What to do with a Rickenbacker (reprise)

[ashcatlt]

I know I've got another thread about this way back, but I've got a new take on it, so I'm starting over.

As some of you may be aware, I'm not a big fan of potentiometers. Just don't really ever use the things. On two of my guitars, all the pots have been replaced by rotary switches. I intend to do the same with the Rickenbacker. At the same time, I'm going to get rid of the floppy old toggle switch as well. So, I've got a total of 6 holes to fill!

The following picture is just a conceptual drawing. It shows the function of the switching modules pretty much the way they will appear on the pickguard - looking down from the outside.

I'm pretty sure I can figure out the wiring for each of these modules, and string them together, but I've got a couple concerns.

For some irrational reason, I'm a big fan of the DP5T rotaries that I've been getting from Mouser. I've used them on 3 guitars and a couple pedals. I've got a couple in my parts bin. It's real easy to just go drop a handful in the cart, and I know exactly what I'm getting. I'd really rather not have to go to any more poles, since the switches start to get bigger. The Rick's got a lot of space in the cavity, but I still worry about fitment.

That said, I'm pretty sure I'll need at least 4 poles on the Mode switch in order to accomplish both S/P and phase reversal. Is there any way we can get this down to no more than 3 poles?

I need a refresher on the implications (and applications) of individual volume controls in a series config. I remember there being issues. I also remember somebody had figured a way to use the S/P switch to change the function of one of the volumes in series mode. I'm afraid this requires a whole pole on the switch, though. If I end up with more than 4 poles, I don't think it's going to happen. Just gonna have to live without it.

The numbers on the V and T controls indicate approximate knob positions, and are really just placeholders. Actual resistance numbers will have to come from experimentation.

On the Neck Tone, I labeled the bottom position as "Woman", but upon reviewing the whole "woman tone" thing, I notice that this (properly implemented) would have less treble cut than the standard cap. I guess I always thought it was the other way around. So this should be labeled "Alt Cap" or something, with a bigger cap value here for an even deeper than standard treble cut. I think I want the standard capacitor (the 0 position) to be the same as normal for a Rick. The other will be determined by experimentation.

You may be wondering "What the heck is a Strangle switch?" The term comes from slang used in Jaguar circles. Some older Rick models apparently had the Bridge pickup permanently run through a capacitor (in series) for a sort of bass cut. I thought it would be nice to get this now and then. While pondering this, I realized that it would affect both pickups in the series modes. So I decided that I could have it bypass the neck coil in the series modes. This will end up in parallel with the neck's tone control, providing quite a range of Half-Parallel/Broadbucker tones. But then I thought that I might want sometimes to strangle both pickups, so I don't want to wire it across the neck coil permanently.

I think I know how to wire this in such a way that it acts the same in the OoP positions as otherwise. Of course, the OoP positions are pretty well strangled to begin with. I had the thought that I might be able to get a "Half OoP" thing happening if I wired it cleverly. Can't get my head around how to do that just yet, though. If it needs another pole, I can live without it.

Anybody ideas, questions, comments on any of this?

[newey]

I'm not clear on this "strangle" switch. I presume "off" means no capacitor is engaged on either pickup. "Parallel" "strangles" both pickups with some cap, and "series" puts the cap only on the bridge, bypassing the neck?

Just mentally laying it out, the rotaries for T and V would be wired across each pickup, and then on to the mode switch. Not clear on where the strangle switch fits into the mix.

Also, depending on the capacitor values, won't the strangle switch replicate, more or less, one or another of the positions on your "hard-wired" tone controls? I realize the benefit of a single switch operation to get a particular sound; I'm just not sure you'll really be adding different tones to what's already there.

I don't recall the original thread, but if this is some sort of vintage Ric, I hope you're at least going to save the stock wiring harness intact!

[ashcatlt]

It's from the mid 90s, and pretty beaten up, but I do intend to keep the original parts as intact as possible.

The Strangle switch is the opposite of the tone control. It's a high pass, or low cut. I thought about including it's function on the bridge tone control, but realized I could get some band pass and/or notch action if I had them seperate. It is somewhat redundant with the neck tone when wired across the neck pickup, but it really will just give me more variations of the "half-parallel" thing. I guess I intend Series and Parallel the opposite of what you figured. It's either in Series with both pups or Parallel to one of them. Doesn't much matter either way, though. I haven't really decide what the most logical switching order is.

