Help with Aguilar OBP-3TK bass preamp

[Scorpionscar]

Hi guys, I'm building a bass with a bridge pick up humbucker type and neck jass bass style pup, both Aguilar. I want to install an Aguilar preamp OBP-3TK. This preamp has 3 pots and one miniswitch. The pots are for bass, middle and treble and the miniswitch is for midrange frecuency selection. As a newbie I have some doubdts:

- Is is possible to use a 9V battery in order to allow the bass work active/passive?
- Do I need two aditional pots for pups volume and balance? In this case, can I use a master volume for both pups and what the values for volume and balance pots should be?

Thanks in advance

Scorpionscar

 

[Aloe]

1. yeah, you can wire a bypass switch (or a push-pull pot), there's a schematic in user's manual. you may do this regardless of 9v or 18v operation.
2. yeah, generally you do (unless you're fine without them). the pot values should be appropriate for used pickups (or chosen by trial)
3. yeah, volume+blend works exactly the same you need: it's master volume and a blend control

please read the user's manual that came with your preamp, it will answer most of your questions, even show that in pictures.

 

[Scorpionscar]

1. yeah, you can wire a bypass switch (or a push-pull pot), there's a schematic in user's manual. you may do this regardless of 9v or 18v operation.
2. yeah, generally you do (unless you're fine without them). the pot values should be appropriate for used pickups (or chosen by trial)
3. yeah, volume+blend works exactly the same you need: it's master volume and a blend control

please read the user's manual that came with your preamp, it will answer most of your questions, even show that in pictures.

Thank you so much for your answer. I have not ordered the OBP3 yet because I need to know what pots do I need for ordering all together. What I really want is a comfiguration like a jazz bass (Volume, volume, tone) and plus install the Aguilar preamp OBP-3TK. I want that can change between active/pasive.

 

[Aloe]

I have not ordered the OBP3 yet because I need to know what pots do I need for ordering all together. What I really want is a comfiguration like a jazz bass (Volume, volume, tone) and plus install the Aguilar preamp OBP-3TK.

well, you need different pots for VVT setup vs a VBT (the blend one), so either get sure, which you want, or order them all. in the manual there're lots of configurations, take a look, which you want to try.

I'd grab linear volumes, if you want VVT. I'd start with two B500K volumes and whatever you prefer for passive tone. when going VBT, get an A500K volume and... either an AC, or MN type pot. 500k will make it sound brighter, 250K will give you better control on taper. also you can install the blend grounded or ungrounded and this forum contains good advice on the broad subject of blend pots and how to wire them.

personally I'd start VVT, it's easier to get done and later you could swap it for something else, once you know, which blend do you prefer. I'd take two B500K, one A500K and a capacitor and you're good to go.

Aguilar in the above linked manual gives an advice like 'contact pickups manufacturer for choosing best pots for the pickups', so give it a try, they're offering great help through email (tho I admit, I last mailed them in pre-covid times).

 

[Scorpionscar]

well, you need different pots for VVT setup vs a VBT (the blend one), so either get sure, which you want, or order them all. in the manual there're lots of configurations, take a look, which you want to try.

I'd grab linear volumes, if you want VVT. I'd start with two B500K volumes and whatever you prefer for passive tone. when going VBT, get an A500K volume and... either an AC, or MN type pot. 500k will make it sound brighter, 250K will give you better control on taper. also you can install the blend grounded or ungrounded and this forum contains good advice on the broad subject of blend pots and how to wire them.

personally I'd start VVT, it's easier to get done and later you could swap it for something else, once you know, which blend do you prefer. I'd take two B500K, one A500K and a capacitor and you're good to go.

Aguilar in the above linked manual gives an advice like 'contact pickups manufacturer for choosing best pots for the pickups', so give it a try, they're offering great help through email (tho I admit, I last mailed them in pre-covid times).

I think I'm going to go to VVT configuration. In the link you posted above, I found one with two volumes:

* could be added a tone pot in the traditional wiring?
* Can I bypass the preamp to pasive mode?
I upload an image with the explanation I want. Your help is very important because I'm not very experienced at bass wiring. Thanks in advance.

Scorpionscar

 

[Aloe]

* could be added a tone pot in the traditional wiring?

yeah, there's a picture of this in the same user manual, it's called 'passive tone control'

* Can I bypass the preamp to pasive mode?

this as well, it's named 'bypass switch'.

this all said, I'd personally use the linear (B-taper pots) for volumes rather than A-taper pots when I have two volumes.

 

[Scorpionscar]

yeah, there's a picture of this in the same user manual, it's called 'passive tone control'



this as well, it's named 'bypass switch'.

this all said, I'd personally use the linear (B-taper pots) for volumes rather than A-taper pots when I have two volumes.

Thank you so much Aloe, your help is very valuable to me. I think I have a clear concept. Now I'm going to order the OBP-3 and the rest of the components, and as soon I recive it, I'll start to work on the electronics. If I have some doubt, I'll comment here. Anyway I'll put pictures of the process and the final result. Thank you so much.

Scorpionscar

 

[Scorpionscar]

I've been wiring the OBP-3 today. With the wiring of the bass, mid and treble, have no problems, is only a matter of following the wiring colors, is clear. For the Volume, Volume, and Tone I followed the Aguilar wiring too with no problems, however in the DPDT I don't understand the upper left lug which I've marked with a red circle, according to the wiring diagram, the wire from this lug goes to the center lug of one volume pot, don't know if neck volume, bridge volume...In the center lug of both volumes goes respectively the pick up wires...

Scorpionscar