Buffer Induced hiss/squeal...

Started by artsinbloodshed, March 14, 2013, 07:08:35 PM

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artsinbloodshed

Hey Guys.
I've experimented some circuits lately (especially high gain stuff) and wanted to pump even more gain to compensate a weak pickup (humbucker,very dark).
Some circuits take buffers pretty good (rats...) some badly (muffs, doc boogey...).
I've done some decoupling (buffer/main circuit) but to reduce the hiss
I always end up by "over filtering" with large cap values (as much as 1N and above for muffs in the feedback filter caps section or caps to ground just before attacking the jfet in dr boogeys with same values...)
Sure, after that it's quite dead silent but overkills the gain of the device, the exact opposite of what I intended to do with a buffer...
other solution is to bias with a higher voltage but once again, you lose gain...

Have you guys encountered the same prob and/or found a solution?
Thanks.
I was born the year Elvis passed away...it probably means something!

J0K3RX

Welcome to my world!!! Having kinda the same problems... any diagrams examples of what you are doing? Have you tried a tube screamer in front of your circuits?
Doesn't matter what you did to get it... If it sounds good, then it is good!

artsinbloodshed

haha, common prob with gainiacs! :)
Nope, I didn't try with a TS so far (don't have any around). Could have been useful though, their buffer is quite renown and I've read some threads about silenced pedal thanks to other pedal buffers...
But , it could be tested with some kind of transplant. didn't test yet cause I was more concentrated on finding what's wrong...
So far, I've stuck to jack orman's simple buffers because of the part count...
I was born the year Elvis passed away...it probably means something!

artsinbloodshed

note: lately i've done a doc boogey according to gaussmarkov schem. quite a bit of a hiss biased at 4.5v but still no gain enough...I like distortion really juicy!
funny thing, I tamed the hiss with caps to ground but killed the gainyness...(increased C5 to 1N and parralleled r13 with 820p) so the buffer was needed to compensate!
this way, buffer+boogie+high value caps are a great combo BUT kills the high harmonics that make it "open" sounded...it's pretty dark but has plenty of gain...
I was born the year Elvis passed away...it probably means something!

J0K3RX

Quote from: artsinbloodshed on March 14, 2013, 07:42:39 PM
note: lately i've done a doc boogey according to gaussmarkov schem. quite a bit of a hiss biased at 4.5v but still no gain enough...I like distortion really juicy!
funny thing, I tamed the hiss with caps to ground but killed the gainyness...(increased C5 to 1N and parralleled r13 with 820p) so the buffer was needed to compensate!
this way, buffer+boogie+high value caps are a great combo BUT kills the high harmonics that make it "open" sounded...it's pretty dark but has plenty of gain...


Didn't really have any problems with the Dr.Boogey but the other pedals I have made I do get a lot of noise, even with the volume pot on the guitar turned all the way down... The Black Forest pedal I made  with an added jfet stage gets noise but kinda got that under control, I think. Now I have an Engl that uses mosfets and jfets and I get this constant hum nad the noise increases as I roll the volume pot back on the guitar... no good!! Did a few things sort of like what you have done sounds like and it kills the highs like you said... Tried a few other things as well like 500ohm resistor on the +9V power jack input along with a 100uf cap right on the power jack between +9V and ground. Then used all shielded wire for everything and seemed to stop it... The I get home today and plug in with the exact same configuration and the hum is back??? WTF???  :icon_evil:
Doesn't matter what you did to get it... If it sounds good, then it is good!