curtisa

It's certainly a great start. Very interested to see where this heads. Does the system rely on your hexaphonic pickup or can any pickup be used alongside your "driver"? I notice that there's still a little bit of superimposed overdiven signal in the sound (eg, 0:52 - 0:58 in your video). This was something that seemed to be completely unavoidable in the old DIY sustainer that a lot of us here at Project Guitar built years ago. There were many theories behind the cause of this at the time - proximity of the driver to the pickup, driver amp being overdriven, driver being overdriven, low-tech of driver circuitry, induction/coupling of driver signal back into sensing pickup etc - but no real fixes. Is one of the areas of your project to tackle this "interference" in the sustained signal and make it operate as cleanly as possible? The hour or so I spent playing a Moog guitar at a store about a year ago seemed to imply it was possible to do completely clean sustain.

Fantastic! Do want!

Phase reversal on a single pickup will have zero effect unless you have another pickup in that guitar to combine with. Humans can't hear phase shifts in a single source unless there's something to compare the phase shift against. Switchable filter capacitors (for tone shaping) or a series/split/parallel switch would be my vote. Edit: Probably also worth mentioning that the switch you have in your guitar (or want to install in your guitar) will have an impact on what switching options are achievable.

OK, I've come up with a kludge that I think works on paper, but I have to really twist my brain into knots to get there. Essentially take the SD diagram you linked to before and reverse the connection order of the phase and S/S/P switches. Using the SD wiring colours: Black from pickup to phase switch bottom-left lug Green from pickup to phase switch bottom-right lug Phase switch middle-left lug to bottom-right lug of S/S/P switch and output Phase switch middle-right lug to bottom-left lug of S/S/P switch and ground Red and white wires from pickup to S/S/P switch as originally draw Your pickup combinations with the phase switch off will then be: Humbucker series Humbucker coil 1 split Humbucker parallel And with the phase switch on: Humbucker series, overall phase reversed Humbucker coil 2 split with reverse phase Humbucker parallel with coils reversed and overall phase reversed Can somebody else confirm this, please? I've got a headache now!

The problem as I see it is that the 'split' function of the series-parallel switch is more or less just a happy accident of substituting an on-on-on switch for a standard on-on switch in that position. When you break down the way 'split' on that switch works electrically it's actually really messy. I can see a way of installing a 'coil select' switch for the split function, but it does all sorts of strange things to your pickup when in 'parallel' or 'series' mode. Unless there's something I'm missing there's not going to be an easy way to do coil select with an on-on-on series/split/parallel switch, particularly with the requirement that it only affects the 'split' mode. Might be possible to do it with a larger 3-way blade switch or a rotary switch, something with a lot more contacts and poles. But that's even assuming you want to add yet another large switch to your guitar for that function.

I think the "buffers" are simplified representations of his per-pickup preamps (first post up top). If you don't want to do volume for each string you can leave out the pots - just connect each pickup signal to the left-hand point of the 10K mixing resistors.

Have a look at this article, particularly section 3. What you want to build is a mixer. With your diagram as shown you are mixing the pickup signals, but doing so passively. The main drawback with your scheme is that each pickup signal is in parallel with 25 other signals, loading each other down, and with 26 stages each pickup will only be capable of delivering 1/26th of their full output at the opamp, requiring 26x more gain at the opamp to make up for the loss. The example at section 3 is a better solution, where the mixing occurs at the inverting input of the opamp. You can still use your 10K resistors, but the adjacent-signal loading that would occur with passive summation is non-existant, and each input maintains its level through the opamp. You may want to consider creating several sub-mixer circuits of say 6-8 pickup signals, which then get passed in groups to a master mixer circuit. Mixing in groups will be less noisy than mixing one batch of 26 signals all at once. If your prototype board is big enough try experimenting with it before committing your design to PCB.

No worries, Chris. I'll try to get them copied this weekend. Once I have them cut and weighed I'll be able to give you a shipping quote.

Off the top of my head I don't see why you can't use the Seymour Duncan switching scheme you linked to. The note at the bottom of SDs schematic could be interpreted a little confusingly, but series/split/parallel + phase reverse should work as drawn. Actually, on second thought I don't think it can work (too early in the moring for me!). Your requirement for a coil select via the phase switch on the humbucker is unusual and presents a problem. The 3-position switch in the SD diagram is a one-trick pony, and I don't think there's an easy way to select which coil gets the split when the on-on-on switch is in the middle position. My original diagram with the phase switch operating as a coil select when the split is operated should work OK, but at the expense of no parallel option.

Off the top of my head I don't see why you can't use the Seymour Duncan switching scheme you linked to. The note at the bottom of SDs schematic could be interpreted a little confusingly, but series/split/parallel + phase reverse should work as drawn. Should be fine. The only difference between SDs version and the one I sketched out is that the inputs and outputs on the switch are reversed. Makes no difference in practice.

