Pro Co Rat installed in an EHX Big Muff

For years we’ve had people send various Big Muff pedals for rehousing into a smaller casing. The circuit board isn’t nearly as large as the casing that it ships in (specifically in the USA reissue) so it’s a great candidate for space savings. Just recently we had a customer request that a Rat be installed inside of the Big Muff to save space. We also installed a Clean Volume knob to each circuit to allow the original signal to be mixed in with the distortion. The end result is two independent distortion circuits in one casing to save space and help simplify a pedalboard.

Assembly Notes: I suspect future builds will utilize the stock LED locations to keep the cost down..

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EHX Deluxe Electric Mistress Rehousing

The Deluxe Electric Mistress is the flanger that we see in here the most. It’s a great sounding flanger but there are so many reasons that it’s not friendly for a gigging musician. We’re offering a standard rehousing service which addresses common problems and keeps the cost lower than doing a custom rehousing each time.

First we’ll take the guts and put them into the 4.5″ x 5.5″ casing that you see above. The jacks are changed to a more conventional layout. We rewire the pedal for true bypass and add a status LED as well. If your pedal is an older model which has a 3-prong cord then we’ll convert it to accept a 24V 2.5mm DC power supply as used in the current models. We found that the best way to rehouse this pedal involves wiring the Color knob in reverse (clockwise is minimum; counterclockwise is max). This is done intentionally and is a result of moving the pots which also support the weight of the PCB. The end result of the changes is a pedal that sounds 100% as it did from the factory but in a smaller, pedalboard-friendly package.

Other add-ons include installing a volume boost circuit to bring the volume up to unity gain or a simple Enhance mod which brings out the highs and lows in order to compensate for the volume drop.

Check out for current pricing and a video to demonstrate the Enhance mod..

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Vintage Small Stone Rehousing

This Small Stone has had quite a history of tinkering and modifications. When it arrived it had broken wires and was literally falling apart. We decided to take it on as a complete rebuild. Every single wire was removed from the circuit board and all modifications were removed so we had a reliable starting point for the restoration. Some of the mods include:

  • Complete rehousing in a 3.5″ x 4.5″ casing with new jacks and switches
  • True bypass with an LED
  • Color switch converted to a stompswitch; the LED turn blue when in Color mode, green when in regular mode, and is off when bypassed
  • Mix and Volume knobs installed
  • Aging capacitors replaced and LFO ticking removed
  • Boss style DC adapter jack installed

Overall this pedal is awesome! These vintage Small Stones just sound amazing and with the new modifications it should provide years of reliable operation..

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Mu-Tron III overload!

We’ve seen all sorts of Mu-Tron III variations throughout the past year. Some early models that don’t have a DC jack, some late models that didn’t have an option for batteries, some bare circuit boards in need of rehousing. These pedals really do sound amazing although their large footprint and heavy casing can be annoying for gigging musicians. My personal favorite mods so far:

1. Install a charge pump so the pedal can operate off of a single 9V battery.

2. Remove the Gain knob and install a Filter Sensitivity knob. The Gain knob adjusts the volume of the pedal both while on and when bypassed which can be a nightmare for keeping a consistent volume throughout your signal chain. Bypassing the Gain knob would set the volume to unity gain; Installing a sensitivity knob would adjust how wide the filter opens without changing the overall volume of the effect.

More info on our Mu-Tron mods can be found on the main site.


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Musitronics Mu-Tron III rehousing

The Mu-Tron III has a legacy of being one of the best envelope filters ever made. Some of the big names that made this pedal so popular include Stevie Wonder, Bootsy Collins, and Jerry Garcia. The pedal sounds excellent but in it’s original state can be a disaster for a gigging musician. The original has a massive enclosure (5″ x 8.75″) and is very heavy with a steel base. It runs on a special dual polarity power supply which makes it not very pedalboard friendly. From the factory it also has a switch to turn off the power which is just one more thing to wear out or become accidentally (unknowingly) switched off.

This pedal functions 100% the same as the original but in a smaller package and a standard 9V adapter jack.

Knobs from left to right: Gain, Peak, Mode

Switches: Drive (left), Range (right)

And a before shot of the original Musitronics 0601 circuit board found inside:


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Boss CE-2 Restoration & Rehousing

This week we received two Boss CE-2 Chorus pedals in different states of disrepair. The first that arrived is pictured above in the left panel. It arrived exactly like that: missing parts, disassembled, and painted black. Although the original paint was beat to hell it still looks better than the faded black paint. Surprisingly the circuit board was 100% original so the restoration was mostly tracking down appropriate replacement hardware.

