Tuesday, 25 December 2012

Merry Christmas

All the very best to everyone and hope you have a fantastic Christmas. I think Miro and myself will probably be too drunk to post much for the next few days, so if we don't make it, see you all in the new year :o)



Fuzzhugger Groundswell Overdrive

Happy Christmas everybody!  Info about the original:

The Groundswell full overdrive with a natural response to picking intensity. It features two transistor based gain stages, so it doesn't have that artificial over-clipped sound like many "overdrive pedals" out there. No compression, just gain and drive! Dual gain stages and a voltage reducer that alters total amount of gain, as well as feel and response to pick attack.

I originally built the Groundswell for myself, my goal being a unique overdrive with a natural feel and sound. After getting a lot of requests to build more, I decided to make it available in small quantities. Users' reactions have been really exciting!


As an idea for a mod it may be worth adding a diode clipping switch to this to give you more dirt options.  Using a 3 position on/off/on with a lug layout like this:

1----4
2----5
3----6

Take a feed from Volume 3 to lug 2
Lug 5 to ground

Solder your favoured diode pairs between lugs 1 & 4, and 3 & 6.  I suggest 2 top to tail 1N4148s or maybe 1N4001s one side and maybe a couple of LEDs or germanium diodes at the other.  The middle position will then be the diode life stock pedal mode.






Monday, 24 December 2012

DOD 280 Compressor

Here we go with another classic optical compressor. Original unit uses VTL5C2, so could get away with using any LDR with 1M dark resistance. So the LDR resistor would be  resistor leads of VTL5C2 and that green LED acts as LED leads of the vactrol. Positive/anode to strip four and negative/cathode to strip one. Haven't built it myself yet..




Sunday, 23 December 2012

Digitech Bad Monkey - Bufferless

Updated 21st January 2013

The Bad Monkey is a very popular low cost pedal which most people have assumed to be a simple Tubescreamer clone but is a little bit more than just a verbatim TS808.  It actually bears a lot more resemblance to the DOD Juice Box which is handy because the person who did the trace couldn't get a couple of the cap values and so they have been inferred from the Juice Box schematic.

The layout is simplified from the schematic, and all the FET buffered switching has been removed so it has been put together with true bypass switching in mind, and the input and output buffers have also been removed, so this can be thought of as a Bad Monkey Eternity if you like! :o)

The cap values that were unknown were the 51p and the 220p. The 51p will be fine and is a commonly used value for this kind of filter (increase if you want to soften the distortion more), but you may want to experiment with the 220p and so I'd suggest socketing that one and seeing what you come up with.

If you want a bit more gain from it, try increasing the 100K Gain pot.

Info from Digitech about the original:

The Bad Monkey Tube Overdrive gives your amp a boost just when you need it. It has been compared to the TS-808 but with having the unique ability to smooth out the distortion by use of the low and high EQ controls. Most overdrive pedals give you one tone control knob thus limiting your tonal options. You asked for a pedal that will maintain your guitar's distinct tone and DigiTech delivered! With its rugged design, separate mixer and amp outputs, and amazing tonal options, this pedal truly is a Bad Monkey. From Blues to Rock to everything in between, it will give you that amazing overdriven tube amp sound that will keep begging you to crank it up!






Saturday, 22 December 2012

Runoffgroove Tonemender

From ROG:The Tonemender is a very flexible, yet simple clean boost with a 3-knob tonestack that allows the user to re-create the classic Fender, Marshall and Vox responses.

We suggest using a TLC2272 for the dual op-amp. The TLC2272 is rated for low-noise and rail-to-rail output, which will offer the highest possible clean boost and dynamic range. The NE5532 is another good choice, but a TL072 can also be used with decent results.

The Mid Shift switch (SW1 on the schematic) selects the center frequency of the midrange dip in the response. The center frequency is moved from around 700Hz (Marshall/Vox) down to 400Hz (Fender) in the HI and LO settings, respectively.

For Fender-style curves, the Mid Shift is placed in the LO setting (closed). To replicate Marshall-style curves, switch the Mid Shift to the HI position (open). Set the Mid control between 12:00 and 5:00 for traditional Marshall settings, with lower settings providing additional flexibility. For a Vox-style response, keep the Mid Shift in the HI setting and set the Mids control fixed at 10:00 and move the Bass between 7:00 and 12:00.

A "flat" equalizer position is set with the Bass and Treble both at minimum, and the Mid control at its midpoint. When Bass and Treble are fully cut, the Mid knob acts as an additional Level control, which is a familiar characteristic of the Fender tonestack.


I've thrown out the previous version as this one is simply better. And definitely verified. There's quite a lot of gain coming from the circuit, so some squeels and noise from the unboxed circuits are expected.




Geiri's demo of his awesome Double Tonemender!



Friday, 21 December 2012

Boss FA-1 FET Preamp

Well it's the 21st here so I'm getting this one in early in case the world ends soon so we can get it verified first.  :o)

Another must try for fans of U2 and The Edge and another one of the boost pedals in his arsenal.  Info from Boss about the long discontinued original:

The FA-1 is an incredibly small Field Effect Tramsistor (FET) based pre-amp. The controls are real easy. There's controls for volume, bass, treble and a low cut filter switch. The amplification is as much as 20 times (26dB) and it has an input impedance higher than any other device.






