Tap Trigger Pedal

My favorite part of running a custom shop is when I have time to work on these oddball projects. We’ve had a few similar prototypes over the years but decided to finalize the design in what you see on this page. The goal was to create a circuit that triggers when physically tapped anywhere on the casing. Then we can tie that trigger into existing circuits such as turning a pedal on or off (as shown below) or functioning as a replacement for a tap tempo pedal.

So you might be wondering what the point of this is- why not just press the on/off switch on the Boss pedal shown below; or why not just use a standard momentary switch for tap tempo? The simplest answer is preference. Footswitches work great for feet but can be clunky and imprecise for musicians sitting at a desk, keyboard players, or anyone using their hands to activate. Tapping a pad is easier to tap on beat than pushing a foot switch. Drummers can trigger a device by tapping the device with a drum stick. This device is for a very specific purpose and likely doesn’t apply to most guitarists.

A quick run down of the controls on the red tap tempo prototype:
• Big Rubber Pad for tapping
• Sensitivity knob – controls how hard you need to tap to trigger the device
• Red LED – indicates when the device triggers. Great for troubleshooting and confirming the device is firing when expected
• Override Toggle Switch – this functions as a backup for when tapping isn’t needed. This momentary toggle switch will short the tip to ground like any traditional tap tempo switch.
• Output jack – 1/4″ out to connect to control device
• 9V DC jack – very low power draw (a few mA) but does require external power.

Below is what this tap tempo prototype looks like when tied into the bypass switch of a modified Boss NF-1.

A quick function check on a modified NF-1

This circuit board was then trimmed down to be smaller than a 9V battery and fit in the battery compartment of any standard pedal. Below is an install of the circuit to control the bypass of a Boss DM-2W. The pedal should only activated when the pedal itself is tapped and should not be sensitive enough to trigger on or off when the jacks are bumped.

This pedal should activate only when the case it tapped and NOT when the jacks are tapped.
A peek at the circuit board with the smallest sensitivity adjustment trimpot installed in the battery compartment.
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Digitech PDS Series Pedals

Digitech PDS 20/20 2000 8000 and 1002

We’ve been posting about these old Digitech PDS series pedals for years both as restoration projects and overhaul mods to make the pedal function better than new. I think we have a good sampling of the delay pedals shown above – all fully restored with various modifications performed depending on what we were experimenting with at the time.

Since these pedals are now approaching 30+ years old we like to do the basic maintenance of cleaning, replacing hardware, install a standard “Boss style” 2.1mm DC jack, new mechanical foot switches, upgrade aging components or just low quality op-amps. The goal is the improve the analog section of the pedal while keeping the original digital circuitry all original when possible. We want the pedal to be reliable but we’re not trying to reinvent the sound. The biggest sonic change that we recommend would be installing a high-cut knob to roll off the treble and give a much more ambient sounding delay.

Other nice-to-have options include replacing the LEDs with something a bit brighter or to just match the color of the pedal. For the PDS 20/20 above we installed a foot switch to bypass the modulation effect making it even more versatile. We’ve also experimented with adding modulation to the PDS 1002 but at the end of the day decided to keep it simple.

So many ICs

Experimental mods listed above are not necessarily available to be ordered. Please check out our modifications page for what’s currently available on the PDS series pedals.

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Custom Fixed Wah

Here’s another personal project used to test out some new designs and ends up going into the collection of oddball pedals. The goal was to take a Crybaby wah circuit and make the smallest PCB possible while also adding functionality. Some favorites from this fixed-way pedal:
1. Added Resonance and Midrange knobs plus a Frequency toggle switch
2. A volume boost circuit plus volume knob since filter pedals can cut the volume when activated.
3. Pads for both a Fasel inductor or the standard one found in Crybaby wahs for years.
4. Expression pedal jack so the pedal could be controlled like a more traditional wah pedal.
5. Socketed transistors to allow for experimenting.

Overall this ends up being a very versatile filter pedal in a reasonably sized Gold 125B enclosure from Small Bear.

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DIY Tool Recommendations

Here’s a list of tools I either use or recommend for people getting into modding and building their own pedals. I’ll update if anything new or exciting comes out but these are the basics:

Soldering Irons:
Hakko FX-888D – A popular mid level soldering iron. Lots of tips available, heats up quick, good overall iron.
Hakko FX-951 – Twice the price of above but is a great choice for extensive SMD soldering.

Soldering / Desoldering Accessories:
Kester Lead-Free Solder – Buy a pound so you don’t run out mid project.
Solder Reel Dispenser – Put your reel of solder on a dispenser for easier positioning.
Hakko 599B Tip Cleaner – Brass shavings to clean the soldering tip instead of a wet sponge.
Solder Sucker – A great option to have on hand in addition to desoldering wick.

Weller 170MN Shearcutters – Seriously, buy a pair of shearcutters. I see so many people using wire cutters which just can’t get in tight against the PCB to clean up the leads after soldering.
Bosch power drill – A good general purpose drill that’s not too heavy or oversized.
Seiko Step Drill Bits – Step drill bits are great to have on hand for opening up holes to a slightly large size. Be sure to check fitment as you drill to make sure you don’t accidentally go one size too far.

