Saturday, 31 May 2014

Free The Tone HB-2 Heat Blaster

Info about the original:
The HEAT BLASTER delivers a truly modern distortion sound, with a tone control plus high-cut and low-cut switches for additional tonal adjustment. The high-cut switch attenuates the presence frequencies in order to produce a mellow tone that retains good projection. With the high-cut switch engaged you can use the tone control to achieve the required degree of projection. This type of setting is ideal for solos. The low-cut switch attenuates the low frequencies, making it easy to attain an ideal blend with bass and drums for a well-balanced band sound. The low-cut switch affects low frequencies that normally cannot be adjusted using amplifier tone controls.

Sure enough, there's something quite familiar going on in there. Talking about a vision that came to the designer in a dream...

Thursday, 29 May 2014

Klon Centaur [Rev 2]

[Updated 4th July 2014 - correction to treble control resistors] 

The older Klon layout was starting to annoy me for a few reasons so I decided to re-do it and start a new thread as this one is obviously currently unverified, and so all discussion here can relate to this layout.

This is a couple of rows smaller and so should fit more easily into a 1590B, and I have included the bass pot mod from the outset so if that's something you don't want to include you can just omit the 150n cap and bass pot itself.

Note that IC3 is rotated 180 degrees from the usual orientation.

Marketing spiel:

"..... Available soon.   

No, honestly!"

And a extra modified version which uses a fat switch instead of an additional bass pot, and also includes a Soft Clipping switch to allow you to add your favourite clipping diodes in the feedback loop of the gain stage.  This switch is a DPDT on/off/on and will allow you to use two back to back pairs, with a centre off position which will be the standard Klon mode.  The main germanium shunt diodes could also be removed from the board and put on a switch allowing you to remove the hard clipping completely, and/or maybe adding the option of a different type of diode in one position, and the stock germaniums in the other, to give you extra flavours and maximum versatility.

For another modification consider using two 100K pots for "Gain" and "Clean" instead of the dual linear pot.  This will give you maximum versatility by allowing you to control both sides of the control independently, and people have noted having good results doing so, giving them additional tones that are impossible to get with the stock Klon configuration.

These layouts are based on Martin Chittum's April 2009 updated schematic (correction to treble resistors included - 4th July 2014), with the only alteration being increased 100u filter caps on both 9V and 18V sides.  The bass pot addition is as per Madbean's mod suggestion.

Wednesday, 28 May 2014

Rothwell Switchblade

There's a partial schematic up at FSB, missing all non-polarized cap values. I thought it would be a nice idea to take a guess at them. The values i selected should take the sound close to the original unit. Of course, if any of you have better guesses on the values, let me know. This design has three clipping stages (not gain stages as PGS demo suggests) and overall footprint isn't your usual copy of a copy. There's a lot of gain coming out of a single TL072 too...

Saturday, 24 May 2014

Barber Compact Direct Drive

Request.  Another great sounding, extremely well made and very fairly priced effect from Dave Barber.  As usual with Barber I'd always say buy this or one of his other pedals to support one of the good builders.

Measuring only 2.3” wide, the NEW Compact Direct Drive brings a colossal catalog of vintage British voice to your pedal-board. We packed the most desirable sounds of the Direct Drive, Direct Drive Low Gain (LG) and Super Sport into one clean and compact pedal. If you like the sound of the early UK combos with kt66 tubes, it's in there. If you bleed for the sound of a 4 input head with a wall of 4x12 cabs, it's in there. If you live for the sound of a carefully modified master volume gem from the early 80's, it's in there too. The Compact Direct Drive uses a simple layout of three knobs, a gain toggle and a harmonics toggle to delivery it's wide array from elastic-bells of GZ34-sag, to the hells-bells of a tight EL34-crush. Throw away the clock, tell the family you're taking a solo holiday, there is a Compact Direct Drive on the way. 

Modded version with Mids control

Friday, 23 May 2014

X Fuzz by deadastronaut

I listened to the clip of this last night and thought it sounded awesome for such a small circuit, so had to do the layout.  Another bonus is that it uses common transistors so no searching for unobtainium, or having to get something in specially.

