OBP-3 Pots

Jeremommy · #1 10-15-2009, 06:23 PM

I just installed an OBP-3. The bass has Bart 69js installed. The sound is good but I lost a lot of volume. The pup spec says to use a 250k volume pot. The volume pot I used is a 500k pot.

Is the wrong volume "K" value the problem? What is "k"? Does the "k"-value of the blend pot matter?

The preamp I replaced had a 25k volume pot and everything seemed fine.

dougray · #2 10-15-2009, 06:38 PM

25K is usually used with "active" pick-ups (battery powered) i would use a 25K volume/blend to see if that solves the volume loss.

aguilar site offers different wiring diagrams.

Doublefunk · #3 10-15-2009, 07:14 PM

Pots (Potentiometers) are measured in Ohms, The K stands for kilo or thousands. So a 500k pot has a maximum value of 500,000 ohms. if your concerned that much about the volume drop I would switch it to a 250k pot since that is what the spec suggests.

**line6man** · #4 10-15-2009, 07:34 PM

DoubleFunk:
You are correct, "K" is the abbreviation of Kilo, which is a unit of measure equal to one thousand, thus 500K= 500,000 ohms.
However, a 250K volume pot gives you less volume than a 500K. It probably wouldn't be a good idea to go with the 250K pot in this case for that reason.

These two threads are relevant to why:
What effect does 1 meg pot have? Also, audio vs. linear
Passive basses and the volume control, an explanation (science warning)

The Aguilar preamps call for 250K/500K pots before their input, but 25K volume controls would usually be used after the preamp, as the preamp outputs a lower impedance signal than the pickups.
It can sometimes be more desirable to use a 25K volume after the preamp because you don't have as much of the treble loss associated with rolling down the volume on a 250K/500K pot ran before the preamp.
Some preamps are designed to work better with 250K/500K pots before the input, and others are designed to work better with 25K pots after the output.
Using 25K volumes does interfere with your ability to still use a volume control in passive mode if you have an active/passive switch, and it makes it impossible to have two volume controls if you prefer them to blends/pickup selectors.

If you are concerned about the volume with a 500K, 250K is certainly not the direction to go to fix that problem.

Jeremommy · #5 10-15-2009, 08:09 PM

500k seems to be the highest ohm volume pot available. And if I understand all the replies correctly it doesn`t appear that the blend or eq pots could be the culprits. The pup height is good. Does anyone have any other other thoughts on a solution?

**line6man** · #6 10-15-2009, 08:12 PM

Quote:

Originally Posted by Jeremommy

500k seems to be the highest ohm volume pot available. And if I understand all the replies correctly it doesn`t appear that the blend or eq pots could be the culprits. The pup height is good. Does anyone have any other other thoughts on a solution?

Actually, you can get a 1M (1,000,000 ohm) pot too, but I don't think that is the best solution to this problem.

What was your preamp and setup before?

Jeremommy · #7 10-15-2009, 08:31 PM

same pups with NTMB-2.

Jeremommy · #8 10-15-2009, 08:52 PM

correction - the preamp was a Bart NTBT-2

Yorke · #9 10-15-2009, 08:55 PM

I am having a similiar problem, I bought a used Ibanez SR406, and intially installed the Aguilar OBP-3. The tech at the store told me to use 25k pots ( I am using the Volume/Volume setup), so I installed it with the original pick-ups.

I noticed a loss of volume, but it was also slightly muddy or missing the top end sparkle.

Next I ordered and installed a set of bartolini Quad Coil pick-ups and once again it was an improvement but not what you would expect.

I just bought a Spector Legend 6 with stock electronics and strings, and it hands down smokes the other bass that has the upgraded excellent electronics.

My room mate just handed me some 500k pots, I am gonna try them out tomorrow and see if it improves the tone.

The best way I can describe it is muddy and muted, I hope this helps.

Yorke

**line6man** · #10 10-15-2009, 09:14 PM

Quote:

Originally Posted by Yorke

I am having a similiar problem, I bought a used Ibanez SR406, and intially installed the Aguilar OBP-3. The tech at the store told me to use 25k pots ( I am using the Volume/Volume setup), so I installed it with the original pick-ups.

I noticed a loss of volume, but it was also slightly muddy or missing the top end sparkle.

The best way I can describe it is muddy and muted

Does the bass have active pickups?

The tech is completely incompetent if he told you to use 25K pots for a volume/volume setup with passive pickups.

If you are using two 25K volume controls before the preamp with passive pickups, you are putting a 12.5K load from the hot to ground, damn right that is going to get muddy! I'm a bit surprised that you are able to even get a decent output.

Switch to the 500Ks and there should be a big difference.

**line6man** · #11 10-15-2009, 09:16 PM

Quote:

Originally Posted by Jeremommy

correction - the preamp was a Bart NTBT-2

Ok, I see that that preamp has a system gain control.
Perhaps you had it turned up to increase the gain?

Jeremommy · #12 10-15-2009, 09:56 PM

The NTBT-2 is vol-blend-treble-bass. It does not have a gain control on the preamp itself if that is what you are getting at. Also, unlike Yorke, the sound quality from from my obp is good. Yorke, please let me know if the 500k pot helps.

Yorke · #13 10-15-2009, 10:25 PM

Oh hell yeah, it made a HUGE difference, problem solved, I used 2-500k pots and it sounded so much better.

There was a Volume increase and it also added some top end back to the overall tone. I was going to wait until tomorrow to change them out, and at the last minute I decided I could not think about it all day while working.

I kept telling my room mate ( bassist) that something wasn't right, I changed strings, it was driving me crazy.

Thanks for posting the original question and thanks for all the great advice, you guys made my weekend.

Yorke

**line6man** · #14 10-15-2009, 10:49 PM

Quote:

Originally Posted by Yorke

Oh hell yeah, it made a HUGE difference, problem solved, I used 2-500k pots and it sounded so much better.

There was a Volume increase and it also added some top end back to the overall tone. I was going to wait until tomorrow to change them out, and at the last minute I decided I could not think about it all day while working.

I kept telling my room mate ( bassist) that something wasn't right, I changed strings, it was driving me crazy.

Thanks for posting the original question and thanks for all the great advice, you guys made my weekend.

Yorke

Cool!.

For the love of God, go find that tech at the store and show him this thread! Tell him to learn what he is doing so he doesn't give customers bad advice!