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Post by bentstavanger on Jul 24, 2017 20:28:48 GMT -5
Hello everyone!
I want to do some modding on the electronics of one of my guitars. It's a solid body tenor, 4 strings, tuned as 1st to 4th string on a regular guitar, sometimes tuned as 2nd to 5th string. But I'm completely new to this, so there's is a lot I need to find out before I get started. There's a ton of question, and I hope you can answer some or all of them:
1) There's a volume and a tone control on the guitar, but I rarely use them. 99% of the time, they are both set on 10, as I control the volume and tone on different gear (volume pedal etc.). What would happen if I simply removed the two pots and let the wires run straight to the output jack? Would I notice any change in sound quality, output level etc.? Would there be any argument for leaving the pots, even though I don't use them?
2) What are the differences between bass pickups and guitar pickups, aside from the string spacing? The guitar I wish to mod has a quite wide string spacing, closer to a bass than a guitar. I wish to know, if I can use a bass pickup.
3) What happens when two or more pickups are sent simultanousely to one output? Are the signals simply summed together, or are there impedance and output issues I need to be aware of? E.g. is there a risk that one pickup can ruin or cancel the sound of another if they don't "fit" together (e.g. a bass PU together with a guitar PU)?
4) I am considering putting a stereo output on the guitar. What will happen when I split the signal from a pickup in two? Will the output level of each channel be cut in half? Will the impedance change? Anything I need to be aware of?
5) In case I split the signal, what would be the arguments for choosing a stereo jack, and what would be the argument for choosing two mono jacks? Are there any significant differences in wiring, sound quality, output levels etc.?
6) In case I choose the stereo jack, would it be possible to wire it in such a way that the two signals were summed in case a mono cable were inserted?
7) In a stereo scenario, would it be possible to wire a selector switch in reverse for each pickup? E.g. could I install a 3-way selector switch for the neck pickup that in the up position sent the signal to L, in the mid position to L&R, and in the down position to R, and likewise install selector switches for the mid and bridge pickups? If possible, I would be able to blend the L and R signal from whichever pickup(s) I wanted to send to that particular signal path. But is it possible at all to do that with a selector switch? Would there be any risk of the left and right signals "bleeding" into each other or otherwise interfere with each other?
It's a lot of questions, but I hope someone can answer some of them. Particularly, I want to know if I can use bass pickups, before I start investing too much money. Maybe some of the other answers will come with experimentation.
Thanks to all! :-D
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Post by newey on Jul 25, 2017 6:16:47 GMT -5
bent-
Hello and Welcome to G-Nutz2!
We don't often get questions about tenor guitars, but the basic principles are the same. I'll try to address your issues in order:
1) If you remove the V and T controls, you will have slightly more output and a bit brighter tone. If you never use them, you can certainly remove them. The only downside is if you would ever sell the guitar, or if it has some vintage value.
2) Bass pickups are wound a bit differently than guitar pickups but you could certainly use one. It might lose a bit of "sparkle" compared to a guitar pickup. A lot would depend on the specs of the individual pickup, and you might be able to find one that looks (at least on paper) to be more guitar-ish. Antigua is our pickup stat guru in the pickup modeling sub-board. I'd suggest shooting him a PM, he can probably give you more info than I can. But I have a P-Bass clone that uses a Strat pickup, so why not?
3) When two pickups are sent simultaneously to output, it's no different than the middle position on a three-way switch. "Summed" would be the right word to use if the two were wired in series, but most of the time on most guitars, they are in parallel, and they are not then "summed", technically speaking. But I get what you mean. If one pickup has more output, it can (and will) overpower the weaker one so that you mostly hear just the more powerful one. Mismatched pickups are often addressed by having a blend control or individual Volumes on each pickup- but you're ruling out pots, it seems. "Impedance" is not an issue in combining guitar pickups, you're not going to hurt anything or blow your amp up, etc.
4) 5) and 6) The only issue as to stereo wiring is whether you will have a common ground or not. If you choose a stereo jack over a mono one, you're stuck with a common ground, which might (I emphasize the might here, it's not necessarily a problem)be an issue if you go into two separate amps. You can set it up such that a mon cable will give you both pickups. You can also use a switched jack as one of two, so that "Jack A" has both signals unless a cable is also inserted into "Jack B", in which case Jack A has channel A only and Jack B has channel B. I have an unfinished stereo project that will (if I ever get it done) be wired in this way.
7) Your switching idea should be possible, although we would have to actually work out some wiring to be sure. Again, the only issue I foresee would be separating the two grounds (which may not even matter, especially if you're going into a stereo amplifier). You will probably need to use double pole switches, not the typical LP-style 3-way switch. There may be simpler switching options, however.
