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Author Topic: JSD 60D crossover David Buckley Jedi Master Film Handler Posts: 525 From: Oxford, N. Canterbury, New Zealand Registered: Aug 2004 posted 01-20-2015 02:26 PM                        One of the undoubted benefits of DSP based solutions, in both the drag 'n drop and fixed function variants, is that all the smarts are in software, so the manufacturer can change their mind once the product is shipped, and change things in a way that prior to the DSP revolution was just not possible. I've done paper and setup software evaluations of a few of the cinema boxes (based on advice received on this very forum) and, of these, the JSD60 appears to the more flexible box than most others. Certainly, if our cinema is ever reborn in the digital era, the JSD60 is at the top of the list in the sound department. Thus, given its all just software(!), and USL are well represented on this forum, couldn't the JSD60 be fixed?  |  IP: Logged Andrew Thomas Master Film Handler Posts: 273 From: Pearland, TX, USA Registered: Jun 2012 posted 01-20-2015 04:24 PM                     Is there a technical reason the JSD 60 can't play 5.1 tracks from the toslink or digital coax port, or is it just product differentiation?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-20-2015 06:58 PM                     The JSD60 can decode AC3 and DTS tracks via the Toslink/S/PDIF port. The lack of ability to decode Lt/Rt from AES 1/2 on the main input I hear is an intrinsic thing due to the architecture of the unit. In terms of all out DSP and flexibility for a Cinema specific product, the Datasat AP20 probably would win that race. The JSD60 has a lot of bang for the buck though and it is in a very tidy 1U frame.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-20-2015 08:00 PM                     I inquired at USL a while ago about the possibility of matrix decoding for main/AES/EBU inputs, and back then USLs Tom Atkinson replied: 'The JSD-60 processor we have will do matrix decoding for the AES/EBU input. This is the only processor that we have that is capable of doing this.' - Carsten  |  IP: Logged Andrew Thomas Master Film Handler Posts: 273 From: Pearland, TX, USA Registered: Jun 2012 posted 01-20-2015 08:21 PM                     quote: Steve G. The JSD60 can decode AC3 and DTS tracks via the Toslink/S/PDIF port. As per the JSD 60 manual, the toslink and digital coax seem to be stereo inputs only. Anytime I have connected a device to them, it is stereo playback only. Am I missing something? quote: USL JSD 60 manual Two Channel Digital Inputs The JSD-60 has an S/PDIF input and a TOSLINK input.  S/PDIF Input. A stereo digital input on an RCA connector marked COAX. It is a standard S/PDIF (Sony Philips Digital Interface) input. Connect to appropriate sources with 75 ohm coaxial cable with RCA connectors on each end. As with the other stereo inputs, various decode methods are available.  TOSLINK Input. A TOSLINK optical digital stereo input is included on the JSD-60. Connect this input to an appropriate source with a standard TOSLINK cable. As with other stereo inputs, various decode methods are available  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 01-20-2015 09:09 PM                        The JSD-60 can decode Dolby Digital or DTS on S/PDIF or TOSLINK inputs. It was not anticipated that there would be a need to decode the multichannel AES/EBU input since DCI specified that the media block would output PCM. The hardware has four DIR/SRC chips (digital receiver / sample rate converter). Chips 1-3 drive the DSP with L, R, C, LFE, Ls, Rs from the AES/EBU inputs. Chip 4 receives AES/EBU pair 4 which can carry HI/VI or Lrs/Rrs depending on the server routing. S/PDIF and TOSLINK drive DIR/SRC number 4. Its output can be routed directly to the DSP for stereo. As an alternative, the output of DIR 4 (SRC is disabled for this since it would mess up the binary encoded data) is routed to the optional DI-84 board which decodes Dolby Digital or DTS. It also applies an "active matrix" to unencoded (stereo) audio. The DI-84 has 3 I2S outputs carrying 6 channels back to DIR/SRC 1-3 sending the decoded L, R, C, LFE, Ls, and Rs to the DSP, just as was handled with the PCM AES/EBU input. It IS possible to decode DTS or Dolby Digital on the AES/EBU input, but, based on the description above, it is decoding AES/EBU pair 4. This is of limited usefulness, but that's the way the hardware is done. The JSD-60 is designed to be as flexible as possible at a reasonable cost. It has its limits, but should serve