Coupling capacitor sizing - my first post

[Pablo1234]

Hello every one, this is my first post and I must say verry cool web site. Wish i would have stumbled onto it before. I am currently testing my Distortion I designed and am extramly happy with it. I use a 4 gain op ap at input decoupled from the input jack then to a twin t -6 db at 100 hz -3 Db at 1K hz and -6 db at 11k for a mid boost. I then go into a tlo74 gain stage non inverting with the feedback tied to the center post of the feed back potentiamiter. Its probably the most common gain stage i have see so far for op amp types. I then split the signle with a 3pdt switch into 2 types of distortion circuits.
The first one is just too 2 Clipping LED's. This one gives me a really nice crunch tone. I absolutly love the sound for playing Cream or Bad Company type stuff.
The other one is another op am circuit with the fender style full wave Rectifier bridge with the LED across the middle. This gives me a really nice sounding Chunky Fuzz I use for my metalica and Megadeth tones. Its spot on for me, the harmonics jump out like crazy and I can play 4 note chords without sounding garbled. It has alot of definition between the notes but still screams on leads. My main concern is that i seam to have mushed up my attack just a bit to much with the mid boost. I took my DS-1 and turned the gain all the way down and volume up and put it befor My distortion and it cleans it right up. I get the raunchiness and attack I am looking for but don't get all that nasty treble from most fender amps.
Before I go and add another tone circuit to my board, I was thinking that maybe I could drop my Coupling caps a bit to get more attack back in my signal. I am a true believer that the less ya have in your system the better off you are.

Currently my Decoupling is like this Guitar - 20uF - 220K I Impedance / TLO74 / 10uF - -6/-3/-6db Twin T / TLO74 NonInverting / 0.47uF - 100k I Impedance / TLO74 / 22uF - 10K output Impedance.
I am going to be adding a few parallel buffers at the input stage for dynamic controls like compression and expansion and such at some point also. I made my own power supply for this thing also, I run +/-12V dc.

So other than Adding another filter, and modifying my decoupling capacitors would you all have any suggestions for me? I am going to be incorporating a Basic stamp to control all the switching on my board as I build it and plan on using FET switching Q111 was what I was thinking. Not sure how much they will color my sound but I plan on making a programmable set up with a few different types of distortion and filters, compression, expansion and FX switching.

[tempus]

Read this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=78514.0

[Pablo1234]

Yes that's a good thread, but I do understand high pass and low pass filtering. I gess to clarify my question - Should I build another tone circuit pre-distortion or should i start reducing my coupling caps a bit. Basicaly the tone is wher I want it minus some attack and I am not sure I want to through a high pass in thier or a whole nother tone circuit as the thing sounds realy good, smooth , with an abundance of harmonic content. I would totaly alter my tone into relms I may or may not like buy doing so. But if i reduce my coupling caps I will roll off some base in the process. But doing it this way am I realy gaining attack 1.5khz-3khz or will I just make it over all more bright.

I think I am going to add another Twin T with a 2 DB gain at 3khz and see what that sounds like. This way I can pull it from the board if I don't like it without modifying the circuit to much.

[blueduck577]

I think I am going to add another Twin T with a 2 DB gain at 3khz and see what that sounds like. This way I can pull it from the board if I don't like it without modifying the circuit to much.

i would personally try changing the coupling caps first, just because each gain stage you add also adds noise, and that can really add up in a dirt box.

[Pablo1234]

Ya that was my first thought, but to tell you the truth the noise level in this dist I made is unbelivably quiet. Even with the gain all the way up and not in an enclouser. I decided to play with the tone useing my MXR 5 band after the dist and I was suprised to find it dont take much to get a little more attack, I am looking at a -1 db dip at 800 and 1700 Hz and its way sharp now. The imput impedance must be a touch difrent then my boss CE-2 becuss with it flat I can hear just a slight difrence but not nough to realy matter, but then I just touch th levels a hair off the notch and bam attack is amazing. I am realy suprised I did this well on this project, I just kind of went at it on paper for a few weeks and put it together. The first go around I used a crappy board from raidio shack, the long and skiny ones and it was a noise maker, this one is also from raiioshack but the board has totaly ifrent, much more copper to solder to.

So now I am looking at putting a -1db notch at 1K with a Q of about .8 or so and see what happens.

http://www.facebook.com/home.php?ref=home#/photo.php?pid=46054&id=100000122123891 for pictures of my board so far. I also have a video but the sound is absolutly horid on my camra

[Pablo1234]

Schematic jpg
http://www.facebook.com/photo.php?pid=48714&l=b1585e46d3&id=100000122123891

Values not shwn yet and I have made a few changes to it so I am not going to put them in till I integrate tyhe switching and tone stack. But this is working prity good as is.