Thank you all very much. I'm really glad about all the positive responses :)
I've uploaded the Service Manual, the raw eeprom dumps as well as some other resources, on my GitHub https://github.com/ravettel/UrsaMajorStargate323 (I had to previously remove all links, because my initial email was flagged as spam). You can also find PDFs of Christopher Moore's patents for the SST and Stargate algorithms on google patents (US4303991A & US4268717A). The service manual is quite long, but most of the circuit is explained in detail from pages 8 to 16 and the schematics start at page 73. I've also uploaded an OCR version. It should make reading/searching a bit easier, but I haven't yet checked it for any OCR errors. Anyway, here's a (sort of) quick overview of how this reverb works and where I'm at: The Stargate 323 is basically a mono-to-stereo multitap delay. Most of the algorithm is stored across several different eproms, which determine the read/write delays of each reverb tap as well as the corresponding gain for the DA conversion. The address bits for most eproms are set by the front panel switches for Program/PreDelay/Decay as well as by several timing signals. The front panel switches are 4-bit gray-code rotary switches (s. page 73/74). There are 16 settings for predelay, but only 8 settings for Program & Decay, which is why there's some circuit trickery involved to get a revolving 3-bit output from those switches. Many eproms also contain duplicate data, to compensate for the redundant MSB of the Program/Decay switches. [Note: The gray-code switches were probably used in the original SST-282 Delay, so I assume it was cheaper to design with their already available stock, instead of sourcing new switches. Also, instead of just pulling the redundant MSBs of some switches to ground, they most likely left them in place for future revisions. As a matter of fact, the Stargate 323 was followed by the Stargate 626, which had exactly the same design but featured additional decay times and a larger memory array.] The timing signals start out simple, with an 8MHz clock and an 8bit counter. So each machine frame consists of 256 bit times. The basic timing circuit is located on Schematic 5 (p.77). Here's where things get overwhelming for me very quickly. TC1 gets inverted and the combined 8bit counter addresses two proms, generating 15 additional timing signals. All those signals pass through two 374 latches, TCB1 gets inverted twice and clocks the two additional "DAC slot address counters" and by the end of the sheet I can't even tell how TCB2 relates to the original non-inverted TC1 anymore. I can get a basic idea of access times, rising edges, falling edges, latches, flipflops, delays etc. through datasheets and youtube videos, but I don't feel like I'll be able to confidently understand it all on my own. So right now it's mostly about understanding the timing signals and counters, so that I can answer questions like "What is the output of the delay eprom at bit time 163". Best, Robert ________________________________ Von: Gary Hall <garyhall...@gmail.com> Gesendet: Montag, 26. April 2021 17:41 An: Yann Orlarey <orla...@grame.fr> Cc: faudiostream-users users <faudiostream-users@lists.sourceforge.net>; Laurent Pottier <laurent.pott...@univ-st-etienne.fr> Betreff: Re: [Faudiostream-users] [Preservation] Porting a digital reverb circuit to faust (Ursa Major Stargate 323) My first time to post. I'm not skilled with Faust, but I had a long history with hardware digital reverby and fx. I cut my teeth at Lexicon, let 1977 up through 1988, shortly after Chris Moore had left, and just before David Griesinger showed up at the door with his prototype digital reverb. I've remained involved with hardware digital fx more then 40 year now. Still have a finger in Emulating the Ursa Major 323 should not be a problem. I haven't seen the schematics (I'd be happy to look at them and comment where I can), but I'm confident that it's similar to Lexicon/Alesis/Eventide and so on. The Spin FV-1 ichip is a very accessible example, and a great platform. For that matter, the FV-1 itself is not exactly an end-of-life part. But it is in an evolutionary dead end. Keith Barr was an exceptional engineer, across the board. But he's been dead now almost 11 years. Hi final achievement has been stuck in time since then. If Barr had lived, we'd be on multiple generations beyond the FV-1. And yet the part is in manufacture still, and applied in any number of highly viable products. This device needs to be ported and extended in compilable form for implementation across a range of platforms. So yeah, save the Ursa Major. But don't forget to rescue the FV-1 and the classic architecture of hardware reverb and multi-fx. GaryInThailand On Mon, Apr 26, 2021 at 9:48 PM Yann Orlarey <orla...