fa1 problem

[Dimitree]

Hi everyone
I was trying to get working again my dismantled fa1 reproduction.. (boss fa-1 schematic: http://www.experimentalistsanonymous.com/diy/Schematics/Distortion%20Boost%20and%20Overdrive/BOSS%20FA1.png)

the pedal works, but there's a boost even when using the treble and the bass pots.. Those add or remove boost, and luckly do also their work, so shape the tone.. But I don't think that the boost is normal..it was not there when I had the pedal working..

Any idea about the problem? I could take voltages if needed

really thanks

[gigimarga]

Hi everyone
I was trying to get working again my dismantled fa1 reproduction.. (boss fa-1 schematic: http://www.experimentalistsanonymous.com/diy/Schematics/Distortion%20Boost%20and%20Overdrive/BOSS%20FA1.png)

the pedal works, but there's a boost even when using the treble and the bass pots.. Those add or remove boost, and luckly do also their work, so shape the tone.. But I don't think that the boost is normal..it was not there when I had the pedal working..

Any idea about the problem? I could take voltages if needed

really thanks

I didn't understand very much your post, but mine sounded like crap until I added two 100pF ceramic caps between the "- input" and the "output" of each half of the op amp.

[Dimitree]

sorry, I don't speak very well english 

I used all the original parts, no changes, and the original ICs and transistor..

the problem is that when incresing the treble and the bass, the volume get higher noticeably, while those 2 pots should only change the frequencies, not the gain..

[gigimarga]

sorry, I don't speak very well english 

Me too...so i don't understand why i didn't understood what you've said
I used a NE5532 and a J201 and it sounded very well (after I added the two 100pF caps) using this great project: http://ustomp.com/?p=6
Instead of the uncertain 47uF NP I used a 0.47uF, as Mark Hammer suggested.

[Dimitree]

thanks, but I don't think it is a problem of parts.. It should sound fine even as is..without mods..
I believe I could have a bad cap or something, but I never encountered such kind of problems so I don't know how to fix

[gigimarga]

good luck

[Dimitree]

I got another little problem with the pedal.. When I set the volume on the guitar at 0, I got a little whine noise when the Volume pot on the pedal is after the center (so from center to full), same with Treble pot..
I don't think it is normal