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Ibanez Musician Bass Club

Discussion in 'Basses [BG]' started by AphekGreg, Apr 14, 2016.


  1. Yes, power and whatever else is around makes a difference. Power in Australia is generally very good too.

    In my studio, I get almost no hum (assuming I'm not near an amp or other power supply). My original studio in Sydney was noisier. I used to regularly use a Rocktron HUSH unit when recording guitars particularly, to minimise hum and RF noise. I picked up a second unit while building the current studio and have rarely needed either one.

    There is one place I play, where I can't use a stock Super 4 equipped Musician, as the hum is so bad. Nobody can work out where it's coming from either.
     
    Jan-Arend Blok likes this.
  2. Hi all. I've got an '80 on the bench. It's my mate's first bass I believe. Original pre long gone. Needs rewiring with Agi 3, and a bit of other work.

    I presume these are the original pickups. They are epoxy potted and they hum pretty badly so I assume they are singles. The thing is though, they are both the same magnetic polarity, so they don't even hum cancel with both on. Is that normal? Has anyone tried remagnetising one so they hum-cancel as a pair like a jazz bass? I could do this, but I'd have to strip the epoxy as far as the bottom of the magnets so recharge them properly.

    Has anyone around here removed the potting? Are they just straight-ahead 4-magnet alnico singles? Or is there a ceramic mag in there instead?

    Cheers.
     
  3. Abner

    Abner

    Jan 2, 2011
    Mississauga
    @AphekGreg probably has the most experience with pickups in this thread. Back on Page 13, maybe even earlier. I believe he did sacrifice a Super 4 at one time, removing the epoxy, but really no way to do it without destroying the winding. Couldn't find the actual post with pics of that, but might be somewhere back there. And he did rebuild one with reverse polarity for hum cancelling. (Maybe we should get him to make one for all of us.) ;)
     
  4. I am working on being able to make them for everybody! Just waiting for the covers. I should have another split single Super 4 done today, that will hopefully sound close to the stock pickup, without the hum. I want to be able to use them individually, not just together, without the hum.

    Nice first bass. Don't attempt to remove the epoxy from the pickup. It's nearly impossible and while noisy, the stock pickups sound great. Reversing the magnetic polarity, would just make them out of phase. One needs to be reverse polarity/reverse wind. Try further shielding the pickup cavities. That will significantly reduce the RF noise. There are already aluminium plates under the pickups. Use copper shielding tape to extend that up the sides of the cavities. Use a multimeter to check all the shielding is connecting? The foil sometime becomes loose, after 40 years and doesn't contact well.

    They use slug magnets. I wasn't able to work out what they were made of, but think they may have been ceramic, which is unusual, I know. The one I pulled apart, wasn't working properly, which is why I sacrificed it. It was a '79 and used different metal to the later ones. The others are a dull grey.

    What year is the bass? If you look at the serial number, the letter is the month (A-L) and the first two number are the year ('79-'81).

    100_2324.jpg

    100_2335.jpg

    100_2349.jpg

    100_2339.jpg
     
    Abner likes this.
  5. It's an '80. I wasn't planning to remove the whole pickup. I was just thinking about removing enough epoxy to expose the bottom of the poles so I could reverse their polarity. From the top, the poles certainly look like alnico, but I wanted to make sure there wasn't a ceramic bar lurking in there. Don't worry, I was planning to reverse the wires to return the signal phase. I've done this before, many times. It is common for 70s and 80s japanese stuff to be like this with all the same polarity pickups.

    Thanks for your reply and pics. I have removed epoxy potted pickups from their covers in the past. In my case, the pickup survived, but the cover didn't. I used boiling water and a scalpel. Epoxy is like rubber at 100c. Unfortunately, so is abs plastic, lol!...
     
    Abner likes this.
  6. Abner

    Abner

    Jan 2, 2011
    Mississauga
    A split coil Super 4? Interesting... very interesting...

    Would that be a Super 2+2?
     
  7. Keep us informed. Interested to see how you go. In this case, the cover is the thing I most want to keep. I can remake the pickup, but not the cover.
     
  8. It would be. Same idea as a P-bass, except the coils are side by side, rather than staggered. I just tested the one I made today and compared it to the clip of the MC30TH with Super 4s and I’m really happy. Almost indistinguishable! I was thinking of keeping the better sounding stock humbucking pickup in the bridge and having this in the neck, but this sounds so good, I need one for the bridge too. I need to contact my mate and see how he’s doing copying the cover?

    I was looking at the Ibanez parts on reproguitarparts.com the other day and found these covers. Was quite excited for a while, until I measured a Super 4 and realised they weren’t quite wide enough. Repro Guitar Parts
     
    Abner likes this.
  9. Abner

    Abner

    Jan 2, 2011
    Mississauga
    I like where this is going...
     