@grame.fr<mailto:orla...@grame.fr>> wrote: Hi, The issue of preserving musical works and equipment is indeed very important and is a challenge for Faust. In 2008-2010 we incorporated in the compiler the possibility to automatically generate the mathematical description of the computations performed by a Faust program (faust2mathdoc) see https://hal.archives-ouvertes.fr/hal-02158742/file/astree-icmc2010.pdf<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhal.archives-ouvertes.fr%2Fhal-02158742%2Ffile%2Fastree-icmc2010.pdf&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552030666%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=pAv7TADAS6GyFhDsRDAulnBc0ttQCE%2FpnfvuzN0hECo%3D&reserved=0>. At the Linux Audio Conference 2010, Sampo Savolainen presented a very nice emulation of the Yamaha YC 20 written in Faust (http://lac.linuxaudio.org/2010/recordings/day1_1215_Emulating_a_Combo_Organ.ogv<https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flac.linuxaudio.org%2F2010%2Frecordings%2Fday1_1215_Emulating_a_Combo_Organ.ogv&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552040661%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=nv%2BVcMks3y7g876yfIqCONPXUgs1hMMkX60DEoUbC0c%3D&reserved=0>) In France, Alain Bonardi and Laurent Pottier have worked a lot on these issues and recreated a number of historical pieces in Faust. Recently João Svidzinski and Vincent Tiffon have published an analysis of "Songes" by Jean-Claude Risset with codes in Faust: (we) are very happy to announce the publication of the analysis of Jean-Claude Risset's Songes (1979) in the IRCAM Analyzes portal (unfortunately only available in French at the moment) . This is a long piece of work initially started with the participation of the composer himself before his death in 2016. This analysis allows the reader to get inside the code itself and discover Risset's world. This is a real immersion in computer music of the 1970s. https://brahms.ircam.fr/analyses/Songes/<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbrahms.ircam.fr%2Fanalyses%2FSonges%2F&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552040661%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=hGKAcVSOEUarskuGK%2FpUrzXUNdO7IlkgnYuONtpfZHM%3D&reserved=0> So yes, this question is very important and I think it could be one of the themes of IFC 2022! Yann Le lun. 26 avr. 2021 à 15:26, Giuseppe Silvi via Faudiostream-users <faudiostream-users@lists.sourceforge.net<mailto:faudiostream-users@lists.sourceforge.net>> a écrit : Dear Robert, I don't know the logic schematics you are speaking about, so I can't define my experience coherent as you require. But you have used some terms care to me: "open source" and "history alive". So I think it could be an exciting project to be shared with a community, merging experiences. Here you can find the SEAM project I founded: https://github.com/s-e-a-m<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fs-e-a-m&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552050654%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Kwi1lhZsV5nYB3wiwBHnho1jwHm%2FXooah6SCOd%2FT9wM%3D&reserved=0> http://seam-world.slack.com/<https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fseam-world.slack.com%2F&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552050654%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=fJkTALgnMj83rUGv6%2FPrqAfqLnH9wa7OyFOZ7Yv6T74%3D&reserved=0> SEAM is a small community, and (thanks to the Faust qualities) there are some history pieces alive. (Reverbs are pieces of interest, like an entire musical composition, like many other things): If You have the pleasure to share something with us, maybe we can discuss the experience we have to help you. Nevertheless, even if you create your repository with some materials, I will look inside it and consider how I can help. I think it is a fascinating matter. PS. the shortest answer to both your questions is yes. Kind Regards Giuseppe Silvi > On 24 Apr 2021, at 16:08, Robert-André Vettel > <ra.vet...@live.de<mailto:ra.vet...