freestompboxes.org

How will it sound with a Burr Brown OPA2134PA? Anyoune tried it?
What other IC's have you tested?

what are original transistors and IC???

lm353 or lf353 or something like that. Not your everyday tl072

I'll be building these for bass and will use opa 2134's I think. I really like those.

The npn/pnp's though Im not sure whats used there.

darkglass wrote:Hello, Im posting one layoout I designed with eagle for the BB Preamp, I used the schem traced by KHE founded in this forum...

So here it is!

Schem
http://darkfinn.googlepages.com/BBSchem.jpg

Layout
http://darkfinn.googlepages.com/Layout.jpg

And PCB
http://darkfinn.googlepages.com/BBPreampPCB.pdf

This layout is not verified though, I finished it yesterday, but Im quite sure it should work.

Best Regards

Douglas.

Enjoy

what about the output transistor here?+4,5V is not connected to base but to emmiter???

I am not convinced by the Q2 connections either...

darkglass wrote:Hello, Im posting one layoout I designed with eagle for the BB Preamp, I used the schem traced by KHE founded in this forum...

So here it is!

Schem



Layout



And PCB

http://darkfinn.googlepages.com/BBPreampPCB.pdf

This layout is not verified though, I finished it yesterday, but Im quite sure it should work.

Best Regards

Douglas.

Enjoy

I tried this version,not working.I fixed output transistor pinouts(original are not correct,Va should go to base not emmiter,and emmiter to ground.)but still doesnt work.does anybody have working layout??

The bias of Q2 doesn't look right. As a test, I suggest you try pick up the signal from terminal 2 of the LEVEL potentiometer. If you hear a sound it's Q2. The connections of IC2A also look wrong.

I would recommend you have a look to this version.

Silent Fly wrote:The bias of Q2 doesn't look right. As a test, I suggest you try pick up the signal from terminal 2 of the LEVEL potentiometer. If you hear a sound it's Q2. The connections of IC2A also look wrong.

I would recommend you have a look to this version.

yes but I am realy bad in layout designing so I ask if somebody has working layout.I have a gig in france for 6 days and I realy need to finihs it till then!!!!!!!!HELP

Hi!
Help me with a small questions.
BB PLUS preamp has a B>A and A>B channel selector. But how? Relays? DPDTs? or?
In the Zvex Box of Rock have been realized as A(on\off)>B(on\off) chanel only.

Da Cat wrote:Thanks kusi, you the man
and the corected version:

OK,I ve built this version,engaged it and all I got is a HUM.Every pot is responding,difference can be heard when I turn gain pot,bass,treble,and the volume increases,but ll that is comming out is a hum sound no metter what you play(no distortion,no nothing).What could be the problem??
Thnx!!

Re-flow your solder. You might have a solder bridge somewhere.

madbean wrote:Re-flow your solder. You might have a solder bridge somewhere.

No,that's not the case,I rechecked all the paths.What else causes only hum sound.Transistors must be ok soldered or else there wouldn't be any sound at all??IC's????Someone help!!

mrkaploca wrote:

madbean wrote:Re-flow your solder. You might have a solder bridge somewhere.

No,that's not the case,I rechecked all the paths.What else causes only hum sound.Transistors must be ok soldered or else there wouldn't be any sound at all??IC's????Someone help!!

You used a layout that somebody said was/you hope is verified. In that case and in fact always, you should check your build against a correct schematic or use the Audio Probe to trace your guitar signal.

mrkaploca wrote:

Da Cat wrote:Thanks kusi, you the man
and the corected version:

OK,I ve built this version,engaged it and all I got is a HUM.Every pot is responding,difference can be heard when I turn gain pot,bass,treble,and the volume increases,but ll that is comming out is a hum sound no metter what you play(no distortion,no nothing).What could be the problem??
Thnx!!

You might have a grounding issue, maybe a connection missed

Hmm, my bb is working fine with this layout i made....
Hum sounds like a ground problem. Check the power filtering diode going to ground - orientation!
Check the schematics kusi posted - i made layout after that one.
And also check the transistors - try 2n5088 or 2n3904.

Da Cat wrote:Hmm, my bb is working fine with this layout i made....
Hum sounds like a ground problem. Check the power filtering diode going to ground - orientation!
Check the schematics kusi posted - i made layout after that one.
And also check the transistors - try 2n5088 or 2n3904.

I changed 2sc1815 transistors to 2n5088 and I finally made it work.Everything works fine except when I increase the gain potentiometer-then there is alot of background noise(hum)present .It can not be heard when I play but when I stop a noise appears.On a very low gain values it's ok.I put 1M log pot instead of linear one and I put 20k resistor(on the second gain stage of the first IC)instead of 19k.Can that cause the problem?
Sorry guys I torture u but I wanna make it right ,I really like the sound of bb preamp!!!
thnx!!!!

anybody with good advice??

mrkaploca wrote:

Da Cat wrote:Hmm, my bb is working fine with this layout i made....
Hum sounds like a ground problem. Check the power filtering diode going to ground - orientation!
Check the schematics kusi posted - i made layout after that one.
And also check the transistors - try 2n5088 or 2n3904.

I changed 2sc1815 transistors to 2n5088 and I finally made it work.Everything works fine except when I increase the gain potentiometer-then there is alot of background noise(hum)present .It can not be heard when I play but when I stop a noise appears.On a very low gain values it's ok.I put 1M log pot instead of linear one and I put 20k resistor(on the second gain stage of the first IC)instead of 19k.Can that cause the problem?
Sorry guys I torture u but I wanna make it right ,I really like the sound of bb preamp!!!
thnx!!!!

So guys what could be the fault??increasing the gain pot a background noise (hum)appears!!!!

Hi!
Could be bad filtering of the power supply --> try with battery.
Could be hum pickup from external source like mains wire, transformers, lighting..... either through guitar pu's or circuitry.
Is the circuit shielded/in a box?
Hope this helps some!
Timo

Has anyone tried this without the buffers? I may try it this weekend if I get time.