Distortion Design: Need Approval Please

[Faber]

Hello all.  I have been working on a distortion stompbox for a few days now and need some feedback about it.  Suggestions and comments please!!!  I'm not trying for an all out fuzz, more of a distortion.

It's a PNP design box.  The gain of each is 172, not counting the 1K pot.

It splits the level into the high and low paths using rolloffs.  33Hz-15kHz for one and 15kHz-33kHz for the other.  It amplifies them both separately, then it puts them back together with a pot.  You can adjust the gain for the high and low separately.  I think it's a cool design... if it works.

The transistors are BC327 because I bought a value pack and I have 10 of these sitting around...
The diodes are up for debate, I haven't really experimented with those yet...

It's called the Up 'N Down.

Here's the link:
http://www.geocities.com/diyfxman22/homebrew.html

Comments PLEASE!!!!!!!!

PLEASE!!!!!

PLEASE!!!!!

[momiel]

After a quick look...
-i think 15 kHz is not a good split point for guitar use. Consider the guitar speaker roll off highs at about 6 kHz. consider about a split point of 600 Hz or so
-you can split guitar signal like this. for a matter of impedance (i'm not so smart to explain you exactly how...) you will lose a lot of signal in the input. you could use a buffer in front of the gain stage...
-the hi pass and low pass filter are not well designed. think of this:
you use two filters for each "side" of the stage (they are both low pass, too. read the wiki info on filters), but you need only one filter for each side: a low pass on the bass side, an high pass on the highs one

maybe there are other problem (i'm shure) but these are the first I see...

[Faber]

Okay, I've been checking around, and I CANNOT for the life of me find a solid number for the highest frequency of a normal, standard tuned guitar.  That is my problem with these filters.

Yes, I do acknowledge that my filter design is very, very bad.  I wasn't thinking.  As a beginner, I am entitled to do that.  So is everyone else!

If someone could help me with filters and what frequencies are good for them, that would be great.  R.G., I could really use your help right about now.

And as for the amount of loss from splitting the signal, I could either increase the gain on the transistors or put another transistor with a smaller gain in front of them to get the signal back to unity.  I think... maybe...  You know, like something that one would use in a 3 band EQ circuit...

[momiel]

use a big muff tonestack. download the tone stack calculator from here and tweak with the big muff tone stack. try 600 Hz as plit point, or even more. in the big muff tone stack you can see a low pass and an high pass. here the output is mixed by the pot, you could use each separate output and mix them later...

[R.G.]

Okay, I've been checking around, and I CANNOT for the life of me find a solid number for the highest frequency of a normal, standard tuned guitar.  That is my problem with these filters.

The international standard for musical notes is A = 440Hz. The lowest E string on a guitar is 82 Hz, so the fifth string is A = 110Hz. That makes A on the second fret, third string be 220 and first string fifth fret be 440. First string E is two octaves up from low E, or 4*82 = 328Hz, first string twelfth fret is 656Hz and first string 24th fret is 1312Hz. Everything above that is harmonics. Electric pickups cut off above 6K-7KHz.

[Faber]

Okay, I've got the darn cutoffs finished, the cut is 212Hz (as close as I could get to the 220Hz of the 2nd fret-G string).  The high "channel" then just amplifies to infinity Hz.  Not sure if that is a good idea.  I tried to add high and low pass filters on each "channel" (in the old schematic) to cut down what they would be amplifying. 

Will it pick up radio signals or anything if I just leave it amplifying everything?

Thank you R.G. and Momiel for your input!!!

The new schematic is up:

http://www.geocities.com/diyfxman22/homebrew.html

If anyone has any more comments about the gain cycle or the diodes, they would be greatly appreciated.

[jrc4558]

try dedicated lowpass and high pass filters, not just caps to ground. may get you a better result for freq splitting

[ambulancevoice]

also, you have on the schematic that the 9- is connected to the ring, but it should be the 9+