[ashcatlt]

Alright, I didn't get much feedback on wiring ideas here, so I went ahead and drew it up as best I could. This is my first attempt at a more or less pure schematic format, so I hope it comes out okay. The mode switch, at least, does a couple different things, and it seemed like it would be easier to follow the logic this way, rather than in a wiring diagram.

Things kind of started to get blurry toward the end of the drawing process, so I'd appreciate it if somebody could make sure I didn't mess up too badly. I've got some stuff to talk about here, but I'm going to stop typing for the same reason...

Will it work?


SW1 - Mode
Off
Parallel
Series
POoP
SOoP
SW2 - Bass Tone
No Load
10
6
0
0 (Alt Cap)
SW3 - Treble Tone
No Load
10
7
3
0
SW4 - Bass Volume and SW5 - Treble Volume
No Load
10
7
3
0
SW 6 - Strangle
Off (Bypassed)
Series
(Half) Parallel

[newey]

Ash-

I didn't have a chance to check all of this, or even most of it. SW1 looks ok.

On your original "control diagram", you have "Bass T", position 4, indicated as "off". The "bass" pickup obviously translates to the neck pickup on your schematic, and SW2 is the neck tone control.

I don't see where position 4 on SW2 is "off", nor do I understand why you would want the neck pickup off anywhere on that switch, since the "Bass V", position 5, is also "off".

I assume that you either changed your mind on that at some point, or that the "off" as originally specified was a mistake on the control diagram.

BTW, it would help in checking your diagram if you had a truth table with it, as it's difficult to have to scroll back up to look at the control diagram to see what each position is supposed to represent, then back down to the schematic, etc.

[ashcatlt]

May 6, 2010 7:44:32 GMT -5 newey said:

On your original "control diagram", you have "Bass T", position 4, indicated as "off". The "bass" pickup obviously translates to the neck pickup on your schematic, and SW2 is the neck tone control.

I don't see where position 4 on SW2 is "off", nor do I understand why you would want the neck pickup off anywhere on that switch, since the "Bass V", position 5, is also "off".

Thanks.

Yeah, it was supposed to say "0". I hope you don't mind, but I just changed it in place, rather than posting a whole new version.

While I was at it, and since nobody has commented on that part yet, I went ahead and replaced the schematic with one where the Strangle switch actually works as intended. I thought I could save a pole by using two caps, but it turns out I need the extra pole and the extra cap.

I'm going to edit the post with the schematic to include a truth table as you suggested.

[newey]

I hope you don't mind, but I just changed it in place, rather than posting a whole new version.

That's fine, but I don't see where you have changed it, it still reads "off" on the control diagram.

I hadn't got to the strangle switch yet, I only got up to SW3. Off to work now, I'll look at it in more detail this evening.

We've had discussions of "hard-wired" V and T controls, but I don't recall anyone actually building such a scheme, so this is interesting and I'm curious if it'll work to your liking.

[ashcatlt]

Darn! I'm sure I uploaded the new image. I'll have to double check.

Just noticed that the V's are wrong. I know how to fix it, but it'll have to wait till after naptime.

[ashcatlt]

newey - I don't know what you are seeing now, or what I was seeing then, but I'm seeing the top image fixed without having to do anything more.

I fixed the Volume controls, and changed it in place again. I guess that updating things this way kind of makes most of the thread meaningless.

In case anybody's wondering what was wrong with the V's, here's how they were drawn before:

This is a variable resistance to ground - a Tone control. The original has been updated with actual voltage dividers.

[newey]

Ash-

That might have been an issue on my end, I've had a few gremlins lately. It's all correct now.

I didn't see any issues with your diagram up to SW 6, the Strangle switch. I can't wrap my head around how that will effect a bass cut.

I'm not saying there's a problem with your wiring; I just don't (yet) understand the circuit. Gotta go stare at it some more.

I know we've discussed a bass cut control in the past, I should go back and look at that again.

[ashcatlt]

I tried to record a test clip of what the strangle switch might sound like, but ran into a number of issues.

Some I think may have been internal to the guitar's wiring. This wiring harness that you've asked me to keep intact has been flaky since shortly after I brought it home.