Thursday, 20 December 2012

Seymour Duncan Pickup Booster

Info from SD's site:
application 
The first effects pedal designed specifically to work together with the pickups in a guitar to achieve optimum gain and resonance for all tonal applications. Works with all musical styles.

description 
By turning the gain control knob you can add pure, flat-EQ gain, ranging from 6dB to 25dB! The Resonance Switch drops the resonant peak of a single coil pickup up to 5KHz, making a single coil sound like a full and fat humbucker. Features fully discrete Class A circuitry along with true bypass. Comes in a heavy-duty steel chassis and runs on a single 9 volt battery.

of note 
For Resonance Switch to work properly, the SFX-01 must be first in the signal chain using passive pickups and a standard guitar cable -- not a wireless unit.




Wednesday, 19 December 2012

Son of Clay Jones Overdrive

Moving on from my last post, here the Clay Jones Overdrive gets the Lovepedal Eternity treatment by Fred Briggs.  Fred has essentially done what Jack Orman did with the Tubescreamer when he published the Son of Screamer schematic, which was adopted pretty much verbatim by Lovepedal for their Eternity, and no doubt a good few other boutique builders too.  So the ultimate mojo Tubescreamer gets a bit more mojo






Tuesday, 18 December 2012

Orpheum Fuzz

How come i can never seem to find any good info about these circuits :|

Anyway. Here's another 60's "classic". Ugly and mean. Simple, yet effective. Added both versions; Silicon and Germanium.

Please take note that the Ge version is positive ground with PNP germanium transistors, while the Si version is NPN with negative ground.



Monday, 17 December 2012

Clay Jones Overdrive

One of the most sought after limited run boutique pedals ever, with them going for over $1500 on eBay, and surprise surprise ..... it was a Tubescreamer that had TGP creaming themselves.  Nothing new there then.






Sunday, 16 December 2012

Cook Spring Reverb

This is the original Cook Spring Reverb design and not the "mark 2". Any spring reverb tank should do just fine...

So strike the above text. The tank type is crucial to get this design to work properly. I have no no idea what sort of tank it should be, so even though this is now verified, you should proceed with caution. The tank you have may or may not be suitable for the design. More accurate information about reverb tanks can be found here: http://sound.westhost.com/articles/reverb.htm



Saturday, 15 December 2012

Brown Sound in a Box II

Description from the General Guitar Gadgets site:

Brown Sound In A Box version 2 (BSIAB2) is an excellent distortion pedal designed by Ed Guidry. Based on the AMZ MiniBooster cascading work done by Jack Orman and further refined by Aron Nelson and Doug Hammond.

This is one of the best heavy Marshall-type distortion boxes that we've heard and it also performs very well on low drive settings.







Modded version with Contour pot



Geiri's demo of his build:


Friday, 14 December 2012

Runoffgroove 22/7

Phew. This board almost made me crazy. There is "only" 28 cuts and 11 links, but i got down to only one resistor over one strip. This one is quite interesting. CMOS Hex inverter based BMP adaptation.

A word about the circuit from ROG:
This circuit was born with the idea of making a CMOS workalike of the well known Electro-Harmonix Big Muff Pi (BMP). We chose the name Twenty-two Sevenths or 22/7 since it is a rational approximation of pi.

The gain and frequency response of each stage were adjusted to match the corresponding stage on a BMP. The result is a rich and full sounding pedal that evokes some of the fuzz sounds circa 1969, as well as some classic singing leads.

Through the years several variations on the tonestack have appeared, but after studying their variants we concluded that these differences correspond more to parts value availability rather than a significant difference in sound. So, the tonestack components were chosen to obtain an "average" BMP sound, which is referred to as CLASSIC mode in this implementation. In addition, a center-off DPDT switch was added in order to obtain two additional sought after sounds from the tonestack: a FLAT setting and a deeper SCOOP mode. In this way, the sonic palette of the 22/7 is greatly expanded.

The interstage coupling caps have been observed to vary between 100nF and 1uF in different versions of the BMP. In this implementation we chose 100n, which produces a more balanced bass/treble mix that works well for chords as well as soloing. If you want heavier and fuzzier bottom end as found in some BMP versions, you may want to replace the five 100nF caps with 1uF.

As this is a high gain circuit, good layout and cabling practices are critical for good performance. Apart from recommending shielded cable for input and output wiring, the entire circuit should be well shielded inside a metallic enclosure so as to reduce AC mains hum pickup to a minimum.




Thursday, 13 December 2012

Runoffgroove Eighteen

Info from Runoffgroove about the project:

Around 1965, Marshall introduced a few amps built around an 18 Watt EL84 powered circuit. While these models were intended for practice, the sound was much better than other small amps. Unfortunately, only a few hundred of these combos were manufactured over the next three years. These rare amps were given the model numbers 1958 for the 2X10" combo, 1973 for the 2X12" combo, and 1974 for the 1X12" version.

The features were two channels with Volume and a single Tone on each, along with Tremolo on one channel and an optional Reverb. The 18W amps consisted of 3 12AX7 type tubes and a pair of EL84 power tubes in push-pull configuration. Legend says Jim Marshall bought the circuit from Watkins Electric Music. Watkins sold a very similar amp they called the "Watkins Dominator."

An internet group for cloning these amps has been established at www.18watt.com. On this site, you will find a verified schematic for the 18 Watt combo. After hearing the sound samples there, we decided to give this circuit a try as a distortion stompbox with FETs in place of the tubes.

We opted to recreate the normal channel. The circuit consists of only one preamp stage, a volume and unique tone control setup, the phase splitter and a single power stage. There is no negative feedback, so distortion will be much easier to achieve. You may notice we used 8k2 as the value of R17 on the 18watt.com schematic. The reason for this is to scale the voltages of the associated JFET to the voltages of the amp. We did find that the sound was closer to the amp when we did this, instead of arbitrarily choosing a value. Please feel free to experiment with this resistor on your own.

