• Bad News: Sadly, the Teensy v3.2 board (a key component for building this module) has been discontinued and is out of stock everywhere. Those who built a Radio Music, Chord Organ or Sound Study AirWAV (a Radio Music clone) prior to 2020 and those who can find a used one are extremely lucky. There was a brief production run of brand new 3.2 modules in October 2023 but these have since sold out and officially signify the end of Teensy 3.2 production
  

• 1) Radio Music v2.x PCB's and all AirWAV PCB's have an issue with distorted sound after the module has been powered on for a while. An easy fix is to attach a 100KΩ resistor between two solder points on back of the Logic PCB (in between the leads of C4). I used a 1206 case size SMD resistor (see image here) but a regular through‑hole resistor with bent leads will also work. The distortion issue is documented at this link on the Music Thing Modular support webpage
  
  
  
• 2) If you have built an AirWAV module, the BOM (dated Oct 4, 2016) has the wrong capacitor types listed for C2 and C3. These should be 100nf Poly Box capacitors but instead they are shown on the BOM as Ceramic capacitors. So... why is this important? Ceramic capacitors tend to behave as microphones and in an audio circuit they will pick up unwanted ambient sounds and voltage crosstalk. C2 and C3 are part of the main Audio Out circuit while most of the other capacitors are connected to ground and used as bypass filters or for decoupling. The original Music Thing Modular BOM is at this link and clearly shows that C2 and C3 should be Poly Box capacitors, not ceramic
  
  
• 3) I've built more than ten Radio Music modules and 99.9% of the time when I encountered a problem, it always turned out to be an issue with the microSD card. If you encounter any problems, I suggest checking these things on the micro SD card first
  • Ensure the number of folders and sample files do not exceed the maximum limits and the proper name format is used
    • 8+3 naming convention [ 12345678.WAV or 12345678.RAW ]
    • 1,200 file limit [ 16 folders x 75 files per folder ]
      Exceeding any of these limits will cause the module to freeze and lock‑up
  • Check the  settings.txt  configuration file. Some combinations will collide with each other and prevent playback
  • Only use a quality name brand microSD card like SanDisk, Kingston or Kodak. Some generic brands keep the module from booting
  • When all else fails, backup all 16 folders + the settings.txt file, reformat and then copy everything back onto the microSD card

• NOTE: These samples were created way, way back in 2015 when the initial firmware required headerless *.RAW format files. If you are using a  settings.txt  file on the microSD card with newer firmware, ensure that  pitchMode=0  or else these samples will playback at an extremely slow speed... about 5x slower
  

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

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

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

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

(Figure H: Click For Larger Image)

          Blue: D6RLBUF1 LFS        Green: D6RLGNF1 LFS
           Red: D6RLRDF1 LFS        White: D6RLWHF1 LFS
     

• UPDATE AUGUST 2021
• A few users are reporting that with some Eurorack cases, Radio Music and Chord Organ will only power on about 50% of the time
  
  
  • Solution #1: Reflow new solder for the two 10µF Electrolytic Capacitors at silkscreen locations C6 and C7
    • This worked for me. I turned my soldering iron temperature higher than normal, used a heatsink and reflowed new solder
    
    
  • Solution #2: Using a low quality generic microSD card will sometimes prevent the module from powering on
    • Use a high quality brand name microSD such as SanDisk or Kingston
    
    
  • Solution #3: Remove the microSD card before powering on. After powering on, plug the microSD card back in for normal operation
    • This is only a temporary fix but prior to discovering Solution #1, I used this method all the time
    
    
  • Solution #4: There is no Solution #4. Some Eurorack case power supplies just won't play nice with this module
    • There are some open issues at the Music Thing Modular support webpage about the power problem: Issue #99 and Issue #84

• Notes:
  
• 1) If you built this module using a v1.0 or v1.1 PCB, the new v2.0 PCB was released July 2023 which improves timing/stability +plus+ provides symmetrical rise and fall rates. A revised BOM and Build Guide is available here
  
