La Révolution Deux

Demeter - Compulator

2012-01-28T00:47:00.000Z

[This post also contains info on the Bajaman Optical Limiter]

The Demeter Compulator has been a popular compressor for a while now. It's got a great level of transparent compression available, is built like and tank and uses decent quality components.

Here's the description from the Demeter website:

"The sound of classic studio optical compression of the 60's and 70's at your feet! The first compressor pedal not to suck the life out of your tone.

Operation is fairly straightforward. There are two inputs on the front side of the unit: a 1/4" input jack on the right and a 1/4" output jack on the left with a battery-ground switch on the input jack.

There are two controls on the unit: compress and volume, plus a foot switch to bypass the effect, and an LED to indicate effect operation. On the side there is a trim pot to set the overall gain of the unit.

Compress affects the amount of gain reduction (compression) of the input signal. Turning this clock wise will give you up to 30dB of gain reduction (depending on input gain). Please note that the Compulators max gain is 26dB (see Trim Pot) so in some circumstances if your instrument is very hot you could achieve less than unity gain if you turn up the compress knob too much.

Volume increases and decreases the output volume of the Compulator. Use this for level matching between the effected and unaffected signal.

Trim pot sets the gain of the compressor's pre-amplifier. If distortion occurs turn this down until the signal is clean. The unit is set at the factory at 20dB of gain which is perfect for most instruments. If you have weaker pickups or want to push the envelope turn it up to its max gain 26dB."

And here's a demo video of the Compulator in action:

Works well doesn't it. Well, I've built a couple of these and I love the tone they provide. I can fully recommend the circuit for anyone who needs a quick and easy compressor. The DIY project has been available for a few years now and was provided by the great Bajaman over at freestompboxes.org, here is the schematic and PCB layout files:

PCB Layout:

PCB Transfer:

So there you go - one of the best compressor pedals out there. I will say many people have asked about the VTL5C10; you've got to use it or at least construct your own optocoupler that matches it's specs.

Bajaman liked the circuit so much he based his own design around it with the Bajaman Optical Limiter, here's the schematic - LA2A style optical limiter:

Here's what he says regarding the optocoupler: "The LEDs used are both standard yellow 5 mm types. the LDR has a resistance of about 90 ohms when exposed to the light - sorry I cannot give you the exact number for this part but i found by purchasing from a number of suppliers that there are two common types in this size (5mm circular with top and bottom sliced off). You can test with a multimeter across the terminals - expose it to sunlight and observe the reading - if it is 350 ohms or higher, then you have the wrong type for this project - it should read around 90 ohms."

And a PCB layout:

And a PCB Transfer:

Limiters and compressor, although similar, do not function in the same manner. A limiter will only limit the peak of the wave and won't increase sustain as a compressor will. This is due to the way the envelope follower is configured. Notice that with the compressor the envelope is taken from the end of the circuit (A feedback config) whereas with the limiter the signal is taken from in front of the attenuation circuit (A feed-forward config). This difference may seem trivial but you need to take into account that the feedback config is effectively reacting to it's own changes. I.e - the envelope follower detects a strong sound wave, it decreases gain in the circuit, as the wave strength falls over time the envelope follower detects this and therefore forces the gain in the circuit to rise, the envelope follower then detects this rise and forces the gain back down and so on and so forth. It is this "feedback" action that gives the illusion of increased natural sustain. In a limiter there is no reaction or feedback effect, the circuit simply sees the strong first peak of the wave and attenuates, once the signal drops below the trigger voltage for attenuation to occur the envelope follower is essentially off. Therefore with the limiter you don't get the pseudo increase in sustain.

For reference here's the freestompboxes.org forum topic: http://freestompboxes.org/viewtopic.php?f=7&t=317

Dunlop - Eric Johnson Signature Fuzz Face

2012-01-27T16:58:00.003Z

Well, Dunlop have just issued the Eric Johnson Signature Fuzz Face - it's supposed to give you those "violin" like sustain tones that Eric Johnson is renown for using. Looky at this video for more info (Also, check out that guy's beard - work of art.):

It's basically the same old Fuzz Face formula with these values in place:

But before you go and build yourself one up I'd read the freestomboxes thread. Marc Alfs of Skreddy and Mr Huge of Way Huge have chimed in and they're well on the way to coming up with some really nice stuff. Check the thread out here: http://www.freestompboxes.org/viewtopic.php?f=7&t=15839

MI Audio - Crunch Box

2012-01-27T11:43:00.000Z

Only joking; here's the real MI Audio Crunch Box:

And here's an internal shot:

The MI Audio Crunch Box is a high gain distortion BeAsT! MI Audio make some great pedals and this is one of their most popular designs. It's schematic has been out on the DIY scene for a while but I still get the odd request for it so I thought I'd upload a project for you....