Although the components designated do not look to be typical Marshall, they do produce results very similar to the soundclips of the amp. Great rock and blues sounds are readily available with this circuit.

Possible Mods:

Use 1M pots for Volume and Tone. It has been documented that some 18W Marshalls were fitted with these instead of the 500k pots specified on the schem.

Add the treble bleed cap to the Volume control to brighten the amp. 220pF is a good starting point, but other values will also work well.

Experiment with different JFETs (use sockets!) in any or all positions.

Try different values for the 4n7 and 10n caps on the Tone control to change the response. Sockets may also be helpful here. The 100k resistor is another point for tweaking.



I can't embed this video unfortunately, but you can view it here



Wednesday, 12 December 2012

Hot Silicon

A few of you were looking for good fuzz circuits....

Gus Smalley modded the circuit from Aron. Aron modded it from tonebender. Both made enhancements and mods along the way. Or so the internet tells me. Anyway. It's supposed to be a silicon adaptation of the classic. It says 2N5089 on the schematic, but i would suggest trying out something a bit lower gain - like 2N2222 or BC109B.
---
Built this last night, just to avoid any issues with it :) Works - and it's definitely not a bad fuzz. I used MPSA18s on my test build, and those work well too. Those were lying around on my desk so i just sticked them in. Didn't socket them so i can't easily try on any lower gain ones in there. But you should. Point in 2N5089s must be within the noise levels. Still. I like this one. It's not a Fuzz Face, it's not BMP, and it doesn't feel that much like the tonebender either.
Tone control may feel a bit odd, but that's to be expected. After all, it is a four transistor tonebender mod.

Just recorded a small clip with the finished box:



Tuesday, 11 December 2012

Analogguru SDD-3000 Preamp

Requested by a few people, this is the pre-amp section of the rack mounted Korg SDD-3000 digital delay.  One for the U2 fans who want to try to get a bit closer to The Edge's tone.

This one based on Analogguru's schematic with a simplified 9V supply.






Monday, 10 December 2012

John Hollis Frobnicator

This one is definitely verified, but:
The LFO section is *very* sensitive to both voltage and current, so if your board doesn't fire up right away (which happened with my second build too), you should consider doing a little daughterboard with 9V regulator, 8V2 zener and a 10-50 trimmer to get the LFO going. That being said - this is not a project for beginners.

---

Mr. Hollis has been known for his modulation circuits. This one seemed like an interesting build so i drew it up. Once again. I'm more or less out of sources for the demos and so on. But i have a hunch that this may be 1:1 with two knob version of Copilot FX Android... Anyway. The circuit does tremolo from mild to wild and flick of a switch turns it into super mean ring modulator - with lots of good stuff on the sweep. Or so i'm told.


Sunday, 9 December 2012

Haunting Mids V3

Straight from the music forum equivalent of the Freemasons, without the funny handshake but your membership can be black-balled.  The original has a trimmer for gain but I have put this as an external pot for my own personal preference in muff-like pedals.  If you'd prefer to keep it authentic then remove the wires and either put a long lead trimmer in there like the Alps RH06, or using flying leads and have a little gain trimmer daughterboard like this.






Saturday, 8 December 2012

Schaller Fuzz '72

Argh. I just hate it when i draw a layout and when i'm posting it, i can't find anything but just a few photos of the original unit - No ad texts, no original ads no nothing. Just a few images from google image search and one youtube clip from different design by the same manufacturer. So i have to go it alone.

Schematic and circuit blueprint does not differ that much from Fuzz Face, so it's safe to assume that this was german made FF-clone of the seventies. Some values are slightly different, but, it basically sounds just like any other silicon Fuzz Face. Built it myself, and i like it. Not a bad thing to have. Use as low hFE transistors you can get. 2N2369 and 2N3903 are good candidates... Built mine with 2n2222 TO-18 metal cans, and.. You guessed it.. It's not that far from my 2N2222 Si Fuzz Face clone - or from my Vox Tonebender '66 clone. So it's not super pretty, but interesting FF adaptation anyway.

If your Q2 bias needs some tweaking, that 3K3 resistor is good place to start. Replacing that with 10K trimmer wouldn't be too back of an idea. One could move that electrolytic connected to 3K3 three columns left and place trimmer as simple variable resistor between rows four and six. Did that to my board, and it's at its sweetest around 4K7-5K.




Friday, 7 December 2012

Boss OD1

Info from Boss:

The OD-1 is by now legendary. Artist of the 70's was mostly using a fuzz distortion sound and the overdrive produced by the OD-1 was not typical. It was however soon accepted as the new standard of guitar sound. The OD-1 features an asymmetric circuit where the positive and negative halves of the waveform isn't distorted equally. The sound is therefore still close to the original even though distortion have been added.







Thursday, 6 December 2012

Carlsbro Suzz

Once again. This one has surprisingly little info around the internets. Seems like a nice alternative for Distortion+. Nice, simple build anyway.

Ad text from fmogearshop (also check the photos there):
Here's a vintage Carlsbro Suzz from the seventies. The name seems to imply that this would be some sort of fuzz pedal, don't you think? Alas, the circuit has more in common with an MXR Distortion + really. So if you're expecting some sort of nasty fuzz, you may be in for a let down. But if you look at it in the proper context, as more of a basic distortion, then it's not too bad at all. Add to that the collectibility of those funky enclosure Carlsbro pedals and you may have yourself a winner.



