more than one ACCENT track in mb808 seq?

[creekree]

hi, all,

i was wondering if there is anything wrong with defining more than one accent track for a mb808 sequencer,

given that the analog drumcircuits feature a second/third accent input, of course.

normally i'd say that there shouldnt be a problem, as i simply would have to connect one pin of a DOUT shift register to the trigger in and one another to the accent in. i then could label those shift register pins in "setup_808_default.asm" as, for instance, "BD1  " and BD1 AC" or something similar.

however, the one thing that got me wondering is this entry in setup_808_default.asm:

; define the track which is used for global accent

; (0=disabled, 1-16: track number)

#define DEFAULT_GLOBAL_ACCENT_TRK 16

what is this global accent track and how would it affect my idea of having more than one accent track? remember, there would NOT be ONE SINGLE accent trigger connected to ALL my analog voices but one for a bassdrum, one for a group of instruments and a third to another single instrument. (i have my reasons for that, will reveal more later when the time has come to reveal something  ;) )

thanks!

[stryd_one]

given that the analog drumcircuits feature a second/third accent input, of course.

I dunno... even if the synths only have one accent input, multiple accent/slide/whatever tracks can still be useful. You just have to have a way to mix them (XOR for example)

[creatorlars]

In order to answer your question, it's neccesary to understand the 808's circuitry a little better (I am assuming you are referring to the 808 drum voices.)

In order to trigger, an 808 voice (such as the BD) needs two signals -- one at the trigger input and one at the accent input.  Customarily, the accent input of ALL modules is connected to the same output from the Accent circuit (which includes the accent level knob.)  What this means is that the accent signal must be always present when the drum is fired, even if there is no accent on that step. 

The difference in intensity/volume comes by the level of voltage at the accent input.  When the accent circuit is not triggered, this voltage is 5V.  When global accent IS triggered, this voltage is determined by the position of the accent pot (somewhere between 5v and 15v.)

So to answer your question -- Yes, it is possible to have more than one accent channel.  But your understanding of the requirements for the Accent signal are not complete.  You can't just send an extra DOUT to the Accent input of the module and disconnect it from the global accent -- in that case you'd be hearing the drum ONLY on accented steps (since the drum requires both signals to trigger), and not at an accented velocity (since the accent voltage would only be 5v).  In order to get the functionality you want, you'll have to clone the accent circuit from the schematics (which you can find on the eight-oh-eight.org forums) for each drum voice you want to have it's own accent.

Please let me know if this is confusing.  I have built several 808 voices for my modular synth and it's been a battle figuring out how it all works. :)  Also I've discovered that you need a 1ms pulse only at one of the two inputs (Trigger and Accent) -- the other signal can be a constant voltage.  I've successfully sent envelope or LFO signals conditioned to fluctuate between 5-15v to the Accent input of my 808 modules with good results.  Also you can send the exact same trigger signal to both Accent and Trigger inputs and the drum will fire fine.

So if you'd prefer to "deactivate" accent on one or several of your modules, rather than adding extra accent channels, you will find that much easier. :)  Just cut the trace from the accent input of the drum voice to the global accent, and short together the trigger and accent inputs.

[creatorlars]

On another note, if you are doing individual accent channels for drum voices, it seems much better to just control them via that drum's parameter layer instead of using up a different track.  I'm not sure if the firmware can already do this or not (send to an extra DOUT based on a parameter layer.)

If you REALLY wanted to beef up your 808's accent potential, you could hook up an AOUT board and send a velocity-dependent CV output to each drum voice's Accent input (added to 5v, to make the range 5-15v.)  I know that would probably require all sorts of firmware adjustments and I don't think MB808 supports full Midi velocity, but in that case you'd have a full range of velocity for every drum voice on every step. :)

[creekree]

creatorlars:

thanks for your input.

let me explain what i am about to do...

i have a broken DR110, the digital board is fried, however, the analog board (and thus all of the voices) are functional.

the DR110 analog board has individual trig inputs but only a global accent input. (they´re s-triggers, so i'll use the moog v to s trig conversion circuit.) lets assume this will be "accent group 1" - one accent track to serve all of its voices. i cant see a way to have individual accents for each of these instruments, so i'll just stick to what Boss developed here.

now, i also am currently building one of microlarges 808 tom boards - as you said, i'll need the accent circuitry found on the eight-oh-eight forums. there goes "accent group 2"...

also i have a 909 kick module that i'd like to throw in for good measure ;) -> "accent group 3" (of course a single instrument is not a group, but let's forget about that for the moment). again, the accent circuit will be employed. at least i assume that the 909 kick works the same as the 808 instruments...

so here we have three different voice groups - being able to have individual accents for each group with it's own accent pot is IMO a nice thing.

since my mb808 seq is not finished yet i can not play with this global accent and figure out what it actually does... why is the DEFAULT_GLOBAL_ACCENT variable specified when i can just rename any track to "acc X" and hook it up to accent circuitry????

on a sidenote: the DR110 clap needs two triggers, one pulse on trig input 1 and a burst of 3 consecutive pulses on input 2. i assume this can be taken care of in the firmware, alas, i have no idea of how to do that. it is not my primary concern right now and i'll try to figure it out later in the building process. however, any input is welcome :)

[creatorlars]

Your plan sounds good.  As far as the firmware goes, I am not sure why the global accent track is any different than another track either.