Here's the MI Audio website description of the Crunch Box (I know - it's an image!):

And the ProGuitarShop video of the Crunch Box in action:

Any how, onto the goods. There are two versions of the Crunch Box schematic a V1 schematic from an early model and a V2 schematic from a later model. Here they both are:

As you can see there are a few changes and the V2 circuit has the internal presence control that is mentioned in the MI Audio description. You could say that the Crunch Box is based on the Marshall Guv'nor without the 3 band tonestack (As is similar with the Lovepedal Superlead):

Here's a vero layout and a tagboard layout for the Crunch Box:

(Thanks to Sinner of http://www.turretboard.org for this one!)

Here's a PCB Layout for the Crunch Box: http://www.box.com/s/0xii4uivpp2nxbx1pkzl

Here's the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=221

OKKO - Diablo Boost+

2012-01-26T10:36:00.001Z

Here's another personal favourite of mine. I just love those ridiculously sized LEDs! Anyway, the OKKO Diablo Boost + was donated to the freestompboxes forum anonymously. It's a great sounding overdrive/booster that when combined with the extra "+" knob can venture into some pretty high gain territory.

Here's a description from the OKKO website:

"The Diablo is a versatile low to medium gain overdrive with an exceptionally dynamic response. It preserves the character of your instruments and is very sensitive to your playing technique. Thanks to the effective and musical controls, the Diablo works equally well with any kind of guitar, amp or playing style. People use it for so many different sounds, you would hardly believe that they use the same pedal.

Besides the usual Gain, Tone and Level knobs, the Diablo has some more interesting controls:
FEED affects the amount of bass in the input signal. You know the problem: an overdrive sound gets muddy rapidly if the input signal is too bass heavy (that’s why the treble booster was invented). With the FEED control you can make even the fattest neck humbucker sound clear and transparent or beef up weak pickups a little.
The BODY control takes effect on mids and compression. Another important feature is the HEADROOM SWITCH. Set to the "HI" position, an internal electronic voltage doubler is activated – the Diablo runs on 18 Volts from a regular 9 V battery or power supply. The higher voltage gives more dynamic range, more headroom and tighter bass – just try it!"

And a demo video of the Diablo in action:

Here's a PDF of the OKKO Diablo schematic file: http://www.box.com/s/qz7r3bgncl3jzgugoe3e

As you can see if you look at the PDF schematic it compares very similarly to this, an old design by Jack Orman:

There's no doubt the Microbooster formula sounds great - there are so many pedals now using them in a cascaded structure - The Catalinbread Dirty Little Secret and Formula No 5, the OKKO Dominator and so on.

Harald Sabro (www.Sabrotone.com) has produced some brilliant verified vero layouts and posted them up on the freestompboxes forums:

Now, those veros don't include the voltage doubler that the original Diablo contains, so if you need to build one of these:

Then all you need to add is a simple switch which will allow you to go between +9v and ~+18v...

Here's a link to the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=1482

Zvex - Super Duper

2012-01-26T10:01:00.001Z

[images of custom shop Super Duper 2 in 1 pedals - how cool is the butterfly?]

Here's a project I'm adding just because I get a lot of requests for the schematic - it's the Zvex Super-Duper-2-in-1. Basically two cascaded Super Hard on circuits with a master volume control at the end.

Here's an internal gutshot of the Super Duper [Note the extra transistors for Millenium bypass switching/polarity protection]:

Here's the description from the Zvex website:
"The SUPER-DUPER 2-IN-1 (TM) has two of my infamous but rather delightful Super Hard-On(TM) pedals in one small box, with two switches and LED indicators. HEY! I responded to your multitude of complaints that I don't put in LED's! Also, in this SUPER-DUPER 2-IN-1 (TM) (gosh I love saying that) is a Master volume control that lets you use it as an overdrive/distortion with any output volume. My my! How conventional, you say! Well, suffice to say, if it weren't there, you'd go deaf with both of those channels cranked up. This pedal is dangerously loud. Don't do what I did, and lean over in front of your speaker cabinet while turning it up. Ouch. Dang.

CHANNEL 1:

This channel is a conventional Super Hard-On (TM), which I will henceforth refer to as the SHO, in order to reduce potential offense to young ears and sensitive persons. Its gain control is on the far right, and it's LED is yellow. If you are familiar with the SHO, you'll know that it's a very sparkly sounding high input-impedance preamp with incredible headroom, wide-ranging gain (unity to 60 X), and a maximum volume that will knock out your fillings. Channel one has no Master Volume control, but it's cascaded into Channel 2, which does...

CHANNEL 2 AND THE MASTER VOLUME:

This channel has the very same circuit as Channel 1, but the bleeder resistor on the output has been replaced with a Master Volume control, which allows the user to turn down the output volume even if the gain is set quite high. The knob on the left is the gain, and the middle knob is the Master Volume, and the LED is red. When both channels are on, or if only Channel 2 is on, the Master Volume is active. If you leave the Master wide open, you have two identical SHO pedals in one box, which are cascaded."