Wednesday, 5 December 2012

Marshall Guvnor

Very similar to the Drive Master posted a couple of days ago, but thought I'd include the full layout to keep things complete.  This version with a diode/LED switch as per a request I had.  If you'd prefer yours to be like the original and have fixed LEDs rather than this switch, then just solder in LEDs directly on the board as per the Drive Master layout.  The 10u cap will need to be moved 3 columns to the right.






Tuesday, 4 December 2012

Colorsound Tonebender Re-Issue

It was surprisingly hard to find a description about this '90s IC powered re-issue. Well. So hard that i didn't find any. Some demo videos are floating around the web....



Monday, 3 December 2012

Marshall Drive Master

From an 80s Marshall ad: Fire your cartage company. You don't need a rack full of gear to get distortion that goes from subtle to stun gun.  If you want all the range of a top studio pro, the Drive Master is for you.






Sunday, 2 December 2012

Escobedo Gargletron

...And what's behind door number two?!

Heh. We talked about doing a "Layout advent calendar" for you all. Mark started on the 1st of december with Landgraff M'OD, and i'm continuing with another Escobedo circuit - The Gargletron. Original sample of the sound can be heard here.
From Tim Escobedo:
"Talking" type effect, two parallel MFB filters tuned by a single 10K pot. Similar to EH Talking Pedal and Craig Anderton's Wah/Anti-Wah design. Gives good wovel sounds.


Saturday, 1 December 2012

Landgraff MO'D

Should be pretty obvious what this one is based on but people rave about it and it does have subtle differences in the schematic, not least of which the clipping switch, that will make this one a worthwhile build.

I'm not sure if this is the official John Landgraff's description of the pedal, but it was the only one I could find:

Bring home the John Landgraff Mo D and watch as your strings bring out a totally new kind of sound. This Landgraff distortion pedal gives out legendarily amazing sounds of distortion effects. With a 3-position selector switch, this vintage distortion pedal allows you to choose between 3 varieties of distortion to enhance your strum. This Landgraff distortion pedal is the second pedal to be created by the leader of pedals and amps, John Landgraff. Users have praised this vintage distortion pedal as giving out simply outstanding, creamy distortion, without a background buzz, characteristic to many other amps. The John Landgraff Mo D will give you distortion like never before and leave your audience craving for more!








Saturday, 24 November 2012

Buzzaround-Alike

Hello new and old friends! On this day AD, we have some exciting news. I, Miro have been dubbed as thee second-in-rank-admin to help Mark around on the blog. Many of you already know me from various post threads :) Anyway. I've started to draw layouts some time ago and we thought we might give a go for these too. My layouts look a bit different  and there is a reason for that. I have been using Linux as my only operating system for last 8 years and the software version Mark uses, well, doesn't work too well on Linux/Java. Comments are open, so please let us know if you think this is a bad move :)

As a tryout for Miro's layouts, we have Mictester's Burns Buzzaround-Alike. Description from Mictester:


The legendary Burns Buzzaround was a slightly unusual germanium fuzz that achieved its (undeserved) reputation for two reasons - some great guitarists used them, and they are virtually unobtainable. The original consisted of two stages - a two-transistor amplifier and a distortion stage that could have both the amount of signal sent to it and the bias point adjusted by external controls. The third control was a crude tone control which fed the output. Originally, the output was unbuffered, and the leads and amplifier following would load the unit, and the top end would be rolled off, and often the tone control would have little effect. 

The first stage in the sound-alike is just a high input impedance op-amp gain stage. You may wish to increase the gain by increasing the value of the feedback resistor, but it sounds pretty good as shown. In the original, the first stage didn't really have much effect on the sound - it just amplified it enough to drive the following stage into conduction. 

The heart of the beast is the germanium transistor stage. Apart from using an NPN transistor, this remains true to the original (why screw up a classic?), and still gives a wide range of sounds from the thin toppy fuzz beloved of sixties bands through to gated spluttery farts, with smooth warm distortion sounds in between!

The final stage is just a buffer - it isolates the tone circuit from the outside world, and allows a full range of control from muffled to glass-shattering!





Escobedo Tripple Fuzz

When i started to draw layouts, i did draw something like 10 of vintage fuzzes that weren't published on this blog earlier. I build most of them and that's when i realized why they weren't posted. Most of them are pure crap. For those who are after "that 60's sound" - the ear piercing super thin fuzz (or just plain ugly IMO) could be satisfied with Shin-Ei and Maestro fuzzes covered here. There are many, but i find only a fraction of those circuits to be any use. For example, the stock version of VOX distortion booster is really not worth your while. I can only speak out my opinions, but the same applies to most Maestro and Höfner schematics out there. But in search for good little fuzz circuits to practise my layout drawing on, i found Tim Escobedo's circuit snippets. These are generally just proof of concept circuits and thus, not necessarily finished products.

This particular one just sounded good to me. It offers plain Elektra distortion-like, boring, but usable distortion with gain at zero. Fuzz rises with a turn of that knob, finally resulting in something really sick with massive made up overtones. It is basically a frequency tripler :) So i though i'd share this one too.

As a few mods, you could increase the 100n cap value at the input, as the base circuit kills a lot of low end when gain is maxed - or - when the circuit is at its best :)
A word about the circuit from Mr. Escobedo:

"This is a fuzz using a "nonselective frequency tripler", originally designed by R. Lockhart Jr. At low gains the sound can be very sweet. As the gain rises, you get a odd splatty fizz going on. And at max gain it's completely nasty. A nice, easy build."



Thursday, 22 November 2012

Engineer's Thumb

Request, with CA3080 instead of LM13700 (but you can use the conversion daughterboard to allow you to use the LM13700 if you prefer).