Others had to do with my "recording rig". I keep most of my crap in my bassist's basement. Since I didn't go drag that stuff over here, I was left with my "home rig" which consists of an ancient - and apparently possessed - SansAmp GT2 connected via even more ancient RadioShaft cables to the line input on my recording computer.

Anyway, I don't currently have resistors to replace the pots. I suspect that these components (and the order in which they come relative to the Strangle cap) will affect the output. When I tried to connect it with the original pots in place, though, I couldn't get a consistent signal out of it.

Even after I clipped the pickup free of the rest of the wiring, and eventually removed the SansAmp (it breaks into self-oscillation on occasion, for no good reason), I couldn't get anything without a whole lot of noise! Nothing I'd want to inflict on y'all.

I did get it to work well enough to where I could hear - and see on the spectrum analyzer - that there was a noticeable effect. By now, it was without the other controls, and there was a BIG reduction in low frequency response. I think it's going to be a lot fun. A "special effect" kind of thing for sure, but if you've heard my music...

The schematic from the Rick site specifies the cap at .0047. Doesn't give units, but I have to assume they'd be the same as the unitless tone caps which are listed as .047 which has to be uF, right? I didn't have anything close, but I did have 5 x 1000pF caps, which I wired in parallel and figure is close enough.

While I was clipping leads, I went ahead and cut the neck pickup free as well, and since they were loose I went ahead and tried the series combination. This is going to be monstrous!

Really wish I could have posted some sound clips, but I'm making progress. It's going to be very difficult to determine proper resistor and cap values unless I can get a bit better sound quality in my tests. Maybe I'll bring home my V-Amp and a couple cables tonight.

[flateric]

Rickenbacker Int'l Corp. is pleased to introduce the Vintage Tone Selector for 4003 Series basses. This additional control is included standard at no additional cost on all 4003 basses beginning in the 2006 model year.

Prior to 1984, Rickenbacker basses utilized a capacitor in the treble pickup circuit to emphasize treble tones coming from that pickup. However, changes in tone preference and a call for higher output led RIC to discontinue the use of this capacitor in favor of a more balanced sound. Nevertheless many users added this capacitor back into the circuit, experimenting with and sometimes preferring the sound of the older configuration, despite the resulting drop in volume.

Yes the 'vintage tone cap' is 4.7nF, so you're close as need be with your 5 x 1000pF parallel caps.

"We have now decided to give our players a choice, allowing the best of both worlds. With a simple pull of the treble tone control, the Vintage Tone Selector will allow a player to move between both sounds at the drop of a hat. Pressed in, you'll hear the familiar balanced tone of the 4003, while pulled out to engage the circuit, you'll appreciate the bite and crispness popularized by such artists as Chris Squire."

I also heard they did this cos the old speaker cabs of the '60's couldn't handle the bass frequencies at higher volume so they had to put in a bass cut switch to avoid wrecking the cabs. One mans bass cut is anothers high biting treble. For me this switch makes them sound dreadfully thin.

[ashcatlt]

Took some measurements here today, and came across a bit of a conundrum.

Before I get into the meat of that matter, I’ll just mention that I was pretty surprised by my readings across the pickups. The Neck came out somewhere right around 14KΩ, with the Bridge right around 12K. That’s about what I get out of the Bridge HB on my strat, hotter than the SD’s on my LP! Also interesting that the Bridge pickup is wound lighter than the Neck. Usually it goes the other way.

Anyway, the schematic linked above specifies 330K for all of the pots save the Mixer, which sits at 500K. RickResource says that the older guitars would have had 500K Tone and Mixer pots, with 250K Volumes. It goes on to say that the Tones and Mixer have more recently been changed to 250K to match the Volumes. I’d assume that mine is new enough to have 250K’s all around, but…

The Tones each measure very close to 450K. Cool, that’s just 10% short of 500K. The other three – both V’s and the M – come out very close to 185K – 26% short of 250K! Even more peculiar is the fact that these are all so close to matching – like w/in 1K of each other. I’d expect that if they were just randomly grabbing pots from the bin, they’d end up with a much larger variation between them.