I have built several of microLARGE's boards -- they are great.  There was a missing trace on the snare board though, and make sure you read all the eight-oh-eight forum build threads for some fixes on the clap and also the noise source (which you will need for the toms I think.)  PM me if you have any build problems with them.

Which 909 kick are you building?  I'm familiar with two board layouts out there.  I spent a long few weeks trying to get one of them working, and it was never 100% there.  I haven't tried the second one.  Sorry, I don't have the links handy.  As far as I know, the accent circuitry mirrors the 808.  I am curious about your success though, because I still have a finished but not 100% working 909 kick on the shelf, with a panel and everything...

Just an idea, and this may be overkill, but you could always use the CGS/Ken Stone Burst Generator module in a preset configuration in order to generate three successive pulses.  In fact if you could find a way to route that module to whatever firmware-selected drum voice you wanted, it'd make a pretty badass addition to a drum machine in general.

[creekree]

creatorlars,

i am going for the 909 kick found at http://www.msc175.de/geraete.htm - it looks very weel thought out and the samples are convincing. the site is in german, but the documentation should be pretty self-explanatory.

if you have trouble understanding something found there contact me - i'm happy to translate for you.

i am aware of the CGS burst generator, but as you said, it might be overkill. also i have space issues - i'm going to build a desktop unit and space is pretty limited in the enclosure that i have (but it is sooo beautiful, just wait and see..).

so far i only plan to use microlarges toms, as i have a snare, clap, cymbals and hihats in the DR110. the voice board is already modded to have control of the voices and sounds pretty cool. IMO the DR110 clap is the best one around, so i am desperate to get it working.

i might even use the noise source of the DR110 for all of the other voices, depending on how that sounds. on the other hand, a second noise source might be a nice idea (with switches for each instrument to select between the two and even cut it out).

the 808 toms apparently are fed with pink noise... ah well, further experimentation on my behalf is needed. do you have experience with feeding different kinds of noise into the 808 toms?

i am not going to build yet another 808/909 clone that tries to be as faithful as possible, i'm more after "something of everything", if you will. for instance, one secret weapon will be a DS7 clone ;)

right now i am sitting in front of the DR110, building v to s trigger converters for it. if only the sequencer was up and running! i am still waiting for some parts to finish it.

[creatorlars]

Your project is exciting, I can't wait to see the finished piece. 

I was not familiar with this 909 clone site!!  Very good information and great projects, as you mentioned.  Thanks for the link.  I have a 9090 board set that I will put together someday, but I am focused on finishing my 808 module clones and modular drumysynth stuff first. 

As far as the burst generator, maybe you can just build a simplified version from the schematics.  The PCB itself is very small (I have it assembled but not put behind a panel yet.)  You could just hardwire the 3-repeats selection and maybe use a trimmer to adjust the time between repeats.  The 808 clap was difficult to finish until I read the notes on the eight-oh-eight.org forums about one of the electrolytic capacitors being reversed in the original 808 schematics. 

The pink noise in the 808 toms is a secondary output from the regular 808 noise source (which sounds beautiful.)  I was able to build the 808 noise source very quickly on protoboard from the schematics and I later modified it according to the notes on the eight-oh-eight.org forums -- which make the snare and clap sound much crisper and brighter. 

I will post my panel layout later, but for my 808 panel I have Send/Receive jacks for both the White Noise and the Pink Noise, as well as the Gain trimmer placed on the panel.  This way I can use the 808 noise's pink and white outputs anywhere to my synth, run them through a filter or some other processing before sending them back to the 808 voices, or just send the 808 modules alternate noise/tone sources in general. 

I'm very much for the something-of-everything approach too.  I modded my Midibox CV to send DOUT triggers to all my drum modules (which are in the same modular case) -- that way my SEQ is independent from the modular case.  And I just added a "Drum Control/Mixer" module that gives me a master drum mix output and distributes trigger signals from the Midibox CV to the various drum modules.  The master mix is also voltage controlled, so I could control it via Midi-to-CV velocity.  The idea is that I can add a pretty much unlimited number of drum modules to the rig, and still have a way to control everything from one place (the Midi-to-CV) and still have a mixed output for everything as well -- making it just as easy to use as a typical drum machine.  So far I have a Thomas Henry Clangora, Thomas Henry UD-1, CGS Cynare, 808 BD, 808 SD, 808 CP, 808 CB -- with boards etched for the rest of the 808 stuff, and panels/PCBs for two Thomas Henry Mega Percussive Synths.  I highly reccomend the Thomas Henry voices.  I'd also like to throw some MS20 filters, a VCO and some simple EGs behind a panel -- I love the percussion sounds made on the MS20 (the resonant EBM kick drum kind of sound, etc.)

Keep us updated on how it goes...