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Post by reTrEaD on Jul 25, 2017 9:04:13 GMT -5
There's a volume and a tone control on the guitar, but I rarely use them. 99% of the time, they are both set on 10, as I control the volume and tone on different gear (volume pedal etc.). What would happen if I simply removed the two pots and let the wires run straight to the output jack? Would I notice any change in sound quality, output level etc.? Would there be any argument for leaving the pots, even though I don't use them? According to your 99% non-usage, there's a 1% argument for keeping them. As Newey mentioned, there will be a slight increase in output if you disconnect both controls. The sound will be moderately brighter if you disconnect one of the two. But it will be much brighter if you disconnect both. You could keep the sound the same as it is now by either wiring the controls so they are still in the circuit and present the same load on the pickups but are not adjustable. Or you could use a resistor to replace the load and remove the controls entirely. Basically just the spacing between the pole pieces. Of course, some pickups have a blade polepiece that spans across all the strings. However there are a wide variety of pickups that have very different characteristics because of the differences in coil form size and shape, number of winding turns, gauge of wire, type and thickness of insulation, polepiece materials, baseplate materials, cover shape and alloy, etc. You may indeed find that two pickups of disparate output levels and/or impedance characteristics do not play well together. You load the pickup more heavily because you have two amplifiers and two cables. A properly designed amplifier has a relatively high impedance. So its impedance is relatively high in relation to the load presented by the guitar controls. But the capacitance of two cables will shift the resonant frequency down a bit. You're unlikely to notice a change in overall output but perhaps a slight difference in tone. It would be rather clumsy to have two cables. But care should be taken when selecting a stereo cable. High capacitance is very undesirable. Not automatically. You would need to have a switch that sums the two outputs and directs both to the tip when a mono cable is used. A mono cable plug inherently connects the ring connection of the stereo jack to the sleeve. You will have no problem if there isn't a situation where a pickup is being directed to both outputs. For instance the neck and bridge pickups directed to L and mid pickup directed to R. But you'll run into problems when trying to send a signal from one pickup to two outputs and another pickup to just one output, if you only use switches. The signal on both outputs will be identical. You can avoid this by using some active electronics, ie: buffers. That does require having a battery in your guitar. Buffering each pickup as well as the two outputs will add a great deal of complexity to this project. But the use of buffers could alleviate most of the problems you're likely to encounter. 1 - You can load each pickup to whatever resistance and capacitance you choose without affecting the load the other pickups see. This can optimize the sound to your tastes. A good bit a trial and error would be necessary, but in the end it may be well worth it. 2 - You can adjust the output level of each pickup's buffer so they are all equal. 3 - The low impedance of a buffer's output means it will be virtually unaffected by cable capacitance. No need to worry about finding a low-capacitance stereo cable.
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Post by bentstavanger on Jul 26, 2017 18:26:52 GMT -5
Hello Newey & reTrEaD, Thanks so much for your answers, that's a lot of useful info! Newey, I am not ruling out pots. I was just thinking of sacrificing one to use the space for an extra jack output in a stereo setup with two mono outputs. That would require less drilling and routing and also look less "crowded", but also mean that either the L or right R would have no pot at all. The guitar I wish to mod is a Warren Ellis Signature Tnor 2P (from Eastwood Guitars), which has a kind of "Jaguarish" layout (see attached picture). So I'm guessing an extra mono jack would easily fit instead of one of the pots (but I might go for the stereo jack). In any case, it's not a vintage instrument or anything. I actually got it cheap (B-stock) directly from Eastwood Guitars. You both mention, that the sound going straight to the output without passing through any pots, will be brighter. I'm assuming this means that the pots have the side effect of working as a permanent hi cut filter (correct?). I guess this depends also on the quality of the pot? A cheap pot changes the sound more than a better one? I am not using amps, rather I am using two signal paths with different effects: 1) Directly into a TC-Helicon VoiceLive 3 which has built in guitar FX as well as amp and speaker sim, 2) Separate octaver, then multi-fx including reverb and delay, then into the AUX of the VoiceLive where it all gets summed into one stereo signal that is then sent to the PA. Right now I'm splitting the signal with a EHX Ravish Sitar, which is an FX in it's own right as well as a splitter when bypassed. Everything is digital, and it's of course not the most beautiful sound that one could imagine, but it's a way of keeping the rig as portable and easy to set up as possible while still getting a reasonably good sound. The reason I'm considering a stereo output from the guitar itself, is that my setup now is limited by having two identical signals send down the two signal paths. That's fine for doing something like a shimmer reverb, but