Designed my Merlin Blencowe and posted on the various DIY sites, this is how he described it:

For a long time I've felt guilty that my pedal board didn't include a compressor. Finally, after about a year of breadboarding, I have produced a circuit that can take on a Dynacomp and win, boasting:

Up to five times more headroom than a Dynacomp
Less noise than a Dynacomp
Same available sustain as a Dynacomp
Fewer parts than a Dynacomp
Cheaper than a Dynacomp
Feedforward side chain
Possibility for all five controls
Fits in 1590B
Millennium bypass

Despite its final simplicity, I went though just about every possible configuration of OTA while chasing acceptable performance. As you can see from the schem, the OTA is working as a current-controlled resistor in the feedback loop of an opamp. This reduces the contribution of OTA noise.

The input signal is also coupled directly to the side chain, which consists of a precision rectifier (U1b) and precision current source (U2a) that dumps more current into the OTA control pin as the audio signal gets larger.

The ratio control blends compressed and uncompressed signals, so its variable from zero to infinite ratio (limiting)!






Tuesday, 13 November 2012

FYA Electronics Apiformis Fuzztortion

Info about the original:

Apiformis Fuzztortion is a pedal that is quite unlike it’s original idol. In it’s heart, it is a dark low medium gain fuzz/distortion that has delusions of grandeur about being an overdrive. And it is doing all that with vintage-like touch, from doomy dark to brightly overdriven, distorted fuzz with vintage, medium sustain.

Apiformis has three controls for tuning the tone to your preferences:

FEED: Controls the load on the input (impedance). From dark, low saturation (0) to medium fuzz (5) and finally full sustained distortion-like fuzz (10). Lower settings can lead to oscillation, which is a feature.

TREBLE: Controls amount of higher frequencies boost on the tone. From dark, nearly muddy (0) to open higher mids (5) and finally to fully boosted top end (10).

LEVEL: Controls the output level of the effect. Level at zeron means that there is no signal passing through. Unity level with bypassed signal comes in with knob on ~11 o’clock. There is plenty of room for overdriving your amp with higher settings of Level control.


Already verified:







Friday, 9 November 2012

Black Arts Toneworks LSTR

Info about the original:

The Black Arts Toneworks LSTR is the red-headed step brother of the Pharaoh. The LSTR provides even more fuzz and mayhem than its brother with the swell of low end you would expect from any Black Arts pedal. This Toneworks beast uses a uniquely interactive tone control circuit allowing for a traditional tone control as well as a control for scooping the mids right out of your signal. This tone circuit allows you to achieve Russian style scooped mids with a smooth attack or huge wide-open fuzz and perfect string definition with ease. The LSTR is hyper-active gain in a box that could get you sent to bed without dinner. 






Thursday, 8 November 2012

Paul Cochrane Tim

A few people have asked for this so thought I'd add it.  If you want to include the loop it's a pretty simple affair.  Volume 2 goes to the tip of a switched socket (Send), and the normally closed contact from the tip goes to the main stomp switch board output lug, and also the tip of a second normal mono socket (Return).  So when no cable is in the Send socket the signal is being passed directly to the main bypass stomp switch.  When a cable is inserted into the Send socket, the contact is broken and so all the signal passes through the Send, back through a return cable to the main stomp.  A 510K resistor is also soldered between the tip and shield of the Return socket to act as a pulldown resistor for the output of whatever is in the loop.

I think if I was going to build this I'd probably add a third stomp and have the loop switchable on the fly to make it a little more versatile.  Then you wouldn't have to bother with a switched socket and could use conventional true bypass wiring of the additional stomp to bring the loop in and out of circuit.









Friday, 2 November 2012

Components

Part 2 of the component guide by Miro, this time looking at active components.  A good read particularly for someone new to the hobby may have a lot of his questions answered.



Part One   |  Part Two


Builder's components, part two - Active components

Good day to you all. This article here is the part two of my component tutorial, aimed for the beginner builders. I've already disclosed the reasons why i'm doing this in the first part of the series. If you're asking me how many volumes i'll write; i really don't know. When i run out of steam i suppose.

Anyway. Let's start with diodes of all types and go on to the transistors.


Diodes

Diodes aren't exactly active components in meaning of the word, but they still are semiconductors. Where resistors slow down the current, diodes can do the same to voltage. But they can do more. We have a few different types of diodes, and they all have their own purposes on the circuits. From light emitting diodes to standard switching diodes to schottkys and zeners and so on. Wikipedia entry for diodes shows the magic-like list of all the different types imaginable. All diodes have anode and cathode. Laymans terms, the anode is positive and cathode is negative side. So if you will, these are polarized in the same manner as polarized caps. We'll be mostly needing LEDs, schottkys and switching diodes for our builds. But let's not get ahead of ourselves.

LED - Light Emitting Diode

LEDs are diodes too. Hence the name. We have usually two different purposes for the LEDs in our circuits - First, we use LEDs outside the boxes to tell us when the pedal is on. Other viable and common use is to clip the signal with LEDs. If you see two LEDs on a board, connected back to back, then that's the clipping stage created with LEDs. They come in variety of sizes, shapes and colours. Most common are round 3mm and 5mm LEDs. There are 8mm and 10mm round LEDs available too. And the LEDs come in various packages, or shapes, like square style, short hat... Note that the longer leg is always the anode (the positive, "+" side) and the shorter is cathode (the negative, "-" side).