The original pedal was designed to run on Boss’s ACA120 adapter. This is the unregulated 9V adapter which they’ve long phased out and replaced with the PSA120 9V regulated adapter. Ibanez, Danelectro, DOD, Digitech, Voodoo Lab, Boss, and almost every other current pedal manufacturer uses a regulated 9V power supply. If you hook up a stock CE-2 to a regulated 9V adapter you’ll likely be providing slightly less voltage than intended and– while it will in no way damage your pedal– will have a dimmer LED. We modify the CE-2 and any other pedal designed for the Boss ACA120 adapter to run on a modern powder supply. This mod is also built into the cost of our Overhaul modification.

Speaking of the Overhaul modification, it also includes sonic and aesthetic upgrades. We replace key capacitors in the audio path including electrolytics with Panasonic metal film caps. Also replaced is the main audio op-amp for more headroom and a cleaner tone. Last we install a blue LED and set it to pulse to the rate of the chorus when activated. This makes a great pedal even better!

Here is another CE-2 we received as nothing more than a circuit board. The casing, jacks, footswitch, knobs, and pots are all replacements. Converted to true bypass and installed a large LED for better visibility. All fun stuff and these two exact pedals are currently (as of 9/25/2012) are listed on eBay! I’d love to see someone commission a true stereo output for their CE-2..

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Boss PD-1 Rocker Distortion- Power Conversion

The Boss PD-1 is a distortion pedal with a treadle to adjust the amount of gain. At the toe you have a “warp” switch which is just a high gain momentary switch. It’s very basic and contrary to popular belief it bears no resemblance with the Boss DS-1. This pedal is unique because it’s one of the only Boss compact stompboxes I’ve seen that was designed to run on a 9V adapter or two C cell batteries. The current draw is under 10mA so large batteries are absolutely not necessary for the pedal to function. It uses that large black box (shown below) to increase the 3V from the battery to 10V. A quick conversion allows this pedal to be run on 9V PSA120 adapters (Boss’s current standard) or a 9V battery. Some shots of the internals before and then a shot of the 9V battery holder:


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Measuring bypass systems

So I always write about true bypass systems and how the idea of zero insertion loss is usually beneficial to a guitarist. In this example I had a DOD Vibrothang sent in because the pedal killed the tone when in the signal chain. Using TrueRTA as shown on I made a quick comparison of the signal loss from a true bypass pedal versus the Vibrothang (before and after modifications). In the stock form the signal starts rolling off around 1KHz and dramatically drops blow 200Hz. Keep in mind that this is when the pedal is bypassed which means if you have this pedal plugged in, you’re always sacrificing part of your signal. This loss in midrange will thin out your guitar’s signal and may become a larger problem when combined with other pedals. After modifying the input and output buffer the insertion loss is significantly less overall and the low end roll off only starts around 100Hz which is perfectly acceptable.

I think a project for the future will be taking a variety of pedals and comparing their bypass systems. Also, note that DOD has used a variety of bypass designs in their history so your model may not have the same problems as the DOD Vibrothang..

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Boss Chorus modifications

I’ve always noticed that the Boss CE-5 and CH-1 chorus pedals sounded unnatural. The pulsing effect wasn’t smooth but seemed to pulse like an engine struggling up a steep incline. The effect is even more noticeable once the pedal is modified with our Vibrato mod. The LFO is the part of the circuit that creates the pulsing cycle; when you turn up the Rate knob you’re directly changing the timing of the LFO. Above is a picture of the waveshape at the output of the LFO showing why the effect has an unnatural pulsing sound. You can see in the bottom half of the image how a symmetrical wave form will give a more natural sound and smooths out the stuttering. Video clips will be posted in the near future.


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Overhauled EHX Bass Micro Synth

FXdoctor modded micro synthOne of my favorite projects from the past few months has to be this overhaul of the Bass Micro Synth. It’s just such a cool pedal. The added footswitch bypasses the Voice Mix section and sends your original guitar tone straight to the filter section of the pedal. It basically takes the pedal and gives you a great envelope filter at the press of a button; no need to fiddle with the sliders during a song. The LED was converted to a bi-color LED so it is now red when in standard mode, green when bypassing the Voice mixer, and off when the pedal is bypassed. There are also three added jacks on the back panel next to the input and output. From left to right we have an expression pedal jack for the Stop frequency (using a 100KB TRS expression pedal) and a send and return for an effects loop. Pedals in the loop are placed after the envelope detector and voice mix but before the filter. This allows you to sub in your own type of distortion/fuzz but can also be used for other effects as needed. Information should be posted with pricing on the main website in the near future..

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