• 2) With a suggestion from Michael Barton for my v2.0 build, I replaced both 2.2K resistors with 10K. This solved an issue I was having with the circuit freezing and LED#2 + LED#3 always remaining on

• I used Tayda Electronics 16mm pots with solder lugs as suggested by one Mod 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 and will save you an enormous amount of assembly time so... it's a no‑brainer)
  • Right Angle PCB Pots
    • [1] B10K (Frequency) Tayda SKU: A-1624
    • [3] B100K - (CV1/CV2/Notch) Tayda SKU: A-1628
    • [1] B10K Dual Gang (Resonance) Tayda SKU: A-1997
    • [3] A25K (IN1/IN2/IN3) Unfortunately, Tayda Electronics does not stock any of the A25K Audio/Log right angle variety so you will need to source these three potentiometers elsewhere
  
  
• 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 Mod 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 Electronics. With the exception of the Styrene Caps (P/N: 23PS210), Ferrite Beads (P/N: BL01RN1A1F1J) and the LM377 (P/N: LM337LZ/NOPB), I was able to source all components from Modular Addict and Tayda Electronics
  
  
• 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 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

• My full kit had eight PCB's to assemble. Yes... that's not a misprint. EIGHT. There is one large square main PCB. Mine was labeled as ED120 v1.1. Three of the rectangular PCB's are used for a majority of the pots and jacks. The other four PCB's are very small and are used to attach the Y, Z and RESET/INHIBIT Jacks and also the EYES Switch. I was a little confused about the four small PCB's because three were blue and labeled "Carrier" and one was green and labeled "Carrier V1.2". I sent an eMail to Elby Designs and was told that the solitary green one labeled "Carrier V1.2" is used for the EYES Switch. The A5K Pot is installed on the Main PCB at silkscreen location P101 (Labeled NL DRIVE on the front panel)
  
  This is how I populated my PCB's with components
  
  • Board Revision(PCB Type): Components(Silkscreen Location)
  • ED120 v1.1(Main PCB): A5K Pot(P101), X Jack(J103) and TAME/WILD Switch (S101)
  • Carrier(Small Blue PCB): Y(J102), Z(J101) and RESET/INHIBIT(J204) Jack
  • Carrier V1.2(Small Green PCB): EYES Switch(S102)
  • Panther - Jack-Switch Board Rev 3.1 (Rectangular PCB): Blue Jacks - CV RATE(J1), CV DAMPING(J2), CV OFFSET(J3) & CV GAIN(J4)
  • Panther - Pot-Carrier Board Rev 1.4 (Rectangular PCB): A100K Log Pots - RATE(P1), DAMPING(P2), OFFSET(P3) & GAIN(P4)
  • Panther - Pot-Carrier Board Rev 1.5 (Rectangular PCB): B100K Linear Pots (P1, P2, P3 & P4 - Attenuators labeled w/Right Arrow ⟶)
    
    
• Connections for the 16‑pin ribbon cables
  • J201 on Main PCB   ➟ ➟  J6 on Pot‑Carrier Board Rev 1.4 (Note: Don't confuse this with J6 on Pot‑Carrier Board Rev 1.5)
  • J202 on Main PCB   ➟ ➟  J6 on Pot‑Carrier Board Rev 1.5 (Note: Don't confuse this with J6 on Pot‑Carrier Board Rev 1.4)
  • J203 on Main PCB   ➟ ➟  J5 on Jack‑Switch Board Rev 3.1
  • J301 on Main PCB   ➟ ➟  Case Power
    
  
  
• If you have PCB revisions different from the ones I've presented here, I recommend that you eMail Elby Designs to get additional info for correct component placement. Elby Designs was friendly and also very fast to respond with technical help
  
  
• One of the best descriptions about this module and how it works is at Ian Fritz's website, the Chaotica designer. There are many audio clips here and also an in‑depth video
  