Wednesday, 21 May 2014

Aefea Drive by Mark Hammer

Request for this new overdrive circuit from Mark Hammer, the "Almost Everything for Everybody ... Almost" Drive, which you can read about here:;topicseen

Monday, 19 May 2014

Electro Harmonix Clone Theory

Request for this nice sounding chorus/vibe pedal.  Thanks to Scruffie for his schematic.  It will fit in a 1590B if you want the aggravation, but a 125B would probably be a better choice.

The effect needs a 15V supply so you can either use a standalone 15V adapter if you have one, or build the included power daughterboard which with double the supply and then uses a regulator to reduce it to a stable 15V.

The schematic was based on a mono version of the old MN3007 Clone Theory, but this is the manufacturers information about the current XO version:

This recreation of the original 1970's Clone Theory is re-known for its very edgy chorus. Stereo outputs provide lush chorus and vibrato with a sparkling wash and liquid elegance.

CLONE THEORY, one of the most lush, deep and warm CHORUS/VIBRATO ever made, now in stereo. The CLONE THEORY’s depth and rate controls swing from one extreme to the other, giving the user an entire realm of possibility for tone.

[20th May: re-jigged slightly reduced the number of links, no corrections were made so the first layout posted should still be good]

and here's the stereo daughterboard for those wanting the option

Friday, 16 May 2014

Univox Micro Fazer

I can't find any information on this one in terms of marketing spiel, but it should be obvious what it's based on :o)

MXR Phase 90 with Script Switch

A few people have requested this so I thought I'd better do it.  This one includes the Script mod on a switch so you can choose either mode.  Don't forget that you really need to match the JFETs for this.  You may get lucky with an unmatched set but the better the match the better the effect, so it's worth a bit of effort.  Use something like a Peak DCA75 if you have one, or this simple build will also allow you to choose the 4 best matches.

Info about the original:
This device has found its way into many of Eddie Van Halen's recordings, adding a shimmery velocity to lead passages or a more dramatic swoosh to muted strumming. Not just for guitars; it works well with bass, keyboards and even vocals. Vary the speed from a subtle, long cycle to a fast, watery warble...and myriad vintage vibrations in between.

[Updated 21st May 2014 - re-jigged to make better use of space but all connections as per the original verified layout]

Modified version with added depth control.  The Depth 1 wire needs to connect in the hole under the link, so it's probably advisable to raise that link slightly to give you room.

Thursday, 15 May 2014

Roger Mayer Page 1

Request.  Info about the original from Roger Mayer:

In 1964 I designed my first fuzz guitar effects pedal that was used by Jimmy Page and Big Jim Sullivan and featured on many early hit records. I am pleased to announce that after 40 years this early ground breaking fuzz will be available again. It uses carefully selected germanium transistors and has the same distortion section as the original 1964 version. An added carefully tuned passive fatness control follows the distortion section and this adds fatness without messing up the guitar's detail or the distortion characteristics. It has all the features of the new Vision Series with Hard Wire and Buffered Dual Outputs and is housed in the same style of new enclosure. This reissue meets our strict guidelines of keeping the best of the old but also adding some new noteworthy modern features and we at Roger Mayer welcome you to step on to a piece of genuine history.

Page 1 Front Panel Controls

DRIVE: This sets the amount of distortion.

FATNESS: A combination circuit tailored to provide control to the overall tone depth and is not just a simple top cut circuit.

OUTPUT:The output level boost available can also be used to drive the amplifier very hard if required.

DOD FX80B Compressor Sustainer

I'm slowly recovering from some sort of an drawer's block. Simply couldn't get any layout to look decent enough to publish. Our friend Myrkky Nuoli requested this after i wrote a piece about the original unit. So i drew it and it turned out nice. It could probably be a lot more compact, but with 21x21 it's still fairly easy fit for 1590B. Built one myself and it sounds very good. It may not offer a lot of boost, but you'll notice if it's not on. For some reason this was the only youtube demo i could find:

Wednesday, 14 May 2014

Micro POG Dual Control [modification]

Hahafender on the forum sent some pictures of the guts of his Micro Pog and wondered how This1sMyne and JHS do their dual control mods, hoping to do similar, preferably like This1sMyne with external controls.  We knew from gut shots of the mod that a 4PDT stomp is used, one pole of which is for the LED indication, and so only one pole is used for each pot.