  10. Me too. I liked the pickup so much, I've built another. I was going to wait until I had plastic covers made, but this sounded too good. I disassembled the one I've had in the bridge of the MC30TH for a few years, as I didn't want to make another cover (that's the hard part). After removing the wire from the pickup robin, I drilled extra spin holes and cut it in half (as it fits the cover). Just wax potting it now, so it will be ready later tonight.

    The two halves are still separate to each other. I used to super glue them back together, but realised it's easier to work with the extra wriggle room.
    Split Super 4 1.jpg
    Split Super 4 2.jpg
     
    DanAdams, Abner and kablag like this.
  11. OK, so hopefully you'll listen to this clip and wonder why they sound the same!!! :hyper: That's the aim anyway. :cool: Here are the same clips I was using recorded with an original Super 4 in the neck position and my reverse wind/polarity version in the bridge - compared to my new hum cancelling versions. Both sets installed in the MC30TH, recorded with preamp off and no processing.

    I think they sound pretty close. The new recording sounds slightly fatter and a little more dull. Hard to know how much is the pickups, variations in my playing or the strings getting duller?

     
  12. From 45 sec, they sound brighter to me.

    I'd look into 3D printing. But you'd probably have to get it done professionally if you don't want to do a fair bit of finishing/polishing. If you know any industrial design students, you could get it scanned and modeled for a carton I reckon... Having said that, the timber covers look great!

    Yeah, I had to replace some of it.
    20200212_142215.jpg

    I spoke to the owner, and he said he doesn't mind a little hum, plus he favours the neck pickup usually, so reversing the mags on one pickup seems to much effort/risk.

    So I went ahead and shielded the pickup route walls just to make it as quiet as possible.

    20200212_144848.jpg

    While I had the pickups out, I did some testing.

    20200212_153456.jpg

    Both pickups are very close in spec. I'd say they are essentially the same pickup. The differences being normal manufacturing variances.

    20200212_150751.jpg
    They have a resistance of 12.8k ohms, a resonant frequency of 4khz, an inductance of 4.25H, and a stray capacitance of 360pF.

    That seems quite a bit of capacitance for a single coil like this. I'm guessing they were machine guided, not scatter wound. Or perhaps the winding wire is slightly thicker than standard and there's a lot of turns on there for this resistance...
     
    Abner likes this.
  13. Janforth

    Janforth Father of Chritobin Madden Challenge 19 Champion Supporting Member

    Oct 23, 2009
    Florida
    Side question please (sorry if this has been covered before), I have '84 mc940 and mc924 models with the super p5s and super j5s pickups, are they wired series or parallel, and what are the passive pots (vol/blend/tone) values?
     
    Last edited: Feb 12, 2020 at 10:36 AM
  14. They are wired in parallel. The pots are all 500k.
    Ibanez MC924-940 (1982) wiring.jpg
     
    Janforth likes this.
  15. A mate of mine, who runs a 3D printing business, is attempting to reproduce the covers for me. The wooden ones are fine. Just a fiddly to make (at least for me). There is something about the old brown plastic, that I love. Probably just that it's the way that model is supposed to look. :)

    I measured the wire when I pulled apart that pickup and it appears to be 43AWG. Hard to be accurate in measurement when it's that small, but it definitely isn't thicker. They are still a bit of a mystery to me.
     
  16. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    Maine
    I think the wood covers are great. I would like those better as they allow for a thumb rest. maybe a darker stain would look more slick.
     
  17. I just added a thumb rest to my '80, as there is a massive gap between the pickups. It's just a stick on rubber foot, so can be removed without damaging the finish. I originally used one when I had a Steinberger and had it between the pickups, for more of a Stingray picking position. I currently have one on my Stingray, so I can rest my thumb where a neck pickup would be. Works well and is very cheap.
    100_7902.jpg

    My problem might be that I made the covers myself, so aren't as impressed. I put an original Super 4 in my MC30TH a few months ago, wanting to see how it compared to the one I made and been using for a few years. It just looked right, when I installed it.

    The stock pickups that came with the MC30TH look a lot better to me, although I still prefer the originals (looks and sound). I would never have thought of making a cover out of wood, if I hadn't seen these though.
    100_7900.jpg
     
    Domespeed likes this.
  18. Abner

    Abner

    Jan 2, 2011
    Mississauga
    I support you efforts to make original-style plastic or Bakelite covers. For some reason, pickup covers, knobs, control plate covers, pickguards (if you really must have one)... these things just never look right to me when made out of wood, no matter how much skill and artistry goes into their design and construction.

    Hey, how about some chrome or gold-plated covers?
     
    hypercarrots and AphekGreg like this.
  19. And my level of skill and artistry is fairly minimal. :D

    Not sure about chrome or gold plated covers? I think it might be too much bling. Nice for shielding the pickup though.
     
  20. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    Maine

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