Here's the ProGuitarShop demo video so you can see the Super Duper in action:

And here's a schematic for you:

If you want a layout, get yourself over to the Super Hard On project and just build two of those ;-) Or get yourself over the Madbean pedals and get a copy of his "FireBomb" project: http://madbeanpedals.com/projects/index.html

Here's the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=696

Premier Guitar - The Ultimate Tube Screamer Mod Guide

2012-01-25T17:13:00.001Z

Here's a great article by Dirk Wacker that has been online for a while over at http://www.premierguitar.com. It's basically a discussion of the most popular mods that can be performed on your good 'ole Tube Screamer - op amp changes, fatness mods, tone shifts, clipping options e.t.c. Here's the link, check it out: http://www.premierguitar.com/Magazine/Issue/2007/Jan/The_Ultimate_Tube_Screamer_Mod_Guide.aspx

Lovepedal - Englishman

2012-01-25T11:54:00.003Z

Here's the Lovepedal Englishman, supposedly an emulation of the classic vintage Vox AC15 / AC30 amps while they're going through meltdown. It's been a popular pedal and it can't be denied that the demo videos do make this thing sound very pleasing.

Here's a more in depth description from the Lovepedal website:

"The ENGLISHMAN™ simulates the classic AC vintage amplifiers right before the amp fries. I have found these vintage amplifiers sound best CRANKED and on the verge of failure.

The unit will also enhance the sound of any amplifier without altering the tone of your guitar. The ENGLISHMAN™ has the ability to act as a super clean boost, semi clean boost, or with the volume & gain pushed higher it is capable of pushing any amp into beautiful harmonic breakup, overdrive and distortion.

With 3 modes of failure the “FAIL™” switch embarks new worlds of natural overdrive and downright amplifier distortion in a good way.

It flat out screams if you want it to or not. Just like the original English amplifiers of a time gone by."

Here's the ProGuitarShop demo video of the Englishman in action:

[R.E.M! I love R.E.M!]

Sounds nice doesn't it. Well, good news - some good fellow has provided freestompboxes.org with a traced project, so now we can build our own rather than pay the ridiculous after market price.

Here's the goods:

As you can see from the bottom picture the Englishman had to have some minor surgery on the way, but here's the schematic [NOTE - One slight mistake - the diodes marked 1N9148 should read 1N4148 (Although you can use 1N914)]:

As you can see from the schematic it's pretty much what's standard with Lovepedal - transistor booster with post gain diode clipping to ground. It differs slightly from his COT 50 designs with a slightly different bias on the transistor and larger input/output caps but that's about it really. The design is based mainly around the old Electro Harmonix LPB-1 Booster, here's the original schematic:

Here's a nice little vero layout for the Englishman (Note - the 2.2k resistor on the vero should be 2.2M):

Here's the freestompboxes.org forum topic for reference: http://www.freestompboxes.org/viewtopic.php?f=7&t=15940

Lovepedal Englishman in for Minor Surgery

2012-01-25T11:15:00.001Z

There's been an anonymous donation to the freestompboxes forum - the Lovepedal Englishman. There's a preliminary schematic along with some pcb images up in the thread here: http://freestompboxes.org/viewtopic.php?f=7&t=15940

So far it's a basic transistor buffer with a diode switch....

I'll be putting up a full project when we're verified ;-)

OKKO - Dominator

2012-01-23T14:29:00.001Z

The OKKO Dominator is a super high gain distortion machine from Germany. I love those massive LEDs they have as a status indicator. They also sound pretty damn mean too! This thing is in the same ball park as the Wampler Triple Wreck - that gives you some idea of the amount of gain this thing has!

Here's a description from the OKKO website:

"After countless hours of tweaking and improving the circuit, I’m proud to present you the DOMINATOR high gain drive.Aggressive british crunch, classic heavy metal, brutal modern high gain stuff or anything in between – the Dominator will do the job.
This box has nothing in common with those overcompressed, artificial sounding "bedroom metal" distortion pedals that disappear in the mix if you try to use them in a real band situation. Raw natural gain structure, explosive attack, tight low end and great chord definition make the difference – the Dominator works equally well at home practice or stage level.

The active 3-band EQ with switchable mid range frequency provides effective and intuitive control over a broad range of sounds.

Just like the other OKKO drive pedals, the Dominator features an internal voltage doubler. The three gain stages and the EQ stage operate on different individually filtered voltages up to 18 volts for optimal dynamic response and very low noise performance.

The Dominator works best in front of a clean amp with some headroom, especially if you use very bass heavy "chugga chugga" settings."

And a demo video of the OKKO Dominator in action:

Here's an internal gut shot:

Here's the schematic drawn up by Saruman:

As you can see it's an opamp clipper running at a higher voltage than usual with the distortion coming from the clipping in those opamps! I'm not usually keen on opamp clipping but it does sound pretty good in the Dominator.

Anyway, heres's a vero layout by Harald Sabro (http://www.sabrotone.com):

http://www.sabrotone.com/wp-content/uploads/2011/01/OkkoDominator.gif

And a PCB layout and associated files by Mundry: http://www.box.com/s/n7iekvtxtgjx6z1rbq3v

And the freestompboxes.org forum thread for reference: http://freestompboxes.org/viewtopic.php?f=7&t=12031

Carl Martin - Plexitone

2012-01-23T12:30:00.001Z

The Carl Martin Plexitone has been around for yonks (good word!) and has remained popular with it's high gain tones and wide versatility allowing the Plexitone to cover most bases required when playing anything other than Folk (Yuk) music.

