EUROCRACK_3D

This Webpage Is A Collection Of My
Favorite Eurorack DIY Builds And Mods


If you find some of this DIY info useful, please consider donating a couple bucks. All donations are used for future DIY synthesizer development. Thanks! SUPER-JX ZONE



A-142-4 Quad Decay (Doepfer)

Expander DIY
                                    
This low cost DIY adds eight toggle switches onto a separate 4HP panel which enables you to switch between self‑oscillating or trigger mode and/or time delay ranges of 2ms/2sec or 20ms/20sec. This add‑on increases the flexibility of this already versatile module

         EUROCRACK A-142-4 Quad Decay Expander DIY   (PDF)
A-142
Radio Music (Music Thing Modular)

Panel/PCB Build Notes & Review
RADIOMUSIC
Radio Music is without a doubt one of the most creative modules in my setup. I have four of them now. The PCB/Panel Kit from ModularAddict.com is one of the best values I've found. Their set also includes the required MicroSD card adapter for free. The updated firmware allowing the use of standard *.WAV files makes it much easier to work with sample data

This module is an easy build because all of the components are through‑hole. It is EXTREMELY cost effective when buying parts from mouser.com and OSH Park. I used an OSH Park Teensy v3.2 board (this Purple OSH Park Edition is available at https://store.oshpark.com/products/teensy-3-1) which works great and is priced about $9 less than others found on the Internet. As a bonus, new firmware now enables you to turn the Radio Music module into a completely different module... the Chord Organ. Instead of playing samples from the MicroSD card, it synthesizes chords

If you are looking for some very weird *.WAV files for your Radio Music module, there are more than 10GB of free samples w/cheatsheets available at these links:

         EUROCRACK Radio Music Weird Samples #1 (Fits on an 8GB MicroSD card)

         EUROCRACK Radio Music Weird Samples #2 (Fits on a 4GB MicroSD card)

         EUROCRACK Radio Music Weird Samples #3 (Fits on a 4GB MicroSD card)

         EUROCRACK Radio Music Weird Samples #4 (Fits on a 1GB MicroSD card)

(You can preview the samples here at SoundCloud)

Discrete SV-VCF (Manhattan Analog)

Panel/PCB Build Notes & Review
RADIOMUSIC
This module is similar to Oberheim's SEM filter and the mixer is inspired by Moog's CP3 module... also built with transistors which gives it a distinct sound. Although this is a labor intensive build, the end results are worth all of your efforts. My best advice for this build is to take a little time and do some research before you start building. If you focus too much on some of the earlier posts at Muff Wiggler, you will be thoroughly confused because they deal with several different PCB versions. I definitely got lost because of "too many" suggestions. I found only a few posts which were actually relevant for my build (v1.4/Main Board + v1.3/Jack Board)
  • I used Tayda 16mm pots with solder lugs as suggested by one Muff Wiggler. Big huge mistake. I was trying to save $$$ by using what I had in my parts kit. The amount of extra time I spent soldering these using solid wire was a giant hassle. Be sure to use right angle PCB mount pots which look like this (they are the same price as pots with solder lugs)
    • Right Angle PCB Pots
      • [3] B100K - (CV1/CV2/Notch) Tayda SKU: A-1628
      • [1] B10K Dual Gang (Resonance) Tayda SKU: A-1997
      • [1] B10K (Frequency) Tayda SKU: A-1624
      • [3] A25K (IN1/IN2/IN3) Unfortunately, Tayda does not stock any of the A25K right angle variety. Search Mammoth for those

  • As suggested by the designer, I opted to use a 1K Tempco resistor at PCB silkscreen location R44*. This special resistor is available from Modular Addict. From what I've read about this, after being powered up for 2+ hours in the case, components tend to heat up and this Tempco is there to prevent temperature drift for that part of the circuit

  • I was unable to find a BOM or build docs at the Manhattan Analog website but I did find a good BOM at this link for reference There is also a Mouser Cart BOM at the Muff Wiggler link above but use that one with caution! Some of the transistors and other parts listed there are quite expensive. The BOM total $$$ was much higher than the parts I was able to source from Modular Addict and Tayda. With the exception of the Styrene Caps (P/N: 23PS210), Ferrite Beads and LM377, I was able to source all components from Modular Addict and Tayda

