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2 channel modification on a J (many pictures).

Discussion in 'Basses [BG]' started by Flux Jetson, Aug 18, 2012.

  1. I modified my new Squier Vintage Modified Jazz 70's bass. So I guess it's a Modified Vintage Modified (oh brother!). I needed a two channel setup where each pickup has it's own output jack. It's part of an http://www.talkbass.com/forum/f36/experimental-fully-modular-bass-rig-902681/ setup that I'm doing. I've posted this thread to get this modification in front of people that aren't following that thread (linked). It ended up being so easy to do, so inexpensive, and so darned successful that I thought it needed more exposure. So here it is.

    I started with this brand new Squier Vintage Modified Jazz 70's Bass. I bought this bass specifically for this project knowing full well that I was going to modify it. I picked it up about two weeks ago.



    Two days ago I completed the installation of the full-length thumbrest. It's a piece of 1/2" aluminum angle that I installed across the playing field, with that thing I have an even reference spanning both extremes of the playing area. It may look odd but it friggin WORKS! I'm all about function-over-form, I'll put looks after function every time when given the choice. My thumb just glides along it's length when I fingerplay to give me the sound I like. It also works for using a pick, my wrist just sorta slides along the length and gives me a perfectly even reference distance no matter where I decide to pick the strings. I can get a super even sound when going from string to string by moving my picking/plucking position to given areas - it really makes life easier. I scribed a line on the pickguard with a cargo knife, then removed the pickguard and completed the cut by scribing that same line over and over with the cargo knife until the unwanted section just came off. Nice straight cut that's nearly dead-flush with the edge of the aluminum. There is less than 1mm gap between the thumbrest and the pcikguard. The only "aw shyte" is the visible screwhole from the piece of the pickguard that was removed. I only had to drill one hole, I ended up using one of the pickguard holes on the neck-end of the thumbrest. It only needs two screws to anchor it. This thing really works!


    After getting the thumbrest project done, and playing it for a few days to get used to it like that, I began the 2-channel modifications. I removed the control plate and found typical *low-cost electric guitar wiring* inside. It was your average ~done quickly~ wiring job in an economy bass. Some of the factory soldering joints actually just broke off while I was fiddling with the wiring (cold/hasty soldering joints). So this is what I was faced with ...


    It wasn't too bad - I have definitely seen far worse in other much higher priced electric guitars/basses.

    Here's the tone control and tone capacitor. It's coming out! I'll be replacing the tone control and tone cap with another output jack. Each pickup will have it's own volume knob and it's own output jack when I finish this. I normally play with the tone control opened up all the way anyhow. So it's pretty useless. And if you'll get around to reading the thread I supplied the link for you'll see why I won't need a tone control (that will be taken care of with sweeping foot controllers).


    I decided to just gut all of the wiring and replace it all. I didn't like how the control plate was used as a grounding bus instead of actually wiring in a ground wire from component to component ultimately connecting to the Sleeve terminal on the output jack. So I desoldered everything, and resoldered it using all new wire, making sure to make better solder joints than the factory did. I added a ground lead from both pots to both output jacks as well so grounding wouldn't depend on how tight the pots and jacks nuts are. There is now no doubt - it's totally grounded.

    This is still stock wiring ....



    (Below) Ok, all done. I just wired it exactly the way it was before I removed the tone control and installed the 2nd output jack. I actually removed the stock output jack and replaced it with a high quality Switchcraft #11. That one was connected to the Bridge pickup's volume control. I added a Switchcraft #12A for the Neck pickup's output and connected it to the neck pickup's volume control. The Neck pickup jack is a "normally closed switching jack" that has a switching terminal. I connected the switched terminal to the bridge pickup jack's Tip terminal. What this setup provides is double functionality. If I want 2-channel operation, I insert a cord into each jack. But if I want to use only one cord and still have both pickups available (just like stock) I insert only one cord into the Bridge pickup's jack. Since the two jacks are connected together via the switched terminal on the neck's jack both pickup's signals are available at the Bridge jack if no cord in inserted in the neck's jack. As soon as a second cord is inserted into the neck's jack, that connection between the two is broken (the normally closed connection is opened) and the jacks become fully independant.

