Tuesday, 29 July 2014

EHX OD Glove

Traced by our very own Miro (nice job buddy), and even though this is displaying an unusual lack of originality for EHX, I'm completely prepared to forgive Mike Matthews simply because it will upset Fulltone which is never a bad thing for me.

Info about this Voodoo Lab Overdrive derivative:
Rich, overtone laden sound that doesn’t get muddy. Responsive controls that take you from sparkling, clean boost through brown crunch and all the way to thick, saturated hi-gain. Advanced features like Tone Shift and selectable 9 or 18V internal voltage for surgical sound sculpting. The new OD Glove delivers overdrive and distortion with impact, and the modern player in mind.

“The OD Glove is unlike any of the overdrives we offer and great!” - Mike Matthews

DAM FZ-781 J Type Fuzz

Thanks to beedotman for the schematic on FSB.  This uses a 4 position rotary switch to swap the output cap, but none of the values used in the switch are confirmed, so as usual with anything like this it's a much better idea to use the values which suit your taste and gear better anyway rather than someone elses choice so I'd consider auditioning them and keeping the ones you think are most useful for you.  It is intended that the caps are soldered directly to the rotary switch as shown in the diagram but you could extend the board by a few columns, solder them there and take wires to the switch if you prefer.

With this being a positive ground effect like the FZ-673 posted yesterday, some people may prefer to use a negative voltage inverter for both to provide -9V to allow this to be daisy chained with negative ground effects.

I can't find an official description for this pedal which I'm assuming was one of DAM's limited runs.  But it sounds pretty good in this vid:

DAM FZ-673

Request.  Info about the hugely expensive final price "can only buy in limited numbers from eBay auction" David Main take on the MK1/ Zonk (7 out of 10 of which are probably in glass cases and haven't been plugged in yet).

I am the fuzz box system demon ~ FZ-673

The beginning. I’ve been brewing this thought for a while and a few favours owed made it finally manifest. In fuzz box terms I guess this is an embodiment of old school and new school, or at least an attempt there of. Basically, the FZ-673 circuit is the Zonk Machine/Tone Bender MKI circuit with a few subtle tweaks to try and make what is a pair of clown sized dinosaur shoes into some kind of laser beam driven UFO controlled fuzz device.
The simple new happenings are, the addition of a tone filter, a boost in output volume and gain plus your handy modern day fixtures of an status LED, battery drawer and DC tap.
The one grander thing I’d been messing around with since I was doing the Holy Roller (the D*A*M MKI style fuzz box circa 2004) was to get that particular circuit to yield not only a lot of gain at full-bore but also to be able to deal out some elements of clean-up and ability to lay down a tone that one would almost describe as an overdrive tone. In essence I was scrubbing out all the heavy decay and choppy gated artefacts that generally occur with this circuit type leaving the user with a purer fuzz tone. I would like to boldly declare this is what you get in the FZ-673. The best of everything, High gain, instant clean-up, but, this fucker needs to be stable, as in, warm. Feeling hot hot hot? Its not like you’d need to keep it on a heat mat or have a hot water bottle permanently gaffer taped to the enclosure but you will hear a significant move in gain in colder climates. It’s nothing that would cause any major headaches but it is a common theme with original MKI circuit types, to hear shifts in the output due to heat, and I do need to mention this point.
I’m basically saying, this pedal will give you op-amp quality overdrive like smoothness but with all the complex glory and freaky exhaled responsiveness of a primitive germanium fuzz circuit…but, only when its been let to adjust to its environment. I’m over emphasizing this point I know and I’m mainly talking about when the pedal is either first unpacked or say moved between different climates or environments.