• I'm always curious about unused pads on DIY builds. I contacted the designer of this one and he explained the following about the unused pads as detailed in this image
  • The two unmarked pads on the front are for a bypass capacitor (100 nF) which isn't really necessary
  • The two pads with holes marked CV and Gate are for possible use if one wants to build the keyboard into some other device, say a real keyboard or some other keypad thing, like an old telephone pad or something else

• Make sure you install all of the tall components on the back of the PCB
  • These components are the two Trimmers, the Power Header and the electrolytic capacitors if you use part numbers other than ones shown on the BOM (i.e. taller than 9mm. Silkscreen outlines on the front of the PCB are misleading. If you install these tall components on the front, you won't be able to fit the front panel in place. You might be able to bend taller electrolytic capacitors downward at a 90 degree angle to make them fit but the two trimmers and power header will absolutely need to be installed on the back. For my build, I used two of these capacitors (Panasonic P/N: EEA-GA1H100) and one of these (Panasonic P/N: ECE-A1HKA2R2I)
    
    
• The standoffs and nuts I used to connect the front panel to the PCB were made of nylon. This is recommended in order to prevent any short‑circuits on the PCB close to where some of the tact switch pins are located. If you decide to use metal standoffs and metal nuts instead, use some plastic washers to raise the standoffs up & away from the PCB
  
  
• There is a Xerox page included with each PCB/Panel kit. There are some misprints with the BOM quantities
  • Only four 200K resistors are shown but you will actually need five 200K resistors
  • Only nine 100K resistors are shown but you will actually need ten 100K resistors

• "Chaos requires three degrees of freedom, or variables. Chaotica has three VC OpAmp integrators that correspond to the three degrees of freedom, so it can oscillate on its own. ChaQuO is a second order system, and an external driving source is required to provide the third degree of freedom. The double‑well chaos (EZ Chaos) board was the first board I designed, and it was intended to be the simplest way for folks to get into a DIY chaos generator. ChaQuO with its built‑in driving source was its follow‑on."

• There is a jumper wire which needs to be soldered onto the Main PCB which runs from the Column 2 PCB 16‑pin header over to the Column 3 PCB 20‑pin header. The easiest way is to run this across the top of the PCB (Figure A and B)
  
  
• Take care when plugging the Main PCB into the four rectangular PCB's. The 16‑pin and 20‑pin headers need to be aligned in the center. It's quite easy to accidentally shift these pin headers left or right and plug the Main PCB board off‑center. The male headers have notches but the female headers do not. Luckily, I discovered my mistake before I turned on the power (Figure C)
  
  
• Before soldering the 16‑pin and 20‑pin headers in place on the Main PCB, assemble all of the PCB's in their correct positions, plug in all of the PCB's into their headers and then solder the pin headers in place on the Main PCB. This will ensure a better fit during the final assembly
  
  
• There are ten PCB's in this kit! Not a misprint. TEN! Lining up the four rectangular PCB's in the correct order is crucial. Refer to the image for the correct order (Figure D)

Figure A (Click For Larger Image)	Figure B (Click For Larger Image)
Figure C (Click For Larger Image)	Figure D (Click For Larger Image)

• The creator 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 mounting holes are versatile because they will accept either PJ301BM or PJ398SM 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 the LM4040, I was able to find everything at Tayda Electronics. 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 a very easy build and it sounds great

• Except for the DMMT3904W 6‑pin Matched Bipolar Transistor in a !!!Microscopic!!! SOT‑363 package, all of the SMT parts were very easy to solder in place. As stated by the module designer in his calibration video, not all DMMT3904W IC's will work because the modern day tolerances of these IC's are "too precise". In a batch of ten, maybe eight will work correctly with his design. After building, you may need to remove the DMMT3904W and try another one if no noise is generated. My first build did not work. Lucky me! After replacing the DMMT3904W with another one from the same batch, it worked perfectly. I'm glad I watched the designer's calibration video first. So... moral of the story... buy ten DMMT3904W IC's in case you need to replace one. They're inexpensive
  
  
• There is a helpful trimmer calibration video on YouTube here
  
  
• EagleCAD Schematics and Board files are here

• Standard mini‑toggle switches from Tayda Electronics 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 Electronics 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 sometimes stocked at the modularaddict.com 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
  