  • There are 13 SMD components. Two on the Main Board and eleven on the Jack Board. For the PCB versions listed above, the components are placed as follows:
    • Jack Board (Back)
      • (2) 0.1uf Caps @ Pad Locations Marked ".1"
      • (2) 22pF Caps @ Pad Locations Marked "C"
      • (2) 330R Resistor @ Pad Locations Marked "3"
      • (4) 47K Resistor @ Pad Locations Marked "4"
      • (1) TL072CDR IC @ Pad Location Marked "072"

    • Main Board (Back)
      • (2) 0.1uf Caps

    Note that if you use a 1K resistor on the front of this board at PCB silkscreen location R44*, there will be two pairs of SMT pads which are not used and left unpopulated. One pair of pads is used for for a 1K SMD mounted resistor (I used a Tempco through hole resistor on the front instead) and the the other pair of pads have large holes in them and are used only as test points. Compared to these test pads, the pads I populated with the 0.1uf capacitors have very, very small holes drilled in them. Much smaller than the test pads. I don't like working with SMD stuff but found all of these components were very easy to solder by hand using a fine tip iron

  • Some of the BOM's floating around are showing expensive bipolar transistors. The designer pretty much says not to bother using expensive transistors. Standard 2N3904 and 2N3906 transistors will work just fine. Quote from the designer - "I couldn't justify $6 for 4 transistors - x4 per board - when 2N390x at 2¢ each work and sound just as nice. As far as matching goes, I've built them with matched and unmatched transistors and couldn't really tell any difference. I recommend loosely matching them as a matter of best practice but it's not something you should worry about."

  • I socketed the resistor at PCB silkscreen location R13* on the Main Board. The designer mentions this value can be experimented with to fine tune the mixer/filter sections. I am currently using a 330K resistor here (the default value is 390K) and it sounds great. As another builder mentioned, this 330K value slightly tames the resonance. I will experiment with other values later on. Suggested values to tinker with here are between 270K and 470K
For calibration, you will definitely need to check out the info at this thread posted by user "negativspace" (Manhattan Analog Designer)
         EUROCRACK https://www.muffwiggler.com/forum/viewtopic.php?p=1529465
         Search for the phrase "Holy crap, this isn't hard"  Smiley


So far I'm really digging this module. I built two and am happy to report these make a good substitution for the Oberheim synth sound I've always craved but never owned. Here are some links with a good collection of demos:

This video demonstrates a very cool effect similar to a track titled "905" on The Who's LP "Who Are You?". That track was played on one of the first multiphonic Polymoog synths way back in 1978. Another synth I've heard which comes close to this great effect is the Roland Super JX‑10/MKS‑70 - Patch G‑3: ROBODROID DELUXE 39 47)
         EUROCRACK https://youtu.be/0ijh0IhOhOQ?t=2m28s

A very detailed overview and demo by DivKid
         EUROCRACK https://www.youtube.com/watch?v=IKi3_4VuUsg

A collection of audio demo clips. Check out "Bendy Bandpass"... oh yeah!
         EUROCRACK https://matttechmodular.co.uk/2015/06/24/manhattan-analog-svvcf-matttech/

Waveslicer (Horstronic)

Panel/PCB Build Notes & Review
WAVESLICER
I was absolutely blown away by all of the amazing sounds I'm getting out of this module!

Three INs, four CV IN's, three OUT's and eleven knobs enable a large array of different "Waveslicing" audio options

A Highly Recommended build for many reasons:
  • The designer really put some thought into the design of this PCB layout. He had the DIY people in mind. There are solder pads on my v2.3 PCB which are double duty... resistors can be either SMD or mounted through hole. I wish more designers would offer this as an option

  • Likewise, the 3.5mm jack holes are quite versatile because they will accept either Thonkiconn, Erthenvar, PJ301BM, or Kobiconn jacks. Very cool when searching your inventory for available parts!