@live.de>> wrote: > > Dear all, > > since I'm going to get into quite a bit of detail, I'll start with the tl;dr > first :D > • has anyone experience with electronic logic circuits and might help > me to analyse and understand some schematics? > • is it possible to port an existing digital circuit (consisting of a > clock, timing signals, counters, latches and memory read/writes) into Faust? > Now for the long version: > In 2019 I was fortunate enough to acquire an old Ursa Major Stargate 323 > hardware reverb from the institute of musicology at the JGU Mainz (thanks > Albert!). Ursa Major was founded by Christopher Moore and is mostly know for > the Space Station Delay, which some industry professionals still swear by. > The Stargate 323 Reverb is an evolution of the Space Station delay > algorithms. Since those reverbs are very rare and no official digital > emulations exist, I want to try and help keeping this piece of reverb history > alive . > > To be clear: I'm talking about straight up reverse-engineering here. If the > moderators think this is something that shouldn't be discussed publicly on > this list, please let me know. The Ursa Major brand was sold to AKG in 1986 > and no products have been released under this brand since then. As far as I > know all related patents have expired. Christopher Moore previously continued > working under the brand name Seven Woods Audio, but the website is not > available anymore and the domain name is now for sale. I also want to make > this project completely open source and do not have any commercial intentions. > > While the reverb algorithms are proprietary, the digital circuit design is > fairly simple by today's standards. Ursa Major was a small company and inside > is just a lot of 8bit EPROMS, Latches, Counters etc. all clocked by an 8Mhz > ceramic oscillator. No CPU or proprietary silicon whatsoever. Because the > entire circuit structure is completely humanly readable, my idea is to just > "port" the digital circuit into modern software instead of trying to > approximate the algorithms. So far I have made quite some progress in > understanding and analysing the digital circuit components. The official > service manual is incredibly detailed and I have also dumped the contents of > all eeproms. But I'm just a hobbyist and if I want this project to succeed, > I'm going to need help. Which brings me back to my initial questions and this > mailing list :) > > I'm happy to hear any questions/ideas/etc.! > > Best, > Robert > > _______________________________________________ > Faudiostream-users mailing list > Faudiostream-users@lists.sourceforge.net<mailto:Faudiostream-users@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/faudiostream-users<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Ffaudiostream-users&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552060648%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=%2Bj0nsw9oOu0yXWkRVOFHdOZtBjMrp%2FgmS4dEHmQPEUQ%3D&reserved=0> _______________________________________________ Faudiostream-users mailing list Faudiostream-users@lists.sourceforge.net<mailto:Faudiostream-users@lists.sourceforge.net> https://lists.sourceforge.net/lists/listinfo/faudiostream-users<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Ffaudiostream-users&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552060648%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=%2Bj0nsw9oOu0yXWkRVOFHdOZtBjMrp%2FgmS4dEHmQPEUQ%3D&reserved=0> _______________________________________________ Faudiostream-users mailing list Faudiostream-users@lists.sourceforge.net<mailto:Faudiostream-users@lists.sourceforge.net> https://lists.sourceforge.net/lists/listinfo/faudiostream-users<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Ffaudiostream-users&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552070646%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=G%2BNL2ml11dyShwr%2FZ3vQ3Up0pe4ThER6uCvMzsyOVFo%3D&reserved=0> -- Gary Hall โสตะ-สติ: Mindfulness with Sound http://soundcloud.com/hua-hin-sound-cloud<https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fsoundcloud.com%2Fhua-hin-sound-cloud&data=04%7C01%7C%7Cb120f92ae2d849f87f0508d908c9e19c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637550485552070646%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=pkPYpZQxB1ziA0q%2Bzbw6dc3uoD6e5X8gwN2COxFQ%2BLw%3D&reserved=0> ph. 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