Popping buttons

The controls are pretty straight forward but there are a few things that need to be understood. The Swell is basically your volume control but its nature is different to a regular your volume adjuster. At around the noon mark it tames a lot of the high end content you’ll hear when you have the filter set to full treble (fully dialled to the left) Inching past noon, and more obviously in the last quarter of the turn, the Swell will really push the gain and overall saturation levels and deliver you a pretty fierce fuzz tone, once the Fuzz control set wide open. The Fuzz control is a lot more ‘normal’ in its delivery of tones and the amount of sustain it lays down than a stock Zonk Machine Fuzz control would offer you. You have a pretty decent gradual increase from chunkiness to full-on fuzziness and little in the way of dead spots. Zonk’s can be either all on nothing at times in this regard. Temperature extremes will affect this dial usage too. A cold winter’s day and the Fuzz dial will need maximising for the full-on fuzz experience. Baking in a sunnier environment and set at full Fuzz the FZ-673 will be stripping paint.
Filter is just that. Nothing overblown just a very crude, but at times pretty damn effective dial for tuning your guitar and/or amp the FZ-673’s circuit. Pick-up type seems to really come into play here and more obviously so cabinet size. P-90’s respond really well and lay down a healthy jumbo sized thick tone with the Filter pushed open. An open sounding mid gain single coil (P-90’s get my vote) seems to do the do and with spare change.

Made from Stars

The construction style you’ll find somewhat familiar. I dig it so I dug it. Only the second time I’ve used a two layer graphic and I’m pretty stoked with the results. It’s pretty new in that regard. The theme? I was aiming to manifest a sci-fi kinda thing, got pretty close I think. FZ = Fuzz. 67 = 1967, the (guestimated year) of the main study Zonk. 73 = Year of Enter the Dragon…and Black Mama, White Mama…irrelevant shit to finish of the name to be honest. I actually wanted to make the finished item to appear almost toy like, kinda like it was made from Lego or something along those lines. The original plan was to use red chicken heads but I think the boundaries of good taste with a dose of humour had been exceeded in that case.

Transistors. Military shit all the way. The Motorola OC75’s I was told were ex-military stock so I combined those with CV7004’s (the military version of the OC45). The little fat UFO style cans of the Motor 75’s had the tone and looks and I thought it made cool and some what geeky change to the usual suspects. I threw in some old school flavours with the capacitors too as to top that whole vibe off…and of course makes it all tastes betterer.

Sunday, 27 July 2014

Ibanez JD9 Jet Driver

And here are the working voltages from ξεναγός.
Q1 - B 2,65 - C 8,67 E 3,06
Q2 - B 2,71 C 8,67 E 3,1
IC1 - 1- 4,27 2- 4,34 3- 4,32 4- 0 5- 4,19 6- 4,27 7- 4,27 8- 8.69
IC2 - 1- 4,27 2- 4,28 3- 4,28 4- 0 5- 4,04 6- 4,36 7- 4,36 8- 8,69

Saturday, 26 July 2014

Madbean Bloviator

Madbean simplification of Bajaman's "Sonic Stump". As you can see, you'll need at least 1590B to box this. If you want the same circuit in a smaller A-box, you should check out Madbean's PCBs.

Klon Centaur Silver Edition

Keith at BYOC reverse engineered a silver edition Klon when developing a PCB and noticed an error on soulsonic's 2009 schematic which was a couple of swapped resistor values around the Treble pot.  He also noticed a few value discrepancies which probably just amount to the difference between the gold and silver Klons.  The swapped resistors have been corrected in all Klon layouts on this site but I didn't want to just make the other changes to the existing layouts as I would like to keep the gold version up for those who would prefer to build it, and so I thought this version deserved its own thread. 
If you prefer to build this kind of circuit on PCB then the BYOC kit can be found here:


I don't know if they are going to start selling the PCB separately but you can of course enquire if you'd prefer to go that route.

Now I can hear some subtle differences when at the upper and lower end of the Treble pot, which will very probably be down to tolerance differences in the pot itself which could be as much as +/-20%.  I have to say in the more central positions I can't really hear any significant difference at all. At most  of the demo settings they sound identical to me, and at some the Silver Pony sounds a bit fuller.  Personally I preferred the Silver Pony.  Great job Keith.

and the corrected schematic

Friday, 25 July 2014

Maxon DS-830 Distortion Master

Skreddy Mayonaise MkIII

The latest incarnation of a very popular classic Skreddy pedal.  Thanks to mmolteratx on FSB for the traced schematic.