    So I can have it both ways ... single channel (exactly like stock) by using only the bridge pickup's jack, or 2-channel by simply inserting a cord into both jacks. In single channel operation both pickups signals come out of the bridge pickup's jack. In 2 channel operation each pickup's signal is sent out it's own jack. Cool, right?

    For the two new Switchcraft jacks, I used thick stainless steel flat washers on top of the control plate, stainless steel inside-star lock washers underneathe the plate, and used Blue Loctite (#242) on the jacks' threads before torque-ing them down good and tight.





    IMGP6394. .

    Ok, all done .... and it works PERFECTLY!!!! In fact since I replaced the all of the wiring, resoldered everything, added actual ground wiring (that bare copper wire that runs full length connecting all of the components' grounds together with a single wire), used high quality jacks, and removed the tone cap and tone control, this bass sounds better (to me). Clearer, more detail. And the jack switching logic works perfectly, just like I had planned it out.

    Here's what was removed....

    And here's the end result .....

    It works far better than I had hoped. Even without connecting it up to any of the panning/fading setup in my experimental rig made with modular synthesizer components (see that thread I linked up at the top of this post). I just started to experiment with it a little bit using the Line-6 M13 and the results were stellar. I used the bridge pickup as the "FX" chain and the neck pickup as the "clean chain". I was able to use the volume knobs like a wet/dry mixer. I tried phasers, flangers, overdrives, EQs, distortions, wild combinations of up to FOUR FX all connected to just the bridge pickup's output while leaving the neck pickup clean and dry. It's so cool that way! I connected the two chains to a two-channel mixer and fed that to my bass amp (details in that thread linked above). The levels were set evenly so all of the mixing was done right at the bass while playing. Friggin Mondo Cooly!!

    I can mix in just the right amount of "wet signal", and there is ABSOLUTELY NO LOW END LOSS! Since I had the neck pickup totally clean and dry it provided all of the low end that I needed, while the bridge pickup was used to carry all sorts of FX. With no boomy-ness (like with phasers or flangers how the low end tends to throb really badly). And I could mix in as much of the affected sound as I wanted with the two volume controls on the bass. This friggin WORKS! No weird flat spots or odd volume quirks either.






    And using the single jack/single channel method worked perfectly as well. Both pickups' signals came out of the bridge's jack with full volume control available if I just didn't insert a cord into the neck pickup's jack. The volume controls worked just like stock in that mode as well.

    I only played it for about two hours with the new setup, so I can't wait to try it with the foot controlled panning rig and the double amp/cab panning setup too! This modification was a huge part of this modular bass rig, and it will turn out to be the cornerstone of the entire rig, of that I have little doubt. I'm very pleased with the way it turned out and have no regrets about doing it, and no intentions of undoing it. I cannot wait to try it with a filter array on each pickup!

    I also discovered that just by turning down the volume controls and turning up either/both preamps (I use ART mic pres as preamps and limiters - I know a lot of members here don't like those but I really like what they do for passive basses. The input impedance really fits these pickups very well). Anyhow, if I turn the bass's volume controls down and compensate by turning the input preamps up, I get all of the tone rolloff I would ever need. It actually sounds a lot better than it did when I used the stock tone control to roll off the highs. Lowering the output volumes also rolls off the highs, but it does it in a different sounding way. Much smoother and richer sounding than the stock tone control offered. And I have individual control over each pickup as well!

    It certainly does work well! Using it with just two graphic EQ stomboxes (one for each channel) would provide TONS of tonal shaping. Or putting a distortion pedal on just one pickup channel would yield great distortion without losing ANY low end. Think of the possibilities! The cost is really low, if you didn't replace the stock jack and just bought one N/C switching jack you'd have less than $5.00 in the whole thing.

    It did require resizing the holes for the new jacks. The tone control hole was too small for the added jack, and the stock jack that I replaced with a high quality Switchcraft had a smaller hole than the Switchcraft needed. So two holes had to be enlarged. I didn't even use a drill, I used a handheld "T-reamer" to do it. Worked great.

    Ok - enormous post. Sorry, but I was so happy with the results I figured other people may be interested in this setup if they knew about it. I did it because it's all part of a larger plan, but it turns out that it works so well by itself that I thought I'd share it. It would be very simple to make a small summing box that would "reconnect" the two signals into one signal so you can use it with a standard bass amp that only has one input. You could even add two separate tone controls to it as well. It would be very easy to make that so you could have a 2-channel bass without the need for a 2-channel mixer. I might be able to help with a drawing or two if needed.

