Making and onboard bass guitar preamp

[Skywalker83]

I have a passive set up on my bass. 2 soapbar pickups, 2 vol pots and a tone pot. I'd like to add an active preamp with a 3 band EQ with a mid sweep/freq select control. and also with a passive/active switch, so i can switch between the passive ciruit and the active preamp.

So in total there would be 6 knobs and a switch.

Bridge p-up vol (pass)
Neck p-up vol (pass)
Tone (pass)
Pup vol (activ) (push pull p-up select pot)
Treble (active)
Bass (active)
Mid/Mid Sweep (active) (stacked pot)
Active/Passive switch

Does anyone have a schematic for such a set up?

[Skywalker83]

Actually a slight change to the lay out...

Tone - for both Passive and Active
Treble - Active
Mid/Mid Sweep - Stacked pot- Active
Bass - Active
Pickup Blend - Passive and Active
Volume - Passive and Active
Passive/Active Switch


There's a preamp made by John East which is almost exactly like what i want , but i reckon if i can figure out how to make it (with my modifications) it would be alot cheaper. My design is a hybrid of the John East U-Retro 01 Deluxe and the U-Retro 5 Knob deluxe.

John East Preamps

[unohu69]

http://www.sputnikmusic.com/lesson.php?lessonid=195

go there and check out their build. Im not 100% if it will do the same thing for a bass. Some of the values may need to be changed to accommodate a Bass I believe a bass pick-up puts out a little more juice than a guitar.

I am A very new noob DIYer, but this is a build I plan on doing for my Ibanez SZ

[Daveze]

Actually, all you really need to do is add is the 3 band preamp.

Have a squizz at the Aguilar wiring diagrams:

http://www.aguilaramp.com/pdf/support_wiring_obp3.pdf

Look at the diagram with the bypass switch, all you're doing is adding a tone knob before the switch. Its been a while since I looked but you might have some drama finding the right pot to do the mid+mid sweep function, I had looked for one but gave up for an unknown reason.

In fact, using an OBP-3 (or similar 3-band) will save you the drama of tuning your DIY design for the right frequency responses and is a reasonable price (IMO). Have you looked at the Audere? The z-mode is rather tremendous (again, IMO).

[Skywalker83]

in my search for some circuits for help with my preamp design i came across the circuit shown below.

My preamp is going to have

Passive/Active DPDT switch
Tone (pasive and active)
Bass and treble stacked pot (Active)
Mid with mid sweep stacked pot (Active)
Volume
Blend

I plan on taking the pickups into the blend pot then to the input (im going to change out the boost switch in the circuit for a trim pot that will go on the board) then throught to the preamp and EQ.

Where would i add the tone pot and the passive/active switch in this circuit?

How would i alter the "Mid" section to include a mid sweep?

[Skywalker83]

forgot to attatch the image DOH!

[unohu69]

O.K. well I went to radio shack (doh!!) and bought the parts I need to build this. However the T1 calls for a BC548. the closest thing I could find was a PN2907. Do I have anything to consider before wiring this up ?[IMG]<a href="http://s107.photobucket.com/albums/m318/unohu69/?action=view&current=preampsch-1.gif" target="_blank"><img src="http://i107.photobucket.com/albums/m318/unohu69/preampsch-1.gif" border="0" alt="preamp ?"></a>[/IMG]




I didn't mean to commandeer this post, just figured since we were on the subject.

[unohu69]

Darn wasn't sure if that image was gonna work... so here goes this .....


i was really disappointed in RS quality. +/- 20% WTF is that. how do I get better quality parts ? +/- 10 or even 1 % ?