Here's the description from the Carl Martin website:

"The Carl Martin PlexiTone, is as the name might indicate an unusual high gain three step rocket of an overdrive.The PlexiTone offers two step overdrive, the crunch channel and the high gain channel, on top of that it gives you an up to 20dB clean boost channel.
The crunch channel goes from subtle overdrive to hard rock gain stage, the high gain channel goes from rock gain stages to absolutely meltdown, with loads of gain and low end, and all in a tone that brings the memory back to the early 80's high gain guitar hero's.
The PlexiTone has as most Carl Martin pedals a built in regulated (+/-12V) power supply, to secure the necessary headroom that gives you the great tone."
Check out this comprehensive demo video of the Plexitone in action:

As you can see it sounds pretty nice. I bet you wanna know what's going on in there. Well here's the schematic provided by GnognoFasciani:

As you can see we've got the standard opamp type clipping circuit with a couple of LEDs in there to provide the distortion BUT with an interesting change - that dual +12v to -12v supply provided by the onboard transformer. This gives the pedal it's great headroom and dynamic appeal by ensuring that the opamp is never pushed into it's clipping region, this means all the clipping is done via the LEDs and not harshly in the opamp itself.

Here's a PCB layout by Bucksears:

As you can see he's used a voltage doubling circuit to supply the opamp with +/-18v - even more headroom! I like this, I like it a lot! Here's the link to the PCB transfer he produced: http://www.box.com/s/qe94dk4inkufhtk2nlid

And here's a link to the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=1113

Nicholas Boscorelli - The Stompbox Cookbook

2012-01-23T11:15:00.002Z

http://dl.dropbox.com/u/1822991/The%2BCookbook.pdf

http://fileshare.eshop.bg/equipment_mfg/books_41.html

There are a couple of links to sites where you can download the pdf of Nicholas Boscorelli's "The Stompbox Cookbook". Just a year or so ago this book was selling for hundreds second hand and it's out of print so no one could access all the info inside without shelling out the $$$. Now thanks to a few generous people it's free for everyone to see. There are some interesting projects in there, nothing too revolutionary but it certainly worth a read. The section on envelope detection and control is quite interesting and it's got really in depth descriptions of most aspects of common stompbox circuits - perfect for a beginner or someone more advanced.

Brunetti - Mercury

2012-01-22T23:20:00.000Z

Brunetti are an Italian company who make some really great sounding amps and stompboxes. The Mercury Box is there overdrive pedal. Here's the description from the Brunetti website:

"Mercury Box is the new Brunetti overdrive/ distortion stomp box. A small metallic box holds together the qualities of the well-known CustomWork Mercury’s channel 2! It is endowed with “FET” technology to reproduce tubes behavior and dynamics as accurately as possible. Mercury Box is extremely versatile, you can move from clear and defined crunch sounds to hard rock “liquid” distortion which is always clean and never shapeless, very smooth and respectful of your instrument timbre, even at high gain levels. Controls are soft and sentive, but effective at the same time. They indeed interact thoroughly as in a real tube amplifier. Mercury Box arises from careful design and long lasting research of Marco Brunetti, and the outcome is innovative and technologically unique. It is not the upgraded clone of a well-know stomp box! These qualities make Mercury Box different, we are sure you will be impressed at first note!"

And a demo video of the Mercury in action (This is a clone built from the verified schematic below):

Here's the schematic: http://www.box.com/s/3ofp8pkkq9bov4uxkjrg

As the schematic shows the Mercury Box has a single op amp gain stage running into two jfet gain stages. Jfets do sound great as a clipping device. The whole circuit is powered at 18v via the charge pump, that adds headroom and dynamic range. All in all it's a pretty well designed circuit and it sounds neat too! One change I would make would be to replace the 22k drain resistors on the Jfet stages with 2 47k trim pots which would allow you to really dial in the sweet spots for maximum gain and sustain.

Here's the freestompboxes.org topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=9846

Penny Pedals - Fingerprint

2012-01-22T22:54:00.001Z

The Penny Pedals Fingerprint has been out for a couple of years and is a decent sounding overdrive pedal that can do full on octave glitch fuzz when the texture and gain knobs are set in the right positions. Here's the *long* description from the Penny Pedals website:

"My newest pedal is a collaboration between myself and artist Laura Bennett. Known for painting unique designs on a few other company's pedals, this is the first time anyone has actually let her create her own pedal from the ground up, including the sound of the circuit and a blank canvas on the box.

Using inspiration from certain bands, sounds, even just random words, the sound of the pedal pays homage to that "wall of sound" heavy distortion. The pedal has lots of available gain and volume, similar to the clear but still insanely heavy sounds of bands like My Bloody Valentine, Smashing Pumpkins, Jesus and Mary Chain, etc... It's a high gain pedal for those who don't want to sound like a cliche heavy metal sound, a nice blend between high gain amp-like distortion, fuzz, gated fuzz, octave fuzz, and everything in between.

