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Rickenbacker Forums->Setup And Technical->How difficult would a dummy coil mod be?
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How difficult would a dummy coil mod be? |
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cassius987
Shark
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Posted: 11/1/2009 3:41:00 PM
While I am not opposed to RWRP, I can't say I'd find it very useful because I really dislike running the two pickups together at full volume on my 4003 (I hate the comb filtering sound compared to the dominant/solo pickup sound, or the "cap-in" sound for some of us). However, the routs for each pickup on a 4003 are fairly generous. How hard would it be to put a dummy coil in parallel with each pickup? There's also the generous bridge routing, like for the foam mute, that could be used for a dummy coil. Has anyone tried this? I know I've seen pickups put in the foam mute cavity before, and 9 volt batteries next to the neck pickup for some active preamp users, so I figure that with some effort it could be doable...
Posts: 1831 Location: Denver, CO, USA Registered: 3/5/2007 10:33:00 AM
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iiipopes
Shark
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Posted: 11/1/2009 9:54:00 PM
The whole point of using a dummy coil would be to have it as far away from the strings as possible in order for it not to pick up any signal from the strings, but still pick up the 60 Hz hum from a source in opposite phase, cancelling it out of the signal coming out of the bass. But it's not a perfect solution, because the added coil changes the impedance of the entire circuit, and therefore the frequency response.
Posts: 2540 Location: Registered: 10/8/2006 4:07:00 PM
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BlueAngel
Shark
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Posted: 11/2/2009 1:46:00 AM
I think running the dummy coil in series is what you want - running it in parallel very heavily loads the real pickup because the impedance of the coil is very low.
In theory, if the coil is as non-inductive as possible - which it will be, if it doesn't have a magnetic core - it should only be as bad as adding a few Kohms of series resistance, which is no worse than backing off the volume control a fraction of a turn. If it has no magnetic core it will barely pick up the string signal either, so it won't matter if it's under the strings, although keeping it out of the magnetic field of the real pickup would be better. It still will change the tone a little - that's impossible to avoid in a passive system.
If you have a spare pickup of more or less any type, of approximately the same number of turns as a Rick pickup, that has a magnet and polepieces that can be removed without damaging the coil, you could try it. I'll see if I have anything suitable, and give it a go.
Posts: 2338 Location: Scotland Registered: 11/17/2005
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cassius987
Shark
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Posted: 11/2/2009 7:18:00 AM
quote: I think running the dummy coil in series is what you want - running it in parallel very heavily loads the real pickup because the impedance of the coil is very low.
I was thinking parallel to mimic the Jazz Bass setup. But you're suggesting it could also work in series, as in PICKUPLEAD>DUMMYLEAD>SWITCH?
Thanks for your thoughts guys. I'm not sure what kind of pickups to use, I didn't realize the pickups had to be so similar. I suppose if I came across some trashed Hi-Gains it may be worth a shot.
Posts: 1831 Location: Denver, CO, USA Registered: 3/5/2007 10:33:00 AM
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BlueAngel
Shark
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Posted: 11/2/2009 8:02:00 AM
quote:I was thinking parallel to mimic the Jazz Bass setup. This works because the second coil is a real pickup, and hence adds signal as well - but even then, each coil heavily loads the other, which is the main reason you get a drop in output when both are at equal volumes (the comb filtering changes the tone more than the volume). If you combine a real pickup in parallel with a dummy coil, the dummy doesn't add any signal so it simply loads down the real coil, not much differently to just adding a plain resistance of the same value across the signal path - usually around 10K which is much lower than a normal passive pickup can deal with.
quote:But you're suggesting it could also work in series, as in PICKUPLEAD>DUMMYLEAD>SWITCH? Yes, exactly - connect the dummy coil in series either between the pickup hot lead and the switch, or between the pickup ground lead and the actual ground - which may reduce the potential for buzz, although I'm not sure. You can do it at the pickup end of the cable if you want to put the dummy coil in the pickup cavity. The coil needs to be the opposite winding direction from the real pickup - if you can't easily tell which that is, try it both ways and see which works.
quote:I didn't realize the pickups had to be so similar. I suppose if I came across some trashed Hi-Gains it may be worth a shot. They don't have to be that similar, it's just that the hum cancellation will be most effective if both the real pickup and the dummy have exactly the same number of turns, and less effective the further you move away from that. Using roughly the same coil dimensions may matter too, but most pickups are at least approximately similar.
