effdub, Author at EffDub Audio

March 3, 2023 effdub

Shoot the Moon Tremolo

The Shoot the Moon Tremolo is an optical tremolo originally based on the excellent Tremulus Lune circuit by 4MS/CommonSound. The audio path is similar, but the LFO has been simplified to three controls: Speed, Depth, and Shape (wave shape). The power supply section has also been overhauled to provide better electrical isolation between the LFO and the audio portions of the circuit, and both sections are physically isolated as well. The result is a dead-quiet tremolo that goes from triangle wave to almost square wave (that is, smooth to choppy).

There is also a Gain control so that the output of the circuit can be set for unity gain; or it could be used as a boosted tremolo, if desired. Additionally, with the Depth at minimum and Boost set to greater than unity gain, the circuit can be used as a handy-dandy op amp booster with no amplitude modulation at all.

Download the Shoot the Moon Tremolo file pack.
Contains: Schematic image, PCB layout image, legacy PCB build guide document with notes, and Eagle CAD files.

Effects Projects

March 3, 2023March 3, 2023 effdub

DuoVibe – Optical Vibe / Phaser Project

The DuoVibe is an optical vibe / phaser and is yet another expansion on Tim Escobedo’s “Wobbletron” circuit snippet first published in 2005 (which is also very similar to the basic phase shift stages in the classic Univibe circuit). I have done several iterations on this cool little building block snippet over the years, and I feel that this one is a nice compromise between simplicity and functionality.

The DuoVibe is a two-stage optical vibe circuit than can also cop subtle phaser tones. The LFO is modified from the Shoot the Moon Tremolo (itself derivative of the Tremulus Lune) and is capable of triangle wave and near-square wave output. The pitch bend in vibe mode is discernible but not capable of “seasick” wobble. With the depth cranked, you can think of it as a sort of “tremolo with pitch funk going on” kind of thing.

There is a Vibe/Phase Mode switch, the name of which indicates its function and purpose. This switch simply toggles a feedback filtering cap value, but is useful despite the simplicity. See the mods section in the downloadable file pack below.

Download the DuoVibe file pack.
Contains: Schematic image, PCB layout image, legacy PCB build guide document with notes, and Eagle CAD files.

Effects Projects

February 24, 2023October 3, 2024 effdub

PT2399 Delay Project – The TweakTone Delay

The TweakTone Delay is a PT2399 delay project with highly filtered repeats and the possibility of very long delay times (and minimal delay line noise). There is also a tone control trimmer to adjust the high-pass cutoff frequency on the repeats.

The circuit is based on the Mad Professor Deep Blue Delay, and has been heavily modified to adjust filtering, repeat/echo volume, feedback characteristics, and increased maximum delay time. The added filter control trimmer is also a differentiator, and it could be wired as an external control, if desired.

TweakTone Project Files / Notes

Download the TweakTone PT2399 delay project file pack, which includes: Schematic image, PCB layout image, legacy PCB build guide document with notes, and Eagle CAD files. The layout is for board-mounted pots and fits in a 125B sized enclosure.

The stock values of this PT2399 delay project yield a max delay time of approximately 550ms – 600ms. With a minor modification (see file pack), max delay time can be extended to almost 900ms. Granted, at these longer delay times, the filtering is very aggressive and murky and you will lose some volume from the repeats, which can also change how much feedback there is.

Longer Delay Time

Change the Time pot to A100K and then add a 270K resistor in parallel with Time. You can add the resistor either to the pot pads on the board, or you can use the pads marked “M1” and “M2” (see below for more info on these). Adding the 270K resistor brings the Time pot’s total resistance value down to about 75K, which is about the limit of what this circuit can handle without getting noisy and producing synth-‐like repeats (more resistance = more delay time). If you don’t have 270K on hand, try 220K, but be aware that this will give you less max delay time. Or you could put multiple resistors in series to get close to 270K.

Modulation Add-On

The pads marked “M1” and “M2” are there to make adding off-‐board modulation neater and easier. The original intent was to use an LFO that drives the classic LED/LDR combo to offer variable resistance as the output. However, you do not have to use an optical LFO, and most any LFO designed for PT2399 use will work fine.

Disclaimer: some links on this page are affiliate links.

Effects Projects

February 24, 2023 effdub

Zen Drive Project – Bodhi

Back in the day, the Zen Drive from Hermida Audio was a super-hot, super-hyped, super-loved boutique overdrive pedal. It was on everyone’s board, from P&W church bands to post-rock hippie ensembles. Many said it was magical and unlike any other drive pedal; some said it was “just a Tubescreamer with big price tag”. Turns out they were both wrong. It’s actually a semi-original drive circuit, starting off like a Tubescreamer but ditching the famous “mid-hump” tone control and opting instead for a simpler buffered passive tone (high) cut, as well as adding the “Voice” control that adjusts frequency gain in the first op amp stage. Cool, I suppose. If you’re into that kind of thing.

