<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr"><span></span></div><div dir="ltr">Sorry about my earlier recommendations; didn’t realize you wanted all analog.<div><br></div><div>As far as switches go, I really like the Intersil (now Renesas) BiCMOS 16x8 crosspoint switch IC. Low ron and very very low crosstalk. I used it when designing the Music Man ‘Game Changer’ guitars for pickup switching, but, it maxes out at 15V.</div><div><a href="https://www.renesas.com/us/en/products/audio-video/video-switching/unbuffered-crosspoint-switches/device/CD22M3494.html">https://www.renesas.com/us/en/products/audio-video/video-switching/unbuffered-crosspoint-switches/device/CD22M3494.html</a><br><br><div id="AppleMailSignature" dir="ltr">Rock & Roll,<div>Oren Levy</div></div><div dir="ltr"><br>On Dec 26, 2018, at 09:09, cheater00 cheater00 <<a href="mailto:cheater00@gmail.com">cheater00@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr"><span>analog switch ICs are terrible, let's just skip them. You're not</span><br><span>making an analog switch ic based system anywhere near close a medium</span><br><span>sized modular, it's insanity and prone to shitloads of interference.</span><br><span>same with mod busses. the switch ICs are very proprietary. I haven't</span><br><span>found a digital multiplexer IC that was good, has anyone got any good</span><br><span>suggestions?</span><br><span></span><br><span>On Wed, Dec 26, 2018 at 5:16 PM Tom Wiltshire <<a href="mailto:tom@electricdruid.net">tom@electricdruid.net</a>> wrote:</span><br><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><span>Why not make a number of “analog virtual patch cables” with analog switch ICs? Each cable has a switch at both ends, one selects between X sources, and the other selects between Y destinations. This is conceptually very similar to a genuine modular with hardware cables, but the control signals can be fanned out to however many voices you have.</span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><span>Alternatively, you could have a “mod buss” type system, where each module output could be sent to a particular destination buss, and each module input could be switch to tap signal from a given buss. Again, control signals for the switches in such a set-up can be fanned out to however many voices are required.</span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><span>For any polyphonic system (except the early oberheims?), the control panel is separated from the voice generation, so you can think about the interface separately from the audio-producing part of the circuit.</span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><span>Tom</span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><span>==================</span><br></blockquote><blockquote type="cite"><span> Electric Druid</span><br></blockquote><blockquote type="cite"><span>Synth & Stompbox DIY</span><br></blockquote><blockquote type="cite"><span>==================</span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><blockquote type="cite"><span>On 25 Dec 2018, at 22:40, cheater00 cheater00 <<a href="mailto:cheater00@gmail.com">cheater00@gmail.com</a>> wrote:</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>I want to make this work for an all-analog synthesizer, but rather</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>than use crosspoint switches I want to use patch cables which makes</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>things much less annoyingly complex and expensive. The thing is, where</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>on a monosynth you have a single patch cable, on a patchable polysynth</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>you have n patch cables, one for each voice. So I am currently trying</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>to work out how to do this using a single patch cable, and frequency</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>domain multiplexing came to mind. I'm 100% certain an FPGA cannot do</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>FDM, since almost all of this is analog, so I'm looking at dedicated</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>radio transmitter chips. At $4 per chip, it's not so bad. The question</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>is how to make the chips talk to a single medium without fighting each</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>other.</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><span>On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <<a href="mailto:ben.pi.bradley@gmail.com">ben.pi.bradley@gmail.com</a>> wrote:</span><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>What you're describing sounds all-digital.</span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>It seems to me a crosspoint switch would be the thing to have on each</span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>(analog) voice, and have them controlled by the usual microcontroller</span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>for a polyphonic analog-signal-path synthesizer. Of course, this is a</span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>woefully incomplete description.</span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>On Tue, Dec 25, 2018 at 4:58 PM oren levy <<a href="mailto:orenlevysticky@gmail.com">orenlevysticky@gmail.com</a>> wrote:</span><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.</span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.</span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won’t require you to think about transmission line theory.</span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>Rock & Roll,</span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>Oren Levy</span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>On Dec 25, 2018, at 11:13, cheater00 cheater00 <<a href="mailto:cheater00@gmail.com">cheater00@gmail.com</a>> wrote:</span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>The objective is to be able to create a way for a single patch cord to</span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>carry 16 voices. I'm not sure how an FPGA in itself will help me, have</span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>you got any ideas?</span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>MADI interfaces are prohibitively expensive.</span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>On Tue, Dec 25, 2018 at 9:19 PM oren levy <<a href="mailto:orenlevysticky@gmail.com">orenlevysticky@gmail.com</a>> wrote:</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>I think you’d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>If you just want to share audio and don’t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>You’d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>Rock & Roll,</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>Oren Levy</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>On Dec 25, 2018, at 10:01, Mike Beauchamp <<a href="mailto:list@mikebeauchamp.com">list@mikebeauchamp.com</a>> wrote:</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>transmission. In a 16 voice system, at about 5 output functions per</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>module, and 12 modules, you can easily use up ~1000 of those, which</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>drops the price to $4. I was wondering what everyone thinks about this</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>sort of scheme.</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span>So there's $4000 worth of just one IC in a single complete polysynth?</span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><span></span><br></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote 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