    Ok, I need to close this out. Thanks. I hope you got a kick out of it.

  2. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    I might paint that thumbrest black or try to use a piece of wood so it's a bit more inconspicuous. I can't get past it.

    I know you said function over looks so if it works for you, awesome!
  3. MrLenny1


    Jan 17, 2009
    Nice job & PIX too.
    Thumbrest a bit extreme but...
  4. MooseLumps


    Nov 4, 2007
  5. throbgod13


    Mar 26, 2005
    could have used a stereo jack, used a TRS cable to a splitter with a blend knob and retained your tone control.. and only had a single cable to run between the bass and the splitter..
  6. Thanks folks. I'll get around to doing finish-work later (painting things and such). Right now this is all prototypical stuff.

    I thought of using a piece of wood, I actually bought a piece of 1/2 x 1/2 trimstock to use in the same way. The problem is that the trimstock sets my hand too far away from the strings (it adds a full half inch to the distance due to it's half inch thickness). Using angled aluminum puts my thumb at almost the same distance as using the pickups as thumbrests.

    Yes, I could have cut short pieces of wood and placed them between the pickups, but that is a LOT more work, and I wasn't even certain I'd like the full length thumbrest in the first place. So since this is a prototype, it made a lot more sense to use a single piece (less holes to drill, WAY less work to do than using 3 or 4 separate pieces of wood fitted inbetween the pickups/bridge which would also require finish sanding/shaping to avoid splinters, many more screws, many more drilled holes, an odd cut on the pickguard for the center thumbrest, the list of negatives continues).

    I'll use it like this until I figure out what placement of thumbrest I actually need, and then when I build the "Race Bass" (that I have in the penciled out stage) I will incorporate those findings in a more refined manner.

    Keep in mind this bass is for prototyping out some ideas. It was purchased for that purpose. Later the body will be cut/trimmed to a different profile as well. I'm disabled with a spinal injury. The condition demands that I keep my right arm close to my body when I play. If I don't, I can only play for about five or ten minutes before the injury comes to the party. If that happens, pain management meds must be increased for several days. If I am forced to do that, my life is turned upside down for at least a week. All because I played a guitar/bass that didn't fit me for more than a few minutes.

    So this body will be cut along the top. I've learned that Exlporer-type top edge profiles work well for dealing with my spinal issue. That profile allows me to play for hours on end without any problems. The general profile of the "Race Bass" that I'll be building soon is essentially a combination of a Steinberger with an upper horn. Or perhaps a reshaped Explorer or Buzzard bass. I also have to keep an eye on overall weight.

    This right arm position is great ...


    This right arm position is ~maybe~. The thing that makes it ok is that the bass's body sortof supports the arm by giving the elbow a place to rest upon, even though the arm is "kicked out" a bit ...



    And this right arm position is definitely something that ruins my life for a week ...


    This is what I had to do to a Telecaster body so I can play a Tele-format. It was a bare alder Warmoth body that I modified to suit me. I essentially used the upper edge of one of my Dean ML guitars (they are a combination of a flying-v and an explorer). I call it "The Shredbilly"...




    So with that information presented, here's a rough pencil sketch of sorta-kinda what I have in mind for the finished Race Bass ...


    It's essentially a combination of this (with the exception of the headless aspect, I plan on using a standard headstock, just a really small one in a 2x2 tuner configuration. Brass nut, stainless steel frets, EMG or Bartolini pickups. Planning on perhaps going with the 2-Tek bridge - maybe) ....


    And the seat/fender combination of these (Look at the profile of the rear fender area .. and then place that profile on the bass body as the upper horn - the upper edge of the bass body acting as the "seat" and the upper horn acting as the "rear fender") ...




    Now you know where the name "Race Bass" comes from. It's angular and minimal like many parts made for race bikes, it's functional and purposeful like a race bike, and it's developmental like a race bike.

    I may throw some of this in the final shape ..


    So to experiment with the body shape, I may cut this Jazz body something like this to test out some of these ideas ...

    Stock shape, to get an image in your head of what that looks like ...

    And what I'm calling "CUT-1" ...


