Synthhead

Got mine this morning. :) Thanks Joachim for sticking with it. 8) On a side note, apologies if I've missed a thread somewhere, but there was a suggestion that eventually the MIDIBOX CV might support the SHX8. Have there been any developments? I googled and found a single post on another forum that mentioned that the MAX SPM08 might be a replacement for the NJU7304. If I read it right, the truth table is the same. The MAX part has a different pinout, which is the same as a CD4051 FWIW.... Just curious..... cheers, Dave

Hi Back to an earlier part of this thread - a suggestion for the feature list; Re-trigger select for the EGs would be useful, i.e. "Normal" mode, where every new note will trigger the EG regardless of whether any other notes are being held down, and "legato" mode where if a note is held down, any new notes don't re-trigger the EG - which is good for trills and solo stuff. Both are useful, Normal is prob. the most useful of the two. Dave.

Me too! - pretty essential for almost all rhythmic synth stuff.... It's a really good time to be building synths..... Am slowly getting together a big standalone synth, and it'll have a midibox heart for control.... Thanks TK - for what I've got in mind, the midibox can actually make it happen! Dave (v. happy analogue synth planner :-)

I was thinking more of parameter controls for a modular synth, or moderately complex fixed architecture synth, where there's already many voltage controllable parameters (cutoff, Res, vco1 mod depth, velocity to filter depth,vco 2 mod depth , etc.... Still, there's always the regular AOUT and midibox 64. Maybe if we're really lucky, maxim will sell off cheap all their remaining stock of 525s to meet rohs regulations. Now that would be a thing...... :) Dave

Nice one TK. Christmas has come early again....... I may be day-dreaming here, but SHX8 support would be mind-blowingly cool......... :D Dave

Hi Marcel. I don't have a link for the stuff I'm working on, as it's all on bits of paper, and breadboard/perfboard right now. But a similar example is here; http://www.uni-bonn.de/~uzs159/switch.html (BTW Rene's site is an excellent place for synth DIYers.....) The switcher circuits are 1 source to many destinations, or many to 1 routers for selecting between different ±5v audio signals (eg. VCO wave outputs), or ±5V control voltages (say from a LFO) , or 0 to +10V control voltages - for example from envelope generators. The stuff I'm working on uses common CMOS 4000 ICs - 4051, 4053, 4066, 4067 etc. 3 or 4 bit bit logic selects which input/ouput is active, simple as that. Well,...er.... hopefully...... :) Switching a 4066 should be straightforward with the MIDIO128, because it's a simple logic controlled quad SPST switch. It would be good to have a rotary encoder as the front end to generate midi CC values for the multi-way switches, as it's footprint on the (crowded) front panel is much smaller than eg; 8 x tactile pushswitches. As an example, one full rotation would produce 8 different consecutive values of a particular Midi CC, cycling back to the first value after 360 dgrees rotation. Each midi message would toggle 3 DOUT pins to the binary values 000 - 111. These 0/+5v pins would connect to the control inputs of the CMOS chips, switching the in/outputs. As an example, using MIDI CC=3, value 0 would not toggle any pins, giving binary logic 000. Value =1 would toggle pin 3 to +5v, with pins 1 and 2 at 0v, giving 001. Value =2 would toggle pin 2 to +5v, whilst pins 1 and 3 were set to 0v,... and so on up to value 7 where pins 1,2,3 were set to +5V = logic 111. Another way might be to have the midibox send 3 midi messages at the same time for a given encoder position, to toggle 3 DOUT output pins. Maybe the midibox 64 can do this, as it's already setup for rotary encoder input? Hope this all makes some kind of sense. I'm planning on getting some boards from Mike or Smash soon, so any thoughts on which midibox app is most likely to be able to do this are welcome. I guess I'm going to have to set up a PC and learn about MIOS and PIC programming ( gulp!) - For a learner, what's the best route in to this? any thoughts? I already have a mac, but It looks like there's more software for the PC....... Here's hoping I can crack it and post something useful back here some day..... ;) Cheers, Dave

Hi guys. I've been lurking around in the edges of the forum for a while, and finally (!) getting plans together for a midibox as modular synth controller. Trouble is, I'm not quite sure which to go for. A midibox 64 = AOUT + SHX8 seems an obvious choice for CV control, but I'm looking for a way to use a midibox to generate 0/+5V logic. I've got some audio/CV routers/switchers on the breadboard right now that need simple 3 or 4 bit logic to select inputs/outputs. What would be ideal, is for, as an example, MIDI CC3 values 0,1,2,3....etc up to 7, to toggle 3 DOUT pins to produce binary 000,001 etc up to 111. This with some interface circuitry would drive the control pins of the switching circuit. For generating these MIDI CCs, rotary encoders would be a very ergonomic solution, given the crowded front panel of the planned synth, if they could be hooked up to the DIN inputs of one or more midiboxes. Has anyone done this sort of stuff before? haven't found anything in the forum so far....and anyone got any recommendations for which midibox to go for? a modded MIDIO128? I'm not a coder, but am expecting to have to do some programming pretty soon. ( when I've got a PC to run the software, and learned some more that is... :) Sorry for all the dumb newbie questions, but I've only been DIY-ing for a year or so, and that's all been analogue synth modules. The midibox looks like the answer, but the switching thing is the main problem that keeps cropping up when designing control circuitry. Any suggestions at all would be most welcome....... Cheers, Dave

