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Author Topic: B-Chain for a Home Theatre System? Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 02-21-2003 12:28 PM                     Is the process of EQ-ing and setting levels the same for aligning the audio system in a home theatre? In particular, what SPL should we be aiming for? I would imagine that 85dBC would be a little too loud for home viewing. Am I wrong?  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 02-21-2003 01:15 PM                        Not necessarily, since DVDs are remixed for the dynamnic range of home equipment. It would also depend on what your neighbours say. If you have a good home system with quality components that match each other, you don`t really need equalisation.  |  IP: Logged Greg Mueller Phenomenal Film Handler Posts: 1687 From: Port Gamble, WA Registered: Jun 99 posted 02-21-2003 01:29 PM                        Manny Film or video?  |  IP: Logged Ron Lacheur Jedi Master Film Handler Posts: 650 From: British Columbia, Canada Registered: Feb 2002 posted 02-21-2003 02:58 PM                     If this is for Home Theater, get yourself a copy of the DVD " Avia " or " Video Essentials " and calibrate your HT with that. Avia suggests setting the dB level at 85dBC while Video Essentials suggests 75dBC.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-21-2003 03:09 PM                        Why would it make a difference whether the picture source is film or video? Shouldn't the sound reproduction system be aligned in the same way regardless? (I'm genuinely curious here.) Obviously, there's no A-chain issue with DVD, though.  |  IP: Logged Greg Mueller Phenomenal Film Handler Posts: 1687 From: Port Gamble, WA Registered: Jun 99 posted 02-21-2003 03:17 PM                        Well mostly because there is no way to do it (that I've seen) with the current DVD/Video home stuff, unless you add a bunch of outboard equipment to the decoder  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 02-21-2003 03:35 PM                     I've never tried this, so my questions will probably be inane... In cinemas I set the 85dB SPL using Dolby pink noise film after the A chain is aligned & set to Dolby level and the house EQ done. So where do you get a reference level pink noise from in a DVD system? This 85dB is valid at Dolby "7" level... what fader reference would you use to set the 85 dB SPL? Even in a properly set up cinema, the fader is rarely run at "7" during real shows, so what does it matter what reference you use? Presumably you would turn the sound level up or down according to your mood and the film... so the only real value of doing the level setting would be to balance the main channels and set the sub and surround levels? (as long a the reference level is reasonable considering headroom vs noise issues)  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 02-21-2003 04:12 PM                     Ron: Thanks, I'm going over to Amazon.com right now. Dave: If one wanted to closely (or even loosely) recreate the experience as heard in the mixing theatre, I would imagine that would necessitate establishing a reference level that -- at least, perceptually -- equates to the 85dBC standard. [And I love that quote about your apprentice!] Greg: This is for audio/video. Michael: The components won't be matched and, even if they were, the manufacturer can't do anything about the room, right? So, I'd think that at least some minimal EQ'ing would remain necessary. What do you think?  |  IP: Logged Ron Lacheur Jedi Master Film Handler Posts: 650 From: British Columbia, Canada Registered: Feb 2002 posted 02-21-2003 09:35 PM                     Manny: Which one did you decide on? Dave: To set a reference level, the receiver ( or preamp/processor ) should have the volume knob at max ( should read 00dB on the display ) then set your levels on your external amps until you reach your desired 85dBC level. I'm sure there's other ways to do it depending on your equipment and setup.  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 02-21-2003 09:36 PM                        Most rooms at home do not have as strong an effect on the sound as a large cinema and the speakers are not behind the screen. Like Greg said, a lot of home equipment does not have eq-ing capabilities comparable to cinema equipment, and adding external equalisation may not be worth the trouble. A good set of speakers with a good frequency response should be enough. They don`t have to handle as high levels and dynamic range like cinema speakers anyway. If you want to do it, eq-ing the front channels should be enough I think. You don`t need the X-curve if it is not a very big room anyway. I think in a home environment tuning by ear is even more admissable than in a movie theater as discussed elsewhere. Dave, most decoder units can play pink noise and some other test tones. It should usually be set to 85dB if measured at all. DVD has less dynamic headroom than digital film soundtracks and most DVDs are mixed to reflect that. The most important thing is of course that all channels have the same level. Where to set the fader is mainly an issue of the best signal-to-noise ratio while there should always be headroom for very soft material  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 02-22-2003 11:03 AM                     This is a lot of good input and I thank you all. I will conduct some experiments based on this input and then post my opinions of how the different approaches affect the sound (in this particular room). (It isn't that I believe my opinion matters in the grand scheme of things, but some closure would probably be nice if someone stumbles onto this thread later on down the line.) Request to Moderator(s):I believe that there are some members who don't read the Yak section. Would it be possible to move this thread to FHF for some more input?  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-22-2003 03:22 PM                     This deals with home theaters and does not really belong in FHF. Not to worry, all of the frequent posters visit all forums.  |  IP: Logged Chris Markiewicz Expert Film Handler Posts: 209 From: Glenaviegh, County Tipperary, Ireland Registered: Aug 2002 posted 02-22-2003 08:03 PM                     The Avia setup disk is very useful for balancing your front channel, surround and subwoofer levels (with your Rat Shack SPL meter, of course). It will also help to optimise your video display for your typical viewing conditions.  |  IP: Logged Nic Margherio Film Handler Posts: 91 From: St. Louis MO, USA Registered: Dec 1999 posted 02-23-2003 01:09 PM                     My home theatre reciever has a quite powerful 3-band, quazi-parametric equalizer built in to it. It provides EQ for all six channels with the front L/R and surround L/R channels grouped together. (You can only apply one EQ curve per pair) I have used it to flatten out obvious response errors in primarily the L,C, and R channels. Unfortunately, I have not been able to find a decent pink noise source to obtain the best results. The best I can do is use a two channel pink noise CD along with the Pro-Logic II decoder to get noise in individual channels. Does anybody know of a Dolby Digital or preferably a DTS-ES DVD that can produce pink noise in individual channels? I have found the Avia pink noise to be next to worthless for this purpose.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 02-23-2003 04:55 PM                     Alas, my favorite online shopping mall (Amazon) does not carry either of the DVD setup discs. In fact, they don't seem to carry *any* setup discs. I'm going to have to find a supplier for that -- one who will accept international credit cards.  |  IP: Logged

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