    So, now you may have a better idea of where this is all headed, and "why" it's headed that way. The full length thumbrest is part of the R&D I'm doing to get the info I need to fully develope the Race Bass. That's also the whole point behind that odd pickup/output wiring, and the experimental filters, preamps, foot-controlled panning, and dual-amp setup. It's all leading to a final set of gear.

    I'm 52. I've been playing what everybody else decided was good for me since 1978. What I mean by that is that I've been using "off the shelf" stuff for all that time. It's time that I design what works for me. I've used many many different things along the way. I now know what certain things offer. This set of tests and experiments will all lead to gear that combines the totality of my experiences, and the things I've come to like. At this stage in my life I feel like I've earned the right to design what I want to use, rather than simply accept what gear companies sell to me. I've been to "school" and learned how to approach and construct most of this stuff by now.

    So I'm doing it. :D :hyper:


  7. seems cool.. could be my preference to make my bass double output

    oh, what's the difference between double output and stereo?
    not mean to hijack this thread btw..
  8. Yup, sure could. However I already considered and dismissed that idea. Requires a special box. I also considered using an XLR connector. Could also have used stacked pots and put tone controls on each pickup's output. Or could have done this - or that - or the other thing. :hyper:

    Keep in mind this is a prototype, it is being used to develop new ideas. Two cords suits that situation better. As far as a tone control is considered, I'm using modular synth filters that are tunable by using foot controls. The point I'm making here is that there are many many variations on this theme that a person could adopt! That's the really cool thing about it. I hope it inspires some people in the end.

    With the two-jack/two-cord approach I use standard guitar cords that I can obtain anywhere in the event I happen to lose one - or one (both) go bad. No special splitter box required either. There's a hundred pros/cons going both directions with this idea. In the end you can do whatever suits you the best. :)

    When I build the Race Bass I just may use a 3-pin XLR connector, depending on how the preamps and panning gear end up finalizing. Right now it's allllll about the R&D.

  9. Thanks! :)

    I don't really think there is a difference, to be honest. I think it's just however you decide to label it. I used "2-channel" because "stereo" sortof implies just a left/right channel orientation. To me, "2-channel" is more diverse sounding, you have two channels that you can do whatever you please with. Not necessarily just a "left-right" setup.

    So "Stereo" - "Double output" - "2 channel" - whatever flicks yer thrillswitch!

    No hijack that I can see- your question is very relevant. So no apology necessary. :)
  10. I just put this comment in another thread and I figured it was a pretty important feature of the 2-channel setup, so I've added it here ...

    "I've been using a mic preamp on each output. I run both pickups' volume knobs at full-on to retain the humbucking affect and then use the mic-pres to adjust the pickup mix to obtain whatever sound it is that I want. This works very well, and it keeps the noise and hum to absolutely minimum levels. Something not available with standard Jazz bass wiring schemes. I found that if I changed the pickup mix using the volume knobs on the bass, the instant I went from full-on with both knobs there would be little noises, a little hum and such (I guess because it upsets the humbucking balance between the two pickups, or something along those lines). Using both pickup volumes wide open cures the heck out of that problem and using the level controls on the mic-preamps restores pickup mixing ability so I can still produce different sounds. This works well."

    So there's that. :) It isn't perfect, and by no means is it "humbucker quiet" but it is a dang sight better than it was. I suppose the mic preamps act like buffers of some sort and help maintane integrity. Not sure exactly! :)
  11. ryansalmond


    Nov 21, 2007
    Cool! Better post some soundclips!
  12. Rip Topaz

    Rip Topaz

    Aug 12, 2005
    Willow Street, PA
    Beta tester for Positive Grid
    My only criticism is that instead of cutting the Jazz body, you should consider just making a new body in the shape you want.

    I suffer from a major spinal injury myself, so I understand your thought process. However, a Jazz bass really isn't the best starting point because of the balance points of the bass. A P-bass body would be more balanced from the start.

    I had to give up my Thunderbirds because the shape caused me to twist my upper body to keep the bass under control.

    Just something to consider. I'll be watching this.
  13. I've already posted fifteen of them with this bass and this mod.

    The two I posted the other day show how the footswitching pickup mix works ....

    Here's a few using this bass and my modular synth processor rig (see the link to that build in my sig).

    There's more, just hit the SoundCloud stuff I have going on.