Zen Drive Clone Project: Bodhi

So I figured I’d rustle up my own Zen Drive PCB layout. I made this one way back in the days when doing so would get you branded as a “pirate” or “thief” or even “terrorist.” Hyperbole is a crutch for the callow and unimaginative carnival barkers of society. 🙂

This layout has offboard wiring of everything, which makes it suitable for the DIY who doesn’t want to be constrained by precise drill layouts. I updated the artwork in 2023, but the original layout dates from 2012.

Download the Bodhi File Pack, which includes Eagle CAD files, schematic and PCB images, and gerber files for having your own PCBs fabricated.

Zen Drive Schematic – Bodhi Version

Effects Projects

February 24, 2023 effdub

Bazz Fuss Project: The Onesie

The Onesie project is my contribution (one of them, anyway) to the long and glorious history of a fantastic DIY fuzz circuit known as the Bazz Fuss. It’s super simple and sounds fantastic. With just one transistor, one diode, two capacitors, one resistor, and one potentiometer, the Bazz Fuss delivers a hell of a lot of fuzzy goodness despite it’s simplistic design. It’s very difficult to get great tone out of such a small number of components, with the only other similarly efficient circuit I can think of being the Electra Distortion.

This iteration of the Bazz Fuss stays true to the original (brought to you by a fellow known as “Hemmo” and popularized by the fine folks at RunoffGroove.com), but is built on a PCB that mounts directly to a 3PDT footswitch. This avoids the necessity of precise enclosure drilling, as you can mount the pot anywhere you like and simply run leads from the switch-mounted PCB.

The layout includes pads for bypass LED and current-limiting resistor, as well as power filtering and reverse power polarity protection. It’s very easy to build, and very cheap to have PCB fabricated. It’s a DIY dream, in other words.

Build Your Own Bazz Fuss Project!

Download the Onesie File Pack, which includes schematic and PCB images, Eagle CAD files, and a bonus turret or eyelet layout image.

Effects Projects

February 24, 2023October 3, 2024 effdub

Electra Distortion – Schematic and Layouts

Several people have asked me to repost my older layouts for the often copied (and frequently sold for big bucks, see below for details) Electra Distortion circuit. This is a surprisingly good-sounding circuit for so few components. No fancy parts needed; just a fun little circuit that swings way above its weight.

The name is a little misleading, though. It’s really not a distortion in the modern sense of the word. At best, it’s a medium overdrive gain-wise.

My old schematic drawing and two different DIY layouts for the Electra Distortion are posted below. One is for perf board and the other is for building the Electra on an eyelet, turret, or strip board.

If you like simplicity and great tone, also check out my “Onsie”, which is a very classic take on the old Bazz Fuss circuit, as well as my “SmallBazz” project, which is a germanium mojo-infused version of the Bazz Fuss.

Electra Distortion Schematic

Electra Distortion DIY Layouts

The first one is for perfboard, while the second is for an eyelet / turret style build.

Cash Cow: The Electra Distortion in the Boutique Pedal World

As mentioned above, the Electra has made its rounds in the boutique pedal world, ranging back to the earlier days when everything was a mystery and before folks like FreeStompBoxes were willing to tear things apart and see what was under the hood. Perhaps the best known, and widest selling, is/was the Church of Tone 50 by Lovepedal. Also knowns as “COT50”, there were no less than a dozen different slight variations of this pedals sold over many years, all being slight mods on the classic Electra original.

Lovepedal also sold other pedals with essentially the same circuit (very minor changes), including: Les Lius, Tchula, Champ, JTM, and others. The mileage squeezed out of this one simple circuit is simply astounding.

Another very successful Electra variant is the Speaker Cranker from Earthquaker Devices.

Disclaimer: some of the links on this page are affiliate links.

DIY Effects Info

February 24, 2023October 3, 2024 effdub

6P14P versus EL84 Vacuum Tubes: What’s the Difference?

If you’ve searched ebay for EL84 / 6BQ5 vacuum tubes, you’re probably also seen listings for mysterious Russian-made tubes with the part number 6P14P (or the Cyrillic alphabet equivalent 6П14П) and wondered what the heck was going on with those. What is the difference, really, between 6P14P versus EL84?

6P14P versus EL84: The Simple Answer

The short/simple answer is: “Not much!” Mostly the differences come down to minor spec variations and that 6P14P tends to last quite a bit longer. A typical operating life for 6P14P is approximately 10,000 hours, whereas the average new-production EL84 tube has an expected life of 3,000 to 5,000 hours.

Another interesting difference is that the 6P14P has an astounding 10% variance in acceptable heater voltage requirements. An EL84, on the other hand, requires a very precise 6.3V heater voltage.