the vast majority of auditorium requirements. Thanks for the comments on the JSD-60. I had a large part in its design and like the way it turned out. Coming up soon are AES/EBU outputs and BLU link outputs. Harold  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 01-21-2015 10:05 AM                     That suggests that rerouting AES pair 1 (L/R) to pair 4 (normally HI/VI) could allow decoding from a DCP with encoded stereo on L/R. Doremi servers can reroute the AES outputs, I'm not sure others have this capability. I don't know if the JSD-60D processor includes the logic to allow this though, it would need to activate the 4xAES input and then route pair 4 through the decoder and the decoder outputs to the main outputs.  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 01-21-2015 10:34 AM                        Yes, the JSD-60 can do that. I have to see if the gui supports it now, but salecting "active matrix" will route as you describe. Harold  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-21-2015 04:05 PM                     I was wondering...why not just wire the JSD60 input so that AES 1/2 lands on the 7/8 input and vice-versa. Then in the "Advance" tab for "8 CH Digital" use the matrix to reroute the outputs. At that point, you could use the matrix on it. You'd just have to get used to AES 1/2 being on the 7/8 input when you wire it. I'm sure Odyssey could come up with a suitable board to avoid remaking cables (or USL could do it).  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-22-2015 08:15 AM                     Steve, I always use an external crossover, USL or QSC depending on what speakers I'm installing. Internal x-overs are usually too limited in whatn hey can do. The main thing IMHO is that the processor power supply never crap out! Mark  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 01-22-2015 10:52 AM                        Speaking of "power supply never craps out," how important is "bypass" circuitry in a cinema sound processor? NATO specifies ( http://mkpe.com/publications/d-cinema/misc/NATO_Digital_Cinema_System_Requirements_release_2-1.pdf section 4.2) that cinema processors shall have a bypass mode where multichannel audio is mixed to mono in case of a failure of the processor. USL includes this in all processors, but it is a bit complicated and increases costs. How important is bypass? How important is a backup power supply? What is the most likely component to fail? Is it the power supply? I look forward to comments! Harold  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-22-2015 12:04 PM                     I think it is very important...having a single point of failure is a problem with DCinema...so many single points of failure can bring the show down. It is not like in film cinema where normally one could keep a the show going with minimal cheap spare parts. I'd think a market for the DAX 602 is as a "back up sound processor" Yeah, you don't have volume control (but could with a mulitgang pot) but in a pinch it could "save the day" if one's CP doesn't have a backup system.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-22-2015 03:05 PM                     Actually when I read the functional diagram of the JSD60 today, I had exactly these questions, Harold. Traditionally, analog cinema processors were complex devices with multiple cascaded, more or less autonomous functional blocks. It was rather easy to decide which blocks could be bypassed in case of circuit failures, and, technically, the analog signal at the input of the processor could still be used to drive an amp, even without slit-loss compensation, NR, dematrix, EQ, leveling. Now, with processors for DCI systems, it is not easy to decide how much sense fallback systems make. You would either have to design redundant mixing stages, or separate certain functions explicitly to enable fallback functions. Most CPs end up in D/A stages today signalwise. One would think that ultimately, a direct hardwired route from AES inputs to a separate D/A bank and a following analog mixdown/adjustment stage would be the ultimate solution for a bypass system, with an optional backup power supply only for that part. But then questions like where to put the AES/EBU receivers, SRC, etc. turn up. Also, should a bypass system switch over automatically to save a running show, or is it sufficient if a manual bypass switch has to be activated? Yes, apparently, power supplies fail rather often it seems. Unlike most of the processor electronics, power supplies are usually OEM sourced. Which seems to imply issues with