    And as I said, for details about the gear I use see this thread in my sig.

    Last edited by a moderator: Apr 16, 2014
  14. I actually think that the Explorer body would provide the best balance for my situation. I haven't bought anything or spent any money towards the ~chopper~ setup yet, so I have time to make some informed choices.

    Thanks for the advice.

    Noted! :)
  15. Steve Dallman

    Steve Dallman Supporting Member

    I built a bass in the early 80's...a headless Explorer, and despite the weight of the zeebrawood I used for the body, it balanced well and was extremely comfortable. I later built a Thunderbird type, expecting the body to be similarly comfortable, but it never was. It always felt awkward.

    In the 70's, I played a 68 Jazz bass. I thought it was comfortable, until I found my 64 P. I sold the Jazz not too long after as I never played it after I got the P.
  16. I drew this up for someone here at Talk Bass. I thought it might be helpful to anyone else wanting to do this modification.

    The diagram works with the photograph below it. The wiring colors don't match, but I think everyone will live though it. :)

    There are several options to this type of setup, you may use a TRS jack (tip-ring-sleeve .... aka "stereo") if you want, but you'd need to construct 3-conductor cabling for that to work. You may also use XLR connectors and use a mic-cable if you wish as well. Whatever. Using two guitar cords is actually easier if you want to use various separate FX-per-pickup. You could use a Mic cable (or a stereo TRS cable) if you want then make a "breakout box" that the cable plugs in to that separates ("splits") the 3-conductor cable into the two separate signal lines. As I said, there are many variations to this theme. Whatever flicks yer thrillswitch.

    ** GREEN lines always = "grounds" in this diagram.

    ** The green line running all the way down the right of the components is the same wiring run as the bare-copper wire in the picture below.

    ** GREY lines are the white wires coming from your pickups.

    ** Make sure to sand the areas on the pot-bodies where you intend to solder on them before you solder. Otherwise you may not obtain a proper solder connection. The roughed-up sanded area also gives something for the solder to grab on to.

    **BE CAREFUL so as to not get any sanding dust or metal particles inside of the pot (it can get in through that tiny open -slot- right there by the pot's solder terminal). So stuff a piece of wadded-up paper (or something) into that region there to prevent any crud from getting into the pot's workings BEFORE you sand on the bodies. This is important if you do not want "scratchy-sounding" controls.


    THE DIAGRAM ABOVE CORRESPONDS WITH THE PICTURE BELOW (the wiring colors do not match at all, but the layout is exactly the same):


    I hope this is helpful.

    Also, here's a new thread that is using this bass as a prototype for some other new ideas ...


  17. gmarcus

    gmarcus Supporting Member

    Apr 4, 2003
    This is soooo cool! Keep up the good work. I think you have invented the perfect DubStep bass rig!
  18. That's heavy praise from a ten-year Talk Bass veteran. Thank you very much!

    The entire rig is actually four pieces:

    1 - The Bass itself.

    2 - The "X-Rig" rack which is essentially my preamp.

    3 - The foot controller/midi-bass pedals setup.

    4 - The FX unit ("Fx Tower") and modular synth that is connected to both the rack and the bass pedals.

    It's getting there. I figure it will take me the rest of this year to get it all pretty much ~done~ (if there is such a thing with a setup like this).

    The 2-channel bass mod has been pretty popular, I've rec'd a lot of correspondence and comments about that in various places/pms/emails, and so on. It certainly is a cool modification that lends itself well to many methods of processing and playing.

    Thanks again for the compliment. I hardly know what dub step is! Haha! :)
  19. RedMoses


    Jul 4, 2012
    Nice concept and wiring but that thumbrest is a serious eye sore!
  20. Yea, I know, but I don't care. Keep in mind this is an experimental bass, I'm trying many new ideas with it (see the "X-bass" link in my sig). So some stuff will stay, some will go. It was purchased for that precise purpose, to try out nearly every idea I've ever wanted to employ.

    By now I've learned what I want and what I do not want in the thumbrest department. Some of it will be removed, other parts will be machined down so that it's lower in certain areas, other parts will remain untouched. It is a tool to be used to develop the bass. Looks don't matter in R&D. If they DO matter, then it isn't a true R&D effort. That full length thumbrest was never meant to stay as it is in these pics.

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