I had the intention to set it up so that when the V’s and T’s were set to “10” it would be exactly the way I’ve always known it, but now I’m just scratching my head. 185K is a bit lower than what we normally use for strat-style singles which usually have significantly lower internal resistance. The parallel combination of the Mixer with the Neck V sits at 97.5K, which is extremely low. I’ve never noticed any major lack of treble in this guitar (when it works). So, like, !

Yes, I have measured these pots out of circuit. The pickups were already snipped loose, and I cut the Neck V loose today in order to confirm my readings. Once this is removed, they’re all pretty much independent.


BTW – You might be wondering why I’m talking about the Mixer here, since it’s not involved in my scheme. In the effort of making this as similar as possible to the unmodded version, I was thinking about hanging a resistor of value equal to the Mixer pot in parallel with the Neck Volume.

On a slightly different note, I’m kind of thinking about going for something more like 10-8-5 or so for the Volume stops. I expect these things to be used mostly in the No Load, 10, or 0 positions, and will likely only use the other positions for blending the pickups. I’m kind of thinking that anything under 5 is going to make that pickup pretty much meaningless in combination.

[newey]

Those pot values are a bit of a conundrum, unless their supplier was supplying pots with a +/- 30% tolerance! Are you sure these are original?

In any event, if you want to replicate the original sound, you'll have to work with those values.

On a slightly different note, I’m kind of thinking about going for something more like 10-8-5 or so for the Volume stops. I expect these things to be used mostly in the No Load, 10, or 0 positions, and will likely only use the other positions for blending the pickups. I’m kind of thinking that anything under 5 is going to make that pickup pretty much meaningless in combination.

Agreed. The "3" setting will probably not mean much, in any combo of the pickups.

[JohnH]

Hi Ash - just having a first look through your thread. I've often thought that using rotary switches is a great idea to replace pots, so you can set sounds very consistently, and have any 'taper'you like as you turn it down, also bringing in caps as well as resistors, or changing the way the control connects to other parts.

I agree that the mode switch inherently needs 4 poles, basicly two to do S/P and two to do phase reverse. I also like the rotary switches from Mouser, and have had a couple of 4P5Ts in this guitar for the last 4 years, and they continue to be very reliable. Concerning their depth, I just measured a spare one and they are 29mm from face (ie at back of pick guard) to back of rear solder lugs.

Since you are up for a two layer switch anyway, how about putting all the pickup selections on it and have it do B. N. B+N, B-N, B*N, B*-N (in whatever order)? that's a 4P6T - same overall size. Or drop the poop setting and have 5 positions.

cheers

John

[ashcatlt]

Well thanks for stopping by John.

I appreciate your suggestion, but I think I'm pretty happy with what I've got here. As is, I can get all of those combos by using the Volume controls. I've got it bypassing the BV control in series mode, which means I can't get to N only from there, but it also means that there will be a bit less loading in this already darker than normal setting.

I did a little more research re: the pot values and came across a thread on the RickResource forum. There was a reference to "250K(200K)" pots, and a couple folks reported measured values in the 185K region. This is less than 10% short of 200K, so... There was also a post from what appeared to be a Rick employee saying that they have used the 330K pots for "at least a decade". This from a post in 2006. Mine is a bit older than that. It had been hanging on the wall for a couple years, I think, before I took it home early in '94. (I worked at the store, and got to rub it with lemon oil, tune it, and play it every couple days for 6 months. Ended up getting it for Cost+5% on a sort of "rent to own" plan) I'm more than sure that the pots are stock, so I guess I'll go with these values.

In another thread, I came across information that these pickups have a very low inductance thanks to very small gauge wire used in the coils. Goes to show that DC resistance tells us close to nothing about any pickup.

I've almost got my Mouser order together. The Alpha switches I'm looking at don't come in a DP3T config, but they do have a 3P3T on a single deck. I hate to waste a pole, but can't think of anything fancy to do with it, so...

Now to consult some log tables and figure those resistor values.


BTW - Couple interesting Rick trivia items:

1) The warranty is voided by using any strings other than Rickenbacker brand.

2) You can't get a replacement for the "R" tailpiece unless you turn in at least half of your old one!

Oh! And I need to find knobs. I've only got 3 of the originals left. That's fine for pots, but I've found these switches to be impossible to turn by hand. I'd like to put a Mixer knob on the mode switch. Partly for the sake of symmetry and partly because the others are generally labeled. A place called MusicZoo has them for a reasonable price, but say they ship in 3-4 wks, which leads me to believe they don't actually have any in stock. Straight from Rick they're about the same price, but I don't think they take PayPal. Luckily, I've proven previously that the Rick knobs fit perfectly the switch shafts, which are slightly bigger than standard split shaft pots.