quality control and also stocking of replacements. A cinema nearby had an early failure of the powersupply in one of USLs competitors devices. It took them 2 months to supply a replacement at the time (which was not at the beginning of the production phase for that device, it was in full sale at the time). They received a temporary replacement CP quickly, but waited 2 months for the replacement power supply and their original CP to be repaired. But Harold - you're at the source for that kind of information - how often do USL CPs fail, and which circuit parts/subsystems fail more often than others? BTW - I built my own backup processor from three cheap ebay S/P-DIF DACs followed by passive adjustment pots. Input and output is DB25 and fits as a plugin replacement between the cables leading from the server/MB and towards the amps. It was very cheap and we can afford to have it stuffed in a drawer even if we never need it. It seems the JSD60 is still quite complex. I would think the design of a CP would not need much more than AES/EBU receivers,maybe followed by SRCs, followed by a single beefy DSP, and then again digital outputs and a DAC bank. Then the only thing left to bypass would be the DSP, and feeding the I/O section from a backup supply. Get's more complex if an internal crossover is used. I guess that's one of the reasons the crossover in the JSD60 is optional. If it can operate autonomously, I can be part of a bypass scheme. If it's integrated in the main DSP, it becomes hard to bypass it without major changes to the amp/speaker wiring. Yes, external crossovers with AES/EBU inputs can compliment a backup scheme, as I depicted earlier in this thread about those cheap Behringers. But they can also be seen as additional points of failure, especially when they ARE cheap Behringers. - Carsten  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 01-23-2015 04:49 PM                        Thanks for the comments, and sorry for the delay (off at ICTA and ISDCF). Because of analog input routing, routing of digital through the DD/DTS decoder, allowing for various output types (analog, analog biamp, AES/EBU, and BLU link), what starts out as a simple processor gets complicated. I've tried to make it as simple as possible. Steve's idea of swapping AES pairs 1 and 4 is VERY CLEVER. I wish I thought of that! Because the JSD-60 has an input mixer for source selection, you can do all kinds of stuff, including things we did not think of. On bypass, the failure rates on the JSD-60 are low enough that I really can't get any meaningful data. The power supply does not seem to be any less reliable than anything else. The bypass circuitry does get a bit complicated. Bypass consists of separate digital receivers for AES/EBU inputs, TOSLINK input, and S/PDIF input, separate D/A for all these, analog switching to get the appropriate input, a digitally controlled analog volume control, balanced analog line driver, analog switches that drop the bypass analog onto the outputs. For biamp systems, there's an additional passive low level crossover for bypass use. There's a microcontroller on the front panel that controls all this stuff and also communicates with the main processor when not in bypass (reads buttons, reads fader encoder, updates LEDs, updates display, etc.). So, bypass does add considerable complexity. And, the cost is in every unit. By the time you have 15 or 20 processors in a building, it might be cheaper to have a spare than to include bypass circuitry in all those units. But, swapping out a processor takes longer than flipping the switch to off (and into bypass). However, I've seen quite a few installations where they bypass power supply is not installed or plugged in, so the benefit is lost. Again, I really appreciate feedback from users. It helps me design stuff that is useful. Harold  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 01-24-2015 07:44 AM                     Thanks all for the feedback. Carsten, the DCX we sent back to Behringer went indeed to Behringer UK, they came back with a workshop slip inside. I believe two units were purchased and they developed the same issue (crackling noise); they were returned from Behringer UK exactly as they left the customer. We marked a screw in one unit and when it came back the mark was still there, so they hadn't even been opened! I understand the units were eventually fixed by the owner by soldering the flat cable directly on the PCB. I cannot recommend such units in a professional environment!  |  IP: Logged

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