Metal Simplex! and what I've done to it!

[coxter]

Hi, I'm so happy i finally got ONE pedal going for me after fiddling around with DIY effects for so many months.

Mods:
I've read many threads about the Metal Simplex too along the way describing it as a 80's rock pedal instead of
a metal one, well yeah pretty much, but by changing the diodes to a pair of 4148 you can get much "metalish"
clipping.

And the tone control is not "trebly" enough for me so i changed the tone cap to a 22pF. LoL I'm not really sure
about what I'm actually doing to the circuit but it just sounds better to me.

However! Its extremely noisy until I added a .1uF cap between the input and ground. The noise is a hissing
sound, I read on some thread that it means its "catching" radio noise and the way to eliminate that is to solder
a 47 pf to the input and ground, but its not enough for me, so i used a 0.022uF at first but its almost noiseless
when i used a 0.1uF. Can anyone tell me what is it that I'm doing? LoL just curious.

I used Red for the Mods I added. and Socketed the 2 x 10K resistors to biasing purposes. Heres the schematic:


Problems:
I'm experiencing the Blatty or Gatey sound when my notes are too soft. But its just a really mild case, but still
irritating nonetheless. I've tried RG's debugging guide.

http://www.geofex.com/fxdebug/bias_prob.htm

But i've not sure i'm doing it right. My multi-meter is not sensitive enough, so these are the voltage readings
I'm getting with respect to ground.

Q1 (The one on the left)

E       B      C
0v   0.5v   1.1v

Q2 (The other one, LoL)

E       B      C
0v   0.7v   1.1v

What i've deduced its that the problem is with Q2 right?
But how am I supposed to rectify it ? Sorry for the noob question.

[toneman]

U have two point one caps  (.1mfd): the input(cap going right)  and the "noise canceler" going down.
Notice they are *both* the same size!!
RF (radio frequency) signals are VERY high frequency...and, in this case, probably are not your "noise".
For low level signals, U are shorting the signal to gnd   
The "noise" could be "gain noise"; that is, trannys are operating at max amplification with no signal.
This is how some fuzzes operate, so some fuzzes have a cut-off point.
Sometimes this is called a "triggered fuzz".  Most fuzzes have very high gain.
Don't know what type of noise U have, but, based on your post, I would say it's Non musical?  maybe more of a "hiss".
Try a lower setting for the gain control....other than that I cannot say...
Definitely try removing the .1 to gnd...then the "triggering", "splatty effect" should go away.
T

[MetalUpYerEye]

I built this one a long while back too. Heard that using 2n5089's instead of the 2n3904's will give you much more gain and a better metal sound. 

[JHS]

Add a resistors (100E or less) or a 470E trimpot beteeen the emitter and ground on both trannies, mayby this reduce the gating effect.

JHS

[lovric]

RF is not you prob. you are killing the signal with the new cond at input. you may also try to lower both collector's resistors to 4k7. it will make a bit more room for trannies to follow the input.

once someone corrects the simplex to the book it might cease to be 'metal'... 

[coxter]

once someone corrects the simplex to the book it might cease to be 'metal'... 

Hehe, I don't really know what that means, but its not very metal to begin with, was just trying to make it sound metal.
I saw the "Scoop" mod thingy add in the dirty sanchez, do you think it'll work with the simplex if i add copy that part wholesale
and add it into the simplex?

---
I think you guys are right, its not radio noise, its probably gain noise. But it works really well, can i just leave it there?
--

Hey Lovric and JHS, now you two got me confused. So where should i place/change my resistors.
Ps: This is just my first pedal, so forgive me if I'm asking anything obvious.

[rtill]

This pedal can have tons of mods.....I've built about 15 of these so far....lots of different sounds you can get.  One thing I like to do to add tons of chunk to this circuit is add a 10 uf in parallel with the first .1 uf, with a 50k-100k pot in front of the 10 uf.  And for assymetrical clipping, try 3 diodes altogether....two on one side, one on the other.

   ----||-----
     |        |
     Z       |
  ->Z       |
  |  Z       |
  |  |       |
  ------||---

hope that looks right.

[lovric]

it doesn't matter what color the cat is as long as it catches mice 
sure try the Sanchez scoop or hammer's RosieRay scoop filter before the tone control. it'll lower the output a bit.

DejanS tried many diode combinations and likes one Si and one Ge best so far.

also see if www.muzique.com/lab/hum.htm helps!

[coxter]

Alrighty thanx, will try to report back in with some good news or recording soon