  Currently out of stock at most places but the PCB/Panel Set and the Full Kit show up sometimes at ModularAddict.com

• 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 lack of 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
  
  
• The four Befaco‑style 10K pots have two case support pegs each which stick out pretty far on the back side of the Control Board. After soldering these case support pegs in place, it's a good idea to cut these somewhat flush with the PCB because they interfere with the socketed IC's and other components on the Main Board (click image for a detailed view)
  
  
• If I don't recognize the brand‑name 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 or mount them on the back
  
  
• 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 as detailed in the Assembly Guide

• From the Galilean Moons User Manual
  
  
• "...the XPAND connector activates the XOR noise output on Galilean Moons and normalizes some of Jupiter Storm’s noise outputs to the VCA inputs of the Galilean Moons module. This arrangement forms a rather powerful synthesis engine with minimal external patching. One of the primary features enabled by expanding a Jupiter Storm is the activation of the XOR noise output seen in the center of the panel jacks on Galilean Moons. This audio output is a harsh XOR gate feedback noise source that can be used to synthesize all manners of unique sounds. The frequency and tone of this noise is determined by Jupiter Storm’s three oscillator frequencies, just like the other outputs on Jupiter Storm. Use it like you would a waveform output from a VCO in your system! Plug it into VCAs, VCFs and otherwise."

• 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 Mod 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 modules on both sides which have a lot of clearance (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
  
  

• 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 Electronics 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 light‑show 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
  

Euro Kastle v2 Guide
(Click For Larger Image)

• The jacks labeled MIX OR OUT and OSC OUT are duplicates. Both will output the same signal
• Formant Synthesis, Phase Distortion and Tonal Noise modes are activated using the upper toggle switch
  • This toggle switch alters output for the jack labeled OSC SQU (labeled in red as osc 2 in the "Operation Guide")

• There are sixty‑three 100K Ohm metal film resistors and the specs for these require a tolerance of 0.1%. Not 1% like most other builds. This bumps up the build price considerably
  
  
• There are some oddball IC's you won't find at Mouser, DigiKey or other big‑name suppliers. Three CoolAudio V2164M Quad VCA SOIC‑16 IC's are needed and you can find them at CabinTech Global for a good price with quick, low‑cost shipping

• About 90% of all components are 0603 SMT/SMD so it takes longer than a through‑hole build. It is absolutely imperative that you solder R13, R39, R17, R37, R19, R35, R25, and R33 in place before mounting the trimpots 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 Bourns 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)

• If you purchased the Modular Addict v3 PCB (text in the upper right corner of the PCB says Modular Addict) you will notice there are no markings to show correct orientation of the diodes (D1, D2) and the IC's (U1 thru U5). You can view the correct orientations for the v3 PCB using this PCB image or reference the PCB image shown at the MMI Modular Github webpage
  
  
• 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
  
  
  
  

1. When I installed the Kammerl firmware on a brand new fresh build, I had to first install the original Clouds Bootloader and Clouds *.HEX files (see the "Cheatsheet" above) and then install the Kammerl firmware
   
   
2. I had an issue the first time I used Kammerl. The Pitch was always stuck at the lowest possible setting. I was never able to set things back to the default using any of the buttons. The only way I was able to correct things was to erase the STM chip and reload the firmware using the sequence below (This was not an issue with the Kammerl firmware but instead was most likely a mistake I made due to my inexperience with using it for the first time. I probably changed and saved some parameters I shouldn't have)

• Run the STM32 ST‑LINK Utility
  • From the dropdown menu
    • Target Connect   >>   Program & Verify...   >>   Install clouds_bootloader.hex
      
      
      

      (click here for instructions)
      • (See the "Cheatsheet" above for the steps used to install firmware)
  • From the dropdown menu
    • Target Connect   >>   Erase Chip
    • Program & Verify...
      • Install clouds_bootloader.hex
      • Install clouds.hex
      • Install clouds_kammerl_firmware_v042.hex

• "Your drum section will never be the same again...
  