After some probing we knew that lug 1 of all the pots connect to ground and that each control increases its own effect as the pot is rotated clockwise.  The original used 5K linear pots for all the controls, and so if we use 10K for all the pots instead (also replacing the existing pots), keep lug 3 common and just switch the wipers, then we know that the entire value of the pot out of circuit will always be in parallel with the pot in circuit and so we get a predictable affect irrespective of the position of the out of circuit pot.  2 x 10K is the 5K used in the original.  This will alter the taper and so reverse log will be the best choice [see discussion below].

For indication with the 4th pole I've shown a bi-colour LED with a common anode so that you will get a different colour for each "channel" selected.  If you're not bothered about LED indication then of course a 3PDT stomp or switch could be used instead.

Tuesday, 13 May 2014

Blakemore Effects R.O.U.S.

Info about the original souped up Rat:
To put it mildly, the R.O.U.S. is a versatile pedal. It’s based off of a classic distortion pedal circuit, but it can do so much more. There is a toggle switch to change the clipping diodes (or completely remove them) so you can go anywhere from a very light overdrive to fullbore rock distortion. Also, I’ve added more EQ options so you don’t have to settle for just having a single tone knob. There are knobs to control bass, treble, and then a texture knob that controls the clipping characteristics, and almost acts as a mids knob. And for those of you who are interested in such things, this pedal does use the coveted LM308 chip.

Monday, 12 May 2014

A Pair o' Preamps - Echoplex and Tillman

Just a couple of little preamps that have been requested.  Some people swear by these little circuits and use them at the input of other effects because they like the way they colour the sound, so a quick build for people to experiment with.

A couple o' variations:

EchoPlex Preamp with charge pump for 18V from a 9V supply

Early version EP3 with volume control

Tillman with Gain Switch

Sunday, 11 May 2014

Black Arts Toneworks Quantum Mystic

Request.  Info about the original:

The Quantum Mystic Overdrive was developed working closely with Mike Scheidt from the Portland Oregon band, Yob. Mike is known for great tone and groundbreaking music in the metal and doom community. We decided to adapt his favorite pedal from the seminal early YOB records into an updated and upgraded circuit. The Quantum Mystic is an opamp based distortion/OD featuring a 3 band active EQ and germanium clipping. It draws cues from Mike favorite old Grey Distortion, boiled down by a wizard, tweeked, manipulated, upgraded and using both mine and Mike’s ear, we sculpted the form you now hear and feel. Use the active Eq to cut frequencies to represent the old school sounds, or use the EQ to boost the final gain stage to go into the heavily saturated and distorted tones of the future. Dial back the distortion, boost the volume and use the active EQ to find sparkling clear boost tones. Dime it all and get a ball molten lead that propels the Universe Throb. Needing a captivating presentation, we summoned the artwork of another underground legend, Arik Roper. We pulled together something pretty special and I think you all will like this one.

Friday, 9 May 2014

Skrydstrup R&D Overdrive ODR-2

May as well add this one too :o)  The layout actually ended up looking quite different but this is very obviously a Cornish SS-2 clone, at a similar sort of price.  There are some differences which I expect will make them noticeably different, so this is probably still worth building even if you build the SS-2 as well, but I certainly wouldn't expect them to be worlds apart in tone.  It would be nice to critically compare the two though.

The same applies as with the SS-2, this is designed with true bypass switching in mind, but if you do want to build it with the buffered bypass, then make a daughterboard of the Cornish Buffer.  The input socket connects directly to the input of the bypass buffer.  The output of the bypass buffer then goes to ODR-2 input and daisy chains to the 3PDT stomp switch, lugs 1 and 4.  The output of the ODR-2 will go to 3PDT lugs 3 and 6, and the output socket connects to 3PDT lugs 2 and 5.

The third pole of the 3PDT is used for LED switching as usual.

Info about the original Cornish copy:

Skrydstrup R&D Overdrive ODR-2
The ODR2 is a smooth, dynamic overdrive unit designed to emulate the overdrive sounds of our highly recognized OD50 Tube Amplifier.

This unit is perfect for overdrive tones ranging from a semi-cranked AC30 to the sound of Hendrix.

The TONE control is not a traditional tone control, but a High Frequency Damping control. Turned all the way up the TONE control is not active.