[newey]

Off the top of my head, wouldn't a 250K pot in parallel with a 500K give approx 330K anyway? So if they replaced all the pots with 330K should work out the same pretty much, No?

I see Ric knobs occasionally on Ebay, might be worth a look.

[ashcatlt]

newey, I think you'd ought to try that again. The average between 250 and 500 is somewhere around 330, yes, but that ain't the same as figuring parallel resistance.

The total resistance of two (or more) resistors in parallel can never be greater than the lowest value resistor.

Since 330 > 250, you've got to be mistaken.

[flateric]

I was also under the impression that stock ric pots were 330k, just to be quirky.
Another bit of trivia - the rickenbacker truss rod cover, you cannot order one as a spare or replacecment unless you return the original one to them first. Ho hum.
basschat.co.uk/index.php?s=&showtopic=36229&view=findpost&p=409492

[ashcatlt]

After rethunkin myself, I had to reread what newey wrote to make sure.

Turns out that 250||500 = 166.66... is very close to 330||330=165.* Close enough for government work, as they say. With both V and T at 10 it's pretty much equivalent, I think. The difference will come when twiddling the knobs.


The truss rod cover has the same rules as the "R" tailpiece. You have to return at least half of it. Apparently this is a form of counter-counterfeiting protection.


* That ain't what newey said, btw. Maybe what he meant, but I think it's important to make the distinction for the sake of any noobs that might come around.

[newey]

* That ain't what newey said, btw. Maybe what he meant, but I think it's important to make the distinction for the sake of any noobs that might come around.

No, it isn't what I said, and Ash is right (per Ohm's law).

I was just thinking it all somehow averaged out the same- but inarticulately stated by me, as well as not calculated, either!

[ashcatlt]

So, the diagram in Reply #3 has been up for 17 days now, and I didn't figure out that it contains a pretty major error until I soldered everything and started to test the resistances is various switch positions.

I don't know whether to be flattered that ya'll think I know enough about what I'm doing that you assumed I wouldn't need a double check or to be disappointed that nobody caught it before now. Newey, you specifically signed off and said that Switch 1 looked good.

Well, on review it's pretty obvious that the series/parallel switching is synchronous with the phase switching. Both parallel options are in phase and both series are out.

Now, I never would have figured that out from simple resistance measurements like I was running except for the second problem I encountered. See, I thought that I would be smart and wire it in such a way that I could unplug the controls (attached to the control cover/pickguard) from the parts which are more permanently attached to the guitar (pickups, bridge, jack). Of course, I neglected to include any of the parts necessary for this in my mouser order.

I've got a couple of pin header type deals, but they are slated for another project, and a bit bigger than what I wanted inside the guitar. What I do have is a surplus of 8-pin IC sockets. Something like this:

They socket together with a very satisfying click.

I'm using tiny little wires anyway, so I tried to very carefully wrap and solder my wires around the fat part of the pins right where they come out from below the socket. You can kind of see that part in the pic above. I thought I had done a good job, and ran continuity tests to make sure that there wasn't any bridging going on between the pins. These things are very small, and with the lighting in my place I just couldn't see in there to tell for sure. Well, I thought everything was fine.

Until I buttoned it up and started running the measurements. It looked like the parallel modes were fine. They came out about 6.xxKΩ, about half of one coil. But the series modes were coming out closer to 12-13K - about half what I should get from two coils in series, as though only one was coming through.

So I opened it back up and started running continuity tests. This is when I found out about the phase thing. Fixed that and was still getting strange readings. The bridge pickup was shorted out in the series positions, and it seems like (at least sometimes) the whole guitar was shorted in the SoOP position.

I traced out the wiring again and again, and just couldn't find anywhere in the switching where this was happening. It was like 03:00 and I was running low on beer and I decided to just snap the "to jack sleeve" off the socket.

Fixed.

Both sockets had split long ways, so I had a "top side" and a "bottom side". The "top side" seems to work fine and is still in there, but the "bottom side" has been scrapped, and I ended up just soldering those three connections. Kind of a bummer. I'll keep my eye out for better solutions. For now, though, all the continuity and resistance measurements work out well. Haven't actually heard the thing yet...