  • The overall DIY cost was very low because of all the easy to find parts. With the exception of two dual‑color LEDs and one LM4040, I was able to find everything at Tayda. I hate builds which use SMD but this one was quite easy because none of the IC's are SMD. They're all through‑hole. There are 24 SMD components (all capacitors)... but don't let that prevent you from getting this PCB/Panel. It was an easy build and it sounds great
Suiseki Phase Shifter (Old Crow)
[ Mid-1970's "Small Stone" Phase Shifter ]

Panel/PCB Build Notes & Review
SUISEKI
The sounds this Phase Shifter effect can produce are very rich and lush. Tangerine Dream and Pink Floyd are hovering nearby when this one is active. Immediately after building this one and hearing it, I ordered a 2nd one to use for stereo effects and/or additional CV's

All components were inexpensive and simple to source (total was under $24). This build was quite easy. There was only one oddball resistor value I did not have in my parts kit (30K) which I sourced from Tayda. This is an inexpensive and feature packed effects module in a small 4HP space. At this low price you should get a pair Smiley
  • I recommend mounting the 10K trimpot (R27) onto the component side of the PCB. I have no idea why the silkscreen for this component is printed on the back or why it's even mentioned as an option in the Build Docs. If you mount it on the back, it seems impossible to install or remove the module from the case!?!? Calibration is a breeze. While turning the trimmer, just listen to how "full" you want it to sound

  • I modified some standard 9mm Alpha pots by carefully bending the three pins straight which effectively turns them into right angle mounted pots

  • I opted to use standard 3.5mm jacks and not the ones on the BOM. With a little manipulation and some hookup wire, the Tip and Ring connectors can be wired to the PCB. The ground pin is then soldered directly onto the PCB for stability

  • As noted in the Build Docs, it is also possible to change this module over to have a "Uni‑Vibe" effect. If you plan to do this, you might want to socket the capacitors at C13, C14, C23 and C24. A toggle switch or some jumpers would have been a nice addition but unfortunately... there's no room
  • The 3mm RedOrange/Green Dual‑Color LED I used was a Lite‑On brand P/N: LTL‑10CHJ

  • Except for the Dual‑Color LED, I found all of the parts at ModularAddict.com and taydaelectronics.com. Using the standard 3.5mm jacks and Alpha pots I already had in my parts kit saved me some extra $$$

    Audio examples available at the Old Crow Website

    The PCB/Panel set is available for purchase at ModularAddict.com
4046 Shaper (Barton)

Panel/PCB Build Notes & Review
BARTON4046
I was able to easily source all the components from Tayda at a minimal cost of only $8 for everything. The PCB is extremely well made and easy to solder. The build guide is easy to follow and there are no surprises. As usual, the panel made by Oscillosaurus looks fantastic

The things I would have changed with my build is to add sockets for the 1uF and 10uF electrolytic caps (Slew Control) and also for the 10K resistor. The build guide mentions that you can substitute different values at the 10K resistor location and I think it would also be interesting to alter the two electrolytic caps for experimentation

I wish I had discovered the Barton DIY PCB's and Panels a long time ago. Barton DIY modules are some incredible value priced gadgets and the 4046 Waveshaper is no exception. The demo video made by Barton is OK but... I encourage you to watch this one made by MidiverseTV instead. It gets into some better sound details and shows the output on an oscilloscope

         EUROCRACK https://www.youtube.com/watch?v=WcAFAW3IVic

The PCB/Panel set is available for purchase at ModularAddict.com
Rampage (Befaco)

Panel/PCB Build Notes & Review
RAMPAGE
With more than 800+ solder connections and 300+ components, the Rampage PCB/Panel is a VERY labor intensive build. However, the payoff is totally worth the effort. The number of new features this single module can add to your rack is staggering (Burst Generator, Polyrythmic Gate Generator, Ping‑Pong LFO, Dual Low Pass Filter, Voltage Controlled Trigger Delay... just to name a few)

I've built more than 25+ different PCB/Panel kits but the Rampage is my first BEFACO project. I was really impressed with the quality double sided PCB's and the accurate/easy to follow assembly guide and BOM. Everything worked the first time when I powered‑up and I'm looking forward to building more BEFACO modules

If you plan to source components yourself such as mini‑toggle switches, resistors, pots and LED's... be aware of the following for PCB v1.3.2 (and other PCB versions)
  • Standard mini‑toggle switches from Tayda and eBay will NOT work because the through‑hole lugs are too wide for the PCB. Use the exact part number as shown in the BOM

