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Jazz Bass Volume Problems

 
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Luvie



Joined: 02 May 2007
Posts: 298
Location: Houston

PostPosted: Wed Jun 23, 2010 8:40 am    Post subject: Jazz Bass Volume Problems Reply with quote

I was hoping someone could help me with an issue I am having on a new Jazz Bass I am wiring up.

I am doing the series/parallel - varitone set up described here:

http://www.reranch.com/reranch/viewtopic.php?t=34714&highlight=varitone

Everything appears to work fine except all of the volume control for both volume pots is in the top 1/4 of the rotation of the knobs. In other words, they are both at full volume when turned all the way up but when I back the volume off they make it to zero volume within only 1/4 of the pot's stroke. It appears to be a steady volume change, meaning it doesn't just turn down a quarter of the way and then drop to zero.

The varitone works fine, the push-pull switch works fine and switches the pups from series to parallel; I just get all my volume control in only a portion of the pots' rotation. The neck pup knob does the same thing whether in series or parallel.

I'm using tonerider pups and 250k pots. The pots came from different sources (one's a switch and one is standard) so I wouldn't think it's a pot problem because they both are doing the same thing. And I built another varitone at the same time as this one and it's in my pbass and works fine so I wouldn't think it would be the cause.

So any words of wisdom would be appreciated!
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rdkienle



Joined: 11 Oct 2006
Posts: 188
Location: Gilroy, California

PostPosted: Wed Jun 23, 2010 8:55 am    Post subject: Reply with quote

Sounds like the PUPs are out of phase. Try switching the wires on just one of the pickups.

BK
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rdkienle



Joined: 11 Oct 2006
Posts: 188
Location: Gilroy, California

PostPosted: Fri Jun 25, 2010 8:20 am    Post subject: Reply with quote

Luvie,

I meant to ask if you have anymore specifics or schematics on the varitone. I am in the middle of a jazz bass project right now and thought I might like to try that.

Also, did you get your problem worked out?

BK
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Luvie



Joined: 02 May 2007
Posts: 298
Location: Houston

PostPosted: Fri Jun 25, 2010 9:17 am    Post subject: Reply with quote

BK-

I hope to pop the control plate off this weekend. I appreciate your suggestion on the pickups being out of phase. I suspect that's not the case as I was pretty careful when I wired it but you never know...

Doing some research I'm beginning to suspect that I have linear taper pots vs. audio taper. I didn't even know there were different kinds of pots other than the different resistances. It's strange that both my regular pot and the push-pull switch pot would be wrong but since I didn't know anything about that I don't know what I ordered. Plus, they both have been laying around in a box of parts for a couple of years so I don't even know where I bought them.

I plan on picking up two new audio taper push pull switch pots this weekend and just rewiring the whole thing. This way, I can add the second push-pull switch to the mix and use it as a kill switch.

Here's where I got the varitone idea:

http://reranch.com/reranch/viewtopic.php?t=32199&highlight=varitone

I made two of them for something fun and inexpensive to do several months back. I put one in my pbass and I love it. The second one was just laying around so I decided to build it into this jazz bass. And volume issues aside, it sounds great in it.

The push-pull switch allowing you to put the pickups in series gives an awesome tone. I'd recommend it to anyone building a jazz bass.

Good luck and thanks for your help!

Luvie
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rdkienle



Joined: 11 Oct 2006
Posts: 188
Location: Gilroy, California

PostPosted: Fri Jun 25, 2010 9:20 pm    Post subject: Reply with quote

Cool, thanks for the update and the wiring schematic. If you do have linear taper pots that is probably the issue.

In terms of the pups being out of phase you can't just go on wire color. Even pups from the same manufacturer may be wired differently in terms of wire color. I put a couple Dimarzio pups in a bass a while back wired them up just based on wire color and guess what - pups were out of phase.

Good luck. Let us know how things turn out.

BK.
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Luvie



Joined: 02 May 2007
Posts: 298
Location: Houston

PostPosted: Sat Jun 26, 2010 9:05 am    Post subject: Reply with quote

OK, thanks! I'll switch the leads before I rewire it. Even if I rewire it with the kill switch, if the leads are marked wrone I'll still have the same problem.

Luvie
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Structo



Joined: 21 Nov 2004
Posts: 26415
Location: Salem, OR

PostPosted: Sat Jun 26, 2010 9:18 am    Post subject: Reply with quote

Linear pots will have a steady decrease in volume.
In other words a linear pot will be 50% resistance at half way.

Where as an audio taper pot is about 20% at half way.

You could either have the pots wired wrong or have reverse taper pots.


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Luvie



Joined: 02 May 2007
Posts: 298
Location: Houston

PostPosted: Mon Jun 28, 2010 9:58 am    Post subject: Reply with quote

Thanks Tom-

So is a reverse taper pot a specific type of pot? Or does it mean I had audio taper pots and wired the lugs backwards?

An update: over the weekend I completely rewired the whole control plate with brand new components (other than the varitone, which I reused). I used a push-pull switch pot in the neck volume position and wired it for series/parallel and used a push-pull switch pot in the bridge volume position and wired it as a kill switch. I did not reverse the leads on the pickups. Bottom line is it works great now. So I either had the wrong components or wired them wrong (I'll go back and relook at the wiring).

In any event, it works fine now and I'm very happy with the varitone, series/parallel, and kill switch mods. I'd recommend any or all those to any jazz bass.

Thanks for your responses and hopefully someone can benefit from this!

Luvie
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sonicblue



Joined: 15 Mar 2007
Posts: 935
Location: CT

PostPosted: Mon Jun 28, 2010 2:33 pm    Post subject: Reply with quote

Reverse taper is a specific type. Often pots will be marked with the resistance value followed by a letter: "A" is audio/logarithmic, "B" is linear, "C" is reverse audio.
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