I'll post some pics and a sound clip or two in coming days, but please don't hold your breath.

[newey]

Newey, you specifically signed off and said that Switch 1 looked good.

I did. Glad you got it worked out, I sure didn't spot it!

[JohnH]

Hi Ash

Checking diagrams for people is hard work, and you have to be in the zone, with some free time. Its much harder than adding random suggestions and odd comments. So I am sorry to say that you diagram came up at a time when my head was not in its usual place! You deserve a review so I’m having another look at it now, while sitting on a train.

Here are a few comments:

1. Initially, the neck seemed to be hanging from hot when in S1 off mode, but then I see that SW1Bd is shunting the whole guitar when off, so not a problem

2. S4 and S5 are a switched version of reversed volume controls. I don’t like to use these myself due to tone loss at low volume, but have you had such independent volume controls on a guitar before, and find them to be OK? I would be particularly worried aout when they get stacked end to end in series mode. With one turned down, its resistors are in line with the whole signal. There may be another version based on a normal volume control arrangement – made into the switched configuration, probably with treble bleed.

3. I can see what you mean about the oop settings, parallel positions 2 and 3 are always the same connections, on each part of S4, as are series positions 3 and 5, so the phase variation is not there yet.

cheers
John

[ashcatlt]

Thanks John.

The "official" scheme from Rickenbacker shows the reverse volume thing as standard on these guitars. They only go down to halfway anyway, and won't likely be turned down all that often, so I'm not real worried. It's a relatively easy fix if I decide I don't like it after playing it a while.

As you get further into it, I think you'll find that I'm bypassing the bridge volume altogether in the series modes. I'm honestly not sure what's going to happen when I start turning down the neck volume here. Will it attenuate the whole guitar, or blend out the neck, or both???

#3 has been fixed (haven't heard it yet, but my meter says...) and I'll post an update for my scheme sometime soon.

[ashcatlt]

Well, I finally got to hear it today, and it works! All of the switches do pretty much what I expect.

The "Strangle" switch is a bit more subtle than I had hoped when on the Bridge pickup alone. There's not really a whole lot of bass coming out of that pickup to begin with. With the Mode switch in Series position, it makes quite a bit more difference.

I realized after listening that the Bridge Volume is not "bypassed altogether" in the Series modes. The Bridge Pickup is not really affected by it, but it's resistance (when not in "No Load" or 0 position) does load the guitar's output. It has a noticeable effect on the overall tone. I may eventually dive back in to just remove that "bypass" feature so I've got independent volume control.

I can hear the tone suck that JohnH was talking about as turn down the Volumes. I'm not sure if I hate it yet.

I can tell that I'm going to have fun with the various "BroadBucker"/half-series options. I've never before played with this. It's not exactly what I thought I expected, but there's all kinds of variations in those switch positions.

Overall, I call it a success. I promise I'll get you some sights and sounds pretty soon here.

[newey]

I promise I'll get you some sights and sounds pretty soon here.

We're gonna hold you to that! Not many Rickenbacker mods hereabouts, good to see one. And I've been anticipating a report on the "Hard V & T" concept, I can see where that might be a keeper.

[ashcatlt]

Finally found the wife's camera so I could shoot some pics.

This one's got the switches labeled:

You can see that I used aluminum foil to shield the thing, but put a piece of black construction paper over the foil, to help avoid accidental shorting. You can't see that I cut out around the pot holes so there would be contact there.

Here's a different angle:

This is my first foray with heat-shrink tubing and I can't figure out how I've ever lived without it! Sometimes takes a little bit more foresight (put the tube on before
twisting the wires together!) but it's so much easier and nicer than tape.

On the right of this next shot you can see the "hot side header" that I made from the IC sockets. On the left you see the wires that were supposed to meet at the "cold side header" which failed.

You can also kind of see the half-assed Faraday cage I built from a piece of cardstock (printed for my kid's arena project) and some foil.

[newey]

That's pretty neat and clean! When I saw the diagram, I was thinking the "spaghetti effect" would be worse than it actually is.

Nice Job, Ash!

[JohnH]

Yes indeed - nicely done!
John