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DIY Stompboxes => Building your own stompbox => Topic started by: Triffid on February 11, 2004, 11:37:47 AM

Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: Triffid on February 11, 2004, 11:37:47 AM
I build a pretty high gain SI Fuzz Face that I think sounds pretty good.  I used BC108's with Hfe's 230 & 310.  I also added a 50k pot @ the input to make it work better with my wah.

My only problem with the sound is that I get a pronounced percusion sound of my pick hitting the string's when I play.  If you look past the that sound, the distortion is pretty pleasing (In my opinion).  

Has anyone experienced these problems?  Is it a product of the high gain?

Thanks in advance
Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: Gearbuilder on February 11, 2004, 02:01:02 PM
Hi,
I had got the same sound on pick attacks with  very high gain on a Fuzz-Face.
It seems that problem is due to high gain silicon transistors or bad biaising .I swapped from other transistors and the problem goes out.
Silicon's give much treble sound than germs and they react quickly on the attacks,third harmonics  are bigger too than on germs ,and if you use high gain transistors ,the distortion is readily available with low signal input,if you hit very hard your strings ,the pick attack is more clear and it's posible to have a percussive sound ( the cut-off level doesn't allows to reproduce very nice distortion too)

Bruno
Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: Triffid on February 11, 2004, 02:43:29 PM
The only thing I biased on this curcuit was the Collector of Q2, I set it to 4.5V using a 10K trim pot.  

I tried a couple of SI trannies I had around, with Hfe 130 & 210.   The problem still seemed to be there.

So, should I try to lower the input signal somehow?  Maybe with a higher
pot value than 50K @ input?

Thanks for you help
Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: Gearbuilder on February 11, 2004, 06:09:21 PM
Hi,
I think that if you have this problem with the fuzz and the volume knobs atfull,it's probably again too much gain on Q1.Try to change the biaising point  ,i've ever seen some good FF with 4 volt or less.Maybe the Q1 resistor has to be tweaked too!
Another questions:does the picking noise is going back when you roll-down your volume pot on your guitar?
 What are your pick-ups?Singles or Humbuckers?
Do you have this problem without the wha in front?


Bruno
Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: Marcos - Munky on February 11, 2004, 06:13:55 PM
I got this in my Obsidian. I think this is because of the high gain.
Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: ErikMiller on February 11, 2004, 08:23:18 PM
I think of the percussive pick attack as a desirable feature, if we're talking about the same thing....
Title: High Gain SI Fuzz Face Pick Percussion Problem
Post by: brett on February 11, 2004, 08:48:09 PM
Blackfire, Si FFs, cranked Odie, you'll get this whenever gain is really high.  It's a fact of life.

To lower it on your FF, try a lower gain tranny in Q1.  A BD139 works well (hFEs mostly from 75 to 175). (It's a mid-power transistor - others work very well in FFs too)
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