The controls are volume, gain, and texture. volume and gain are pretty easy to understand and work in the traditional ways, but texture is a unique feature. The only way I could create the tone we were after for this was to make the circuit as amp-like as possible, and that's where the texture control comes in; it is sort of similar to the negative feedback found on some amps, except controllable. At it's lowest settings, it lets the rest of the circuit take over for nice "normal" distortion pedal sounds, from clean-ish "just there" grit to high gain crunchy tones. As you turn the texture up, things get more fuzzy, and seem to have even more gain with more of a fuzz than distortion flavor... then, about half way, a slight gate kicks in, allowing you to have an eerie brief silence between notes (this depending on the gain knob also)... and with the gain full up, and the texture maxed, odd, crazy octaves and random notes happen, almost uncontrollable... low notes instantly trigger a lower octave then jump up to the root, creating broken robot type sounds reminiscent of a traditional octave fuzz... high notes fizzle and chords make sounds that are just... well... weird.

Truly a fun, unique collaboration and an awesome looking and sounding pedal."

Here's a demo video of the Penny Pedals Fingerprint in action:

Here's the schematic drawn up by CultureJam:

Here is a vero layout:

Note that the newer Fingerprint pedals have a bypass switch to switch the gain pot to full on. Aparently the NJM386 is pretty important to the overall sound of the pedal. It's just another 386 design (there are a few about now!), but they do produce a fairly decent tone. The only real interesting part here is the texture control which is just operating as a feedback loop to force the circuit into oscillation. The Experimentalists Anonymous Parallel Universe utilizes a 386 chip but it forces it into oscillation in a slightly different manner and it's got a wider range of tones than the Fingerprint (Although it is more complicated to build!). If you're into making a racket build one of these - here's the schematics for the old and new versions (both are decent enough):

And, as usual, the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=2503

DAM - Meathead

2012-01-22T22:33:00.000Z

The D*A*M Meathead has been used by many top guitarists - Josh Homme of Queens of the Stone Age is one. Taking that into account you can imagine what this thing sounds like - it's a massive fuzz tone! Here's a description from the D*A*M website:

"The Meathead. Often imitated, never surpassed. Little box, big idea. Caveman style fuzz tones for killing dinosaurs. Crank it up and hit that switch. Ka-pow! The flavour is thick and raw with a throaty woody bark. Optimum clarity and saturation are delivered with a long syrupy sustain at mountainous volumes. The bass to treble response is perfectly balanced for a heavy but dynamic fuzz tone that will project as well as it can saturate. A most excellently low background noise is achieved through careful transistor selection and biasing which further enforces the Meathead's fluid and articulate sonic capabilities."

And a demo video of the D*A*M Meathead in action:

Here's a schematic drawn by Analogguru:

And a veroboard layout by Mike:

Here's the freestompboxes forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=2713

Lovepedal - BBB 07, Dragon, Black Beauty Balance

2012-01-22T21:50:00.000Z

Over at freestompboxes Greg took apart his Lovepedal Dragon Fuzz (Also known as the BBB 07, Balance, Black Beauty and so on.) Here's the description from the Lovepedal site:

"The first control, a (blend pot) control that will take you from vintage Dallas Rangemaster to 67 Ge fuzz face heaven and everything in between, even tweed amp tones are in there. 2nd control is a saturation blend. 3rd is a Master volume. A very versatile unit that can blend many different shades of Ge fuzz face, Dallas Rangemaster, Distortion, Overdrive, Flat boost, Warm clean boost. the possibilities are endless..

Stable Handpicked Germanium mil spec transistor ensures the smoothest, harmonically rich, musical amp like tone available, ANYWHERE.

Internal trim pot lets you select the bias at anytime.

"The BBB is really an interesting pedal.
While it has an un-mistakable vintage tendency, it also has a unique voice. It blends a germanium treble booster and a fuzz in a single pedal. Not only do you have these two tones at your fingertips, you can BLEND them. This may sound simple, but the results are nothing short of stunning. This mix makes for some very tasty fuzz/boost tones. The pedal is remarkably tunable for having just three knobs; Vol, Fuzz, Blend.""
And here's a demo video of the BBB 07, Dragon e.t.c in action:

Here's some images of the pedal, an instruction/setting image and the schematic:

As the schematic suggests the transistors type was swapped about in different versions. Try as many as you like until you find a decent sound. It's just a simple fuzz face type circuit but it is a good sounding variation..

Here is the freestompboxes forum: http://www.freestompboxes.org/viewtopic.php?f=7&t=12734

Lovepedal - Provalve

2012-01-22T20:32:00.000Z

The Lovepedal Provalve. It's been about for a while and indeed preceded the Provalve 2. Here's a description:

And a demo video of the Lovepedal Provalve in action:

Soulsonic reverse engineered one and had this to say:

"Just a single 386. Initial inspection reveals it to be pretty much identical to the Purple Plexi. Switching between A and B just toggles between the two gain controls. And they both function and sound identically, so it's just a way to toggle between two different preset gain levels. It uses FETs to do the switching. It has the Cusack-designed relay switching stuff for the bypass.