  • Likewise, standard pots from Tayda will not work because BEFACO pots have a unique footprint and some are the dual‑gang variety with six "through‑hole" solder pins. These special pots are available at the ModularAddict PARTS webpage

  • Resistor spaces on the PCB's are designed for use with smaller 1/8W resistors having a body length of 3.25mm. I always use 1/4W resistors for my builds because I currently have a bazillion of these in my parts inventory. I populated the entire board with the larger 1/4W variety instead which have a body length of 6mm. They worked but I had to insert each one at a 45 degree angle which led to spacing problems while trying to sandwich the two PCB's together. Using longer header socket pins solved this issue

  • If you plan on using IC sockets, be aware that there is virtually no clearance between the two circuit boards. I had to use some longer than normal header socket pins when joining the two PCB's together. If you plan to solder the IC's directly onto the PCB instead, this is a non‑issue

  • Because of the low clearance between PCB's, you may need to mount the two electrolytic caps horizontally if they are not the "low profile" variety

  • The BOM calls for 2mm LED's. I only keep 3mm LED's in my inventory. Although these are too big to fit completely into the front panel holes, they still worked when recessed. However, there is a slight bleed‑through to adjacent LED's when they are lit. I opted not to purchase the 2mm variety LED's because they are priced 10x higher than more commonly found 3mm LED's. If you are picky about LED bleed‑through, you may want to source expensive 2mm LED's instead

    The PCB/Panel set is available for purchase at ModularAddict.com
P0wr (VPME.DE)

Panel/PCB Build Notes & Review
P0WR
I'm crazy about this P0wr utility module from vpme.de. I think every Eurorack DIY'er needs one of these. This is very convenient when testing and calibrating new builds. Sure... you could have a ribbon cable sticking out the side of your rack instead but this module looks classy *PLUS* safety‑wise, the mini‑toggle switch keeps the 16‑pin header connector powered off when you're not using it

This is a super easy build, a low‑cost PCB/Panel and requires less than $2 in parts!!! The oddball connector sandwiched in the middle was supplied with my panel. As mentioned in the build thread at Muff Wiggler, some Chinese mini‑toggle switches are too big. For my Chinese mini‑toggle switch, I had to use a Dremel tool and carefully file down the solder lugs and some red plastic before the oddball connector would mate flush with both panels. I would recommend buying a correct sized toggle switch to avoid the hassle. This module has been working overtime in my rack lately. Incredibly useful!!!

The PCB/Panel set is available for purchase at ModularAddict.com
Burst (Befaco)

Kit Build Notes & Review
BURST
Another Unique And Feature Packed Module From Befaco!

(+Fast ▻▻▻ Slow Down) / (+Slow ▻▻▻ Speed Up) / 64 Triggers / Probability Knob... oh yeaaah! This one is a definite winner!!! I was really looking forward to getting this one built and in the rack. It produces some incredible patterns unlike any other modules I own. There are a couple of IN's and OUT's for a wide variety of control to sync other modules and/or receive CV's for mode changes

  • All my other Befaco builds used the PCB/Panel while sourcing my own parts. This is the first Befaco "Full Kit" I've assembled and I was quite happy to use the smaller 1/8W resistors. In the past I've used 1/4W resistors and the space was nearly unmanageable. Like all the other Befaco PCB's, everything is crowded so pay close attention to the resistor silkscreen locations

  • When attaching the two PCB's, ensure that one of the flat sides of the brass standoff is parallel and flush with the edge of the nearby IC socket. Otherwise the PCB's won't align properly

  • If I don't recognize the brandname of caps in a "Full Kit", I always replace them with high quality caps from a manufacturer like Nichicon, TDK, Panasonic or WIMA. Luckily there were only fifteen caps for this build. The ones in the kit were Huang(?) so they went straight into the trashcan. If you decide to use different brand caps, be aware that the electrolytics used here are low profile so they can fit between the layered PCB's. If using taller caps, you will need to shield and bend the leads at a right angle

