ikay

The JC electronics are different to a regular bass. It has a low impedance pickup with a tapped transformer to change the impedance and tonal characteristics via a 3-way switch. Vol and tone pots are 2.5k log. I found this wiring diagram on the web.

Here's a selection of 2,5k log pots from Mouser:

https://www.mouser.co.uk/Passive-Components/Potentiometers-Trimmers-Rheostats/Potentiometers/_/N-9q0yp?P=1yzekj1Z1yzvm31

The Bourns one at the bottom of the list looks like it should do the job.

There's a long thread on TB about this very problem - https://www.talkbass.com/threads/epi-jack-casady-volume-pot-replacement-again.1057712/

Finding replacement pots (2.5k log) seems to be next to impossible but on page 3 there are a few alternative suggestions:

SUGGESTION 1

There is a solution. If you get stereo 5K pots (which are way easier to find than 2K5) and wire both halves in parallel you get the desired value. I think the fact that you have two separate pots in parallel may also reduce crackle as they wear.

SUGGESTION 2

Order a good CTS / Orangedrop combination as for a PB (two 250K's, 0.047muF), remove the 2.5K pots and connect the JC Electar pick-up directly to the rotary switch input. Connect the transformer output to the two new pots as you can find in any PB scheme, then to the output. Before changing anything, confirm yourself that you can find the right wires in this "old-world telephone exchange"!

Result:
- no cracks anymore!
- the sound is not changed, except for the effect of the tone pot. Depends on the rotary switch position and input impedance of your amplifier or device. But that was also the case before modification (some years ago I posted a question about this, but few JC-bassists seem to use different amps, I guess...).
- no more searching for the right pots, the new ones are regular.
- the JC Bass seems not critical for changing the wiring, the sound is still in your fingers.

Now £20!! Anyone?

This is an internal preamp and equalizer designed for use with hybrid guitars and basses with both piezo and magnetic pickups. Can also be used with piezo only. The 3-band EQ and phase switch are for fine tuning the piezo sound and only affect the piezo signal, the mag pickup is mixed in at the end of the signal chain.

Very compact (50 x 30 x 13mm) and easy to tuck away in an existing control cavity. Perfect for anyone wanting to experiment with a piezo bass or add a piezo pickup to a regular bass. I had it installed as a piezo buffer on my ACG for a while and sounded great. The ACG now has an East modular preamp and this is just sitting in my parts drawer. Comes with installation instructions.

Price includes postage within the UK.

Unused set of MarkBass Rack Ears for Little Mark series amps (LMII, LMIII, LM250, LM Tube, Little Marcus etc). Includes amp mounting screws and washers. Bought a few years ago with the intention of racking my rig but never got round to it. Price includes postage within the UK.

ACG/Armstrong RFB Triple Coil Pickup from my 2010 Recurve. This was wired with a 3-way switch giving SC / SC+HB / HB but had a slight hum that couldn't be eliminated so was eventually swapped out for an RFB dual-coil humbucker. The wiring terminals on the back are exposed so there is scope to experiment with different wiring configs. Having a clear out of my parts box and seems a shame to just chuck it in the bin so free + cost of postage (£3.20 Royal Mail second class) to anyone who wants to have a play. Dimensions are 118 x 48 x 20 mm.

A set of used Evah Weich's that I bought some time ago here on BC to try but never got round to using. A good clean set of strings that look to have plenty of life left in them. Having a clear out so £45 including postage in the UK.

3U Spider rack case including AudioHead AH500 2-Channel Power Amp, 250W+250W into 4ohms. Switchable to Stereo, Parallel or Bridged mode. Solid workhorse amp suitable for live or studio use. Bought new in early 2000s. I used it to run stage monitors for a live band. Has been well used but is in good working condition. The mounting ears aren't quite standard 19" rack size (very slightly short) but it's securely fastened with oversize washers and is perfectly usable. Now surplus to requirements. Having a major house clear out as need the space, hence ludicrous price.

Collection only from Rudgwick, West Sussex (near Horsham)

The neck pickup in this demo of the Sims Super Quad is close enough to the P position to give you some idea. The first 30secs demo the neck pup in split coil mode (standard P) followed by humbucker (parallel), then single coil. 

The raised pole pieces look fine. Some J pups have staggered pole pieces like this to compensate for the string radius. If fretted notes on the A string all sound strong, that indicates all is generally good with the string, frets and pickups. A weak open A would then suggest an issue with the nut, or somewhere up that end.

On second thoughts it could be an on-on-on or on-off-on switch (with float in the 'off' position). You might need to disconnect it and check the terminal connections in each position to determine exactly what type it is.