Hi. Good point, but how big are we talking here? postcard? paperback book? Given that a lot of people are going to use the AOUT with analogue gear - hardware synths/modules and modular synths etc, size may not be that much of a problem, except of course, bigger pcbs = higher cost. When adding the SHX8, the panel area will have to be large anyway, if sockets are installed for all 64 CV outs. I guess including LCD and programming controls, it would fit in a 19" 2U panel, if using 3.5mm jacks or banana plugs. Modular synths are often the size of a bookcase, so no problem if mounting there. ;D One way might be to build-in thru holes for stacking pcbs, like the CORE and DIN into the AOUTs pcb. This way they could be mounted on spacers above the board, reducing the overall footprint for all the pcbs, although the height will increase of course. I know that plenty of people will want to keep their midibox design small as possible ( me included) and that there may be many other uses other than just analogue gear. But given that a midibox + SH board should easily outperform either the PAIA midi2CV8 ( US $92, 16.5cm x 10cm), or Doepfer MCV24, (US$ 500, 1U 19" rack), personally I'd put up with a bigger board than usual, especially in terms of the cost difference. Not knocking either product, (I have 2 Paia boxes) but the midibox CV looks like a killer! Incidentally, Vishay may be worth a look, as they seem to do a large range of resistor networks, but their web page keeps crashing my computer every time I look. 2nd time writing this post! :( cheers all, Dave

Hi. Watching this space with great interest! 8). That sounds like a very useful choice.The major problem I've had with midi-cv converters is zipper noise when controlling filter cutoffs -Â particularly with resonance, and at low cutoff freqs. The Paia midi2CV8 (which I think is 8-bit) was very "zippery" when controlling an EFM diode ladder VCF . Problem solved by passing the CV output through a simple lag circuit IÂ found on the net. When adjusted, this gave adequate control speed when waggling a fader to control cutoff, resonance etc. Applying this fix to the Pitch Wheel wasn't so successful - adjusting the lag speed to completely remove zipper noise made the response of the wheel WAY too slow - so I guess there's a definite case for high resolution when controlling pitch. Is it planned for the SHX8 still to be compatible with the new AOUT board? I suppose any smoothing lag on an 8-bit output would have to be post-SHX.....?? Very exited about this development. Nice one TK :) Dave

I agree with Martin Haverland about the Opcode stuff. I put a stealth port in my G4 mac, and have been using an opcode studio 4 (8x8) for a couple of years with no bother at all. Rock solid, and fast. I paid about £50, but they're probably cheaper now. cheers. Dave

Hi. The plan is to build a multi-output midi-CV converter to control an analogue synth that I'm building. The MB CV would be the best for this job (low latency) when the SHX8 is supported, but as you pointed out, TK is busy with a little FM project..... :) The MB64 would be an interim solution for now, as it would be a control surface, as well as having the ability to generate lots of CV outputs. If only the MAX525 chips weren't quite so expensive - about £24 each + tax! On the other hand, the nearest rival is a ready made Doepfer unit with only 24 CV outputs that costs about £350 + tax. ( everything is expensive in the U.K. :( Once the MB CV gets SHX8 support, I think a lot of analogue synth DIY guys are going to be very interested. I'll probably go for an MB64 now, as I'm keen to get stuck in to building the 1st midibox. I guess I can always upgrade later as changes happen. Cheers Dave

Hi. I'm planning my first midibox, hopefully to include an AOUT and SHX8. At the moment, only the MB64 supports the extension. I couldn't find any posts mentioning this combination in the forum. Has anyone built such a midibox? Any ideas welcomed. cheers, Dave

Hi All! I'm really looking forward to the multiple AOUT boards. I'm building a modular synth based on EFM/CGS boards, and had nearly given up on MIDI-CV control of most or all parameters. I hope that multiple AOUTs may sort this out! Some thoughts. Is there a way in which the midibox64 can assign an AIN pot to output 3 or 4 bit logic via a DOUT to control say a 4052, or 4067 CMOS IC? This would be very handy for eg. switching between oscillator waveforms, or routing paths. Would this require modding MIOS? I hope not - I'm not a coder! Also, is the output voltage scalable, and what is the maximum? I'm new to electronics, although not to synths, so although there's nowt' wrong with my soldering, I'm still in electronics kindergarten, so apologies if some of these questions have been answered. (I'm still wading through the old posts for info!) T.K - This synth is a childhood dream that I'm bringing to life Thanks for doing what you do and sharing it. It's nice to be here. Regards, Dave.