Info about Marc's original:
A faithful recreation of that old-school big box that gave us our start
Creamy, sustaining, amp-blowing-up, huge distortion with a grainy, ear-pleasing, low-fi edge and just the right amount of 'hair'
Heavy does not have to mean harsh or unnatural or even modern
Finally a tone control that is actually useful and powerful, yet does not sound bad at any setting
Makes a single-coil pickup sound more like a humbucker, yet doesn't completely obliterate the guitar's tone
Makes a clean amp sound like a dirty, cranked amp, even at low volume--preamp or power-tube distortion not required.

The tone of these transistors is nearly identical to the NOS units the original Mayonaise used (they look the same, too).  Just a couple of minor capacitor tweaks take it the rest of the way there.  Made of the same types of parts as used in our first product ever, which was a sonic clone of the circa 1971 "triangle knob" version fuzz box that used the legendary and unobtainable FS36999 transistors.

Has all that original pillowiness, grit, compression, and near infinite sustain as the original.

Thursday, 24 July 2014

HAO Rumble Mod

Request.  It's probably worth considering using 2 independent 500K log pots and separating the boost and drive sides.  It seems a little restrictive to have them as a dual pot rather than being able to set their gain individually and of course it may also be preferable to make the toggle a stomp so that you can change "channels" on the fly.  A little wide to fit in a 1590B horizontally, but will fit in mounted vertically no problem.

Info about the original:
The ultimate overdrive unit, the HAO Rumble MOD RM-1 uses hand-selected components to provide the purest, smoothest, thickest overdrive ever. The problem with most OD’s lies in mismatched input/output impedances that can make components work overtime. The Rumble’s input and output buffers provide proper impedance matching, allowing its circuitry to focus purely on generating the fattest overdrive possible. The Rumble’s two modes of operation – Clean Boost in Mode #1 and Overdrive in Mode #2 – allow for a variety of applications and tonal options. If you’ve been searching for that $10K amp sound but are several $K short of the mark, the HAO Rumble MOD is the economical answer to your tone quest.

Sunday, 20 July 2014

Perf Boosters

Just a bit of a bonus utility layout really.  I quite like perf with some things, and there's no doubt you can get circuits more compact than with stripboard.  I do find as a building medium it's more of a pain with larger circuits as making the tracks as you go and trying to keep it all neat can get old pretty quickly for me.  But I did a couple of compact boosters in an effort to minimise the required space that I can use in dual effects or maybe with those quiet circuits that need a bit of an extra push.  So as I've done them I thought I may as well share them in case they come in handy for anyone else.

Wednesday, 16 July 2014

Pink Jimi Photon Flying Spaghetti Monster

Pink's latest original. It's suggested that "Bloom n' Boost" switch should be taken as a stomp. And you should probably play around with the clipping diodes too. The feedback loop transistor reportedly needs to be a high gain PNP Germanium for the circuit to work right. Don't know about you guys, but i'm going to build one for myself. You'll find Jimi's complete thread about the design on FSB.

Tuesday, 15 July 2014

OKKO Dominator

Modded slightly to include a Mid Range pot instead of the switch in the original to give you complete variable control of the mids frequency rather than just 3 preset values.

I've done the charge pump on a separate board in an attempt to keep it 1590B friendly by allowing you to tuck the charge pump board out of the way somewhere, but with 6 pots I don't think too many people will want to do this anyway, so maybe some would prefer to simply add 5 rows to the bottom of the main board to keep it all integrated.  It will fit into a 125B with those extra rows.

As with other layouts I have included a couple of axial caps simply because I have them in that size, but there's no problem using radial in there if that's what you've got.

Info about the original:
Aggressive british crunch, classic heavy metal, brutal modern high gain or anything in between – the Dominator easily does 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. (For extensive descriptions of the controls please refer to the user manual).

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.

Monday, 14 July 2014

Dunlop JBF-3 Joe Bonamassa Fuzz Face

Request, and as it was a quicky I thought I may as well get it out of the way.  A tweaked positive ground Fuzz Face using Russian germanium transistors.  Being positive ground as usual I would suggest trying it with a negative voltage inverter to supply the -9V and allow you to use a 0V ground and allow you to daisy chain with all the rest of your pedals.  Note the required pin orientation and arrange them accordingly.