  • Assembly time was quick and easy with no surprises. Compared to a Crush Delay or other "non‑Rampage" Befaco build, this one has a low parts count. Calibration was a breeze. Just hold down some buttons during power‑up
DivKid has a great overview at this link
         EUROCRACK https://www.youtube.com/watch?v=KMNqizaTN1o

The full kit is available for purchase at ModularAddict.com
Jupiter Storm (HexInverter)

Panel/PCB Build Notes & Review
JUPITER_STORM
This module can really crank out some crazy noise and random outer‑space sound effects

This is one of the more interesting noise generators I own and it's definitely a keeper. There are some extremely unique sound effects you can achieve once you start toying with the outputs on the I, IV, VIII and XI Noise Channels. The IC's and other components were inexpensive and easy to source. All IC's are priced less than 50¢ each. Note that for best results, the designer recommends using only Texas Instruments brand IC's for IC2, IC4, IC6, IC7 and IC8. Also, be aware that no additional parts are included for mounting the PCB onto the panel. You're on your own

The through hole build and off‑board wiring was very easy except for a few annoying hurdles with my Version 1.1 PCB:
  • Mounting the crazy oversized PCB onto the panel is an all‑afternoon event. If mounted to the panel at a right angle, the depth measures 90mm (about 3 1/2 inches) and it's impossible to fit into some Eurorack cases which are enclosed (ones with a backplate like the PGH Case[90]). I ended up following some suggestions at a Muff Wiggler thread and used some sheet metal bent at right angles to mount it parallel to the panel. However, this still presents a major issue because it overlaps each side of the panel by 11mm (about 1/2 inch). The PCB is much wider than the panel. I'm only able to install it into my case as long as there is a blank space on either side of it or if it is installed next to a module which has a lot of clearance on one side (however, no modules like that exist in my rack)

  • Standard sized SPDT mini toggle switches will not fit into the panel holes. I had to drill the panel holes slightly larger before a Tayda SKU: A‑4567 would fit

    Despite the many hassles needed to mount the PCB onto the panel and then make it fit into a standard Eurorack case, I highly recommend this DIY module. During the mounting and installation phase you will absolutely be cursing it the entire time but hey... I think all modules receive threats and curses during a build. This one will get a double dose of four‑letters thrown at it

    The PCB/Panel set is available for purchase at ModularAddict.com
4013 Dual Flip‑Flop (Omiindustriies)

Panel/PCB Build Notes & Review
4013
I had one professor during my Electrical Engineering studies who spent three weeks of a Digital Microcircuits course explaining the logic of JK Flip-Flops. After three weeks, the only person in the class who really understood how it worked was the professor! I feel like I'm back in school trying to wrap my head around this one. It's an excellent module for creating random, glitchy behavior. Using it with my Noise Reap VFD+ produces some amazing psychedelic cacophony and SciFi turbulence I've never heard before. This one is a definite keeper!

  • I really like the PCB the designer used for this one!!! The solder pads are very large and because of that, it was the easiest SMT module I've built to date. Like all PCB's with four‑point‑cross GROUND pads, you will want to turn up the soldering iron to a higher setting when soldering any GROUND pads

  • The holes in the panel for 3mm LED's are better suited for 2mm LED's. If you use 3mm LED's, they will be recessed. Not really a major issue unless you like to have your LED's stick out the front panel. I used Tayda 3mm super bright LED's and replaced all twelve 4.7K resistors with 10K resistors (Blue/White/UV/Red/Green/Orange). The six different colors make a mesmerizing lightshow when it's a poppin'

  • The PCB silkscreen shows values and IC part#'s for easy placement of all components except R1. I had to pause in the middle of soldering and find a schematic to determine that R1 = 47 Ohms

  • The part count is small (less than 60 SMT) and all components are priced low, low, low. The most expensive component was the TL074IDR IC at 82 each... only three are needed

    The PCB/Panel set is available for purchase at ModularAddict.com
Quad Trapezoidal LFO (Barton)

Panel/PCB Build Notes & Review
QTLFO
The Barton QTLFO is a very interesting module the way it feeds itself different envelope timing sequences. It's not what one would typically call a "random" setting but it certainly adds unpredictable patterns into the beat. It outputs four trapezoidal waveforms which are synchronized with each other. One envelope begins to rise when the previous envelope falls and reaches zero. After the fourth envelope reaches zero, the entire sequence cycles again and again. Each output has a separate knob to control the envelope rise and fall time