Don't know. I've only seen photos of the contraption fitted to Munky's guitar in magazines, never in person. Does it snap in from the top, or screw in from underneath, or something else?

Thanks Scott. It's close, but I was sure there was one more recent than that. The pictorial at the end is the right idea. However the video method is only valid for bushings that are hollow all the way through. Some studs, such as those supplied with the Wilkinson VS100 or Ibanez Lo Pro are solid-bottomed, and the video method in that post won't work. Only if the holes are a bit loose fitting. The ones I've extracted have all been press-fit only. A little bit of PVA may add enough lubrication to help slightly tight bushings go in smoothly. Go carefully pressing the bushings in - the trem route on the Lo Pro doesn't leave much wood behind the posts, and it's really easy for tight fitting bushing to split the wood as they go in. Firm finger pressure should be enough. Save using the wooden mallet for when there's lots of timber around the bushing hole (eg, Les Pauls).

Good points on the tiny template jig. The arm extends about 3" past the front edge of the wide crosspiece, so there's a fair bit of a gap ahead of the business end. The arm itself isn't (and wasn't!) meant to be used as a handle, just a method of holding the workpiece in the firing line of the cutter. The idea is to hold the big chunky piece. Next step is to add a couple of handles to either side of the crosspiece so that I'm able to grip and manoeuvre it around properly, but as a proof-of-concept it works really well.

My borderline-ADD brain won't allow me to forget to add one. Have to have something there otherwise it will bug me for eternity...or until I devise a new way to make the trussrod access look dressy. A cavity cover is next on my list of things to do in between waiting for parts to arrive (decided to ditch the stainless steel frets and get some plain vanilla fretwire on this one).

No disk sander here. Anyway, now the jig is made I can spit these things out in a few minutes each. Plus I can change the edge bevel to a different profile by switching router bits.

Neck cut to taper. 20mm at fret 1, 22m at number 12. Tried using the new spindle sander to rough out the volute. Teeny bit off at the bass side, but nothing that won't carve out. Would be easier to execute with a volute perpendicular to the neck centre line (dang wonky frets!): Problem - trussrod cover required, but you don't want to use nasty black plastic. Solution - make one out of timber. Problem - how to pattern-route something so small without losing fingers? Solution:

There used to be a good video and write-up here somewhere but I can't find it. I use a similar technique to this: I'd suggest using a block of wood with a hole drilled through it rather than the PVC pipe offcut used in the video - spreads the pressure out over a larger area - but the principle is the same. Depsite what some people suggest do not use a claw hammer or pliers to lever the studs out. Assuming you can protect the finish from damage while using these tools, both methods will pull the studs out of the body at a slight angle which will oval the holes the studs are being extracted from. The studs need to come out vertically to maintain the round shape of the hole.

Curiouser and curiouser. Do tell.

Here you go. Note that the diagram is not to scale, so don't use it directly as a cutting guide printed at 1:1

I made some moderately accurate measurements of a Lo Pro 7 route from my RG7620 before I sold it a few years back, but I don't have any data for the Lo TRS 7. I don't have the intonation reference points from Lo Pro 7 either. If that's any use to you I can send them through. According to this installation manual the stud holes need to be located 10.7mm closer to the nut than your scale length - eg, if scale length = 25.5" (647.7mm) then studs need to be drilled at a distance of 637mm from the nut.

Correct. By running opamps and 4066s on +/-5V supplies and substituting one transistor level shifter for every 4049 inverter you should be able to achieve the required switching without having to resort to DC offsets for each 4066 switching element. Out of curiosity what are you using to control all these switching functions? Some kind of microcontroller? I forgot to mention earlier, I'm intrigued by your electroharp, I'm liking where it's going and the sounds you're getting from it - very innovative!

I used to have a chair like that when I was growing up. They were popular for a while in the late-70s (at least down here they were). Mine wasn't fold-up like yours. Had a fixed frame with a woven wicker clamshell seat. Was one of the most comfortable chairs I had until the bottom fell out of the wicker.

I have considered registering over at anzlf.com, but for whatever reason I've never actually gotten around to doing it. Bit more progress to report. Headplate (focus, dammit!): The big squeeze: And carve done. The "raindrops" on the body is just some epoxy that's being used to fill some pinholes in the top. Difficult to get a sense of the contours on this one as the top is such a pale colour:

Yes, I probably should've mentioned that this will invert the output. Logic 1 (+5V) at the input will translate as logic 0 (-5V) at the output, so you can do away with your 4049 inverters.

The "u" in "uF" is western-ised typing for the Greek letter "μ", which in turn is engineering speak for "micro" or 1 millionth. The caps used in your guitar are smaller still and are measured in nF ("n" being for "nano" or 1 billionth). 47μF and 47nF differ by a factor of 1000. Sometimes the value is printed directly on the side of the cap (0.022 = 0.022uF = 22nF = 22 nano-Farads). Other times they are printed as a code which needs to be deciphered (223 = 0.022 = 0.022uF = 22nF). More here.