The construction is solid enough; except for the jacks - they don't butt up flush against the side of the enclosure, so if you try to tighten down on the nuts, the plastic part of the jack starts to bend out and deform. The nuts were loose when I received it, and they won't stay tight for anything. I wish the battery cable had some strain relief because it looks like something that would break after extended use.

The ground plane on the board does a decent job of keeping out hum, which is good because the metal enclosure is not grounded to the circuit at any point... it may as well be in a plastic enclosure. The box itself has a "lumpy" appearance - like it wasn't cast well. There's no markings on it... so it's neither a Hammond nor an NSC. Looks like the same generic box HBE uses.

The sound is not very good. It does an okay heavy distortion, but in comparison, the Jaw Breaker can get a similar sound, but much much better quality. The worst part - other than the very obvious noise at max gain - is that there is this sputtery static-y sound as the note decays; at any gain setting. Where it could otherwise sound possibly okay at low gain, this bad decay ruins it. The tone control is worthless and just makes it sound muddy. It's obnoxiously loud - I like loud, but I'd prefer not to have to keep the knob all the way down at 9 o'clock.... the extra volume is pretty much wasted."

I don't think he liked it that much....

The circuit is just a Lovepedal Purple Plexi with a switchable gain control.

Theevilone built one up - here's some images of his build:

Here's the freestompboxes.org forum thread for reference: http://www.freestompboxes.org/viewtopic.php?f=7&t=4244

Crowther Audio - Hotcake Overdrive

2012-01-22T19:06:00.000Z

Here's the Crowther Audio Hot Cake overdrive. Here's the description:

"The Hotcake was first produced in 1976, while Paul Crowther was in the UK with the band, Split Enz. The Hotcake is designed to leave the undistorted component of the guitar sound unchanged, while providing a nice fat distortion sound without resorting to a treble cut circuit which will also affect the guitar tonality. With the Drive and Presence controls set to minimum, and the Level at around 2 o'clock, you should be hard pressed to hear any change in the sound at all when you switch the Hotcake in and out. You can get a clean volume boost by increasing the Level control. Increasing the Drive will give you a thick distortion sound with a little bit of edge to it, and the Presence control adds some mid-range punch to the sounds. The Hotcake also handles chords well. It is recommended that the Hotcake is patched between the guitar and amplifier, rather than into an amplifier's effect loop. Generally speaking, if you are happy with your guitar and amplifier combination, the Hotcake will work well as a primary distortion. "
Here's a demo video of the Crowther Hot Cake:

There are two schematics for this one - a 1977 version and a 2003 version:

As the schematic shows it achieves it's overdrive by pushing the opamp into clipping. It should sound terrible but it doesn't. It's been noted by Bajaman that the 1977 Hot Cake is smoother and more "Marshallesque" while the newer 2003 version has a glassier more Fenderish character....

Here's a PCB layout for the Crowther Audio Hot Cake. It's done by SoulSonic and utilizes "mojotastic" components: http://www.box.com/s/da2mzsrsm7ysy0u555ts

Here's the freestompboxes.org forum topic for reference: http://www.freestompboxes.org/viewtopic.php?f=7&t=85

Durham - Crazy Horse

2012-01-22T18:36:00.002Z

The Durham Crazy Horse - an overdrive/boost/fuzz unit. It's pretty expensive too at $250 for a new one. Here's the description from the Durham website:

"This is, I believe, the most adaptable distortion/fuzz pedal on the market. Definitely not a one trick pony! Though the inspiration for this pedal came from a legendary tone, it’s versatility is endless. The controls required to obtain that classic tone also allow you to get any other tone you may dream up."

And a ProGuitarShop demo video of the Crazy Horse in action:

And a schematic from Phibies:

As you can see it's an opamp gain stage into a fuzz face type circuit. I don't know why they don't use that opamp that's after the first stage to buffer the tone section. Strange that.

Here's a PCB layout from Barcode: http://www.box.com/s/ndfz4e7spslljuuruevj

Here's the freestompboxes.org forum topic for reference: http://www.freestompboxes.org/viewtopic.php?f=7&t=3186

Catalinbread - Formula No 5

2012-01-22T18:16:00.000Z

I like CAtalinbread pedals, Nick does a really good job designing and building some great sounding boxes. Here's the Catalinbread Formula No 5 - a supposed 5E3 emulator from them. It sounds great and, justifiably, there's been a lot of interest in the pedal. Here's the description from the Catalinbread website:

"The Formula № 5 was inspired by old tweed amps, most notably the 5E3 circuit. The character of the 5E3 is very unique. It has very minimal power filtering, low plate voltages, elemental tone stack, and does next to nothing to control the low end between gain stages, not to mention the under-rated output transformer and speaker. The entire system runs inefficiently resulting in a loose bass, greasy mids, cutting treble, and incredible grit – none of these qualities were ideal or intentional back in the day. In spite of this, over the past five decades the amp inspired some of the coolest, most sought after guitar tones ever recorded."

Here's a demo video of the Catalinbread Formula No 5:

Here's the schematic provided by Coldcraft after a unit was traced over on freestompboxes:

As you can see it's a combination of two cascaded "mu" booster stages with a tone/gain section in the middle - much like the Catalinbread Dirty Little Secret. It sounds great and that mis-biased first booster stage creates some great asymetrical clipping harmonics. I'd build/buy this pedal - it rocks.

