Baja Music Man guitar and bass onboard preamps

Duckman · Post by **Duckman** » 20 Jan 2010, 21:04

Ok, nice. I'll try.

In theory, the buffer does'nt apply any gain, does'nt it?
Any way, the trimpot it's a good idea and I'll work in both options to find the better.

Thanks, Jarno!!

bajaman · Post by **bajaman** » 21 Jan 2010, 00:08

omit c1 and r14

bajaman

RnFR · Post by **RnFR** » 21 Jan 2010, 00:32

bajaman wrote:omit c1 and r14
bajaman

i think you mean r13?

Duckman · Post by **Duckman** » 21 Jan 2010, 01:12

RnFR wrote:
bajaman wrote:omit c1 and r14
bajaman
i think you mean r13?

Yes! I knew it!

sorry! Just happy to guessit well

I re drawit and rename components to clear it... (hope it's correct now)
I test it as soon as I got the parts.

Thanks guys!!

bajaman · Post by **bajaman** » 21 Jan 2010, 03:32

Yes - remove C1 AND R13

They are NOT neccessary

Then connect the POSITIVE terminal of C11 directly to the junction of pin 1 (source of fet) and R12.
If you leave C1 and R13 in the circuit, then reverse the polarity of C11 (otherwise it is reverse biased

)
If you remove C1 and R13 from the circuit, then leave the polarity of C11 as it is (connect the POSITIVE terminal to the FET source)
cheers
bajaman

Duckman · Post by **Duckman** » 21 Jan 2010, 05:33

Sorry!

I uploaded the same schemo again

but this is the correct and sure to follow the Baja recommendations

bajaman · Post by **bajaman** » 21 Jan 2010, 22:06

xaxxop · Post by **xaxxop** » 26 Jan 2010, 18:34

bajaman wrote:Hi Gryphix
There should be 4x 1uf capacitors - the 10uf connected to the volume pot on the layout drawing is wrong; it should be 1uf - the schematic is correct - sorry.
Cheers
bajaman

Hi Baja! Are you sure? i'll build one for my olp over a year ago with 2 cap 10uf. I'm a little confused

the attached picture is http://myweb.ecomplanet.com/TOWN8019/my ... ge0019.htm this is original board?

What is right? 2-10uf or 1-10uf

thank you! have a nice day

bajaman · Post by **bajaman** » 26 Jan 2010, 19:08

It does appear to be a 10uf output coupling capacitor and not a 1uf as in my schematic.
I would use a 10uf as in the board layout picture - I will change the schematics.
cheers
bajaman

artu44 · Post by **artu44** » 23 Feb 2010, 18:19

As regards Sabre II guitar pre, months ago I found this schematics copied by hand from a low s/n guitar by Skipp May
http://home.swbell.net/mellis99/musicman.html
Now I see in the excellent job from bajaman few differences from that old original but enough to exclude human error by Skip. Maybe the two versions are referring to different periods?

bajaman · Post by **bajaman** » 23 Feb 2010, 19:56

very intersting - thanks for the link

bajaman

junjie · Post by **junjie** » 28 Feb 2010, 15:37

sir bajaman do you have the new schematic of musicman stingray preamp with the edited version of the values for the ouput coupling capacitor. thanks

bajaman · Post by **bajaman** » 28 Feb 2010, 19:52

PaulBass · Post by **PaulBass** » 02 Mar 2010, 09:02

I'm having a problem with an aftermarket StingRay preamp I bought on ebay. when I plug the bass into any effects pedals all I get is a low distorted sound. but when I plug the bass directly into the amp it sounds fine. I changed and tested the battery. when I test the output jack with a multimeter it says 7.02 in DCV mode and 38μ in DCA mode. my knowledge of electronics is limited so I don't know what these numbers mean. Did I get a bad preamp? Its brand new. Is there a way to fix this problem?

bajaman · Post by **bajaman** » 02 Mar 2010, 09:59

try adding a dc blocking coupling capacitor to the output socket.
bajaman

PaulBass · Post by **PaulBass** » 02 Mar 2010, 17:34

bajaman wrote:try adding a dc blocking coupling capacitor to the output socket.
bajaman

what value would you suggest. 10uf? 1uf? I'm wondering why the cap on the board isn't blocking the DC. could it be a short circuit? bad soldering? bad cap? thanks

PaulBass · Post by **PaulBass** » 02 Mar 2010, 23:22

bajaman wrote:try adding a dc blocking coupling capacitor to the output socket.
bajaman

I tried putting a 1uf and 10uf caps before the output jack and neither worked. all I got was a low signal with both caps. The 1uf cap put out 1.5mv and the 10uf cap put out 60mv. I bought this preamp at this link https://cgi.ebay.com/ws/eBayISAPI.dll?V ... 0390578219 for $39. looks like I got what I paid for. is there anyway I can fix this?

bajaman · Post by **bajaman** » 02 Mar 2010, 23:29

is there anyway I can fix this?

Yes - send it back to them because it is faulty - either get a refund or ask them to send you one that actually does work

bajaman

PaulBass · Post by **PaulBass** » 02 Mar 2010, 23:40

bajaman wrote:
is there anyway I can fix this?
Yes - send it back to them because it is faulty - either get a refund or ask them to send you one that actually does work
bajaman

I bought it a few months ago and there was only a 3 day exchange in the auction. I'm new to installing preamps and that was the first one I installed. I didn't find out later that you had to test everything with a multimeter. I figured since I got a signal everything was fine. I would have been better off trying to build one myself. I'm surprised the preamp didn't blow the amp.

Jarno · Post by **Jarno** » 03 Mar 2010, 08:45

Looks like somebody is using your work commercially, Baja. That's not very nice/ honest/ professional.

Paul, do you have a picture of the copper side of the board?

Baja Music Man guitar and bass onboard preamps [documentation]