sometimes I would like to be able to have only one or two string going to one path, while all the strings go to the other (e.g. if I want to play a bass line dropped one or two octaves). I checked out The Submarine pickup (and others) which can be set up with no work at all. It picks up just one or two strings and can easily be moved around to suit the player's needs. That's fine, but then when I need to have all the strings in the second signal path, I would have to change around some cables between songs. Either that, or I would have to set up with 3 signal paths, more cables and pedals. So I was thinking along the lines of replacing the neck pickup with 4 single pole pickups, and route these through 4 selectors or toggles that would send the signal of each string to L (together with the bridge PU), R, or both. There are not so many single pole PUs available off the shelf (none actually), but I talked to EMG about their 4SW system used in some NS basses (that's why I asked about bass PUs). They are willing to sell them directly from the factory at a reasonable price, but they are probably not usable for my purpose. The thing is, they come with a dedicated preamp that sums the signal (I think), so at the end of the day it's actually just one PU. But I have seen many smaller manufacturers who will wind any kind of custom pickup, so I'm sure I can solve that part of the puzzle. But the stereo wiring is a bit complicated for me to understand. reTrEaD, you write that if I send one PU to one output but another PU to both outputs, then both outputs end up being the same. In the scenario I describe above, that would mean that if I sent all 4 strings to L and only 4th string to R, then actually all 4 strings would end up going to both outputs (unless I use a buffer circuit). Is that correct? And does it go for both the stereo jack solution as well as the 2x mono jacks solution? Am I correct in assuming, that the phenomenon occurs because the L and R signal paths would somehow be "shorted" through the selector switches? I would really like to avoid putting any active circuitry into the instrument, I just want to find the simplest solution. So here is another idea I came up with: 1) I leave the existing PUs, pots and wiring as they are, except I put in a stereo jack output (instead of the mono). 2) I route out a new PU cavity (mid) for the single pole PUs, as well as a cavity on the lower part of the pickguard for 4 toggle switches to turn on and off these PUs individually. 3) I connect bridge and neck PUs to the tip and sleeve. If I understand it correctly, then this is the L channel, and this is the signal I would get from plugging in a mono cable. That means I could play the instrument with the exact same sounds and functionalities as now, if I should wish to play without the extra signal path. 4) The 4 single pole PUs going through the toggles would be wired to ring and sleeve of the output jack. When plugging in a stereo cable, I would then get a signal on the R channel carrying whatever string(s) I would want to run through the secondary FX. E.g. one or two lowest strings for playing bass, all four strings for shimmer reverb, top one or two strings for an interesting effect on the melody line etc. A sort of simplified hexaphonic PU. The R channel would then have no Vol and Tone pots, but there would be no problem in shaping the sound through the different FX in that path. Would this idea work? Or would there be a simpler way of accomplishing what I wish to do? Thanks for your inputs! :-D Attachments:
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Post by reTrEaD on Jul 26, 2017 23:25:37 GMT -5
I was just thinking of sacrificing one to use the space for an extra jack output in a stereo setup with two mono outputs. That would require less drilling and routing and also look less "crowded", but also mean that either the L or right R would have no pot at all. If you want to use the hole currently occupied by the tone pot for a second jack, you could still have two volume pots, one for each output. They make concentric pots and the knobs would look something like this: A cheap pot doesn't turn as smoothly and is more prone to crackling noises when turned, as the pot ages. But both will have the same effect on the tone/brightness. Yes, correct. Yes, same problem regardless of stereo jack or two mono jacks. Exactly. If any given pickup is connected to L and also connected to R, then L and R are inherently connected together. Therefore, anything else connected to L will also be connected to R. And anything else connected to R will be connected to L. That plan seems very direct and workable. Whether the tip works out to be L and ring is R depends on what you plug the cable into. But I reckon that isn't much of an issue either way. The fact that you will still be able to plug in a mono cable and be able to have the same functionality you currently have seems very nice indeed. You might choose to try disconnecting the tone pot from the guitar now, and see if the sound isn't overly bright to your tastes. If that works out well, you could use the tone pot as a volume pot for your individual pickups. Tone pots and volume pots are the same. It's just how they are connected in the circuit that makes them different. A pot used as a tone control will be used in conjunction with a capacitor. Another option would be to have volume and tone for each circuit. Use two concentric pots. If having a volume control for the individual pickups isn't necessary, just leave the volume and tone controls as they are now. If you find the individual pickups to be unpleasantly bright, you can add a simple resistor to load them down and tame down the brightness.