Here's a vero layout by Roseblood11:

Here's the freestompboxes.org topic for reference: http://www.freestompboxes.org/viewtopic.php?f=7&t=9373

Xotic - BB Preamp

2012-01-22T17:56:00.001Z

Here's the Xotic BB Preamp pedal, a popular boost/overdrive pedal. There's a description on the Xotic website:

"The BB Preamp offers awide variety of sounds. It's capable of a 30dB+ clean boost with an adjustable ±15dB two band active EQ which adds a wide range of harmonic content to your ideal sound.
The BB also utilizes a pre-gain stage which allows the Pedal to go from a very pristine clean to a very smooth,compressed, overdriven sound.
True bypass for eliminating any signal interference when switched off.
Can be used with AC adaptor (optional) or 9V Battery.
"The BB Preamp is a great sounding soft Distortion and Sustain pedal. It really produces a great fat singing lead tone! The BB gives you a more sustained focused lead tone than the AC. Between the RC, AC, and BB, you can cover all your boost, overdrive, and gain needs!
Josh Smith""

Here's th ProGuitarShop demo video of the Xotic BB Preamp in action:

Here's the great MadBeanPedals Project file with a schematic, PCB Layout and wiring diagram: http://madbeanpedals.com/projects/Glitterrattii/docs/Glitterrattii.pdf

As you can see from the schematic it's an op amp based clipping stage into a tone and boost section. Nothing revolutionary but it works well

Here's a vero layout from Hewie:

Here's the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=11

Lovepedal - Delux 60 Mosfet

2012-01-20T23:34:00.002Z

These things are RARE. It's a Lovepedal Delux 60 Mosfet - they were also sold in a dual format known as the "Twin 60". Greg from the Freestompboxes.org forum bought one and opened it up - here's what he found:

He drew up a quick schematic too and kindly gave me permission to use it (Cheers Greg!):

Don't even ask me what that 47k resistor is doing in parallel to the 100k volume control - I know, it makes no sense. I'll quote Greg on this one:

"An observation. I think Sean has tried to set the .1uF - 47K High Pass filter on the output of the Mosfet so that it keeps guitar frequencies intact. Theoretically it would be 34Hz. But, considering the Volume pot is in parallel with the 47K the filter is actually set higher than he probably intended."

Maybe he did mean it? He also goes on to make the point that if you connected the Karl fuzz directly after this the high pass filter would jump to 370Hz (Due to the 5k pot on the Karl's input..). Hmmm, probably not great!

Brand new Klon Centaur finally here!

2012-01-20T17:14:00.001Z

So the new Klon Centaur is finally here, with a prototype at NAMM '12 Bill Finnegan has introduced it to the pedal world!

Here's an image of the prototype:

Here's an image of a switch that we're guessing is a buffer on/bypass switch:

It's taken years to get here, but there you go. What do you reckon? We're assured that the look of the final product will change though. Hmmm. Personally I wished he'd kept that cast enclosure, maybe just streamlined it a bit. Oh well, we'll see won't we!

Xotic - EP Booster

2012-01-20T14:15:00.002Z

The Xotic EP Booster has been causing a fuss for a while now. Supposedly based around the legendary Echoplex EP-3 preamp it's been recognised as one of the best boosters currently available.

Here's the description from the Xotic website:

"What do the tones of renowned guitarist such as Page, EVH and Johnson have in common? They all used the legendary echo machine EP-3 as a pre-amp.We've captured that magic in a new Xotic Effects pedal, the EP Booster.

We've used the highest quality parts available with a discrete FET design and low impedance output, the EP Booster provides up to +20dB of unadulterated boost with multi-dimensional, shimmering highs and lows, and no ear fatigue. The internal DIP switches let you choose the boost frequencies, and EQ settings.

Housed in a small 3.5"x 1.5" x 1.5" case with blue LED and transparent knob, the EP Booster can be powered by 9-volt up to 18-volts.

A simple pure boost that pays reverence to the magical EP-3 and captures the celebrated tones of the world's most famous players.
The EP-Booster,great tone starts here!"

And, of course, a ProGuitarShop demo video for you:

Well, the freestompboxes crowd whipped one apart and took a look inside (Thanks to Greg for the initial tracing):

The original transistors are supposedly 2N5457 and 2SC1815. As you can see it doesn't greatly resemble the EchoPlex EP-3 preamp:

But hey, nevermind, because this thing sounds pretty good. Here's a PCB layout provided by Masca of Handmades.br: http://www.mediafire.com/?eb0byo1n9s524q2

I would make a few modifications to this - firstly it's got to run on 18volts! Then I'd replace the drain resistor with a 25k trim so you could dial in a sweet spot of your choosing. For extra control I would swap out that low pass filter for a version of Mark Hammer's "Stupidly Wonderful Tone Control", that would give you a real handle over your top end. Finally - what's with that nasty BJT transistor output buffer? I'd use a Jfet or Mosfet follower - better fidelity and clipping characteristics!

