Roland CR-8000 CompuRhythm - mods

The Roland CompuRhythm CR-8000 came out in 1981 & is without a doubt one of  Roland's finest drum machines. Often referred to as the "poor man's 808" I think it has its own unique character that is neither TR-808 nor CR-78.... but something in between. It's high hats are legendary and that bass drum certainly has a kick to it, but it has a few flaws. A lack of individual outs, and its very basic programmability are some of the limitations.



Moddifying the drum will help this instrument reach its true potential.
My friend Paul A (aka: Cobramatic), has given me permission to document some of his mods.

Paul used a combination of mods from Josh Gumi's excellent site GumiElectronic and some
Analogue Solutions mods but he also came up with a couple of mods to the mods on his own.
Most of the mods involve replacing fixed resistors with pots. The mod for the bass decay is awesome and uses just a cap and a few more resistors.

Gumi's site describes dozens of mods but Paul wanted to keep everything within the original case. So due to the lack of room a choice had to be made re the ones that appealed the most.

With this many mods there is just enough room to get 24 mini pots and switches in the top cover
(maybe a few more if you are brave) but closing all up afterwards is a real challenge with all those wires.

Obviously a breakout box is another way to go for those with the skill and patience to use ribbon cables and connectors. Plus you could also add switches to everything & even some "tone pre-sets" using fixed resistors if you are really game.

Paul did the 6 main individual outs - a must-do in his opinion. It's also theoretically possible to take out all 13 drums but this involves much more wiring. And beware, that steel plate on the back is 2mm thick and needs some careful and rigorous drilling to get through.

Paul doesn't like the suggestion of utilising the existing footswitch and sync jacks
because then you loose that valuable functionality. (especially the sync pulse outs). They are invaluable with CV/gate synths and modular's. He also uses it to sync up his modded Bentley Rhythm Ace for even more analog goodness.

 Josh's suggested voice swap to get the Tom's on a different output is a very good idea which will possibly be a future mod. For now Paul has left it out ... you know, you can't do everything.

"The sound bending is way way greater than a normal machine of course - going from crazy tuning to booming decays (open up decay all the way) and overdriven sounds". Paul now has tuneable bass drums, hats, cowbells, toms, snares and to top it off, "the worlds snappiest clap".

At the last minute he added the snare boost circuit and mounted that next to the on off switch
(so he didn't have to open her up again!).

Final thoughts
"There are an amazing set of tones now available. the Bass Drum (make sure you also do the separate decay mod circuit), Snare, Clap and Tom's are really worth doing. Hats are great too - I did my own hats mod to switch between  808 style and noise/sizzle maracas sounds which also gives the ride cymbal a fantastic harder metallic strike. The cowbell is cool if you love it but I notice it did  introduce a slight noise hum into the snare channel - no idea why, but it is not critical  and can be turned down when not using the Cow Bell"..

"Be very careful when you open her up - there is a high voltage power section that you must be very careful with while testing the mods". Paul taped plastic over this section so he wouldn't accidently touch it.
It's good to play safe. Electricity can KILL YOU

"I (Paul) also blew the fuses because I accidently let the voices board slip onto the programming board while powered up - ooopps, this could have blown the whole project and I did it twice!!! Be a lot more careful than I was and don't even try it if you cant identify the High Voltage power zone from the rest. You have been warned!"

(Sorry that the pic is upside down)

Some people say that the CR8000 is a poor mans 808 - but with these mods Paul say's he will take it any day of the week  Plus at way way way less than an 808 price even if you add $100 of pots, components, knobs and wires, you can get for yourself a highly customisable & awesome sounding analog drum machine with dinsync in and out (get a dinsync / midi swing convertor and you are set).
This coupled with the amazing "Register and Arranger" section which are not available on any other machine.
make this one brilliant piece of kit.

It's great for jamming. Plus you get to have 8 programmable 2 bar presets and 4 programmable fills which you can mix with the other presets at will. Programming it is easy once you get the hang of it (but yeah, obviously not as good as on a 808 style machine).

"This baby is definitely my favourite drum machine now - hands down.(thanks again to Josh Gumiela for the well documented mods and info on his site)".

Many thanks to Paul for his efforts. May it encourage others to get out their soldering irons and have a go.

More Links:
1. CR-8000 description & features.
2. Roland CR-8000 :: GumiElectronic
3. Roland CR 8000 with mods mov - YouTube
4. Roland cr 8000 analogue solutions tonal mod video


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For more info on the history of Roland Drum Machines click here

Roland CR-8000 CompuRhythm Drum Machine - Description.