Suhr's 'silent backplate' system for Strats uses a completely different shape of coil - very wide and flat, mounted in the vibrato spring cavity cover - and seems to work.
Posts: 2338 Location: Scotland Registered: 11/17/2005
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cassius987
Shark
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Posted: 11/2/2009 4:50:00 PM
I wonder if SKU 03604 (BASE PICKUP COIL) in the boutique is what I'm after? For only $6.00 it might be worth a shot.
Posts: 1831 Location: Denver, CO, USA Registered: 3/5/2007 10:33:00 AM
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BlueAngel
Shark
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Posted: 11/3/2009 12:04:00 AM
quote:I wonder if SKU 03604 (BASE PICKUP COIL) in the boutique is what I'm after? For only $6.00 it might be worth a shot. Hard to tell without a pic, but I think that's the large flat plastic baseplate that the coil mounts on and the height screws go into - I can't believe the pickup coil itself would be that cheap.
I had a look at mine, and you're going to need something a little narrower (for the neck pickup) and much flatter (for the bridge pickup) to get them into the same cavities. A cut-down Jazz Bass pickup definitely does fit in the mute cavity though, and if you get a US Standard-type one with the plastic bobbin, you can push the magnets out without damaging the coil.
Posts: 2338 Location: Scotland Registered: 11/17/2005
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cjj
Shark
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Posted: 11/3/2009 7:00:00 AM
quote:quote:I wonder if SKU 03604 (BASE PICKUP COIL) in the boutique is what I'm after? For only $6.00 it might be worth a shot. Hard to tell without a pic, but I think that's the large flat plastic baseplate that the coil mounts on and the height screws go into -
Yeah, it's just the plate, no coil...
Posts: 663 Location: N. Montana, next door to the middle of nowhere... Registered: 1/16/2008 1:58:00 PM
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cassius987
Shark
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Posted: 11/6/2009 11:38:00 AM
Hrm. So a cut-down J pup in the bridge rout and then what would fit in the neck pickup region? If it's as small as a 9 volt battery I know I've seen that made to work before, without routing...
I just experienced the worse hum in my life the other night: I was giving my 2007 bass a full setup and my wife complained that I was being too distant and paying to much attention to my "other wife" so I took everything into the living room so we could talk while I did my setup. Well, we're all about CFLs in every room except for the room I normally do my work. I checked pickup output after a bit and WHOA. Now that was hum worse than anything I've ever heard--it wasn't even the pleasant, steady 60 Hz variety. It definitely outdid any neon signs in any bars I have played. Ironically because there were so many lightbulbs on the bass had only one orientation that was hum free and I would have had to have been in an anti-gravity chamber to play in that position.
In truth, I rarely encounter problems with hum--especially in a live music setting. But noticing that every now and then it can get bad, combined with my distaste for the comb-filtered sound, has really gotten my juices flowing on this project, especially for my 2007 which I want to maintain its Hi-Gain pickups for that unique crystalline tone.
Posts: 1831 Location: Denver, CO, USA Registered: 3/5/2007 10:33:00 AM
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BlueAngel
Shark
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Posted: 11/7/2009 3:55:00 AM
I actually think another cut-down Jazz coil might fit in the neck pickup cavity, alongside the pickup. The cavity is big enough to support both the 1" and 1/2" spacings (with a tiny amount of routing, to the body wings not the neck section for the 1/2" position) and a Jazz coil is only about 1/2" wide, so it should go.