Anyhow, I might draw a schematic up!

[EDIT] - I told you I'd draw a schematic up, here's the business:

As you can see I've added a master volume control, a tone control (treble roll off) - you could call this control "Sparkle" for added mojo. I replaced the nasty BJT transistor voltage follower with a nice JFET type. I ommited the "bass boost" switch, I didn't like it, it muddied up the boost, you could add it back in if you want. I also included a quick schematic for a voltage doubler to allow you to power this circuit at 18v (where it sounds best) with a single 9v battery. Well, what you waiting for? Go build one :-)

[EDIT2] - If you want to actually reduce the low end present in the circuit I'd reduce the input cap to 33nF and change the bypass cap on the "Boost" control to 220nF ~ 470nF ~ 1uF depending on your preference. I'd also recommend one other small change - replace the drain resistor on the first FET with a 10k trim pot then use it to dial in a 5.5v bias on the Jfet's drain to make sure you've got it in the "sweet spot". Just thought I'd add that ;-)

[EDIT3] - One last thing, for those interested in booster circuits which add colouration to your tone check this out (schematic below), it's a prototype I was working on back in 2009! The values in the treble control need tweaking to find the best response but it sounds pretty good "as is". This thing also sounds best at 18 volts :-) Build it up and tell me what you think:

For reference here is the freestompboxes.org forum topic: http://www.freestompboxes.org/viewtopic.php?f=7&t=7881

Himmelstrutz - Fetto Overdrive / Distortion

2012-01-19T13:40:00.003Z

Yep, here is another one - the Himmelstrutz Fetto. Well know for it's amplike response and great tones, it's been a while coming. Thanks *again* to fsb.org (lawnchair and soulsonic in particular) it's insides are available to view.

Firstly a description from the Himmelstrutz guys:

"Jump on FETTO Standard when your guitar and amp can't ride the lightning on reasonable levels, when you need anything between clean to really distorted sounds—to convince your audience, band and girlfriend(s) that the sound isn't the reason why your music is boring.
Perfect string separation, all the way from smooth overdrive to heavy distortion. Never lose the character of your instrument or amplifier. Designed to match the volume control on your guitar perfectly. Most pedals sounds just like a pedal. Not the case with the FETTOs which sound like an extension of your amplifier. Have you heard this before? Well, this time it's true."

Heh, I like that description. Here's a demo video of the Himmelstrutz Fetto:

Here's a schematic drawn by Soulsonic:

As the schematic shows it's a jfet emulation of a tube preamp design (http://runoffgroove.com), as the jfets are unknown you'll have to experiment. Start with 2N5257 I think, keep trying different types (with the right pinout) until you find some that bias up nicely. All of the jumper switches can be included on the outside of the pedal if you want, it's make for a super adjustable overdrive!

Harald Sabro has produced a great vero layout (http://www.sabrotone.com):

For more info and reference visit the freestompboxes forum topic here: http://www.freestompboxes.org/viewtopic.php?f=7&t=7353

Death by Audio - Robot

2012-01-19T13:16:00.003Z

More Death by Audio, this time it's the Robot pitch shifter. My description? It's crazy. Words cannot explain this thing, just have a listen to it (more ProGuitarShop, are there any pedals these guys haven't had?):

Here's the description from the Death by Audio website:

"The Robot is a low fidelity 8 bit pitch transposer with absolutely no feelings what-so-ever. It is completely synthetic and transforms any input into a spuree of resynthesized robot jargon.

THE CONTROL KNOB: The control knob is located on the right hand side of the pedal. The knob controls the pitch of the effect in NORMAL, OCTAVE DOWN, and OCTAVE UP modes. When in ARPEGGIATOR mode it adjusts the speed of the arpeggiation.

MODES OF OPERATION:

NORMAL: Same pitch with 8 bit digital conversion with the CONTROL KNOB fully clockwise. Turning the CONTROL KNOB down bends the pitch down.
OCTAVE DOWN: The CONTROL KNOB turned fully clockwise yields a nasty octave down sound. Turning the CONTROL KNOB down bends the pitch further down.
OCTAVE UP: The CONTROL KNOB turned fully clockwise yields a nasty octave up sound. Turning the CONTROL KNOB down bends the pitch down.
ARPEGGIATOR: The pitch arpeggiates in a sequence. The CONTROL KNOB adjusts the speed of the arpeggiation."

Here's a PCB picture provided by Glass_Hero:

And he's drawn the schematic up too (excellent work!):

Now, you need to know how to wire up that rotary switch to switch between the modes. The Death by Audio guys have used a 4P3T rotary switch to allow you to select normal "robot" mod, octave up, octave down and arpeg mode. I'd wire in three spst which switch chip pins 1,2 and 3 (SW0-SW2) to ground. Then you can select different modes independently with much more range.

To really understand the HT8950 switching check out it's datasheet: http://www.mediafire.com/?3cq894a5ynbn7pl, that's got the switching table in it which will allow you to select exactly what modes you want.

Here's the freestompboxes.org forum thread for reference: http://freestompboxes.org/viewtopic.php?f=7&t=12112