The Roland CompuRhythm CR-8000 came out in 1981.
It's without a doubt one of Roland's classic drum machines with roots that go back to the  famous CR-78 (produced in 1978) & the TR-808 (which came out just one year before in 1980).
The 8000 & 5000 also look a lot like the Korg KR-55 which came out in 1979. There must have been  intense rivalry between these two Japanese corporations and I suspect the CR5000/8000 was a response to Korg's KR-33/55.

The unmodified CR-8000 weighs in at 3.2Kg, with 12 knobs & 32 buttons.

I really like the the digital tempo display. It's very accurate at giving a precise BPM reading.

The digital display was not a feature on the slightly earlier CR-5000 

The CR 8000 also adds the user programmable presets and fills.

Unmodified, the CR-8000 has a trigger out (+5V pulses) so you can clock external gear.

Sadly there is just one audio output, but unlike the CR-5000, the 8000 has DinSync (24ppqm).

dinsync I/O at 24PPQ

DRUM (weight: 3.8Kg) Main panel features a display, a data encoder, 11 knobs and 32 buttons.
- See more at: http://www.polynominal.com/site/studio/gear/drum/roland-cr-8000/roland-cr-8000.html#sthash.bPBX691N.dpuf

DRUM (weight: 3.8Kg) Main panel features a display, a data encoder, 11 knobs and 32 buttons.
- See more at: http://www.polynominal.com/site/studio/gear/drum/roland-cr-8000/roland-cr-8000.html#sthash.bPBX691N.dpuf

Another advantage the CR-8000 had over the 5000 was the "Programmable Rhythm Section".

Here you can program your own beats, one instrument at a time,  in step time. 

The drum uses two 1.5V batteries to store your patterns in 8 slots when the machine is turned off.

The CPU used is a 8-bit micro-controller - a 8049/8048 chip. (40 pins)

CPU NEC D8049C232

There is a knob above that allows you to pick the instrument you wish to program.

To the right of the Program section is the "Voice Level". This essentially is a 6 channel mixer. The Cr8000 has in total 13 sounds so compromises had to me made with the mixer. The channels are:

1. Bass Drum

2. Tom Tom /Rim Shot /Snare

3. Conga

4. Claves/ Cowbell,

5. Cymbal/ High Hat. (the HH is unique...and one of the strengths in this machine)

6. Hand Clap.

Another advantage the CR-8000 has is the "accent" dial.

I think the unmodded CR-8000 sounds like a cross between the CR-78 & TR-808. It's often referred to a the poor man's 808. Though it really shines when you start to mod it.

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For more info on the history of Roland Drum Machines click here

Korg SQ-1 Vs monotribe.

A few test videos using the Korg SQ-1.
Sorry for the poor audio - this was recorded on a smart phone.

Here is a link to a SQ-1 & a Korg MS-20 mini

And a link to a trial sq-1 & monotribe video - demo 1

Amer Fort - Rajasthan - India

The Amer Fort & palace was built in the 16th century by the Rajput Maharajas.
The Palace & castle are divided into 4 sections or courtyards, each with it's own gate, style and history. It's just 11kms from Jaipur.

Lattice window.

The Jaleb Chowk (Main Courtyard).

This is where returning armies would display their war booty to the populace ... parading around the courtyard. Women would often view this area from the veiled windows of the palace above the crowds.

Diwan- E- Aam or The Hall of Public Audience.

These 40 pillars were erected by Mirza Raja Jai Singh between 1631-40. It's an assembly hall built of red sandstone and white shell plaster - looks like marble. Each  column is topped by a capital in the shape of an elephant.

 

Suraj Pol (Sun Gate) - on the right.

To the left (not in view) is the Moon Gate

Diwan- E- Aam or The Hall of Public Audience

 The Maharajahs used to receive the public here, listening to their problems regarding the kingdom.

This space is significant as it combines both Hindu and Muslim architecture.

Maota Lake and Garden

The Jai Mandir (Hall of Victory) or the Mirror Palace is noted for its inlaid panels and multi-mirrored ceiling. The painted glass & mirrors was imported from Belguim.

  A carved marble relief panel. These can be see all over the hall. So delicate.

Baradhari pavilion at Man Singh I Palace Square.

kORG SQ-1 sequencer - First impressions & tests

This (the Korg SQ-1) just arrived yesterday so I'd though it would be fun to test with a few of my Korgs.
I was surprised by just how small it is when compared with its older brother, the SQ-10

Barely the size of a Korg Volca. And it runs on batteries. First a test with the MS-20 mini.No Midi used here. All old school CV/trigger

Sequencer resolution Quarter/eigth/16th notes...

