I’m a big fan of the Fishman Aura Spectrum DI. If you don’t have something like the Taylor Expression system on your acoustic, it can vastly improve your plugged in sound, particularly for live situations. If you have a piezo on an electric or slimline guitar, it does the same, but because of the more “neutral” sound, I’ve found you can use it to give you all sorts of different acoustic sounds. Fender even do this with their Acoustasonic Tele.
Since using it to give multiple sounds on an acoustic guitar, something I’ve wanted to be able to do is switch presets with a footswitch. I had a look at the circuit and figured out a straight forward way to do this. Warning: This will void your warranty and I am not responsible for any damage to your pedal.
I now recommend wiring up both sides of the DPDT switch and wiring to pins 3/4 instead of pins 1/2. The reason for this is that it puts on the “preset” slots at the end (13-16), and means you only loose 4 slots. This makes more sense to me because I set the presets all the same (my main sound) and that set an alternative on the dial. If you like to set up pairs of sounds with a different preset on each one, then use my original mod of just soldering a single side of the DPDT to pin 1.
How I did it:
1. Use pliers to remove the ring around the anti-feedback switch. The anti-feedback switch is a momentary switch and we need a latching one.
2. Use hex keys to remove the base of the pedal, and remove the battery clip as you do.
3. Locate the rear of the anti-feedback switch and remove the clip for that too.
4. VERY CAREFULLY use a sharp craft knife or scalpel to cut down each side of the switch to remove the plastic washer that stops you removing it. I found if I bent the switch to one side while I did this it made it easier. I’ve owned two versions of the Fishman Aura DI, and the older ones didn’t have this, so you could just remove the switch, if you do you’re lucky, this step took me a couple of hours!
5. Insert the new switch, I used some rubber washers to space it. Alpha’s small DPDT footswitches fit, and appear to be the same as what Fishman are using. They’re available on eBay: http://www.ebay.co.uk/itm/131175360378
6. Connect one pin of the switch to the 2nd pin of the 16 position rotary encoder (bit 1), and another pin to ground.
– There are multiple ground points, use the one that’s easiest, but I used the ground for the rotary encoder.
– From left to right the pins of the rotary encoder are: Input, bit 1, bit 2, bit 3, bit 4
How it works:
The 16 way preset switch is basically a rotary encoder counting from 0-15 in binary. As it counts, it connects each of the 4-bits to ground. We’ve connected the switch to bit 1, which means that it will increase any of the off positions (in binary even) by 1. So it will switch between preset 1 and 2, or preset 3 and 4, 5 and 6, etc. If you are on an even position (in binary odd), bit 1 is already grounded so the switch does nothing, i.e. positions 2,4,6,8 won’t be switched.
– If you could get access to the other side of the PCB, you could disconnect the input to the rotary encoder and switch that. This would give you a better switching system, where you always switched between preset 1, and what you had set on the preset dial. I didn’t feel confident disassembling things that much though, so elected for the simpler system.
Recently been interested in changing the neck pickup on my guitar to a humbucker that has a coil tap that doesn’t seem to have such a large drop in volume. There seem to be a few different ways to do this:
Dimarzio had their DP157 Multibuckers which where two of their rails pickups in one. While both rails where humbucking, one was designed to sound like a humbucker, the other a single coil. Dimarzio discontinued it, and when I emailed to ask why they said “the parts used for it are no longer available”, I’m not sure why that should be in our technologically advanced age, but maybe its because of a legal dispute or something.
Lindy Fralin have their Unbucker pickup which has two heavily mismatched coils. When its coil split, it then has a higher output coil than a humbucker that is just split in half. It sounds pretty good, the disadvantage is that you don’t have full hum cancelling in humbucker mode:
3) Asymmetric coil tapping
Asymmetric coil tapping, doesn’t split the pickup in half like a coil split, it takes one coil and then a few extra winds from the other coil. The disadvantage here is that you don’t have a true single coil anymore: http://www.geminipickups.co.uk/coil_taps_31.html
Finally, this is an idea I had, how I think it should work though is mismatched coils like the Unbucker so that the coil split has more than half the winds, but also a coil tap of the overwound coil when in humbucking mode so that the coils are matched again and you get a proper humbucking tone and hum cancellation. I think it can still be done with a 4 conductor cable, but the connection points would be different than a standard one. Something like:
-------------------------- Single coil hot
| 1.5K |
Coil 1 ------------------- Humbucking hot
| 4K |
-------------------------- Single coil ground
Coil 2 | 4K |
-------------------------- Humbucking ground
How it would work is that when you want a single coil you would connect the extra windings on coil 1 and use the middle point between the coils as ground. For Humbucking you would coil tap coil 1 it had the same number of winds as coil 2 and use the humbucking ground. In this example in humbucker mode you get an 8K true humbucker. In single coil you get 5.5K true single.
I also found out PRS are doing something similar, but I can’t say its exactly the same: