Pick-Up Output

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jcreasy
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Pick-Up Output

Post by jcreasy »

I've got a 4001 that was rebuilt by a forum member. After a custom, checkerboard re-paint, it hung on my wall for years. I recently pulled it down had a set it up and have started playing bass in a project.

Plays great and looks even better. However, the bridge pick-up output is weak compared to the neck. I have to roll off the neck volume to about 3/4 or so to get the same output volume. I tried raising the pick-up to get volume but I've got it just below where the strings do not hit the pole pieces (when playing, obviously). I really don't have a point of reference but the neck pick-up does not seem too high in the pickguard and the strings are not hitting those pole pieces.

The guy I am playing with seems to think something in wiring, but I just don't get it. Completely passive electronics and no modifications from a standard Rick harness. Jack is clean and I am not getting any noise from pots.

As you can tell, I am not a gearhead, and bass guitar is a new neighborhood for me, but I am missing something? Is it possible I've got a "... bad" pick-up? Is there some wiring or bad pot or something?
These are both hi-gains and I removed the "... horseshoe cover." Does that matter? Surely not?

Any help appreciated... Meantime, I'm going to head to local music store and demo and 4003 in a few days to compare.

Thanks,

JKC
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bassduke49
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Re: Pick-Up Output

Post by bassduke49 »

Does it have an unmodified wiring harness? All 4001 had the .0047 microfarad capacitor wired into the circuit to limit bass response from the bridge pickup (to make it more "trebley"). If that is the case, it can be bypassed with a piece of wire. If it was rebuilt without that capacitor, then it must be something else. :?
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jcreasy
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Re: Pick-Up Output

Post by jcreasy »

This is all Greek to me. I will lift the hood and take a PIC to post. Rebuilt from Rick parts so, not sure about the harness and all the proverbial "... flux capacitors" in there! That may be it, because it was rebuilt about 10 or 15 years ago, so the 4003s where in and the 4001s were out? Maybe a mismatch with harness and pick-ups? Maybe I can bypass?

(Half kidding with the "... flux capacitor" comment, but you are talking to a guy who is used to guitars straight in with no pedals and a tube, twin channel amp. I don't even use a footswitch and only one of my guitars has been hot-rodded... So all, plug and play).

Back to the point (and I seem to recall the 360s and 330s had a similar "... circuit" in the '60's), if the 4001s were all wired that way, did they all have a weaker bridge pick-up signal?

Thanks for your feedback and hope you enjoy your holiday week.

JKC
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jdogric12
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Re: Pick-Up Output

Post by jdogric12 »

That's not unusual on a naturally aged late 70's or early 80's Rick, but with all the monkeying that's been done on yours it could be anything. I'd get a reading on the pickups and check out that harness - or have someone who knows what's what do so.
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cassius987
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Re: Pick-Up Output

Post by cassius987 »

As Paul said, it could be the 0.0047 µF cap that was in-line with the bridge pickup. This passes high-frequency signal but blocks some low frequencies, and later on it was taken out of the bass wiring so this did not happen.

However, in my experience, when two pickups are fairly well balanced, the neck pickup is always a bit "louder". So keep that in mind. This is the usual desired configuration, where the bridge pickup provides the "presence" and the neck pickup provides the "girth". In fact, some 4003s are the opposite, probably because the bridge pickup has a bigger magnet than the neck pickup. It's not inherent in the design, as two equally matched pickups (like two Toasters) set at equal pickup-to-string height will have the usual volume balance.

Also, there's a chance that you're hearing the effect of comb-filtering. This would be if you do not have a 0.0047 µF cap. When both pickups are at full volume, they'll scoop each other out a bit. Rolling either one back to 3/4, as you mentioned, will make the overall sound louder (especially the mid frequencies). You can hear this on any two-pickup bass for the most part, especially a modern 4003, a Jazz Bass or a PJ bass.

If it's not one of those three scenarios, something is probably wrong with your pickup or wiring harness, such as a partial short-out of the bridge pickup.
jcreasy
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Re: Pick-Up Output

Post by jcreasy »

First off, thanks for the feedback.

I loosened the pick-guard, and there is an orange barrel (presumably the cap) from the bass tone pot to the pick-up toggle and another from the treble tone pot to the pick-up toggle. (Green Wire). I googled .0047 cap, so I think that is what I am looking at. I could not swing it around to get a PIC.

