BassBalls Biasing.

[Kipper4]

Help me out guys.
My bassballs is now passing audio but it doesnt sound like it should yet.
The first thing i looked at was the power supply in the debug and some how i ommited to connect the +9v to the voltage divider.
easily solved.
Now how do i set up the trimmers to bias it please.
I did a mark Hammer mod and i'm using an external pot for the second trimmer.
thanks

[Mark Hammer]

Nothing particularly magical about it, although I suppose EHX sets them up according to a standard so all new units sound the same in the store.  Just tweak until it sweeps.  About 50-60% of the full range of the pot should be usable.  Just get yourself out of the 40-50% that isn't.

[Kipper4]

ok i'll try it in the morning its too late now mate thanks for the advice.
I think something else isnt right though my voltage on pin 3 of ic1 is only 1.3v it should be near 4.5v
i qaucks a small amount on the initial transiant but sounds way too clean and not like it should im sure.
thanks  Mark
I followed your advice btw and made the 2nd trimmer an external pot.

[Kipper4]

My filter envelopes arent doing what theyre supposed to i'm not getting that talkbox kinda sound.
Its a bit qaucky but not full on like in Mak Hammers video.
dont get me wrong i'm pleased its passing audio that something to be grateful off.

I'm gonna give it the once over with the meter.
No subs that i remember if there are theyre within the 10%

[Mark Hammer]

Sounds a bit like the dreaded under-signalitis.

1) Are you absolutely certain you have your transistors oriented correctly?

2) Assuming the transistors are oriented correctly, and that we are not dealing with one of those pesky units where the pinout is opposite from what you thought, do the filter sections vary with trimpot/pot adjustments?  Alternatively, if you vary the resistance of either R14 or R19, does the filter frequency change?

3) If you rig up a simple audio probe by plugging the output of the pedal into your amp, and running an alligator clip or probe to the negative side of C2, do you get a signal as loud as your bypass signal?

4) If all those things check out positive, then you may well have "the dreaded undersignalitis" - a condition wherein the gain of the envelope follower needs to be increased a bit.  That would involve replacing R5 with a somewhat higher value, like 270k or even 330k.  Another change to improve responsiveness is to sbstitute a germanium or schottky diode for the 1N4148 used.  That will conserve more envelope signal.

[Kipper4]

thanks Mark i'll test the theory tommorow now. I really appreciate your help. I've heard say your the man when it comes to bassballs.
I continued debugging tonight and found some connection errors pin 3 of ic1 was not connected to VB sorted that and while i was doing it another wire snapped off. I put it back where i thought it came from and now it passes sound but just faintly unless LOL i remove the ground connection then i get a full on bypass loudness. as soon as i reconnect the earth to the jacks it goes.
I've %^&*ed up some place.
Dammed you bassball. Its getting the better of me.
I'm really wishing i'd followed the layout in the schematic dept now.
if all else fails i will redo it with the layout.
I wont be beaten yet. i have come across this gnd issue before but i cant remember how i fixed it or what the problem was.
I should keep a log of faults.
Thanks Mark
Best regards
Rich

[Mark Hammer]

Don't worry, Rich.  We'll get you to the finish line.

[Kipper4]

i decided on a complete rebuild from Bob layout. I've run out of time to trial it tonight.
I'll write back and let you know how it goes Mark.
I found quite a few mistakes in the other board. I'll probably put it right when I have more time.

[Kipper4]

I got the switch and pots on it today and i have to say thanks Bob and Mark and the rest of the contributors over on this thread because mine struck up first time and it sounds like it should


Go here. Check it out, build it

http://www.diystompboxes.com/smfforum/index.php?topic=101858.msg907728;topicseen#msg907728