This one is a low‑cost, low‑count component build. The components used are very common and excluding the PCB/Panel, the cost was less than $12 (USD). The most expensive components are the four anti‑log potentiometers at 50 each! The build time took only a few hours and it's very simple

The PCB/Panel set is available for purchase at ModularAddict.com

QTLFO
Channel 1 envelope begins to rise when Channel 2 falls to zero
Channel 2 envelope begins to rise when Channel 3 falls to zero
Channel 3 envelope begins to rise when Channel 4 falls to zero
Channel 4 envelope begins to rise when Channel 1 falls to zero
Two Nine Five (MMI)

Panel/PCB Build Notes & Review
295
This is an adaptation of the Buchla Model 295 10‑Channel Comb Filter

Looks are deceiving. At first glance it looks like an ordinary Equalizer but it's much more than that. This Comb Filter adds a delayed version of a signal to itself causing constructive and destructive interference. The crazy sound filtering you can get out of this module is impressive!
  • About 90% of all components are 0603 SMT so it takes a little longer than your average through‑hole build. It is absolutely imperative that you solder R13, R39, R17, R37, R19, R35, R25, and R33 properly before mounting the trim pots as they will be very difficult to reach once all components are in place

  • There are eight trimpots on the back which allow individual tuning of each Band Frequency, Q's, and Amplitude. Mouser was out of stock of the red sliders at the time of my build so I opted to go with orange and it looks great sporting the 10 LED sliders. This Bournes slider pot is available in three colors
              Red: (P/N: 652-PTL20-10R0-103B2)
            Green: (P/N: 652-PTL20-10G0-103B2)
           Orange: (P/N: 652-PTL20-10O0-103B2)
  • The BOM shows a pricey SMT 10‑Pin Power Header. I'm notorious for being a cheapskate so whenever possible, I try to use inexpensive parts at hand and modify. I took a 20 Double Row Pin Header and used small needle‑nose pliers and bent the pins at opposite right angles. It worked great but soldering that part was a slight challenge because of the tight quarters. Even if you use the expensive part, this component will be a tricky soldering job


    TAYDA-A-198_BENT


Here is a audio demo at SoundCloud of the Buchla Model 295 with some random slider action
         EUROCRACK https://soundcloud.com/about_blank_music/buchla-model-295-demo

The PCB/Panel set is available for purchase at ModularAddict.com




CROSSREFs
Favorite DIY Tools And DIY Vendors

Tips For DIY Freaks Who Like To Save $$$. I picked this selection of gadgets and vendors because of the extremely LOW cost. I use everything shown here almost every day and highly recommend each one

               Link Arrow Favorite DIY Tools And DIY Vendors



Safety Precautions and Disclaimer:
Modifications made to any factory stock equipment will always pose an element of risk. Sometimes mistakes are made which are irreversible. Improper soldering and handling of electricity can cause serious injury and damage the synthesizer. Use caution when handling static sensitive devices and the PCB. Make sure you are properly grounded, working on a static‑free workbench or table and wearing eye protection during any soldering tasks. The author is not responsible for any damage or injury resulting from this DIY info. Use this DIY information at your own risk. And, I can't stress enough, the importance of wearing eye protection while soldering. That stuff flies everywhere sometimes!


ANIMATED_STAR I think this topic is important enough to place on all of my synth INFO webpages

POWER_TRANSISTORS
I buy a lot of broken synths on eBay and I'm able to fix about 90% of everything I find. It's usually a simple fix. If you have a synth with no power or intermittent problems after it warms up, it's probably due to the fact that back in the 1980's Roland and other synth makers used sub‑par solder and/or not enough solder to hold components in place. After 30+ years, the solder begins to break down and hairline fractures appear. This occurs at a higher rate for components which generate a lot of heat like Bridge Rectifiers, Power Transistors, large Electrolytic Capacitors, power input jacks and audio sockets which get a lot of use. The best approach is to use a magnifying glass and carefully inspect the backside of the circuit board. If you spot any suspect areas, re‑flow a hefty amount of NEW solder


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