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Post by bentstavanger on Jul 30, 2017 15:20:28 GMT -5
Another option would be to have volume and tone for each circuit. Use two concentric pots. Hello reTrEaD, That's a great idea with the concentric pots! From a quick online search I found that there are many type of pots that can do different things, including push-pull pots with different functions. A neat way of getting more possibilities crammed into one instrument. I might do that. It seems like my next step is to get the individual pickups. So I've sent an email to EMG asking them if I can use the 4SW system without the preamp to get the individual signals. Also I'm checking out different custom shops. But before I order something, I want to ask you this: Would it be possible to "split" the poles apart on a pickup with individually wound magnets? If I could simply cannibalize an old pickup by cutting some wires and soldering some new output cables onto them, it would give me a chance to make some cheap experiments with my idea, before forking out dough on something custom made... :-)
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Post by reTrEaD on Aug 1, 2017 6:12:54 GMT -5
Standard guitar pickups don't have coils wound around each individual polepiece. Rather, they have one oval-shaped coil wound all the polepieces. There are a rare few pickups that do have separate coils wound around each polepiece but they tend to be rather expensive.
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Post by bentstavanger on Aug 2, 2017 9:28:23 GMT -5
There are a rare few pickups that do have separate coils wound around each polepiece but they tend to be rather expensive. Got it, thanks! Yes' I've seen very few of the individually wound pole pick ups, didn't really look at the price. If they are expensive, I might as well get something custom made. The EMG 4SW only works with the dedicated preamp (summed), unfortunately. Anyway I found several options for custom pickups. I had another thought: Instead of on/off toggles for the individual pickup, I could give them each a vol pot. That would make it possible to have complete control of the output of each string, to the point of switching it off completely. And on more thought: Instead of vol pots, make them blend pots wired in reverse, so that each pickup could be sent to L or R or some mixture of the two (effectively panning the pickups). Would that work, or would I end up with the same problem you described above (with the selector switches), where L and R are "shorted" and the output in L and R becomes identical? :-)
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Post by newey on Aug 3, 2017 6:13:06 GMT -5
Yup. Essentially, the only way to avoid the problem RT has identified is if each channel is completely separate from the other, going out to its own jack.
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Post by bentstavanger on Aug 20, 2017 18:19:48 GMT -5
Yup. Essentially, the only way to avoid the problem RT has identified is if each channel is completely separate from the other, going out to its own jack. OK, thanks. :-) How about this idea: two sets of single pole pick ups (L/R for each string) wired to four blend pots in the way outlined in option 3 on this page: www.stewmac.com/How-To/Online_Resources/Learn_About_Guitar_Pickups_and_Electronics_and_Wiring/Blend_Pot_Wiring.htmlThe way I understand this wiring, the two signals don't actually blend, they just have their volumes controlled by one pot, so that when A goes up, B goes down and vice versa. Could this work, or would L and R (or Tip and Ring) still be shorted? If it could work, this would not give the option of silencing one string completely, however. Unless I could find a blend pot that were also push/pull to be used as on/off for one of the channels. Then the other channel could simply be turned all the way down, and that string would effectively be turned off. Does such a pot even exist?
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Post by newey on Aug 21, 2017 5:08:35 GMT -5
The StewMac diagram (the one for a stereo setup) should work OK. But be aware: Blend vs. Pan potsThe images have gone away from ChrisK's thread, but you'll get the gist. No Push/Pull true blend pots exist, nor (AFAIK) are there any pan pots with a P/P. We have seen a dual-gang pot with a P/P (which could be wired as a "blend" pot, but it would lack the center detent that blend or pan pots have. It's just two regular pot elements on a single shaft.
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Post by bentstavanger on Sept 15, 2017 8:35:41 GMT -5
OK, thanks a lot for the heads up on that. Actually, the PAN pot might be useful for what I am trying to accomplish, since in a certain sense I would be panning each string between L and R. The ultimate goal is not to create a stereo perspective for the listener (although I might do that in some cases), but rather to create two different signal paths with different fx. The pan pots would then make it possible to create a gradual transition from on signal chain to the other, going from the low to the high register on the instrument. Or just the lowest string could be going to the L channel for e.g. faux bass, while the rest of the strings would be panned fully R, etc. With blend or pan pots the possibilities of signal routing would literally be infinite, as opposed to mini-toggles which would give many, but limited, possibilities. Using the pan pot would mean (as I understand from reading ChrisK's thread) that the total output of a string in terms of volume would remain constant no matter how I dial the pot (this of course does not take into account, what happens to the L and R signals after leaving the instrument). This might be useful for me, since I imagine it would be easier in a live situation to control the total volume while changing the panning, without having to adjust the levels of the two signal chains. But is there anything else I would need to consider? Is the only difference between blend and pan the way they mix the two signals, or are there also other differences, e.g. treble roll-off or something else? :-)
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Post by newey on Sept 15, 2017 9:18:16 GMT -5
No, I think you've got the gist, and I think you're right, for the purpose you are using this the pan pot may do OK. Treble roll-off shouldn't really change, that's more a function of pot value and taper.
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