Aguilar OBP1 DB924 repair

[karma78]

Hi everyone,

A friend of mine gave me a Agular DB924 bass Fet Preamp to repair !
As I'm electronic technician, I thought I could repair it easily but....when I opened it, I was surprised to find some silicon inside !

As I cannot find the schematic of the preamp on the net and repair it is an impossible mission, I decided to open it .............yes open the Preamp and remove the silicon.

After 2 hours, I finally saw the components !
My goal now, is to rebuild this Preamp ! So I trace the circuit, and try to get the value of the components !
But now I have a question : This Preamp contains 3 transistors but i'm pretty sure only the first one is FET.
Do you guys have some answers ? Someone has already built a clone of that Preamp ?

Here are 2 photos of the circuit of the DB924 - we can easily see " OBP1" on the 2nd picture !
https://goo.gl/photos/mV2PT95wrHdmNEAY7
https://goo.gl/photos/LCpxq99ZyFznD4UB9

Any information on that Preamp is welcomed
Thank you
Karma ( France )

 

[Treb]

The DB924 is an OBP1 as an external preamp. The OBP1 is similar (but not the same!) as the Sadowsky bass preamp. Alex Aguilar designed the Sadowsky preamp and later on the OBP1. I've not seen any OBP1 schematic online. There are some schematics of "Sadowsky preamps" out there, I don't know if they are accurate. Don't bother asking Sadowsky if they are, I doubt they'll tell you anything else than "no comment". Perhaps the Sadowsky clones are a good starting point. AFAIK both the Sadowsky and the Aguilar are FET based preamps as opposed to opamp based.

Trying to find a used but working OBP1 and mount it inside the DB924 enclosure is what I would do.