Posts: 2338 Location: Scotland Registered: 11/17/2005
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cassius987
Shark
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Posted: 11/7/2009 1:02:00 PM
Maybe I could just contact someone like Lindy Fralin and have him make me the dummy coils to my specs? That might be easier than choosing the right kind of pickups from the huge list of J Bass pickup options...
Posts: 1831 Location: Denver, CO, USA Registered: 3/5/2007 10:33:00 AM
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JohnHall
RIC CEO
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Posted: 11/7/2009 2:53:00 PM
quote:I wonder if SKU 03604 (BASE PICKUP COIL) in the boutique is what I'm after? For only $6.00 it might be worth a shot. It's not a coil, just the mounting plate. The description omits commas; if it was BASE, PICKUP COIL, it might make more sense.
FYI, we've never had any success with dummy coils, though we've tried them in many configurations. If it really was that simple, we'd have done it already.
Posts: 3053 Location: Santa Ana, CA Registered: 8/9/2005
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BlueAngel
Shark
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Posted: 11/8/2009 2:55:00 AM
quote:FYI, we've never had any success with dummy coils, though we've tried them in many configurations. If it really was that simple, we'd have done it already. Did some of the 50s Combo models use them? I'm sure I read that somewhere - or was it a type of humbucking pickup? I've never actually seen any of those guitars personally.
I know getting a dummy coil to work is not simple - I've heard the Suhr 'silent backplate system' for Strats, and (despite what's claimed) it most certainly does change the tone, and in a way I don't like. But I can see that for some players and situations it would be an acceptable compromise. I don't really like stacked humbuckers either, but I also know that some players like them, even if they don't sound exactly like a single coil (which they don't).
quote:Maybe I could just contact someone like Lindy Fralin and have him make me the dummy coils to my specs? That might be easier than choosing the right kind of pickups from the huge list of J Bass pickup options...
Another coil that might fit in the pickup cavities in a 4003 is one coil from any guitar humbucker - they have removable polepieces. Even something very cheap will work - the tone quality of the pickup is irrelevant as long as it has about the right number of turns, which a high-wound humbucker might have. Just go into any guitar shop and ask for a scrap cheap humbucker, as hot as possible - most techs will have junk like that that's been taken out of guitars. I should have something lying around I can try too.
Posts: 2338 Location: Scotland Registered: 11/17/2005
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ricslinger
Shark
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Posted: 11/8/2009 8:52:00 AM
There was a Combo 800 in the '50s that used what Rick called a "multiple unit" pickup,which was an early humbucker design.
Posts: 778 Location: Reno,Nevada Registered: 2/10/2007 10:08:00 PM
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cassius987
Shark
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Posted: 11/8/2009 10:52:00 AM
quote:FYI, we've never had any success with dummy coils, though we've tried them in many configurations. If it really was that simple, we'd have done it already.
That's unfortunate. I want to keep this bass with its stock Hi-Gains (although HB-1s truly are great sounding... just played another 4004 and was very pleased), but the hum is something I'd really like to tell to go buck off. ;)
Posts: 1831 Location: Denver, CO, USA Registered: 3/5/2007 10:33:00 AM
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basmansam
Mackerel
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Posted: 11/9/2009 5:18:00 PM
quote:quote:I wonder if SKU 03604 (BASE PICKUP COIL) in the boutique is what I'm after? For only $6.00 it might be worth a shot. It's not a coil, just the mounting plate. The description omits commas; if it was BASE, PICKUP COIL, it might make more sense.
FYI, we've never had any success with dummy coils, though we've tried them in many configurations. If it really was that simple, we'd have done it already.
Maybe the description should read: "Treble P-up base plate or Treble P-up mounting plate".
I really thought it was just a pick up coil not a base plate.
Posts: 20 Location: Vermont Registered: 9/10/2005
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