Info about the original:
Following in the footsteps of Fuzz Face masters Eric Johnson, David Gilmour, and Jimi Hendrix—Joe Bonamassa relies on his Fuzz Face to deliver his trademark searing leads. Tested and developed over several world tours, the JBF3 Joe Bonamassa Signature Fuzz Face is voiced specifically for Joe’s humbucker-driven tone, adding sustain and thickness for a rich, creamy fuzz. This pedal’s hand-wired circuitry is built around matched NOS Russian military germanium transistors for their characteristic warmth and growl. The JBF3 also features classic Omeg pots, housed in a polished copper finish that will patina over time. “I wanted this Fuzz Face to be a pedal that would instantly transform your tone,” Joe says. “It drives you to a different place as a player. Kick on the inspiration box!” Production of the Joe Bonamassa Signature Fuzz Face is limited to a single batch each year.

Sunday, 13 July 2014

Idiotbox Blowerbox

There are few manufacturers that raise an interest to simply go and get the original. I have no idea who the person behind Idiotbox is, but his designs, workmanship and artwork do please me to some degree. Plus his pricing seems to be on solid ground too. This one sounds particularly good. It has some wild distortion/fuzz tones for both, guitar and a bass...

This layout was originally based on a traced schematic by p.eat on FSB. That schematic had a few errors, which johnk helped to sort out. For this layout, i've subbed the parallel polarity protection for a series one and replaced the 10K JFET drain resistor with a 20K trimmer. This way you won't be able to kill your board with a reverse polarity and you'll be able to get everything you can out from that J201. JFET has also a 1M resistor path from gate to ground. This resistor isn't present in the original, but it will keep the JFET operation stable and it will not affect the sound.

A word about the original:
 The Idiotbox Blower Box Bass Distortion was designed with recreating the classic tone of Blacky from the early Voivod albums. It does everything from a mild grind to full-on massive distortion. It's awesome and you should have one...


Vox V830 Distortion Booster

Yes. It is big. I've omitted the complex power supply, but left most of the noise reduction measures in tact. Transistor controlled LED circuitry is also gone. With dual gang gain pot and the board size, this will be a tricky but doable fit in 1590B.

Marketing spiel from ten years ago:
Attention: Guitarist who want the fattest distortion. 
Classic distortion, warm tone and high gain. The V830 delivers distortion that goes from 'just enough" to blistering. And its VOX, all analog circuit ensures that your guitar's sound is always warm and natural - no matter what level of distortion you dial in.

Versatile, to fit your style and the way you want to play.
Whether you're into low string riffs on an axe tuned down to D, or paint peeling high notes, the V830's unique design gives you great distortion without losing it's edge and becoming muddy. Even power chords never loose their harmony. The VOX Distortion Booster, for guitar with an attitude!

Three controls - that's all you need. 
The Distortion Booster's DRIVE, LEVEL and TONE knobs give you all the control you need to get the tone you want. It couldn't be any faster or easier to get the sound you need. And, VOX's true-bypass switching ensures that your direct sound is unaltered when you hit the footswitch and bypass the pedal's circuitry.

Saturday, 12 July 2014

Vox V810 Valve-Tone

Yup. Vox made TS. I omitted the overly complex  power supply section and transistor based LED operation. Input and output buffers are 2SC2389 in the original units. You could also use those instead of 2N5088/2N5089. Just mind the pinout. Schematic i have has the output pulldown resistor at 1K, which seems way too small for me. I left that at 100K, like we find in some other TS derivatives. You could, of course, try the 1K in that position. It could also work as the output cap in most Vox pedals is also ridiculous 100µ. The high pass filter the output cap and that resistor creates has roll off frequency of 0,1-1Hz, depending on the value between 1K and 100K, so i don't think that value will affect the sound at all. Either way. It's so lightly modified TS, that it may be more preferable unit to some when compared against the green classic.

Friday, 11 July 2014

Carl Martin Rock Drive

The mellower little brother of CM Heavy Drive. Original units share the PCB with each other, but there are number of differences on the circuits.

Carl Martin Heavy Drive

Just noticed we didn't have any CM designs on the library yet. Demo vid i found isn't the greatest quality, but it has a Dinosaur Jr. riff, followed by some White Stripes, so i just had to post it. Made me feel like 25 all over again. Pedal seems like a nice distortion unit too. The low noise MC33097 quad opamp may be required for best results, but i see no reason why TL074 or LM324 wouldn't work here too.