  Take the user interface of an euclidean sequencer, a healthy dose of machine learning and graph algorithms, megabytes of drum loops, hours of intensive computations and you've got a drum pattern generator like no other
  
  Grids' "brain" is a map of the typical drum patterns used in (mostly electronic) music, laid out by similarity, trained on a large corpus of drum loops. The module can smoothly interpolate and navigate from one pattern to the other, at the whim of a knob move or a CV
  
  But Grids' knowledge of drum patterns goes far beyond what would be achieved with presets – given a position in the map, thousands of variations can be intuitively generated by controlling the "event density" of each of the 3 channels (bd, sd, hh) – gradually moving from a sparse backbone to a deliciously rich pattern with ghost notes, rolls and fills. ... especially when modulated by a noise source!
  
  Add CV-control on these parameters and you can add subtle or drastic variations to the drum pattern. If you don't want to waste a noise source or Sample & Hold for that, Grids has its own internal source of randomness that can unpredictably spice the pattern, in an always meaningful way
  
  Building the rhythmic foundation of your tracks with Grids is fun, surprisingly intuitive, with modulation and variations possibilities that will rapidly make you forget x0x-style sequencers"

====================  ===  =======  =============  =================================  ==============================================
MAKE/MODEL            HP   COST/HP  DEPTH          PROS                               CONS
====================  ===  =======  =============  =================================  ==============================================
Doepfer A-100PMS12    672    $2.73  Fixed @ 4.01"  Sturdy Travel-Ready Shell / Deep   Very Heavy @45 lbs. & Very Difficult To Move
PGH EP-420 (Black)    420    $2.86  3.49" - 5.89"  Thick Baltic Birch / Very Deep     Heavy & Difficult To Move When Filled
PGH Core 420 (Black)  420    $2.38  1.37" - 2.93"  Thick Baltic Birch / Deep          Not Portable If Attached To EP-420
PGH Core 420 (Plain)  420    $2.15  1.37" - 2.93"  Thick Baltic Birch / Deep          Not Portable If Attached To EP-420 / Unstained
Doepfer A-100LC9      252    $1.86  Fixed @ 4.29"  Low Price / Very Deep              Very Thin Wood Shell / Unstained Plywood
TipTop Audio Mantis   208    $1.62  1.96" - 2.39"  Very Low Price / Moderately Deep   External PSU / Plastic Shell
Intelligel Case-7U    208    $3.37  Fixed @ 2.69"  Extra 1U Module Row / Audio Jacks  External PSU / Very High Price                
Arturia RackBrute 6U  176    $2.04  2.19" - 2.95"  Sturdy Aluminum Shell / Deep       PSU Is A Module & Not Built Into The Case
Make Noise 104 Skiff  104    $2.41  2.01" - 2.56"  Sturdy Aluminum Shell / Deep       External PSU / Shallow Depth
Moog 104 Skiff        104    $2.40  1.73" - 1.88"  Sturdy Aluminum Shell              External PSU / Extremely Shallow Depth
Cre8Audio Nifty Case   84    $2.37  Fixed @ 2.17"  Built-in Converter Connections     External PSU / Build Quality Issues Reported
====================================================================================================================================

Notes: 1) After my 2021 review, production costs for the EP-420 went up an extra $200. The "COST/HP" ratio isn't what it used to be
       2) The "COST/HP" ratio is based on current pricing from February 2024 and does not include any shipping fees or taxes
       3) Some cases are larger than others. To equal an EP-420, you need five Cre8Audio Nifty cases (adds five extra wall warts!)
       4) Pittsburgh Modular gets my vote for Best Overall Eurorack Cases because of their high quality build, features and price

