**NEW** Faim Fuzz. Simple Ge fuzz

[mac]

I found this on my first guitar, a Faim, hence the name of the circuit. I can not precise the build date but I guess it was manufactured in late 60s. The original distortion circuit that came inside has two Toshibas 2SB56 Ge transistors, hfe around 80 & 150 and leaking less than 50uA like all Toshibas transistors I have, ie, 2SA49/52/53 and 2SB54. I accidentally blew up one diode and some electro caps long long time ago. The diodes look like Ge, glass case with one red band, similar to the 1N34s Aron sells, but the voltage drop is 510mV which is high for Ge, so maybe they are Si disguised as Ge.
I repaired it some time ago. I replaced the dead diode with a 1N4007 and some fried electro caps. I connected it and after decades of silence it began fuzzing again. A nice fat retro fuzz that worth a try.

This is the original schematic:



I breadboarded a copy of the circuit using a pair of Toshibas 2SB54 I have, similar to the originals. I tweaked caps and portions of the circuit. I used 4.7uF poly caps instead of the 10uF electro. They sound better and will not age like electros. But they are big. Maybe tantalums work. 10uF seems good for the crappy mics the Faim guitar has, that's why I used 4.7uF. I also added a gain pot and a variable tone control. And I tried negative ground with the clipping diodes to gnd (0v). This is the modded schematic:



One of the advantages of the circuit is that it is tempearute and hfe stable. Si & Ge can be used and the collector voltage will be always around 6.4V - 6.7V. And I guess that PNP neg gnd versions will not induce motorboating, but...

Hope you like it.


mac

[alderbody]

Hey mac,

the links don't seem to work...   

btw, i'm about to salvage some old toshiba 2SB54,56 and stuff, so this project sounds tempting.

any clips?

ThanX

[mac]

Sorry, I have to move the schem to another site 

mac

[alderbody]

Aha!, now they are visible... 

I'll copy them, if you don't mind...

btw, here's the link to my Ge tranny finding:
http://www.diystompboxes.com/smfforum/index.php?topic=51189.0

could you by any chance help me with the pinouts of the devices mentioned in my last post?

thanks again!

[MartyMart]

Hi Mac , tried this as an NPN Ge version, obviously reversing the PS/Caps.
At first, it was just a nice fat booster, then looking at the schem, I thought that
the originals "47k" from Q1's emiter looked a bit large ! and was not causing my si
diodes to turn on.
Your update with a "pot" here makes sense but could be 10k or 22k.
I changed the 47k to 4k7 and got instant FAT FUZZ
Using OC140's hfe 84 and 148 , nice fuzz that's almost a good OD sound.
I also used 2u2's for all the 10uf's and omitted the scoop/tone at the end, so
from Q2, it's 2u2/diodes & 100pf cap across -> 250KB vol pot.
Nice
MM.

[mac]

Marty, there was an error in the schematic I've just corrected. The 47K must be bypassed with the 10uF. Sorry 

This is the corrected original:


mac

[MartyMart]

Thanks Mac, that makes more sense !
I still like the 4k7 there though .... I'll give it a try tomorrow

MM

[MetalGod]

whats going on with the 47k emitter resistor on Q1? - never seen that resistor connected in any other way than to ground.  can someone explain what's happening here?

[mac]

MetalGod, Marty made me found a mistake in the schematic that I've fixed. The original 47K sets Q1 collector at near 8.7V and pushes Q2  gently. With a lower value Q1 will begin to hit Q2 harder resulting in more gain.
Now what is the 100R doing there, I just don't know. Maybe a kind of decoupling resistor?

Marty, I suggest using a 50-100k pot instead of the 47k and tune to taste. Also maybe the 1uf in the original can be 0.1uF.

mac

[MartyMart]

Here's the version that I built and modified :

http://aronnelson.com/gallery/Martys-layouts-and-photos/Faim_Fuzz_NPN?full=1
Sound sample :
http://aronnelson.com/gallery/albums/album72/Faim_Fuzz.mp3

It's an NPN negative ground version using OC140's and sounds incredible !!
hfe of Q1 84 - hfe of Q2 148 leakage under 100Ua
Fuzz pot goes from totally clean boost ( adjust vol pot ) to nice overdrive and Fuzz at
the top end of the pot.
50k A pot or a 25k B pot both work fine here .

Mac - hope it's OK to post this "hacked up" NPN version ??

Cheers,
Marty.

[MartyMart]

"BUMP" - incase this was missed !!

MM

[Willy]

Hi, Mac, I´m from Argentina. This is my mail:
willye@citynet.net.ar

Willy

[mac]

Marty, glad to hear you like it. Now that it's in your gallery it won't get lost among thousands of threads. The demo is a nice addition.
Did you try a wah in front? It seems that the circuit have low input Z and would suck some tone from the wah. If this is the case an input pot can be added.

Mac - hope it's OK to post this "hacked up" NPN version ??

... as long as a reference to the original "hacker" is included it's ok for me... just ego   

Hi, Mac, I´m from Argentina. This is my mail:
willye@citynet.net.ar

Willy, estamos en contacto. Un abrazo.

mac

[askwho69]

Hi all i was planning to put a Tube Reamer inside my guitar as booster... any one knows how to wire it up? My guitar has a booster inside and i dont like the sound of it...

[LucifersTrip]

Since all the schematic links are dead, does anyone still have it?

thanx

[mac]

They are in my gallery now.





mac

[LucifersTrip]

They are in my gallery now.

Excellent!   thanx much   ...man, the designer really loved those 10uf's

[mac]

I can think of two reasons for those 10uf,
the guitar is really crappy, although it's very sweet, and as it lacks lows the designer used 10uf, or
the fabric has tons of 10uf in stock 

You can experiment with lower inter-stage caps, and try a 1uf - 2.2uf at Q1 emiter.

I also think that the last 10uf cap should be facing in the other direction, but it works anyway.

mac