Thursday, 10 July 2014

Ramble FX Marvel Drive

Request, thanks to PedalBlotter for his hard graft in tracing the circuit.  This is a bit of an awkward circuit to try to find a good middle point to do it on two levels (like my Muff layouts) and have an even spread of components on the board, so I've just done it in a long single row.  At 25 x 10 it will still easily fit in a 1590B rotated 90 degrees with lots of space at the sides :o) but I've also included a vertical layout for those who would prefer to build it that way.

Info about the original:

Great for AC/DC, Led Zeppelin, Hendrix and more!

From the KRRR-ANG of the high strings to the growl of the low strings, Marvel Drive delivers all of the tone that made the Marshall™ plexi legendary.

Topped with a genuine plexi faceplate, the Marvel Drive uses 4 separate JFET gain stages to create the ultimate in touch sensative, dynamic distortion. Each stage contributes to the harmonics and distortion in much the same way each tube does in an amplifier.

A well known secret to great tone out of the vintage, 4 input Marshall™ amps is to use a patch cable to connect 2 of the inputs together. When this is done, the HIGH TREBLE and the NORMAL volumes can be blended together for the perfect crunchy combination.

That is what Marvel Drive recreates. Marvel Drive uses 2 JFET gain stages in parallel, one with a bright and throaty scream, and one that brings the thump of a full stack. This configuration delivers a powerful way to get the perfect setting.

Wednesday, 9 July 2014

Rub-a-Dub Reverb

And the standard version using the more widely available and cheaper BTDR2 bricks.  This is set to be around unity but if you want a boost then experiment with the 12K resistor.  18K will give you a slight boost.

Tuesday, 8 July 2014

Rub-a-Dub Reverb Deluxe

Request.  This is a 1776 Effects project with more info available here.  Check out their other projects and PCBs available at their store:

The Rub-a-Dub Deluxe utilizes the new Accutronics BTDR-3H. The
BTDR-3H allows the reverb decay to be adjustable. In addition, the
Rub-a-Dub Deluxe also adds a tone control (based on Culturejam’s
Box of Hall) and a trim pot to allow for a volume boost or cut.

Sunday, 6 July 2014

Diamante Compressor

I'll add a Diamond Compressor layout at some point, but this one was a must for me and I'm surprised it's taken me this long to do the layout.  This is Fred Brigg's stripped down version of the Diamond, which is essentially the same but without the Tilt EQ section of the circuit or the (admittedly funky) colour changing LED depth indication part.  As someone who tends to leave EQ around the middle default setting anyway this made perfect sense for me, and as the omitted sections added a lot to the circuit size, and now with only two pots, it means it will be an easy one for a 1590B.  My rack tray thanks you Fred :o)

The other thing Fred changed was the input buffer which is now opamp instead of BJT, but the main compression part and envelope detector is as per the original and so should be comparable.

The circuit uses a VTL5C3 Vactrol which is 10M off resistance.  I'm not sure whether you will get a low enough on resistance with a 10M LDR and LED combo, but by all means give it a shot and let us know how you get on.  If you do want to try an LED/LDR instead, just use the points shown where the Vactrol is connecting.  Right hand side is LED with cathode at the lower connection, left side LDR.

Read more about it on Fred's page here.  I can't find a video of the Diamante, so here's the Diamond to give you an idea what to expect

[15th July 2014 addition]

And this is a modified version to include the tilt eq.  I have kept it true to Fred's Diamante philosophy and swapped the BJT buffer used in the original for an opamp buffer, using the second channel of the opamp added for the eq.  Because the tilt eq is inverting I made the buffer inverting too so that the output will be back in phase.  This won't matter to most people but thought that if maybe a bass player wanted to use this with a blend circuit, then having the output out of phase could cause cancellation issues.  I noticed before that the original tilt scheme from the 70s preamp also has an inverting buffer, so this is also in keeping with that.