• Purchased an Arduino Uno board. The cost is about $10(USD) and looks like the board in Figure 1
• Purchased a Type‑A to Type‑B USB cable. Looks like this and is used with the Uno Board
• Purchased a Type‑A to Mini‑B USB cable. Looks like this and was bundled with my Grains DIY kit
  • This is required for installing firmware on the Nano Board
• Purchased a set of Dupont Female to Male jumper wires. Looks like this and are at taydaelectronics.com
• Downloaded the free Arduino IDE software (Mac or Windows ‑ www.arduino.cc/en/main/software)
  • This software is needed to Reflash/Repair/Install the bootloader and install firmware into the EEPROM IC on the Nano Board
    
• Reflashed/Repaired/Installed the bootloader on the Nano Board's EEPROM IC
  
• Installed Grains firmware on the Nano Board's EEPROM IC via Type‑A to Mini‑B USB cable
  

Figure 1
Model# Arduino UNO R3 MEGA328P

• Tools  ▻  Board  ▻  Arduino AVR Boards  ▻  Arduino Nano
• Tools  ▻  Processor  ▻  ATmega328P
• Tools  ▻  Port  ▻  (Your Serial Port)
  • On a Mac it shows up something similar to   /dev/cu.usbserial‑1410
  • On a PC something similar to  COM4
• Tools  ▻  Programmer  ▻  Arduino as ISP
• File  ▻  Open  ▻  (Choose a new firmware file. This will be something similar to pwm‑saw‑vca‑vcf.ino)
  • This firmware file must have the extension of *.ino
• Sketch  ▻  Verify/Compile (returns with the message "Done Compiling")
• Sketch  ▻  Upload (Returns with the message "Done Uploading")
  
  
• If there are no errors returned, unplug USB cable from the Nano Board, plug the Grains module into your Eurorack case and test the new firmware

   QU = Quijada
   CY = Cymbal
   MA = Maracas
   CW = Cow Bell
   CL = Claves
   BD = Bass Drum
  BG2 = Bongo
   GU = Guiro

• There are no schematics, no build documentation and no BOM online for downloading
• The designer (Old Crow Modular) has not answered any of my support eMails for any modules dating all the way back to 2017
• And yes... I was stupid enough to buy it anyway. I do like challenges

     0 Chorus/Reverb
     1 Flange/Reverb
     2 Tremolo/reverb
     3 Pitch/Shift
     4 Pitch/Echo
     5 Test
     6 Reverb 1
     7 Reverb 2

• Arduino UNO board. It costs about $10(USD) and looks like the board in Figure 1 (see the Grains module above)
• Type‑A to Type‑B USB cable. Looks like this and is used with the Arduino Uno Board
  
• Set of Dupont Male to Male jumper wires. Looks like this and is at taydaelectronics.com
  
• Project Breadboard. Looks like this and is used to program the ATtiny85 IC
  
• Free Arduino IDE software (Mac or Windows ‑ www.arduino.cc/en/main/software)
  • This software is needed to program the ATtiny85 IC
  • A one‑liner from the mxmxmx docs says this can also be used to load custom user EEPROM code. So far... no luck

Figure A
Jumper "i" For Internal Patches
(click for larger image)

      ✓ Focusrite Scarlett 2i4 2nd Gen    ✓ MOTU 823 mk3               ✓ RME FireFace UC 2X2
      ✓ Focusrite Scarlett 4i4 2nd Gen    ✓ ESI Midimate eX            ✓ M-Audio Profire 2626
      ✓ Focusrite Scarlett 6i6 3rd Gen    ✓ Yamaha UX 16 USB/MIDI      ✓ Tie Studio MIDI 1i1o
      ✓ Miditech MIDIface II Thru         ✓ iConnectivity mioXC 1x1    ✓ Miditech MIDIface 4x4
      ✓ ESI Midimate II                   ✓ iConnectivity mio 1x1

     ✗ AVID/M-Audio Fast Track Pro      ✗ M-Audio MIDISport UNO      ✗ M-Audio MIDISport 1x1
     ✗ M-Audio Uno                      ✗ Lekato MIDI USB            ✗ DigitalLife MIDI-C01
     ✗ Fore MIDI Interface              ✗ Hosa USM-422 MIDI          ✗ M-Audio MIDISport 2X2
     ✗ Hosongnic, HiFangeow, etc...