Blend pot issue, need help!

[David King]

John, What is the brand of the blend pot? The older ones were Noble which have a logo that looks like an "S". The newer ones are Alpha brand which will say "alpha" on the side. They are wired opposite to each other. Do you have a multimeter?
When you say you grounded the pot do you mean you soldered a wire to the side of the case or is it being grounded through the cavity shielding when you tighten the mounting nut? I suspect you are looking at a recent issue Bartolini schematic and trying to wire the Noble pot backwards as described in my first post.

[John Meyers]

The brand of blend pot is "ALPR" (?) This is what it looks like to me on the side. It is not an ALPHA. I think everything is working ok now. I played the bass last night and everything seems to be working ok. I do not like having a pot and switch and batteries hanging out of it but it is working. So now I can re-locate the batteries and get the correct value stacked pot I will be good to go. The Bass does sing and maybe I do not hate the Bart electronics as much as I thought I did, maybe it was more of the pick ups I did not like after all. Let me ask this now that I seem to have the bugs worked out. The P bass pickup seems to be a lot weaker in volume than the MM style pick up. When I go from the bridge to the neck pickup I get a big volume drop. Does this sound normal? I know MM sytle pickups are strong by nature but was not sure how a p bass should react. I want to replace the P-bass pickup eventually and if I do and want a more balanced volume between pickups, would I wook for a P bass pickup with a simillar "K" value? Pot Value, pickup value these things drive me crazy!

[David King]

John,
P pickups are generally among of the loudest, most efficient bass pickups out there. It's supposed to have 10,000 turns of wire which is hot by any standard.
An 80's Fender P pickup may have lost some strength in the magnets if it's been kicking around in a box for decades. You can recharge the magnets with a little stack of neodymium round magnets applied simultaneously to the top and bottom of each magnet pole. ($1.99 at Harbor freight). MAKE SURE YOU KEEP THE MAGNET POLARITIES THE SAME. (Let the magnets choose the way they want to stick together, don't force them together or you will flip the pickup poles.)
Meanwhile try lowering the music man pickup away from the strings.

You have an Alps brand blend pot. According to your drawing you still have it wired backwards.
With the lugs facing you, top-left and bottom right lugs go to Ground.
Bottom left and top right go to Hot.
Neck pickup goes to center lug closest to the shaft. (Neck to "neck")
Bridge pickup goes to center lug closest to the back of the pot (bridge to back).

"Pre" and "post eq" means the volume pot is either between the pickups and the preamp input (yellow wire) or after the preamp (green wire) in the signal chain (not really an actual chain but just a way engineers like to describe where a signal starts and where it goes next).
The preamp fundamentally changes the nature of the signal and if you have a 25k volume pot it needs to be connected to the green wire and the output jack.

I can't give you a comprehensive understanding of basic electronics in a single post and it doesn't sound like you are ready to go there anyway.

The rule of thumb for electric guitars is: Use a 250K log taper (A) for passive single coil pickups (P and J pickups are considered single coil).
"Passive' implies there there is no battery, no transistors.
Use a 500K "A" taper volume pot for dual coil pickups (Music Man, PAF etc).
Use a 25K "A" taper for active pickups and active electronics. ("Active" implies a battery and transistors.)

[John Meyers]

Once again you amaze me with the amount of knowledge you have and the kindness to share is even better. I will give it a try on switching the ground and hot on the Blend pot. Also you mention the Pre and post eqing Green and yellow wires. I have the yellow going to the Volume and green to Blend. Do you think I need to switch these as well?

I may also try the magnet trick to the P bass pick up. When you do this how long do you leave the magnets on the pick ups and will one set of magnets charge each coil? Just not sure if doing this discharges the magnets and if I would need an extra set. And yes these have been bouncing around from box to box and no telling what they would be stored with as well for about 15 years or more. They came from my first bass an old Jap P bass that just rocked. I wish I still had it. Thanks again.

[John Meyers]

Well I got the ground and hot wire switched and what do you know it works like a charm. Also I have the volume and blend pots wired correctly green going to volume and yellow to blend. So no need to switch them. The only thing I did need to do with this blend pot was to ground the ground lug to the body of the pot. That got rid of the static I had when touching the knob. I found the correct stack pot at best bass gear, so I will order that and all should be great. Again thank you for all your help.

I about forgot. I did the magnet trick to the P bass pick-up and it seem to help along with raising the pick up as well. Now the two pick-ups are just about even to one another when panning.

Let me ask this of anyone. About the Bartolini electronics NTMB, do any of you think they are bass heavy by nature, or kinda smooths everything out? The reason I ask is, when I had hard wired the MM style pickup to my amp it sounded great and just nailed the stingray sound to a T. After adding the electronics, it has seemed to tame the sound of the pickup when everything is set flat. Is this just do to signle being routed through all the pots and electronics, that it will have to alter the sound some?

[David King]

Hot wiring a pickup to the jack is an old standby to get the best tone. You can accomplish that with a push/pull switch or two.

[John Meyers]

David do you know if you can do a push pull switch with the Bart electronics. I know you mentioned in another thread I had about these electronics that they cannot be hooked up to be active/passive? If I was to do this would it give a big pop sound when switching if at all?

[David King]

Big pop as there's a DC offset between the input and output. There is a phase reversal between input and output as well but that's never a problem.
Just turn down the volume before you switch over. Once you've paid to recone your bass drivers a few times you won't forget to turn down.
Most bass amps have some limiting circuit to protect the drivers from massive transients so not a problem usually. That's not always the case for FOH.