Cornish SS-2

Pete's highly acclaimed Overdrive/Distortion box of the stars.  The original obviously includes the Cornish buffered bypass switching which isn't shown here as it is assumed most people will use the usual 3PDT mechanical bypass.

But if you do want to build it like Pete, then make a daughterboard of the Cornish Buffer.  The input socket connects directly to the input of the bypass buffer.  The output of the bypass buffer then goes to SS-2 input and daisy chains to the 3PDT stomp switch, lugs 1 and 4.  The output from Volume 2 of the SS-2 will go to 3PDT lugs 3 and 6, and the output socket connects to 3PDT lugs 2 and 5.

The third pole of the 3PDT is used for LED switching as usual.

Info from Cornish about his very expensive and much sought after stompbox:
The Pete Cornish SS-2™ satisfies a tremendous void in the Musicians palette of tone colors. Totally different from any overdrive/distortion effect that has ever been previously available; it is amazingly responsive to changes in both Guitar volume and picking articulation. It has the best “bottom end retention” ever heard in an effect, whilst the mid-range is sweet and very transparent. The SS-2™ retains all the tonal nuances of your guitar and is subtle and yet capable of amazing power and sustain. Using the SS-2™ with a clean amp it is possible to progress from subtle overdriven amp sounds, through rhythmic crunch, up to a blues' lead. The tonal characteristics and dynamics of the guitar are maintained even when using this pedal at its maximum gain.


Thursday, 8 May 2014

Madbean Rump Roast

Another request for a discontinued Madbean board, this one based on the Dr. Z Carmen Ghia preamp.

Info about the original project and board:
The Rump Roast finds its origins in the preamp section of the Dr. Z Carmen Ghia amplifier. The Carmen Ghia is a very understated and elegant design consisting of a single tone and gain control. This simplicity makes it an ideal candidate for pedal conversion. Standard practice in porting an amp design into a pedal is to use JFET transistors, such as the J201 or 2N5457, in place of pre-amp tubes. While it is impossible to correctly match the dynamics or compression of a tube cooking at a couple hundred volts, discreet emulation in a pedal does offer some nice tones and at least retains some of the character of the amp it emulates.

In the case of the Rump Roast, the design is broken down into two JFET gain stages with a simple cut control for tone and attenuator for gain in between. Some modifications have been made to “pedalize” this design. C1 has been added to trim off a little top end of the guitar signal (above 15kHz) due to the amount of boost on tap. C2 and C3 is a single 680n cap in the Carmen Ghia. These were broken into two parallel 220n and 470n caps which are more widely available for pedal building.

The tonal range has also been altered and enhanced. In the amp, C5 is a 250pF cap. While this does offer a very wide range of cut control (the tone pot works to cut high end as it is turned up), I found that at its lowest setting it was far too bright for a pedal. Therefore, this was changed to a 680pF cap to tame it a little. Additionally, a switch was added to put a 68n cap in parallel to provide another range of cut control. Together, the two ranges offer a lot of flexibility in shaping the tone of this design.

Lastly, an option was added to use a master volume at the end of the circuit. This offers even more flexibility. Without the volume control, the Rump Roast acts as a boost, providing a huge amount of gain to cook the front end of an amp. With the volume control added, it becomes more like an overdrive. This lets you tame the volume, at the cost of some of the overall gain. It is possible to make these options switchable, depending on what your needs are at any given time. See the wiring diagrams below where this is illustrated.

The controls are as follows:
TONE: This cuts the amount of high end as you turn the control up.
GAIN: This controls a wide range of boost. At minimum, it will be close to (or slightly above) bypass signal. As you turn it up you will get a large amount of boost.
VOLUME: If used, this will allow you to make the Rump Roast behave more like an overdrive than a boost.

A 500kA pot may be substituted for the Gain control.
Other JFETS may also be used, but be sure to check pin-out before soldering.

Now verified by Miro.
" Sounds very good with quite unconventional tone controls (including the bright switch). However. I didn't like the volume control's feel and range, so i swapped the 220K for 120K and volume pot for 200K linear. This way the lower gain settings become usable. Other good change could be to up the 10K at gain 1 to 22K-47K to make more of its sweep usable. Sounds very good indeed.

