4001 wiring

[toddholiday]

So I have two 4001s (78 and 81). Have had them both since the late 80's. The 78 model I play weekly at practice and a couple times a month at shows. Has every sound I want. The 2nd 4001 not so much. It's a practice around the house bass. It doesn't have the same output in terms of volume or tone. The volume is lower and the tone knobs dont seem to have the same range. It goes from total bass sound to all treble sound in less than a 90 degree turn on the knob. Would like to get it sounding as good as the other 4001.

So in taking them both apart I see the capacitors are different. Do I need to replace the wiring harness?
The wiring from the 4001 I like:

And the wiring for the one not used I want to have sound like the other. The orange capacitors are twice as large as the yellow 47s.

[BigJohnAZ]

If the caps are the same, 2 .047's and the one .0047, then I would guess it has to do with the pickups and maybe how high/low they are. I'm sure you will get a more definitive answer from the electronic gurus on the site. Also, basses are like kids, no two are alike lol

[johnallg]

If the caps are the same, 2 .047's and the one .0047, then I would guess it has to do with the pickups and maybe how high/low they are. I'm sure you will get a more definitive answer from the electronic gurus on the site. Also, basses are like kids, no two are alike lol

What John said.

[stevebasshead]

I'll echo what's already been said above and add that over the years capacitor values can drift away from their original specs/tolerances too, which would potentially affect the tonal output in addition to any other differences between the basses/pickups.

[RickyBubba]

I will gladly pay shipping to take the defective one off your hands!

Hope you can get it sorted out.

Honestly when you look at the two pictures, the second one looks like it may have been dorked around with, given the burns on some of the wiring. Maybe somebody messed with it and didn't get the connections all right?

I would look closely at the paths of the wires on the 2nd one. Maybe a bad solder connection?

[Lefty4003S8]

Ah huh huh huh huh (Butthead laugh)......He said Dorked......

[aceonbass]

There's nothing wrong with the wiring on either harness. The orange caps are Sprague's, and the yellow ones are Cornell-Dubillier's, but there isn't an obvious difference in tone between them. While the specs on these can drift over time, I've not found it to be by very much at all. Measuring the pickups output will help narrow down the problem, but it's also very possible that the pots were way off their rated specs when the bass was built. This can have a very noticeable effect on the sound. As most know, bypassing the .0047uF cap will have a HUGE effect on the bridge pickups sound of either harness.