You can find a vast variety of different colours, diffused and "water clear". Clear ones are usually brighter, and they usually need higher resistance to produce same ammount of light than diffused ones. By the way, the resistance between power souce and the anode (or in some cases, cathode and ground) means how bright or dim the LED is once it's on. Diffused ones are coloured and clear ones are just transparent, no matter what's the colour when it is on. You can find red, green, yellow, pink, white, blue, orange and more as diffused and clear. Note that usually the pink, white and blue are more expensive than red, green and yellow. There are good(ish) starter packs out there, but usually their prices can be beaten by just checkin some cheap part store like Tayda. You probably want to have many different colours in stock.

Well. We also have multicoloured and other special LEDs out there. These have either common cathode or common anode. Which you might need depends on where you're going to use them. And how. One purpose would be to use two coloured LED as indicator in build where you may have two circuits in a single box. That would need common anode type. Anode feeds the current for both colours and two anodes go to their respective switches to be connected to ground. But. I bet there's enough to learn with basic LEDs as these are much more often used in our purposes.

It may be good to start with stocking up on your favourite colours in 3mm and 5mm, diffused or not, that's, of course, based on what you like.

As i mentioned above, LEDs are also commonly used as clipping diodes. Different colours have different and distinct tonal differences. Colour makes more difference than the size than shape of the LED. You can always socket the two back to back clipping diodes on your build and try out different combinations. For example, red and blue sound completely different. That's one more thing to try out.

*Hint: Try out one red LED straight on to a 9V battery. Longer leg to plus terminal and shorter to minus. This experiment will cost you one 2-3 cent LED, but you'll never forget to use a resistor between the power source and the LED.

General use diodes

Switching diodes and schottkys are the most common in our builds. For basic silicon clipping, we'll want 1N4148 switching diode. These are cheap and commonly used diodes. I think it's good to know that 1N4148 and 1N914 are the same thing. 1N4148 replaced its leakier predecessor 1N914 some decades ago. But. Now if you buy 1N914, it's going to be exactly the same as 1N4148, just marked as 1N914. Internet tells us that manufacturers do this because there is still demand for 1N914 due to mass of perfectly good and usable schematics from past decades. But they are still the same as 1N4148s. Unless you can dig up some really old NOS 1n914s...

Many designs use 1N5817 or 1N4001 schottkys as polarity protection. You might want to stock up on those too. The latter drops more of the voltage than the former. But former costs a lot more in comparison. If schematic or layout has 1N5817 in it, you can safely use 1N4001 in its place. In theory, all barrier schottkys are meant to pass the current 1:1 on the "right" direction and stop the current from passing in the wrong direction completely. This is the basic operation of all diodes.

Ah, but then we have all the magic diodes. Germanium diodes, like 1N34A, 1N270, OA91 and super lenghty list of others. The list goes on forever. Foe example, 1N60Ps are quite cheap and they are good to have. Others.. Well. A diode is a diode is a diode. For clipping stages, you'll get tonal differences with different diodes, but the rule of thumb is that germanium diodes will always be more quiet than their silicon counterpart. Germanium diodes cost roughly at least seven times what modern silicon diodes cost. And for NOS, the prices go through the roof. If the design has two 1N270s (like, for example, in DOD OD250) in it, you won't be totally off by swapping them with two 1N4148s. It won't sound 1:1 with the original, but i can promise you that this is something you will want to try eventually.

Some designs use zener diodes. These are more special cases. I personally don't see the point in sourcing and stocking all the possible values from 1V to 36V and beyound, as you'll probably need just 4,3V or 4,7V, 5,1V and 9,1V zeners in your first year(s) of building. It's really rare that some application needs exactly 4,7V zener - in my experience, the circuit will work fine with 5,1V zener in it's place. So just like with the humble resistors, you can always use the closest value you have at hand.

All of the above are marked with a stripe, regardless of the package. The stripe marks the cathode side of the diode. Did you already forget? Cathode is the negative (-) side of the diode. It's the anode that is positive.

As diodes go, they are generally somewhat cheap components and easy to stock up on due to wide availability. So, in addition to LEDs, you'll need at least a fair batch of 1N4148s and 1N4001s. In addition, some zeners won't hurt you. But you could always stock up on all of them..



The almighty Transistor

Now we're getting to the point where the real magic happens. Well. It's not that much of a magic than just plain good old physics. Transistors are used to amplify the current - which in this case is our signal. All transistors work in the same general principle - turning signal's current to stronger current with help of voltage, bias voltage and ground. This is the point where i urge you to always check the datasheet. It's easy. Just fire up google or any other search engine and type in the model of the transistor and a word "datasheet". Once you've done that several times on one particular transistor, you'll start to remember stuff like the pinout and hFE (which is the number that tell us about the transistors real gain).

Ok. Transistors are discrete devices that can amplify our signal. There are too many models and too many little differences between them to list them all. But the things we need to know are that we are commonly using BJTs (bipolar junction transistors), which is just referred to as, well, the transistor. Then we have MOSFETs and JFETs. Those are the most common three.


Bipolar Junction Transistors

Or the transistor. It has always three legs. One is called the collector, one is called the base and one is called the emitter. That's at least three legs. Transistors with four legs and some other special ones with two bases exist too. Usually we're going to need the basic ones with pinout like emitter-base-collector or base-collector-emitter.

One great discovery happened when former me ordered a silicon fuzz face kit. Former me opened bag and was baffled. "Did they mistakenly send the wrong transistors? Are these germanium instead of the silicon i ordered? I don't know what to do!?". Check the datasheet you idiot. Silicon bipolar junction transistors come in variety of packages. The metal can does not automatically mean that the device is germanium (i'll tell you more about the germs later). 2N2222 come in TO-18 package, which is metal can. BC108, BC109, 2N2907 and massive amount of others come in TO-18 as well. And they all are silicon devices. Normal black plastic package, the TO-92 is used in more devices though. Metal can gives the mojo feeling to a transistor. In case of 2N2222(A), you can get both packages, the TO-18 and TO-92, and it's still exactly the same device. There are others like this too.