Clean first, gain at 12 o'clock and ending with gain maxed. Signal path as follows:

Tokai Telecaster w/ Seymour Duncan STL-1 on bridge -> this circuit -> Laney VC15-110 -> AudioTechnica MB2K -> Behringer shitmix -> M-Audio 2496 -> Ardour2 -> mp3

All non-hifi noise is due to my shitty bench gear rather than from the circuit itself. "

Wednesday, 7 May 2014

BYOC Tremolo

Request.  The stomp is wired in an unusual way so I have shown exactly how to do it.  The reason for this is that during bypass the input to the effect is grounded and the emitter of the LFO transistor is disconnected from ground, and so stops the LFO continuing to cycle during bypass.  This is a really good method because you can be sure that no LFO bleed-through will be heard as people have experienced with other effects with oscillators.  The indicator LED connections are shown and this will pulse in sync with the oscillator, and because the bypass method stops the oscillator when off, this means the LED will be off too.

Info about the original BYOC project and board:

The tremolo has become one of b.y.o.c.'s most popular kits through word of mouth. And with good reason....the difficulty of the build is low, it's simple to use, and it just sounds good. This kit is based on the EA(Electronics Austrailia) Tremolo. It's a great vintage sounding trem like you would find on an old Blackface Fender Amp. The amplitude modulation is done with transistors, so unlike most opto-coupler based trems, you don't get an "on/off" sound on slower speed settings and there is much less current draw. It's also a lot easier to build. And the LED status light blinks in time with the speed. 

Madbean Spackler

Another discontinued Madbean PCB, this time for his modded Demeter Fat Control.

Info about the project:
The Spackler is a modified version of the Demeter® Fat Control™. The effect is a midrange boost that will push the front end of an amplifier while boosting the lower-mid frequency range resulting in what some might call added “warmth” and “depth” to a guitar signal. The Fat Control™ works well as a standalone effect, or before another effect like a dirt box. The Spackler adds one extra control for the total gain amount available for the boost.

The stock design has a buffered bypass. While some may find this useful, the Spackler allows you to also wire in a hard bypass.

The controls are as follows
GAIN: This control allows you to vary the overall gain produced by the circuit. At fully counterclockwise the gain will be approximately that of the bypassed signal. At fully clockwise gain will increase for added volume and midrange boost.
FAT: This control blends between the “buffered” and mid boosted signals. Note that the first stage of the opamp is not a true buffer, but it will sound just like one if you hook the Spackler up using the buffered bypass wiring diagram below.

I can't find a vid of the Spackler, but just imagine this with a gain control :o)

Tuesday, 6 May 2014

Madbean Boneyard

A project from Madbean which he no longer supplies PCBs for, which is based on the Carl Martin Plexitone.  The switch allows you to put either the Crunch or Hi-Gain pot in circuit and so effectively makes this a dual channel effect allowing you to select between two preset gain levels.  So only a SPDT stomp is required for the channel selection, but I have suggested a DPDT in the notes giving you a second pole for LED indication.  A good opportunity to use those bi-colour LEDs.

One note, this is a high gain distortion and a few people have noted a problem with oscillation in their build, so keep cable lengths short and consider using shielded cables for input and output wires.  I have added other suggestions to calm the oscillation people encountered with this pedal, so hopefully it won't be a problem, particularly when boxed.

Info about the original project:

The Boneyard is a highly modified Plexitone™, which is a high-gain distortion modeled after the classic 60's Marshall amps identified by their Plexiglass panels. The stock unit is powered by an onboard transformer running at +/- 12v and features volume, tone, two gain controls, a boost, and three footswitches for a wide variety of tonal options. To simplify the design, the Boneyard eliminates the transformer and instead uses a voltage inverter to power the effect at +/-9v. The Boneyard also eliminates the Boost function and converts the entire circuit to true-bypass.

And a version with the additional boost pot and switch

Monday, 5 May 2014

Axess BS-2 Buffer

And seeing as I'm doing little ones tonight, this is the buffer section of the now discontinued (both product and company) Axess BS-2 Buffer/Splitter, and for once isn't just a rehash of a generic unity gain buffer (although to be fair none of these are going to be too far removed).

A charge pump gives the NE5532 a +/- 9V supply and so it is running with a 18V swing.  I'm not sure what benefits you get from running a buffer at a higher voltage, but I'll leave that for those building it to judge.

