EH Memory Toy Calibration Procedure
This is my own experimentally-determined procedure, it did not come from EH. You will need an oscilloscope and a signal generator. For best results, do the steps in order. Given the wild variability in these units from the factory, even a unit that has never had the trimpots touched might benefit. (I had one that sounded terrible from the factory, which cleaned right up after calibration.)
1. During calibration use the power supply you will be using normally — whether battery, 9.6VDC, or 9VDC regulated. The pedal is sensitive to supply variations (particularly with respect to its oscillation threshold), so don’t calibrate on one supply and then use it on a different one.
2. Set the mod depth with TRIM8 first, by ear, while listening to the pedal. You may have already done this.
3. Connect a 200Hz sine wave signal to the input on the bench (nothing in the output). I use a large signal amplitude (1Vrms) to ensure that I will be able to clip the BBD chips to see where their limits are while biasing. Set the delay control to max, feedback to mind, and blend to max, and turn the mod off.
4. Hook up the scope probe to the test point labeled “BBD1.” Adjust TRIM1 to get a center-biased signal. As you turn up the amplitude of your signal generator, you should be able to see both top and a bottom halves clip at the same time. If one side clips first, it’s not center-biased.
5. Repeat step 4 with the other test points. Adjust TRIM2 while checking BBD2, TRIM3 while checking BBD3, and TRIM5 while checking BBD4.
6. Disconnect the signal generator with the scope probe still connected to BBD4. After adjusting the timebase down on the scope, you’ll be able to see the clock signal here. TRIM6 is the clock nulling control. Turn it back and forth to see what happens to the clock signal. You want all the horizontals in a row, not offset from each other (when they are offset, you get whine and grit in the delayed sound). This is a ROUGH adjustment — the clock signal is not perfectly symmetrical, so what looks good on the scope here is not necessarily optimal for sound.
7. Fine-adjust TRIM6 by ear while listening to a guitar signal in the pedal. Set the pedal to max delay, with mod ON, feedback up about 2/3, and blend up about 2/3. There is a broad range over which whine is not audible, but you will find that repeats will sound “grainy” if the clock null is not optimally adjusted. With some care, you can get a reasonably grain-free repeat sound, using VERY small adjustments to TRIM6.
8. After the clock null is set optimally, use TRIM4 to set the feedback loop gain to your taste. Generally, I set this control so that the pedal oscillates with the feedback knob at max, but not at lower settings. This is a matter of personal preference.
9. Finally, use TRIM7 (if your pedal has it, early units do not) to set the overall gain of the pedal. This should be set so that it doesn’t feel like there is either a volume boost or a volume drop, versus the bypassed sound, when engaging the pedal. I generally set this for a unity gain sound with blend at midpoint.4 notes
Custom high-gain distortion. Three levels of asymmetry, with the usual gain/tone/volume controls.
Maybe I should call it “The Most Expensive [Looking] Distortion In The World.” I don’t always polish enclosures, but when I do, I use ridiculously expensive machined knobs. Stay fuzzy, my friends.74 notes
Anonymous said: Where do you get your solid-core uncovered wire? Do you have other wire recommendations?
It’s just regular 16AWG tin-plated buss wire. Nothing special. Most electronics supply houses (or MI-specific retailers, like tube dealers) have it, in whatever gauge you need. I use it for certain amp-building applications where I need the wire to hold a shape and stay put (e.g. Soldano-style flying heater wires) as well as wiring up connector plates where I want to be able to use the wire itself as a terminal to solder to.1 note
Speakon + 1/4” cabinet connector dish, with impedance (series/parallel) selector switch. As I’ve written before, Speakon is a fantastic connector standard and it’s a shame that it’s only used on bass gear. Tube guitar amps could benefit enormously from the security it provides, given the destruction caused by the sudden open-load condition when the speaker cable gets pulled by accident. I make/use this connector dish on all my cabinets.15 notes
Anarchotremitivist Mark II (opto trem). The previous version was fairly close to the Demeter Tremulator but with some significant component differences. It did a Fenderish “bouncy” pulsing tremolo sound — which was great — but very little else. I wanted more flexibility, so this has now morphed into something much wackier. It runs at 12V for headroom (both in the LFO and for the clean signal), and uses a vactrol instead of optoisolator. Large controls are rate and depth, as before. Smaller controls are, right to left: symmetry, LFO shape, and make-up gain. It can make just about any tremolo sound imaginable.5 notes
Here’s a self-indulgent post about my favorite thing in the world of guitar right now. I’m using this setup to record the film score (in collab with Mike Armine) to Justin Jackson's feature documentary on Rosetta. It’s low-key, ambient, and droney (of course!) — but more importantly, it’s tonally really clean. This little corner is making the most beautiful clean guitar sound I’ve ever heard, the end product of no small amount of research, experimentation, and building. I love the sound of a Fender Twin; this is its opposite.
Custom EGC Firebird > varitone box > Klone > tuner > 5-knob compressor > TR-2 tremolo > Memory Toy > OCD/Rat hybrid (rarely used) > patch bay > modded CE-3 (stereo) > vol pedal (stereo) > Space Echo (stereo) > Tera Echo (stereo) > patch bay (stereo) > Atomium Model A head (both inputs driven) > Atomium V212 ported cab w/ Weber Alnico Silver Bell & Alnico Blue Dog.
MODS for 5150 II / 6505+
These are my combined mods for the II/+ version. The lead channel is the same as the first 5150/6505 except for three capacitors and a resistor. The clean channel is completely different, using a separate 12AX7 rather than swapping out circuit values inside the same gain structure.
Disclaimer: DO THESE MODIFICATIONS AT YOUR OWN RISK. YOU SHOULD KNOW HOW TO WORK SAFELY ON HIGH-VOLTAGE CIRCUITS BEFORE ATTEMPTING THESE. I will NOT provide support for DIYers doing these mods, so please do not ask. I developed them myself (they are not a knockoff of Voodoo or FJA, which I have never heard nor seen in person), and I’m posting them for informational purposes. If you need help, I can do these mods for you affordably.