Well of course the transistor catalogue of you local electronics shop is quite different from what it was 30 years ago. But the transistor is still just a transistor. To begin with, you should source the most widely used cheap transistors. It doesn't matter what the original schematic says, if it uses BJT (that's Bipolar Junction Transistor), then any BJT will do the job. It probably won't sound exactly 1:1 with the original, but will it sound worse? If the hFE range is the same, then probably not. The basic, most widely used transistors, and thus making a good sourcing tip, would be:
-2N2222(A) (BJT NPN +75 hFE)
-2N3904 (BJT NPN ~300 hFE)
-2N5088 (BJT NPN 400-800 hFE)
-2N5089 (BJT NPN low-noise 500-1200 hFE)
-2N2907 (BJT PNP +70 hFE)
-2N3906 (BJT PNP ~250 hFE)
With batch of each one of those, you'll be able to build almost any circuit that uses bipolar junction transistor. (Heh. If some of the hFEs are not 100% correct, please remember that i didn't check any datasheets for writing that information. I just grabbed the hFEs from my brain's memory banks.)

Now.. What's the deal with NPN and PNP? Doesn't that make all this a bit complicated? Yeah. I guess it does. At the beginning of the building hobby it surely does. Well it's quite simple after all. It is affected by the direction of the current. That's why normally we'll need negative 9V with circuits that are using PNPs. This is one of those things that is slightly too complicated to unleash on a beginner. Anyway, I suggest that you familiarise yourself with NPN transistors and negative ground builds until you are sure you can take on PNP designs.

*Hint: Build yourself a silicon Fuzz Face clone with two 2N3904s. That way your parts on the board will cost you less than 15 cents. That doesn't include the board material, pots, wires, footswitch, nor that possible trimpot. And it won't sound anywhere near the classic germanium AC128 Fuzz Face. But. The parts for the board still cost you less than 15 cents.

NPN and PNP is the same thing with germanium transistors. Germaniums are currently used in pedals and not much elsewhere. They leak current. Even the best ones do. That's the fault that guitar effect designers have used for their advantage since the sixties. Plus the fact that silicon devices, invented in 1954, were expensive at the time. That's the main reason guitar effects used germanium transistors for so long. Then you might ask why most of the germanium circuits are PNP? Well. History has it that most PNP germanium device models were much more consistent than their NPN counterparts. NPN germaniums exist. Good ones are just mostly gone. If you check the ebay for NPN germaniums, there are some, but they cost a lot more than PNPs of the same gain range. I've hoarded some germanium transistors, and i can tell you that none of the germanium transistors are consistant enough to just take from the bag and rock. It never works that way. Only measuring the gain and compensating the leakage in that measurement can lead to working germanium build.

Anyway. Good way to start out would probably be with the common NPN bipolar junction transistors and when you feel ready, then get your hands dirty with PNP and germaniums. Germs sound amazing due to their faults, but you may have to pay up to 500 times more for basically inferior device.

Always check the datasheet. That is the one message i can't repeat enough. What we want to know from them are just a) The pinout, and b) hFE=gain range. Those two are the ones you'll need over and over again. There is always way too much information on those documents, but you will manage fine with those two pieces of information.

*Hint: If fyou store all your different transistors in small plastic bags (like i do), you could write the basic information you'll need on the bags. Like for my bag of 2N3904s: NPN - EBC - ~300. Then i know straight away the pinout and general range of hFE.

Another type of BJT is the Darlington. Darlington is a device that basically has two normal BJTs piggybacking inside one transistor box. That configuration can lead to massive gains, like 20000 (twenty-thousand) hFE. Some manufacturers, like Devi Ever and Death by Audio seem to be in love with these. Basic two models would be 2N5306 and MPSA13. Both good sourcing targets. Wikipedia has nice article about the Darlington configuration that explains a lot. Just a hint for those who are interested.


Field Effect Transistors

JFETs and MOSFETs? Why on earth we do have so many different types of transistors? Well, the operation is quite different between bipolar junction transistors and field effect transistors. More importantly, the sound is completely different due to different bandwidth. FETs alledgedly sound nearly like tubes. That is not completely off, as you can get tube-like sound from these transistors and they were supposed to be solid state replacement for tubes to begin with... In harsh reality, only thing that sounds exactly lika a tube is a tube. FET's operation is based on electric fields, but that's a bit steep for now.. FET is older invention than BJT, but mass manufacturing of these devices started some time after BJTs. So, FET stands for Field-Effect Transistor and MOSFET for Metal Oxide Semiconductor Field-Effect Transistor. MOSFETs are notoriously delicate to high voltages. Even simple static charge can kill the device, so handle those with care. Pins of a FET are called the Drain, Gate and Source. Those translate loosely to drain being like the collector, gate like the base and source being like the emitter on a BJT. Usually the pinouts are drain-gate-source and gate-drain-source. Like i said above, the characteristics of a FET make it sound much more like the vacuum tube than squeeky clean counterpart, the BJT. FETs do not have hFE to tell you the gain. That is listed as IDSS and GFS in their datasheets. Those translate to current being put out by the transistor.

Basic and the most popular devices are without a doubt 2N5457, 2N5458, J201, MPF102, 2N7000 and 2N5259. There is much much more to FETs, as this is just a short introduction. FETs sound amazing in many applications and they are somewhere between germanium and silicon BJT when it comes to ease of use - Silicon BJT being the simplest and easiest device to build circuits with.