The trimmer will let you tweak the gain to make sure you're at unity, or wherever you want to be.  If you increase that trimmer to say a 5K then you can get a boost with your buff.  Note that the charge pump IC is mounted upside down from the norm.

Info about the original:
The BS2 has been designed as a solution to several problems that we’ve solved using custom-made buffers/splitters over the past several years. As a buffer, the BS2 should be used as early in the signal path as possible. Ideally it should be the first thing your guitar plugs into to, but unfortunately that can’t always be the case. Some Fuzz and WAH pedals do not like to be fed with a buffered signal. If you find these pedals don't sound right with the buffer in front of them, simply connect the buffer after these devices. In this situation, it would be ideal if these pedals had true bypass switching to ensure the BS2 gets the best possible signal it can... Using the BS2 in this application will prevent the loss of (1) signal level, (2) high end frequency response and (3) low end punch that is caused by cable capacitance and poorly designed input stage/circuitry of some effect pedals.

JHS Little Black Buffer

Traced from gutshots on the blog forum posted by hahafender, thanks for the pics buddy :o).  Some of the traces on the unused side of the opamp weren't visible but the left hand side is a generic opamp buffer and that's the important bit.  I think the resistors used on the other side we're just used as suggested by the IC manufacturers to do to unused channels.  Not sure why he didn't just use a TL071 and so not require the 2 additional resistors, but I suppose that does make it at least appear further removed from the common opamp circuit that we've seen lots of times before.

Info about the original:
This may be the greatest weapon you didn’t know you needed.

For those of us who are a little “pedal happy” there can be some downfall to our tone. When running a pedal board with more than one or two effects, something called “capacitance” happens. This natural problem happens due to the amount of cable or line that your signal has to travel through, not to mention bad switching systems in certain pedals. The result is a very audible amount of high-end loss, weak signal, flabby bass and uncharacteristic pickup behavior in guitars. Another problem is the assumption that all “true bypass” is good. This isn’t true and actually can be worse than imagined.

This is where the “Little Black Buffer” steps in providing the perfect input impedance to your rig and giving you the final result of clear, natural tone that sounds like you're plugged straight into your amp no matter how many pedals you use.

Boss HM-3 Hyper Metal

Another one for the metal heads.  The 2SK184 JFETs can still be obtained from some sellers on eBay, but it's just a buffer at the end of the day so you can use others with the same pinout like 2SK117, 2SK170, 2SK30, BF244A etc.  The transistors used in the gyrators though don't seem to be readily available and I couldn't even find a specific datasheet so I've used a CBE pinout so you can use a modern NPN transistor like the 2N3904 or 2N5088 etc.

There was a DIP8 version of the M5218L made by Mitsubishi, but they may be hard to source now, so any common dual opamp can be used in there such as JRC4558, TL072, NE5532, LM358 etc.

Info about the original:

Despite its compact size, this effect can put out a richand truly powerful distortion sound which can sustain for very long durations.

Two specially designed Color Mix controls provide for wide ranging tone control.

Whether for solos or for backing, it makes possible a well balanced new age metal sound.

Saturday, 3 May 2014

2, 4 & 8 Band Gyrator EQ

Moving on from the HM2 which obviously has quite a powerful EQ, I thought I could use the circuit to make a handy standalone EQ.  I was going to just use a quad opamp and make this 2 band with 2 of the channels being used as the input buffer and output gain stage, but thought it would still be pretty compact using a dual opamp for the input and output and so settled on 4 bands.

I have included a table showing the example frequencies you can achieve using common component values for R1, C1 and C2, and just altering the value of the R2 resistor.  Another option would be using 4 x 10K multi-turn trimmers instead of the R2 resistors so you could vary the frequency for every band and really fine tune it to the gear you're using.

You can use the Excel calculator I posted here to select your own components and get the frequency and Q you want if you prefer to fine tune the bandwidth.  I also included a trimmer so you can set to unity precisely, or give a slight boost if you like.

And now everything is modular of course, there's no problem in adding another opamp to give you a further 4 bands.

And the baby of the family

Friday, 2 May 2014

Boss HM-2 Heavy Metal

And for those who DO want the chugga chugga crushing lows! :o)

And I didn't expect it but this will fit in a 1590B too (doh!) so the Lite version may not get built quite as often now.  But still a good exercise in adapting these things and I'm glad there is a more compact version available if someone wants to use it.

