Re: Xotic - BB Preamp
Posted: 18 Jun 2009, 13:42
How will it sound with a Burr Brown OPA2134PA? Anyoune tried it?
What other IC's have you tested?
What other IC's have you tested?
what about the output transistor here?+4,5V is not connected to base but to emmiter???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
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??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
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!!!!!!!!HELPSilent 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.
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??
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!!madbean wrote:Re-flow your solder. You might have a solder bridge somewhere.
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: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!!madbean wrote:Re-flow your solder. You might have a solder bridge somewhere.
You might have a grounding issue, maybe a connection missedmrkaploca wrote: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!!
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?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.
So guys what could be the fault??increasing the gain pot a background noise (hum)appears!!!!mrkaploca wrote: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?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.
Sorry guys I torture u but I wanna make it right ,I really like the sound of bb preamp!!!
thnx!!!!