So this one is basically an all opamp Diamond Compressor, just omitting the funky LED

[updated 11th Nov 2014]

Saturday, 5 July 2014

ProTone Body Rot II

The spiel on this slightly modded Krank Distortus Maximus:
If you’re tired of the metal distortion pedals mass produced in Asia, designed by guys in their late 50′s that have no idea how metal sounds TODAY, then you NEED to hear the Body Rot II. In case you hadn’t noticed, metal is what we do… its what we are.
The Body Rot II started off with the heart of the original Body Rot distortion pedal with some added tone shaping EQ… but we knew that wasn’t enough.

With so many boutique companies jumping on the ultra heavy distortion pedal band wagon Pro Tone had started with the Body Rot distortion, we knew we had to create something massive. We knew that the Body Rot II had to be something that would send a jolt to the competition and silence the naysayers. The Body Rot II Continues to do just that.

Friday, 4 July 2014

Earthquaker Devices Monarch Overdrive

30th October 2014 - Put on hold pending investigation :o)

Info about the original:

The Earthquaker Devices Monarch Overdrive is an FET, all discrete dirt machine that will get you some truly vintage and organic overdrive. The Monarch Overdrive is based on a certain UK hard rock amp's input stage that shares the same color as the Monarch's brilliant design. This pedal provides high gains that are largely compression free, for a truly organic and natural sounding overdrive tone that really gets the sound of an overdriven vintage amp. The treble and bass controls are essentially frequency boosters, and not simply the run-of-the-mill roll off filters found in most all overdrive pedals. These controls are centered in the preamp section and really provide some depth to the tone and overdrive characteristics of the pedal. This provides you with a solid bottom end and clear and crisp top ends for rich harmonic overtones that ooze vintage overdrive. This is the overdrive pedal to get for larger-than life fat chord work and a thick and significant bottom end. The Earthquaker Devices Monarch Overdrive can also be used with higher voltages to yield more headroom, a fatter and more focused tone and a wider gain range.

The Earthquaker Devices Monarch Overdrive is one thick and meaty overdrive. Taking the best elements of a vintage UK rock amp, this pedal delivers some balls-out tone. As with other Earthquaker Devices, you have some real control over the tonal characteristics of this overdrive, by boosting frequencies rather than rolling them off. The Monarch Overdrive gives you some real vintage overdrive, but also some real tonal variety when you call for it.

    Gain: Controls the amount of overdrive
    Level: Controls level of output
    Treble: Boosts highs
    Bass: Boosts lows
    Power: Regulated 9-18v power supply with negative 2.1 mm center barrel

Joe Davisson Antiquity Fuzz

Noticed this one and thought i'd do a quickie. Here you go with Joe Davisson's improvements on the classic fuzz face.
Note from Analog Alchemy website:
Placing a diode at the input of a silicon Fuzz-Face type circuit improves the tone by preventing saturation of Q1. Adjust the 5.6k resistor until Q2's collector is near 4.5v for the best sound

EHX Hot Tubes

Another one that was missing from the library. Original units call for 2M pot for the overdrive control, but as the demo below suggest, the middle position of that knob should be mild enough. So i see no harm in using 1M pot for that instead. That'll give you the latter half of the sweep.

...aaand i built one for myself. 1M lin pot for the drive works really well. At minimum setting the effect is slight overdrive with a nice tube sounding overdrive going on. When maxed it's a very high gain driver and sounds really nice. I think i may need to get myself an original nano version to compare them. But yes. This sounds very good. One more thing. I usually sub log volume pots for linear as i like the sweep better. On this one. Nope. You'll definitely want it to be logarithmic.

Tuesday, 1 July 2014

Boss CE-2B

And I may as well add this one as a separate layout so we know what versions the comments are based on.  This changes a cap value and adds an Effect Level pot to the CE-2.  If you want to add an Effect Level pot to the guitar CE-2, just use this layout and swap the 12n cap to the left of Q3 for a 33n.  Or if you want the option of using both, use a DPDT on/on toggle like this:


Solder a 12n between 1 and 4, solder a 33n between 3 and 6, and connect wires 2 and 5 to the holes that the 12n should have connected to on the board.

This obviously isn't yet verified but it's so close to the guitar version that it will be good to go.

The BOSS Bass Chorus CE-2B is designed specially for a bass guitar, giving you the best result when used with a bass guitar.

The Rate, Depth and the Effect Level knobs serve to create various chorus effects.