As for output and the comments on bass being different than guitar in that regard, I'll say that my 360s are pretty even and I use the 5th knob to roll in and out of balance. I really think the bridge is too weak. I've heard of older pick-ups failing but these are modern hi-gains in an older bass. Plus, I had the body bare when painted and the member who did the wiring did it fresh, so it wasn't a take-apart Frankenstein.

In any event, I'm going to take it to dealer and let everyone know what I find out.

Again, appreciate the replies.

JKC
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jps
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Re: Pick-Up Output

Post by jps »

Without photos of the harness in the bass it makes it really hard to advise. Any pics are better than none. You mention a green wire in ( ), what is this? You seem to imply something in relation to this and the .0047 cap.
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bassduke49
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Re: Pick-Up Output

Post by bassduke49 »

Understand that there are also two(?) other caps in there, and they are labeled .047 and you'll need those. The one you may want to bypass is .0047, so be careful.
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jcreasy
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Re: Pick-Up Output

Post by jcreasy »

I will pull and take a PIC tonight. I'll loosen strings and see if I can swing the pickguard out.

It looked like this...

http://www.rickysounds.co.uk/Spare-Part ... ssmall.jpg
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jps
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Re: Pick-Up Output

Post by jps »

That's a stock harness, absolutely nothing wrong with them. Also, if you are a bit careful (if necessary, place a towel on the body) you can slide the pickguard assembly out from under the strings without loosening them. Just slightly lift the strings with one hand while doing so.
jcreasy
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Re: Pick-Up Output

Post by jcreasy »

Yep, looked standard to me and neatly done. Kenny Howes did the fitting out for me, on a bass blank... So, no real monkey business or tinkering from someone unfamiliar.

On the previous reply with "... combing" effect and stuff, I'm not sure that is what I am hearing. In neck position, it is louder than in bridge position, and very noticeably. In mid-position, I am currently rolling off neck volume as described. Seems to me if it was a combing effect, I'd be having similar output when not in middle position?

Not to beat a dead horse, but thanks for the feedback and I'll let everyone know what I discover.

JKC
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aceonbass
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Re: Pick-Up Output

Post by aceonbass »

jps wrote:That's a stock harness, absolutely nothing wrong with them.
That's an after market harness configured like a stock harness. Without seeing your actual harness, it's not possible to see if there might be an issue with it. For instance, sometimes the factory practice of grounding pot lugs to the side of the pot casing can result in solder leaking into the case through the cam stop hole adjacent to C2 lug, down the pot lug into the case, or excessive heat being transferred to the plastic cam inside the pot. You can also get a bad pot once in awhile.
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iiipopes
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Re: Pick-Up Output

Post by iiipopes »

aceonbass wrote:
jps wrote:That's a stock harness, absolutely nothing wrong with them.
That's an after market harness configured like a stock harness. Without seeing your actual harness, it's not possible to see if there might be an issue with it. For instance, sometimes the factory practice of grounding pot lugs to the side of the pot casing can result in solder leaking into the case through the cam stop hole adjacent to C2 lug, down the pot lug into the case, or excessive heat being transferred to the plastic cam inside the pot. You can also get a bad pot once in awhile.
This.^ The "nominal" 250kohm pots on my 1981 12-string actually measured out to @170kohms - way beyond the nominal 20% tolerance. Also, the 5th knob on guitars should NOT have the third lug grounded. Even Mr. JH acknowledged the factory schematic is wrong on this detail.


I do agree that the .0047 in-line cap to the bridge pickup cuts a lot of fundamental, which by definition cuts overall output. Fender used a .0063 on the Jaguar bridge pickup, and I prefer a .01 inline on a Jazz bass treble pickup to eliminate the impedance volume drop with both pickups dimed. I found out this works on my 4002, with the pickups essentially being in J-bass positions, and is the stock wiring: http://rickenbacker.com/pdfs/19513.pdf .
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cassius987
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Re: Pick-Up Output

Post by cassius987 »

Detailed pics of all wiring would be ideal, for sure. Also, if you or a pal can take an ohm meter and get measurements of the mono output with the selector switch in each position, that will help.
jcreasy
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Re: Pick-Up Output

Post by jcreasy »

Took it to dealer (been a customer since my first guitar in '82 or so). They said there is a short in pick-up because ohm reading is way off. (This is all Greek to me).

They want to send it to Lindy Fralin to rewind, or replace with Rick pick-up or an aftermarket.

I am not looking to "... hot rod" the bass, but a few questions.

Anyone have bridge pick-up laying around they want to sell?
Anyone familiar with any of the aftermarket pick-ups and how they sound?

Thanks kids,

JKC
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