 .

A comparison of the controls of the SQ-10 and the SQ-1 above.

One interesting observation I made regarding the clock speed of both sequencers.
was that if I connected the multiple pulse out of the SQ-10 into the sync in of the SQ-1,
 the SQ-1 ran at twice the speed of the SQ-10.

Korg equipment (eg KPR-77, DDM-110 & DDM-220) uses 48 pulses per quarter note. I guess the SQ-10 is the same. But it seems that the SQ-1 runs at the Roland standard of 24 pulses per quarter note (PPQN for short)..... thus the doubling of its speed when clocked by the SQ-10.

The SQ-10 is a S-trig sequencer.

The SQ-1 can be both a S-trig & V trig sequencer..
Re Gate out polarity of the SQ-1.
When the Mode button is unlit, -ve polarity (volatge fall) is selected - This is the S-trig.
When the Mode button is lit, +ve polarity (volatge rise) is selected - This is a V-trig.
The Gates output level are 10V.
The Sync Out jack outputs a 5V pulse (15ms long)
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A brief summary of  Sequencers & Sequencing Resolution - PPQN

You will often see the letters PPQN or PPq used in reference to old drum machines & sequencers.

What does it all mean and how does this help one to clock a Roland drum machine to a Korg SQ-10 sequencer? Early sequencers and drum machines had resolutions in the order of 24 or 48 pulses or 'ticks' per quarter note (ppqn).

A sequencers resolution is defined as its ability to divide the beat of a quarter note into
a pulses. The more pulses, the more accurate a sequencer is.

Common divisions used by sequencers are :
24 parts - 24 ppqn
48 pulses - 48 ppqn
96 parts - 96 ppq
192 ppqn, etc etc etc

MIDI clock = 24 pulses, so called "ticks" per quarter note
Roland equipment (606,707.727,808.909) use 24 pulses per quarter note (PPQN for short), known as DIN Sync24.
A notable Roland exception is the CR-78 which uses 12ppqn.

Korg equipment (eg KPR-77, DDM-110 & DDM-220) uses 48 pulses per quarter note.
Oberheim (DMX) & Linn is 96ppqn.
The SCI Drumtraks handles 24, 48, and 96 ppqn
EMU drumulator - 24ppqn - needs a din to 1/4 Y cable,

Links
+ Modular Clocks - Analog, MIDI , PPQN

(To be continued)
If there are any mistakes or omissions, please write to me.
J

CGS 86 - Build notes for the Serge Touch Keyboard

Firstly, I'd like to thank Ken Stone of Cat Girl Synths for making this kit possible.
You can find his build instructions here:
http://www.cgs.synth.net/modules/cgs86_trk.html

Useful Links:
1. Muffwiggler Thread
2. That famous Synapse Article by Arpad Benares (care of Cyndustries)
3. PAiA - Touch switches (like those used on their Programable Drum Set)

I'm currently waiting for some pots to arrive for the TKB build.
The Serge TKB also uses a touch keyboard and it seems logical to build the CGS 86 at the same time.
I think these two projects share many common concepts. If I understand this correctly, both use the capacitance principle (not FSR - force sensing resistors).

It looks like the two BC547 transistors on the small driver PCB make up the emitter coupled astable oscillator (Multivibrator circuit). They produce that famous square wave of 100khz. 

The second larger PCB is called the detector since it detects when the output of the astable osc changes. When you touch a key, some of that square wave is shunted to ground and the Op Amp's (The LM3900's) output goes +ve in response.

I'm hoping the CGS 86 will compliment the TKB. Possibly, I'll instal them in the same boat.

Here are the virgin PCBs:

You will need two of the larger green PCBs if you wish to use all 16 touch plates.

IC headers, Resistors, Diodes first.

Serge TKB build - Part 5 - Potentiometer boards.

This is the fifth stage of the Serge TKB build - Potentiometer boards.

The further I get into this project the more I realize this is not just a clone that I'm building. Like the original TKBs of the 1970's this project also comes as a kit. It has the blessing of Serge Tcherepnin himself and is the real deal brought to 21st century standards.

*** Click here for the TKB Build Index ***

The virgin Pot Boards

The first part of this section involves inserting 64 x 1M resistors.

That's 16 resistors per board..

This is so much easier to do in this modern kit as these 4 boards replace the wires that joined the pots & resistors found in vintage TKBs.

 Can you imagine having to wire this up back in the 1970's ??? :-(

And you will need 4 of these headers.

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 *** Click here for the TKB Build Index ***
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