This one has also been verified by our resident Finnish metal head who sent me a comparison clip against an original and it sounds identical to me, so you're good to go on the build!  Thanks again to Miro, the building machine! :o)

Here's the clip, so you can guess which is which

Info about the original:

The HM-2 is a distortion effect specially designed for Heavy Metal music.  In spite of its compact body, it features an extremely wide dynamic range, therefore allowing rich, dynamic distortion sounds.  Also, the HM-2 can be effectively used even with a single coil pickup guitar lo low output level, because of its high gain.  Wide variety of tone color creation is made possible with two Color Mix Controls.

Why aye bonnie lad, blondegraemey's demo:

And after the discussion below, a modded version with additional mids pot.

Boss HM-2 Heavy Metal Lite

Quite a few people have asked for a layout for this over the last couple of years, and I was always put off because with 3 x ICs and at least 3 transistors (depending on which schematic I used for the layout) there was no way it was going to fit in a 1590B, and you know what I'm like, I have a pet hate about putting a pedal that you can have in a Boss-sized box into a 1590BB.  I know some people don't mind, but I have a rack tray and space is at a premium so it does matter to me.  I'd just prefer to use an original if my own version was going to be physically bigger. 

Eventually Fredrik (Freppo) decided to do one himself, and he did and excellent job which you can find posted on the blog forum here, so I forgot about it for a few months.  But I spend a lot of time just looking at schematics to see how the manufacturers do certain things, and I was looking at the HM2 scheme, and just thought how much smaller it would be without the gyrator tone stack that's used and so decided I was going to do my own version using an active Baxandall stack instead to see how compact it could become.  This may not be capable of the "crushing lows" some people will want a HM2 for, but for others like me who just want a compact high gain distortion with a great tone control it could fit the bill perfectly.  This is a graph showing the frequency response of the new tone stack and as you can see you can still get a nice boost in highs and lows,

but this was based on an opamp supplied with +/-15V and so a larger voltage swing than the 0 to 9V we usually have in our effects, and so in practise you won't get that sort of dB boost.  It should however give you noticeably more of boost running the effect at 18V and so for anyone who wants a bit more meat out of the stack, I would suggest making sure appropriately rated caps are used and trying 18V.

This has been verified by a very nice man from Finland :o) and so is safe to build for those who fancy a Lite version of the HM2.  As noted, this won't give you the exact response you can get from the original especially at 9V, and so if you're in a Swedish death metal band you may prefer Fredrik's layout, but it's still one of the highest gain stompboxes we have on here according to Miro and I think it has a very nice tone control in its own right, and so reckon it will be of interest to some.

If anyone wants to further experiment with the response of the tone control, or maybe to use it in another effect, check out this calculator:

Thursday, 1 May 2014

Subdecay Stupid Box V1

Request from the forum.  Info from Brian about the original circuit:

The Stupid box was the first pedal introduced by Subdecay Studios in 2003.  I had been looking for something to get a big ballsy sound out of my amp, but my ultra clean 100 watt 6L6 based tube amp combo just did not seem to agree with anything I threw in front of it.  Sustain, and good harmonic response were a must.   After going through plenty of overdrives and distortions, and building a few 'clones', I finally decided to build my own. 

I wanted something with a big low end, without getting muddy, and an in your face sound, without the high end sizzle I got with a lot of other pedals.  After a few weeks of experimenting after band practice, I came up with the stupid box.

Fire Custom Shop Power Booster

Request for this very nice sounding and versatile booster from a Brazilian pedal builder Fire Custom Shop.  The switch selects between clean and dirty mode.  In dirty mode it puts diodes in the feedback loop of a non-inverting amplifier, and changes the frequency response of the high pass filter at the stage.  Following that is an active Baxandall tone stack and finally a buffer stage. Should give a nice boost in a wide range of frequencies.

Info about the original:
Power Booster is designed to be a different kind of booster pedal, which could be used both as booster of gain, as volume booster and to be even more perfect in your setup included two stages of equalization, a control for bass and another control for the treble, as well as key Clean/Dirt which opens a universe of sounds.

You will be surprised with the countless ways to improve and/or modify their timbres. Try all these possibilities with the Power Booster.

The video demo is in Portuguese but the playing is international :o)