FETs can be used for clipping too. You could try them with source as anode and gate + drain as cathode. This will result in soft clipping. Once again, tube-like soft clipping.

There is a huge number of different types of transistors out there. Radio frequency and microwave. Exotic semiconducting composite materials, like hybrids between silicon and germanium and so on. And while we do use them mainly for amplifying guitar or bass signals, they can be used for other purposes too - like electronic switching.

*Hint: The datasheet!

That's it for now. In the next chapter we'll talk about opamps and other integrated circuits...

Thursday, 1 November 2012

Secret Sauce

Something for you all (especially Miro!) to do with your low gain germaniums that you thought were going in the bin.  Info from mictester about his circuit:

I've got back to the work bench recently, and found that I had a lot of germanium diodes and transistors. Most of the transistors were very low gain rubbish, but all have that soft knee where they begin to conduct when used as diodes. They might not be particularly good transistors, but they're great for some things....

This Christmas, as usual, I'm going to ship a few pedals to a few friends as presents. This year's project is a slightly unusual one because it has germanium in it.... Usually, I hate germanium devices, but in this case, they give the pedal a sound all its own. It doesn't sound much like anything else out there, but you've already heard this on a few records!

Possible modifications include the addition of tone controls at the output end, changing the feedback resistors around the op-amps for more or less gain, rolling off the output by increasing the capacitor in parallel with the feedback resistor.at the final op-amp..... As usual, the circuit has a high input impedance and low output impedance, but has a solid copper bypass because that's what seems to be wanted again at the moment.


UPDATED 3rd Nov 2012


Sunday, 28 October 2012

Barber Dirty Bomb

This is a great sounding effect by Dave Barber, modified to put the Sub Bass pot external.  Dave sells effects at great prices and their build quality is second to none, so this is one of those builders that everyone should support where possible.  So if you get an opportunity to buy any of his other effects at any time then do it, you won't be disappointed.

Info about the original:

Extremely versatile, high gain distortion, provides wider range of stellar tones.
From ultra chunky, to scooped and back to thick again.

Toggle switch selects mid range character for
three distinct modes.
Sweet and powerful Vintage two band E.Q.

Internal adjustable
Bass Boost for powerful sub frequencies.
True bypass footswitch delivers clarity when bypassed.

All hand wired in the USA, traditional award winning Barber layout and wiring. Cascading FET circuit, with MOSFET distortion for incredibly realistic tube quality sounds. 








BOM:
Group Name
Quantity
Resistors 91R
1
Resistors 1K
2
Resistors 2K2
1
Resistors 3K
1
Resistors 10K
6
Resistors 13K3
1
Resistors 91K
1
Resistors 100K
3
Resistors 220K
1
Resistors 470K
1
Resistors 820K
1
Resistors 1M
2
Resistors 2M2
1
Capacitors 100p
1
Capacitors 120p
1
Capacitors 1n
3
Capacitors 3n3
1
Capacitors 3n9
2
Capacitors 10n
2
Capacitors 56n
2
Capacitors 100n
1
Capacitors 220n
1
Capacitors 330n
1
Capacitors 2u2
1
Capacitors 47u
1
Capacitors 100u
3
Diodes 1N4148
2
Transistors 2N7000
2
IC TL072
2

Friday, 26 October 2012

Emma ReezaFRATzitz RF1

Requested by a few people.  Horrible to do a layout for because of multiple cascading stages with close connections from a 14 pin IC which means you can quickly run out of space, but managed to work my way through it eventually.  At 22 columns wide it will just fit in a 1590B if you file the sides down (or use a bench grinder like me), but would be more comfortable and with more room for wiring with a 125B.  Turn it 90 degrees though and it would probably fit more comfortably in the 1590B, even with 22 columns to accomodate vertically,   This has a built in buffered bypass and so only needs a SPDT stomp, or DPDT if you want to include LED indication. If you would prefer to use a 3PDT stomp and conventional true bypass switching, then the Stomp 4 connection becomes the output, you can omit the Stomp 6 connection completely, and also ignore the 2.5mm pitch 150n and 470K at the top right hand side.

Info about the Emma original:

A unique type of  OD/dist. pedal that was designed to emulate as faithfully as possible the distortion characteristics of a real tube amp.

With the inclusion of a bias control the user is allowed to adjust the inner workings of the amplifier from class B ( far left) to class A ( far right) and anywhere in between, altering the harmonic structure of the signal and providing a much wider  variety of tonal options than your standard OD/ dist. pedal.

Additional controls for Level, Gain,and a Hi Cut/ Hi Boost tone circuit allow the user to fine tune the Reezafratzitz to taste.







BOM:

Resistors 120R
1
Resistors 10K
4
Resistors 22K
4
Resistors 27K
1
Resistors 100K
6
Resistors 150K
2
Resistors 470K
6
Resistors 1M
4
Capacitors 47p
5
Capacitors 100p
2
Capacitors 1n
2
Capacitors 6n8
4
Capacitors 47n
2
Capacitors 150n
4
Capacitors 100u
3
IC CD4069
1
Transistors BC549
1



Modified version with additional Bass and Mids controls





BOM:

Capacitors 47p 5
Capacitors 100p 2
Capacitors 1n 2
Capacitors 2n2 1
Capacitors 6n8 4
Capacitors 47n 2
Capacitors 150n 4
Capacitors 100u 3
Resistors 100K 4
Resistors 10K 6
Resistors 120R 1
Resistors 150K 2
Resistors 1M 4
Resistors 22K 4
Resistors 27K 1
Resistors 470K 6
Resistors 47K 2
IC CD4069 1
Transistors Q1 1