6P14P tubes (valves) are pin-compatible with EL84 / 6BQ5 tubes and will work just about anywhere you would normally use an EL84, including guitar amps, tube radios, and hi-fi stereo gear (like dual mono-block amplifiers). It’s possible there is an application where a 6P14P wouldn’t be up to the task, but I’ve not run across one yet.

6P14P History: Soviet Military

I’m not Soviet-era tube expert, but based on a plethora of Google research, it would seem that 6P14P tubes were made from the 1960s through at least the early 1990s. They were made specifically for Soviet military use and are very robust, being heavier and generally having a much longer service life than a comparable EL84. As far as I can tell, all 6P14P tubes were made at the Reflektor manufacturing plant in Saratov, Russia. This is the same factory that makes Sovtek tubes, as well as several other popular new-production and reissue tube brands, including: Electro-Harmonix, Tung Sol, and Mullard (and probably others, but note that the new Telefunken tubes are made by JJ Tubes in Slovakia).

6P14P Date Codes

Most tube manufacturers don’t include date codes on their tubes at all, and this includes the vintage brands of the past. However, 6P14P tubes do have a very simple date included on almost all the tubes I’ve seen. It’s right under the logo and part number and is a very simple four-digit code showing the month and then last two digits of the year. In the photo below, the tube shown has a date code of 07 82, signifying it was was made in July of 1982.

Also note that during some years, the month and date numbers will be reversed. I have one 6P14P, for example, with a date code of 91 05, meaning it was made in May of 1991.

Where to Buy 6P14P Tubes

These tubes are readily available on ebay and generally at very reasonable prices. However, almost all sellers are in former Soviet states (Ukraine and Belarus are popular), shipping costs can be high, and mostly what is available is pulled (used) old-stock tubes. Still, for the price and because 6P14P tubes tend to be very hardy, the risk is low as a US buyer.

Disclaimer: some links on this page are affiliate links.

Effects Projects

February 23, 2023February 24, 2023 effdub

Box of Hall – DIY Reverb

I came up with the Box of Hall reverb circuit way back in 2012. The Belton BTDR-2 bricks had just come out, and I wanted to have the first working circuit out on the DIY scene. A whole LOT of people copied this design and called it their own, but this one is the original (from your old pal culturejam).

To be blunt, this design is largely based on the Belton application note’s example circuit, but I added a high-pass filter tone control and changed up other filter cutoff curves as well. I also added an op amp buffer for the virtual ground (VREF) used to bias the other three op amps in the circuit. A subsequent version also added a wet feedback loop to allow for better control of decay time, as well as wacky ambient swell capabilities. I will post that version sometime in the future. But for now, this is a nice, simple reverb circuit that anyone can build and that will sound great.

There is a fair bit of modulation happening in all circuits using the BTDR-2 brick, and that’s something that’s just a part of the brick. You can’t dial it out (but apparently you can drill it out). But, it sounds pretty cool and adds a nice extra layer of complexity in the background. So if you like modulated reverb, you definitely want to build one of these.

Download the Box of Hall Reverb file pack, which contains schematic and layout images, as well as Eagle CAD files (suitable for editing or ordering PCBs directly).

Here’s a demo of the Box of Hall Reverb done by some other guy:

Effects Projects

February 23, 2023February 24, 2023 effdub

SmallBazz – Germanium Bazz Fuss for DIY

I can promise that you haven’t seen this exact circuit configuration in some over-priced boutique pedal. What we have here is my wacko take on the classic Bazz Fuss, a mainstay DIY favorite owing to its low parts count and surprisingly amazing fuzz tone. The original uses a darlington integrated circuit in a transistor-sized package (MPSA13), so I thought I’d spice things up with a discrete darlington arrangement but with germanium transistors instead of silicon. More mojo, amirite? Germanium Bazz Fuss is the coolest.

And to add to the quirkiness of this particular circuit, I decided to go with an oddball transistor: the NPN Germanium 2N1101, which is readily available from Small Bear Electronics. Why this particular part number? Two main reasons: 1) it’s NPN and much easier to deal with in terms of biasing and power supply setup, and 2) I’ve never seen it used in any circuit, and that’s enough for me. Also, it’s cheap and easy to source (at least for now as of 2023). The drawback? It’s not at all a standard package, doesn’t readily fit any existing PCB layouts, and doesn’t exist as a part in any of the common PCB creation applications.

So I created my own part for the 2N1101 in Eagle CAD and set off to create a fun new version of the Bazz Fuss. I added a few extra features: a switch to toggle between two feedback clipping diodes, a gain control, and a bias trimmer to dial in those finicky Germanium transistors. Here’s the schematic:

Once more for the SEO: Germanium Bazz Fuss.