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Warm Audio Jet Phaser – Part 1

Warm Audio Jet Phaser Modifications

We love the old Roland AP7 Jet Phaser and have seen a few in over the years for modifications and repairs. Warm Audio’s clone is fairly accurate to the original which means it benefits from our modifications to separate out the Phaser and Fuzz circuit into two separate foot switches that can be activated independently. We also break out the goofy 6-position Mode switch which combines the bypass switch for the fuzz, tone control for the fuzz, and depth control for the phaser.

It’s interesting to note that the pedal is being marketed as true bypass, however the two units we’ve reviewed absolutely are not true bypass and use the same FET bypass system found on the pedal this was copied from. The first one we received also had a defective power supply that sounded considerably worse than battery power. A bit concerning for quality control on an otherwise beautiful pedal.

Mods include:
1. Install additional center footswitch so Phaser and Fuzz can be activated separately.
2. Convert pedal to true bypass.
3. Install status LEDs for phaser, fuzz, and fast footswitch.
4. Install fuzz Tone knob in place of the Mode 6-position rotary switch.
5. Install phaser Depth 3-way toggle switch: Low, Medium, and High settings.
6. Install volume boost circuit to increase the output of the phase circuit. This can be adjusted internally

This pedal has a unique design with a thick, aluminum plate on top of a steel enclosure. That makes it time consuming to drill and requires special hardware with a longer shaft. For those reasons the mods on this page will not be offered in this form as an Overhaul mod. We expect to have a more practical overhaul mod available in the near future which utilizes the two existing footswitches to act as bypass for fuzz and phase circuits.

Don’t own one already? Purchase a stock Jet Phaser and have it modified.

Factory footswitch hole showing the steel chassis with thick, aluminum plate.

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Tubescreamer TS9 / TS808 PCB Assembly

This circuit board started out as a way for us to test some PCB design features that we wanted to bring to other products that we offer. In the first photo you can see our first shot at making tubescreamer circuit board and our revised board (lower) that was cleaned up a few years later.

This 54mm x 21mm layout can fit in a 1590B enclosure (think MXR Phase 90) or we could put two in a single 125-B enclosure. This is a great option to be installed in a Big Muff like in our Tripel Big Muff.

Overall this was a fun build. Some key upgrades include using film caps instead of 1uF electrolytic caps, a socket for the op amp that holds a vintage JRC4558DD, Nichicon high voltage caps so it can operate at 18V if needed, and TS808 resistors are labeled separately since that’s a common swap on the TS9 circuits. Another design choice was to place the diodes on the back side of the PCB. This gives easy access for installing diode-selecting switches in the future or if we wanted to try some oversized or oddball diodes. Below is a quick video of what a typical assembly process looks like. It’s a 2 minute video but covers about a 30 minute process. Please enjoy the generic, royalty-free rock music.

PCB assembly video
Finished project; white knobs are a stand-in until the black aluminum knobs arrive.
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Boss CE-1 Power Conversion

Our Boss CE-1 power conversion bypasses the internal power transformer and allows the pedal to be powered by an 18V DC power source rather than plugging into a 120V AC power source. This can be helpful for people that live in areas with different voltage standards or just for making the pedal pedalboard-friendly as it’ll be compatible with an isolated 18V DC power supply.

We’ve found that the Dunlop ECB-004 is a great option for our mods as it’s readily available and high quality. However, any quality power supply can be used if it’s:
1. 18V DC
2. Tip Negative
3. 2.1mm Barrel Jack
4. 100mA or higher
5. Isolated (no daisy chains or Y cables)

Another consideration for this project was the value of the pedal and preventing any permanent modifications to the pedal. This mod is entirely reversible with the stock transformer remaining untouched, the power switch wiring isn’t modified, the new power circuit (small, purple rectangle seen above) is mounted using pre-existing holes in the chassis, and the DC jack fits in the stock power cable hole.

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Make Your Own Cables

There are plenty of reasons to build your own cables which I’m not going to get into here. If you’ve decided to go ahead and customize your pedalboard, repair your broken cables, or build new ones from scratch these are our recommendations:

Pedalboard & Patch Cables- really anything that isn’t going to be strained, pulled, and unplugged constantly:

  • Jack- right angle, smaller barrel for tighter boards, gold contacts for corrosion resistance.
    • Amphenol ACPM-RB-AU
  • Wire- thin, flexible, easy to work with.

Instrument Cable – long leads that will need to take abuse:

  • Jacks- very durable, unique clamp keeps the wire from pulling out, easy to solder.
  • Wire- durable, coils nicely without tangling, excellent shielding and conductivity.

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Ibanez TS-9 Tubescreamer PCB Repair

Copper washer (left) to repair a broken PCB (right)

The 9 Series Ibanez pedals secure the PCB to the chassis using a single screw right next to the DC jack. As these pedals age and become fragile the board can crack around the mounting hole. A copper washer is a quick way to repair the board and prevent further damage.

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Shin-ei Uni-Vibe controller (Part 3)

This is an update to a previous post writing about a hand controller to replace the rocking “wah” style foot controller for the vintage Shin-ei Uni-Vibe pedal. Unfortunately for these pedals you can’t switch them on/off and can’t adjust the rate without a controller of some sort. This is a great option for studio use or for anyone with less space on their board and don’t need to adjust the rate on the fly. This updated version has a 5-pin DIN jack rather than an attached cord for more flexibly in cable length. Currently posted for sale on the FXdoctor store.

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