Adding Distortion To EMG Pickups

[afu]

I have a set of James Hetfield pickups from EMG. I got the idea to add some diodes and give it on-board distortion. The preamp has more headroom than the 81, but I have no problem getting a good sound. It's kind of a cross between an OD and a fuzz. It buzzes like a fuzz, but is subtle. Using Raw mode or Pushed on my Dual Rectifier gets some very cool tones. Playing the clean channel allows for some wild dynamics. I also tried it through my Harmony and I was ready to drop acid and say everything is groovy.

Here's a diagram:
https://www.dropbox.com/s/0uqpgelc1grbgj3/EMG%20Fuzz%20Circuit.jpg

 

[afu]

Here's an alternate way that offers more control over the fuzzstortion and sounds better.

https://www.dropbox.com/s/f3eixl6pgxin6ax/EMG%20Fuzz%20Circuit%20Ver2.jpg

 

[Jorn218]

That is pretty intuitive afu. Do you have any sound clips of this? Maybe a/b switching the diodes in and out showing the difference between without and with diodes?

I only have an old set of hard wired EMG's and the only mod I have found that actually works for me is the 18v mod. I did the reversible version of that mod. The only thing I noticed with that mod is with the amount of "distortion" I use in my setup, the mod cleaned up the pickups so that my picking was discernible at volume. Cleans got a bit more sparkly as well, but the output gain overall was about the same. So I figure the 18v mod only adds some clean headroom, but output remains the same FWIW.

 

[afu]

I tore my rotator cuff and look/feel like a cripple right now, so I'm not making a video yet. I played yesterday for a little bit after tweaking to that design and I'm in a lot of pain for doing so. The mod's mix control actually takes almost all of the clipping out unless you really, really SLAM the strings. My JH pickups are in a guitar that had the 18V mod for an 81/85 set and I never changed it, so I'm using the higher voltage, too. I'm going to eventually make it 9V again and see what the difference is.

With the older EMGs, the 18 Volt mod improves clarity by supplying more voltage to the op amp. It can only put out as much as the source voltage. A 9 volt battery is divided to supply +/-4.5 volts. That's why they list the maximum output voltage as that. When you do 18V, it gets split to provide +/-9 volts to the op amp. Since an op amp cannot output a larger voltage than it's supply, it's easier to clip at the lower voltage as it approaches the max. Raising the supply doesn't really make your output much higher (if at all), it makes it cleaner and it sounds better.

With the Fuzz mod, I have my Modern mode on channel three with the volume at 9:30 or 10 and the gain set around 9. It sounds like a Big Muff without the brick wall compression. In Raw on channel 2 and gain at about 10, it is more like a Fuzz Face. Channel 1 Clean sounds like the Gibson Fuzz on '(I Can't Get No) Satisfaction'. The end result is very dependent on the amp and how the player plays, but it's fairly intuitive to get the feel of it.

When I turn the mix down, I get more headroom and the volume change is rather subtle. I can tell it increases a little, but it isn't incredibly different. The diodes are cutting my headroom to roughly .7V/1.4V + the pot's voltage drop when they are full on. It's most apparent on the 6th and 5 strings, since they oscillate more. I haven't put the meter on it to confirm how far it rises, but when I turn the mix completely down it becomes rather difficult to create clipping, as much more of the original signal voltage is being applied to the circuit by the larger voltage drop across the pot.

 

[afu]

Also, I talked to Seymour Duncan and they told me how to split a Blackout. I have an untested diagram almost ready that has the split and fuzz on a 5-way Strat switch. If you ignore the switch and the splitting, the fuzz control would apply to your hard wired guitar. The pickups would go to the switch and then into the pots.

 

[afu]

https://www.dropbox.com/s/8eu7wihylme9ox4/Blackouts%205%20way%20diode%20split.jpg

This the Super Strat Blackouts coil split and fuzz mod. It's untested, but the coil splitting and fuzzing have been done before, separately, with other pickups. I'm just "synergizing the paradigms". Just kidding. I saw that phrase earlier and it makes me laugh.

To be honest, there are so many ways to go about something like this: switches, push/pull pots, a small circuit board with a few more chingaderos on it. For about $10, someone could make a clean preamp booster for passive pickups and completely design a full blown fuzz/distortion/OD into it with minimal parts (a push/pull pot or DPDT switch, a few resistors, a cap or two, an IC, and diodes). Replace the diodes and IC with some transistors and you can have a quite useful old school fuzz without having to pay someone else to put it in a box, mark it up 300%, and call it "boutique".

 

[afu]

I messed around earlier and had some observations and opinions about the EMG mod.

1) There is a possibility of having the pickups too close and sending such a strong, square signal that the diodes do little, but make a BLAT tone.
2) The lower the threshold, the better this works for variety/touch/dynamics. I ended up putting a different combo of two diodes into it to make the response easier to control, but I prefer the asymmetrical sound. I have some germanium diodes on order and will experiment with them as soon as they arrive.
3) I tried swapping the order of pots, swapping connections on the tabs, moving the pickup height, and placing the diodes on the other pickup. I ended up back at the version 2 wiring, with the diode change, and backed the pickups off from the extremely close position I had them at.
4) The pickup height is crucial to determining if the character of the clipping will be soft, hard, fuzz, buzz, or BLAAAAAATT! These are small adjustments. 3 turns of the screws moved me from softville to BLAT Land. It requires some tinkering and finesse.
5) Having it always on by removing the mix control and placing the diode wires on the tone sounded really, really good, but the flexibility of adding original signal back in is a good trade off.

I just designed and started building a new amp. This is my distraction from the frustration of advanced math and gutting a crappy amplifier.

 

[afu]

I set up a blog at: http://warpedmusician.wordpress.com/

That way, I don't take up more and more space expanding on this. There's other stuff there, too.