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Old 30th September 2008, 07:46 PM   #1
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Default Fuzz Face DIY: need more fuzz

Hi all,


I recently started with my first DIY guitar effect: a fuzz face. I got the parts from a local electronics store, they did not have the preferred transistors for the fuzz face, so I took the only germanium transistors he got: AC187K.

The fuzz works, but to my opinion, not enough The lower notes don't have much fuzz (olmost nothing). Also, when I play single notes (just 1 string), there is not much fuzz, even on the higher strings. When I play 2 strings together, there is much more fuzz, but again, only at the higher notes, not at the lower notes.

The guy from the store was saying something about these transistors beiing used for high frequencies. could it be that the lower frequencies are filtered out? According to the datasheet: fab MHZ Min = 1. Is this the minimal frequency for the transistor to work?

If this is true, it could explain why is't behaving like this. I can imagine that, when playing 2 strings at the same time, the output signal of the guitar is much more distorted, having much higher frequencies. Only at this point the fuzz would sound fully... Does anyone agree?

In the meanwhile, i'm looking for the right transistors, just trying to explain this strange behaviour

If anyone has advice, thanks!


Thomas
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Old 30th September 2008, 08:18 PM   #2
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Hi,

Th fuzz face is a very simple circuit. It's performance depends heavely on the few components it uses.. get some bc109 and build it again.. check the Hfe (current gain) of the transistor.. higher Hfe will give more fuzz..

Could you post a schematic of the circuit as you build it ?

grtz, Thijs
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Old 30th September 2008, 08:26 PM   #3
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http://www.geofex.com/article_folder...ace/fftech.htm

I looked at the data for the AC187K, it's an NPN with an hfe of 100-500, so not the end of the world, keep going.

tschrama, telling someone who put the effort into finding germanium transistors to quit and use silicon is like telling someone with a flat on their Ferrari to buy a Fiat.
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Old 30th September 2008, 09:18 PM   #4
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hehehe

but hee he seems to be a newbie with this stuff , so I was trying first to get him around the circuit in a Fiat..

He can always upgrade to a Ferrari later..

PS
the current ' Jimi hendrix Fuzz Face' is build around the BC109 .. that's why I came up with that particular type..

PPS
great link!

PPS nope.. not BC109 but BC108..see http://nl.youtube.com/watch?v=0EqrQPbOhDo
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Old 30th September 2008, 09:33 PM   #5
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Didn't the original Fuzz Face use a PNP germanium?

I'm planning to build a Fuzz Face clone myself, and picked up some GT308V PNP Germanium's off of Ebay for a very reasonable price ($20/50) They have very low leakage and had hfe's of 55-90 so should be good for the Fuzz Face circuit.

Another good site is:

http://fuzzcentral.ssguitar.com/fuzzface.php

- Gary
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Old 30th September 2008, 09:39 PM   #6
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Quote:
Originally posted by The-Planet
Didn't the original Fuzz Face use a PNP germanium?
Yes
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Old 23rd November 2008, 08:21 AM   #7
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Talking Might want to build this if more fuzz needed

just finished this diy fuzz factory in arion enclosure but with a difference to original


http://uk.youtube.com/watch?v=hr99z456exA
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Old 25th November 2008, 11:05 PM   #8
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If this is your first project, I recommend buying a pair of matched transistors from Small Bear and building the circuit with quality trimpots for all the resistors. That way you can the resistors in the circuit to the values supplied with the transistor pair so that they will be biased properly. I also recommend using a 1k linear pot in place of the 8k2 bias resistor so that you can tweak its value to compensate for different operating temperatures or just to get different sounds.


The first fuzz face I built was a stock circuit with transistors measuring around 95 (q1) and 140 (q2) hfe, and it sounds good, produces more fuzz than a tweaked circuit at the expense of cleaning up less as the guitar volume is rolled back.
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Old 27th November 2008, 05:15 AM   #9
wxn is offline wxn  Lithuania
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Default Re: Fuzz Face DIY: need more fuzz

Quote:
Originally posted by ThomasDIY

The fuzz works, but to my opinion, not enough The lower notes don't have much fuzz (olmost nothing). Also, when I play single notes (just 1 string), there is not much fuzz, even on the higher strings. When I play 2 strings together, there is much more fuzz, but again, only at the higher notes, not at the lower notes.
I doubt that the transistor itself has anything to do with what you are experiencing.

First, you need more gain. That can be achieved by using a higher hfe transistor, but any means of pre-fuzz amplification will do.

Second, it's a common practice to put an EQ pre and post fuzz, so that you can shape your signal. In this case you would boost bass a bit in the pre-fuzz EQ so that lower frequencies would clip earlier and therefore buzz more.
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Old 27th November 2008, 02:28 PM   #10
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If you use a booster circuit between the fuzz circuit and the guitar, it will make the fuzz circuit respond a lot differently than if it were connected directly to the guitar, though (it would sound more like a high gain distortiong such as a Big Muff than like the classic Fuzz Face sound). I'd recommend getting higher gain transistors myself. The hfe 90 one should be perfect for Q1, so you really only need a single transistor with an hfe between maybe 95 and 115 for Q2. You can use the lower gain one that you already have in a Dallas Rangemaster clone (which is a really nice pedal to have around) or similar.
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