# Aguilar OBP-3 - Mid push/pull pop?

Discussion in 'Pickups & Electronics [BG]' started by FunkMetalBass, Apr 26, 2010.

1. ### FunkMetalBass

Aug 5, 2005
Phoenix, Arizona 85029
Endorsing Artist: J.C. Basses
The thread title really says it all. Anybody have any suggestion for eliminating that damn pop when the mid push/pull is used? I suspect it's something to do with the two unused lugs.

2. ### GODSBASSMAN

Feb 2, 2005
S. Carolina
See the Aguilar site wiring diagrams, very helpful. has to do about resistors in the circuit.

3. ### line6man

Yep, resistors across the switch terminals should do it.

Sep 9, 2006
Tijuana Mex.
5. ### FunkMetalBass

Aug 5, 2005
Phoenix, Arizona 85029
Endorsing Artist: J.C. Basses
I've found some 1M resistors in 1/4W, 1/2W, and 1W - Which should I use?

If my physics knowledge is correct, running the preamp at 9V will need at least the 1/4W and the 18V will need at least the 1/2W?

6. ### line6man

It doesn't matter what you wattage you use, they should all be sufficient.

Your entire preamp circuit draws about 0.009 to 0.018 watts at 9V, or 0.018 to 0.036 watts at 18V. Well below the 0.25 watt limit of your lowest wattage resistors.

7. ### FunkMetalBass

Aug 5, 2005
Phoenix, Arizona 85029
Endorsing Artist: J.C. Basses
Ah, okay, that's perfect then. RadioShack has a 5-pack of resistors for \$0.99 and I've got two basses that need this mod. Thanks, L6M.

8. ### line6man

I misplaced the decimal point in the part you quoted, read the post again.

9. ### FunkMetalBass

Aug 5, 2005
Phoenix, Arizona 85029
Endorsing Artist: J.C. Basses
Can I ask how you calculated those? Either I'm estimating incorrectly, or I suck at crunching numbers (go figure that I'll be receiving a math degree w/ a physics minor soon...)

10. ### line6man

It's a very simple formula:
Voltage * Current = Wattage

V= 9 or 18.
I= 0.001 to 0.002.

11. ### FunkMetalBass

Aug 5, 2005
Phoenix, Arizona 85029
Endorsing Artist: J.C. Basses
The current is where you've lost me. I was just using P = V^2 / R.

12. ### wvbassSupporting Member

Mar 1, 2004
West Virginia
V=IR, so I = V/R

So,

P = V * I

is the same as

P = V * V/R

or

P = V^2/R

No reason to get lost. You two said the same thing.

I am interested in where the numbers for the OBP-3's current draw came from, though.

13. ### line6man

See, you're overcomplicating things.

The way I saw it was that if I'm looking for a measure of wattage, I don't know how much current is being passed through the resistors in that part of the circuit, so I just looked at how much current is drawn by the preamp as a whole, which is a couple of milliamps at most.
The preamp is running on 9V or 18V, so I can just multiply by the current, and there is my maximum wattage.

FWIW, these resistors are just there to quiet the switch pop, they aren't really a part of the EQ circuit.