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Author Topic: SPL levels for different surround groups in an EX configuration Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 04-16-2005 03:42 AM                        When setting up an EX B-chain, how do you determine the SPL level for left and left back, or right and right back surround channel groups? The total left or right side should be 82dBC, as in "classic" installations, but how do you set the relation between, say, left wall and left back to achieve the overall desired SPL level on that side, e.g. with 4 left and 2 back left surround speakers, or 4 left and 3 back left speakers?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-16-2005 07:36 AM                     This begs the question...have you read the manual? They do go over this information in all of the products I've seen.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-16-2005 10:45 AM                     You're even bothering to put EX in????? Why? Mark  |  IP: Logged Jim Ziegler Jedi Master Film Handler Posts: 753 From: West Hollywood, CA Registered: Jul 99 posted 04-16-2005 11:32 AM                     Probably for the same reason people give money to THX - so they call tell the public they have it.  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 04-16-2005 02:01 PM                        I read the SA10 manual where the procedure is described in all detail. I did not find any specific info in the CP650 manual. Logically, the setting of the SPL levels (side wall=80dB, side+back=82dB) should be the same. My question mainly aims at whether this formula should be modified, depending on the the relation of the actual number of speakers in each group. Why we put it in? It actually just happened (by "EXident"). Our friends at QSC recommend the surround speakers in an EX fashion, and we also got the Cat.790 option card to be ready for external digital sound sources. So the EX just happens to be there.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-16-2005 03:02 PM                     Michael...I must admit...the bulk of our EX installations with CP650s also have EX come along for the ride with access to the S/PDIF input for the DVD and other digital devices. On the CP650, if you use their mic input...I think it tells you what level to set the channels to (once you calibrate it). Anyway, you are correct, the procedure is the same....are you sure the CP650 manual does not discuss the level?  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 04-16-2005 09:33 PM                        Do you make your own interface cables or do you use the Odyssey set? It's not cheap, but very convenient and quick. I wouldn't swear that the manual doesn't discuss these details, but I don't recall seeing it in there. I haven't set up a CP650 myself - next week will be the first time. I plan to use my IE-33, but I will also use the internal mic to see how that goes.  |  IP: Logged Robbie Hidalgo Film Handler Posts: 47 From: Los Angeles, CA USA Registered: Dec 2003 posted 04-17-2005 01:01 AM                     Mr. Schaffer, quote: Michael Schaffer My question mainly aims at whether this formula should be modified, depending on the the relation of the actual number of speakers in each group. 4x2 vs. 4x3? No.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-17-2005 01:14 AM                     I always make my own cables. Dsubs are just too quick and easy to make. We generally stock 6, 8 and 12 pair snake (Belden), 4-pair digital snake (110-Ohm cable) and such. In fact, Michael, we also custom make our digital reader cables (even did a couple of SDDS 3000 series since Sony only had 10m and 50m cables...who needs that much length?). Our Dolby Digital cables run in metalic tubing and flex all of the way to the soundhead. it is much easier to pull in cable without ends on them. No wasted cable either and no wasted video level or signal degredation going through extra cable. I much prefer Belden's cable over Carol's for Dolby Digital...not as stiff.  |  IP: Logged Robbie Hidalgo Film Handler Posts: 47 From: Los Angeles, CA USA Registered: Dec 2003 posted 04-17-2005 01:55 AM                     Dr. Guttag, "Dsubs are just to quick and easy to make"... Wow, wish I heard that more often than "what were you idiots thinking!" (Then again, did you mean crimp or solder?) You know, the 3k's SDI I/F runs about 100Mhz. Tell me you actually found a supplier for those connectors and didn't splice the ends of the stock 10m cables...? On the other hand, a 2k cable, now there's a fun thing to make... Oops. Sorry Michael. Clearly this is now utterly off-topic. In that case...I'll just ditto what Mark said.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-17-2005 03:38 PM                     Robbie, We crimp our cables. Use high-grade stuff (AMP and gold crimps) so it goes about as fast, if not faster than properly dressing a phoenix connector. What I fault Sony for in their Dsubs are the 2.6mm jack screws...that was just plain BS...4-40 is the standard dsub screw...2.6mm is Japan only...very arrogant...I don't see Sony forcing 2.6mm on their laptops...they seem to have 4-40 for them. When we made the SCIv2...we make sure that we supplied the 2.6mm hardware on our Dsubs to ensure any remotes would be able to plug in afterwards without changing any hardware. With respect to the SDDS 3000 cables...yes we found the "5W4" dsub connector (amphenol) but we did a test on splicing the ends of a standard cable and the test proved to be sufficient. Why was Sony wigging out on that one? The cable we use is 3GHz swept rated (HD-SDI RG-6). We crimped on BNC connectors to the ends, used true 75-Ohm barrel connectors to splice in. The cable we used between the ends was of higher grade than Sony used. The only potential problems would be at the barrel connectors but again...no problems were found and I doubt you could see any ringing at the connectors at 100MHz. I guess having made many video cables (both compression and traditional hex-crimp) making a video extension cable just didn't seem like any big deal. Again, the power cable was a larger gauge than Sony used (and probably at least as high a grade)...less loss there. This was done on a Kinoton projector where the cable is routed out of the front of the column and connects up to the reader without a bunch of dangly crap. All of the cables on this installation came up from the floor into the column so it appears to be wireless. So just what problems have you encountered by splcing the cable? Do people just solder on more cable? Use CATV cable or what?  |  IP: Logged Robbie Hidalgo Film Handler Posts: 47 From: Los Angeles, CA USA Registered: Dec 2003 posted 04-18-2005 05:01 PM                     Hi Steve, There had been several initial installs during the beta period where the reader cables had to be installed in conduit too small to fit the 3000 connector ends. So of course, being molded on, several integrators just cut off an end to fish the cable through the conduit, then tack soldered the end back on. In the handful of episodes I heard about, there was no SDDS decoding at all (as if the reader weren't there). Not to say that there weren't loads of successful efforts at this, but of course I'd never hear about it when/if it worked...My guess has always been a shielding or poor workmanship issue, but it's an indefinitive conclusion. Somwhere around here we've got a victim cable from years ago, I'll try to dig it up and look at it more closely just for curiosity's sake. The metric D-Sub screws are an inconvenience to say the least. But I'm certain no malice was intended; Japanese-standard-issue became the default. Once their parts-order cycle starts for production, it's a major undertaking to change - the QA process is time, function, and cost intensive, and nothing, not even a screw post, gets modified without an entire by-the-book product re-evaluation by QA. Needless to say, the design groups over there practically hold office parties for QA approvals, but I imagine are also more reluctant than not to revisit the process, unless of course a safety or operational issue is at stake. You'd also probably be surprised how much they have to pay for standard (non-metric) hardware there. That's how we ended up sourcing the metric equivalents here. Hence, the eventual inclusion of the infamous "connector kit" with the metric screws thrown in during the 3000 era... As for crimps, well...OK. (Not a fan). But the BNC with adapter idea seems reasonable. It's good to hear that something other than the OEM cable is actually working!  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-18-2005 10:29 PM                     Ya know...I went up against a Mil-spec guy on an installation where he soldered and I crimped...my connectors went together faster and had no reliability issues. Again, it is in the quality of the components and the crimper that makes the difference. With a solder on Dsub...you have the quality of the solder job, the shrink-back of the wire that are potential pit falls...with a crimp you get a molecular bond. How many BNCs have you seen that are soldered on versus crimp? Those connection typically have much more critical connections for successful operation. As to cutting the ends..I've seen the results from even a Dolby Digital installation where a tech cut the ends, and then spliced what he had...some sort of 15-conductor cable (not even paired or shielded (maybe an overall shield)...he ran the Dolby digital signal and I think even analog in the same cable. The net result was as system that didn't work very well. I'm curious...just where have you had problems with cimped on Dsubs? I vary rarely use solder cup Dsubs anymore because I have not found any advantage. As to the cable that wouldn't work after it was butchered...I suspect that putting a scope on the cable and with appropriate test signals, the cause for the signal failure could be quickly identified.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-18-2005 10:39 PM                     quote: Steve Guttag The cable we use is 3GHz swept rated (HD-SDI RG-6). Now thats a bit of a statement for any cable company to make. Even though a slight trace of 3ghz signal might be detectable its gotta be down quite a lot at that frequency and the cable would be very temperatuire and humidity dependant! The only real reliable way to get signals around that high in frequency in to use solid waveguide transmission line designed for a specific use frequency. The loss at that frequency in even the best cable would be astromonical, ditto for even nitrogen or argon pressurized Heliax. Today computer manufacturers are etching in place waveguides as traces on motherboards for todays high speed CPU's to operate properly!! Mark  |  IP: Logged Robbie Hidalgo Film Handler Posts: 47 From: Los Angeles, CA USA Registered: Dec 2003 posted 04-19-2005 02:39 AM                     Steve, no question about the speed of crimp vs. solder I will admit. Indeed it is predominantly a quality issue as you pointed out. Ironically, there's a site now with an intermittant, and I remember cringing while I was watching the crimping crew on the floor when that (remaining unnamed) theater was installed. Albeit, it may have nothing to do with the crimps, but because they are crimped, the possibility of them playing a role has crossed my mind out of necessity...and that's because surely, even you must have seen a squirrly interconnect due to crimps along the line somewhere. Broken "wings", bent (cheap) pins, poor mating, my favorites are the pins which push back out of the hole when the connector is being reinserted. This is even more fun when the shell is back on and you have no idea what could be wrong with the connection that you just checked! So OK, in semi-permanent installs, you are correct: fast integration, using high quality components makes the crimp vs. solder-cup consideration nearly moot. However, certainly, anywhere that the connectors will see a reasonable amount of in and out in their lives, I'll take solder over crimp every time. It's just that one extra potential that I prefer to leave out of the system equation whenever possible (IMHO). Not that I haven't seen plenty of...er...less-than-ideal solder D-Sub jobs in my life...(but they're still not as "iffy"...again IMHO). Mark, what the hell! The guy down at the local CB shop told me that RG-6 is flat from DC to light! Although I suppose none of this is helping Michael with his 650 EX installation...  |  IP: Logged

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