It's a 3-way switch (Ground/Float/Ploat) so should be a DPDT on-on-on switch with 6 terminals. 

This thread explains the Float and Ploat settings: 

My ACG came with a dual EQ01 filter which I persevered with for several years but eventually swapped out for an East modular 3-band preamp.

I spent plenty of time getting to know and understand the filters in a variety of musical situations, but in the end the tonal range was just too extreme for my needs and I found it difficult to make fine adjustments in the small range that I found useful. I particularly missed being able to make small tweaks to cut or boost the mids which the EQ01 didn't allow for.

I'm still intriqued by filters though and now have a Lemme 'state-variable filter' in an outboard pedal, so I can mess around with it on different basses. Mostly for experimental purposes.

They crop up quite frequently on the FB Rickenfakers forum - https://www.facebook.com/groups/78514186083/

This thread on TB says Skyline 5s have always had graphite reinforcement bars (4s don't):

https://www.talkbass.com/threads/lakland-skyline-5s-are-graphite-reinforced.165673/

Skyline necks are flat-sawn though, not quarter-sawn.

Don't know about the Bob Glaub, but I have an early Lakland Skyline Jazz with Fralins. Sounds fabulous. I think they're standard wind as I'm generally not keen on the slightly darker sound of overwound pickups. 

EDIT - Just found the extract below on the Lakland site. Doesn't mention the wind, but it's all about old school tone so probably standard.

Bob Glaub and Lakland spent considerable time finding the right pickup. After many A/B tests, the team chose a Lindy Fralin split-coil humbucker that they connect to 250k volume and tone controls. Fralin rewinds a ton of vintage pickups, so it’s no surprise his single-coils and humbuckers have a wonderful Old School sound.

Speaking of tone, the BG sounds like a good P-Bass should: strong low-mids, a slight upper-midrange bite, and a taut top. The bass sounded way fat through an Ampeg SVT rig. A hi-fi setup brought out the instrument’s woodiness with even more low-mid definition. Like all time-tested P-Basses, the Glaub sits well in a variety of situations, both live and in the studio.

https://www.lakland.com/testimonials/review-of-skyline-44-64-vintage-p/

The stock pickups sound pretty good to me so I'd def try that before swapping them out. I love my TRB5 series 1 (been one of my mainstays for over 20 years now) but every so often I wish it had a regular mid control rather the 3-way switch. I'd be interested to hear how the stock pickups sound with the Uni Pre if you do decide to go down that route.

20 hours ago, hooky_lowdown said:

... you may need to adjust the pickup height though.

+1 If the strings are currently hitting your open pole pieces then they will certainly hit any top covering unless you lower them which will slightly reduce the output.

9 hours ago, PlungerModerno said:

Cool vid. I imagine if the pickup was a little farther from the strings the effect of being above or off the poles would be a lot more subtle, as the field will be more even farther from the poles.

Yes that's true. Lowering pickups can help to give a more even balance across the strings, but you also lose some punch and volume.

On 23/02/2021 at 23:37, WilliamV said:

Just how critical is it that the strings are directly over the poles on pickups?

It depends on the type of pickup poles. Pickups with a 'double pole' configuration (eg. standard Fender) give a fairly broad and even magnetic field so string alignment isn't that critical. Pickups with single poles are far mores sensitive to string alignment. See vid below - if you jump to 3m 40s he demonstrates the effect of sideways displacement of the pickup which is quite significant.

Yes, the saddles can be adjusted a little wider if needed. 

I had a Roxy B5 for a short while. Lovely bass and I would definitely have kept it were it not for a couple of small niggles that just didn't quite work for me. These were quite minor issues and I actually wish that I'd kept it! Here's my list of pro and cons:

Pros - Excellent build quality, great neck and fretwork (could easily dial in a low buzz-free setup), quality ETS bridge and hardware, loved the single Xtender pickup - much more versatile than you'd expect with series/parallel switching, excellent Glock preamp and active/passive switch, sounded fantastic and played superbly.

Cons - at 9lbs 7oz mine was a bit on the heavy side for me (I was hoping for closer to 9lbs but it was a distance purchase so took pot luck. I know some B5s are much closer to 9lbs), the body and headstock felt a bit chunky and no forearm contour, it felt a touch neck heavy.

This might help (see schematics in fourth post down) - https://forums.vintageguitarandbass.com/gibson-basses/eb0-wiring/

Here's a 14v adaptor on Amazon. 3amp rating is fine, your Backbeat will only take what it needs.

https://www.amazon.co.uk/ARyee-S19B300NW-S19B360BW-S22B360HW-S22A330BW/dp/B079M8R6Y2/