more BSAIB2 questions...

[shanter]

ok so i finally finished my BSIAB2, and ive got to say its one amazing little pedal. but theres one thing about it that really bothers me. the distortion is great and very dynamic, but it seems like the pedal needs a lowpassfilter to get rid of some of the high frequencies. even when i roll off the tone on my guitar i still get this high frequency distortion that really spoils the pedal. and even when i roll the tone on the pedal back and forth it doesnt go away.

i did make a few mods to the pedal using the duncan tone stack calculator, but nothing that would really increase the high frequencies. if anything, the pedal's volume decreased a bit when i changed around the tone stack.

another thing is that i didnt use any ceramic caps and didnt use the 470pf siver mica for C5, i used a 470 poly cap...the red type from smallbear. could these changed have a tonal impact on the pedal??

here are two pics of the complete pedal...

[Stephen]

What do you mean as high frequencies..I play mine with the tone knob almost to max treble and it still is good to me??? I dont like the bass I like the pinch harmonics.....Is it squelling    looks really better than mine ..man you did a good job..I am using this as my gain pedal now it keeps the guitar sound there not added mush from distortion..LOOKS good though maybe bad fet??? Try some different ones you think?

[Ed G.]

Wow, that looks great.
Does that board have plated through-holes, or did you just solder the other side? It looks very pro.
As far as the treble, some find it too dark, you find it too bright. You can reduce the treble by increasing the size of the resistors (I think they're 10K) right before the caps on the LPF. Tweak it a bit.

[shanter]

thanks guys, the board is from expressPCB the miniboard service, i was unsure if the layout was correct cause the board was ordered for someone else and was rushed a bit, but to my surprise it fired up right away 

the distortion has nice body to it, but it seems like it also peaks at a high frequency andding a sort of fizzyness to the distortion...its difficult to explain. and i cant tun the tone knob all the way up cause it becomes too bright.

let me list the mods i did...

all 2n5457
used .01mF for C8
no ceramic caps
and 450mf for C6
and actually a 450mF for C5


i might have to do more tweaking

[modsquad]

OMG the inside is beautiful.  I hate that.  I got mine to work but don't open it up and look at the wiring.  My next one I planned out better.  As far as the sound.  I have to say mine is stock and I have to turn up the treble even with my strats and tele set on the neck pickup.  I am not sure what the culprit is on yours.  I find if you roll off the gain some you get more bass and less crunch.

Stan

[Stephen]

I am not really up on BSIAB but all the dual miniboosters I have built have a brightness to the tone ...Is it like the sound of a string being pinch when you dont want that sound?? That is all that happens to mine..It kind of has a unique string squeak which is fun to toy with!! Adds a little harmonics to playing with your palm mutes and chord progressions....Maybe if you tiried a delay or compressor with it or maybe this is what it is....Double again on the nice job!!  man that is nice!!1

[shanter]

thanks again,  .

ill tell ya tho, ive been at this pedal stuff for a year now and this is the only pedal ive completed. ive done about 5 or so in the past, but im so anal about things that they never reach my pedal board. either its not made clean enough or the effect was not what i expected. its a curse to be so anal.

anyways, i found the culpriet. it was C8!! i changed it back to .1 and it cut out those higher frequencies...it was sort of a metallic sound coming from the pedal, the distortion was sort of two layered. the great overdrive and then this tinny metallic sound creeping up in the back.

if anyone is interested in the layout its availabe and verified. its a tight fitting layout, might need a bit of tweaking for some of the larger caps, but its not at all necessary.

shant

[jrc4558]

return the C8 to 0.1uF. I htink thats what gives you the unwanted "sheen".

[shanter]

ok so i took the pedal back to stock and it sounds much better but i still get this unwanted high frequency distortion a bit, but only when i use my strat w/ texas specials. i played my explorer (with really hot pickups) through it and it sounds so much better it had a nice roundness to the distortion. so could it bossibly be the tone cap in my strat letting throuhg too much sparkle??

so then i did the .0022uF mod by bucksears and i removed c13 and i did open the pedal up much more.

but if i wanted to filter out higher frequencies how can i do this?? should i increase on the the 10k resistors after the tone stack? or shoudl i decrese them..?? or how would i calculate this value??

sorry for all the questions, i jsut want to tweak this until im 100% happy with it, its probly the best distortion pedal ive played though in my life. other than the unwanted 'sheen', as constantin stated, its fantastic.

-shant

[jrc4558]

Thanks to Mr. Orman at www.muzique.com we have a neat gadget which tells us what frequency the filter's corner is at.
Here it is: http://www.muzique.com/schem/filter.htm
To decrease the corner frequency of an RC lowpass filter you need to increase either the resistor, or the capacitor. You may even tune the two filters to different frequencies. the overlapping range will have a radical -12dB rolloff (per octave), whereas the part of a filter that's tuned to a lower frequency that doesn't overlap with the other will only have -6dB. This was you may get rid of unwanted shrill, but not kill the sheen completely too.
For example - leave R18, R17, and C14 stock, but increase C13 to 0.0027uF. This way you'll get -12dB above 7238Hz and -6dB from 5897.6Hz to 7238Hz