it a glance over and doublecheck it's ass?

Scruffie · Post by **Scruffie** » 23 Mar 2009, 03:49

I'l do my best to double check it, im not amazing at transcribing schematics to veroboard but i'l certainly do my best, but as i said there is a perfectly good one in my collection although its never a bad thing to make your own layout, good practice.

Zvex - Fuzz Factory [traced]