Film-Tech Forum ARCHIVE: B-Chain for a Home Theatre System?

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Posted by Manny Knowles (Member # 1171) on 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?

Posted by Michael Schaffer (Member # 1204) on 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.

Posted by Greg Mueller (Member # 17) on 02-21-2003, 01:29 PM:

Manny
Film or video?

Posted by Ron Lacheur (Member # 1126) on 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.

Posted by Scott Norwood (Member # 30) on 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.

Posted by Greg Mueller (Member # 17) on 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

Posted by Dave Macaulay (Member # 813) on 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)

Posted by Manny Knowles (Member # 1171) on 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?

Posted by Ron Lacheur (Member # 1126) on 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.

Posted by Michael Schaffer (Member # 1204) on 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

Posted by Manny Knowles (Member # 1171) on 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?

Posted by Brad Miller (Member # 2) on 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.

Posted by Chris Markiewicz (Member # 1415) on 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.

Posted by Nic Margherio (Member # 273) on 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.

Posted by Manny Knowles (Member # 1171) on 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.

Posted by Antonio Marcheselli (Member # 373) on 03-16-2003, 04:47 PM:

Ron,

I do not agree with you. To have a similar situation with cinema, you should set the knob to -20dB and set 85dB (or 75, I read it too) on the amps.

Just today I made a test with my home yamaha. At -20dB the LFE output reach 0.0dB without clipping.

Bye
Antonio

Posted by Mark Gulbrandsen (Member # 72) on 03-16-2003, 05:58 PM:

I've done this several times both with my R-2 and with my Ivie and a single mic. I've done it both for home film systems, and home video. Always sounds better when eq'd, especially in the mids. Keep in mind though that if you have extremely flat response speakers doing this is not really nesessary. I ahve DYnaudio speakers that are very flat...depending on placement.... but eq'ing a so-so set of speakers does make a drastic improvement.
Mark

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-16-2003, 06:00 PM:

That means that the majority of all 'audiophiles' will never need to eq their system because we all know that they'd never have 'so-so' speakers -- their stuff is only the best. [Big Grin]

Posted by Ron Lacheur (Member # 1126) on 03-16-2003, 06:17 PM:

Thanks for the correction Antonio,

You probably just saved my future speakers!

I must have read 2 different threads at a HT forum, and confused them.

Posted by Mark Gulbrandsen (Member # 72) on 03-16-2003, 08:02 PM:

Daryl,
It does make a huge improvement with those so called system speakers, or such as the stuff you'd get at Ultimate Electronics, or other department store outlets.
Mark

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-16-2003, 08:16 PM:

I totally agree Mark. It's just funny how some people think that the speakers they likely paid way too much for are always second to none -- at least until they can afford an even more expensive pair.

Of course, like you pointed out, placement and the room can make huge differences that may require an eq to flatten the systems response.

I used to have a pair of dbx 1231's in my car, but I won't go there. [Smile]

Posted by Bobby Henderson (Member # 840) on 03-16-2003, 09:24 PM:

IMHO, good home theater equipment (particularly the combination of receiver/surround controller and speakers) should have a really good tone without adding in any extra, outboard EQ.

For good mid-range priced speakers, I like Paradigms. They have a smooth, clean sound that doesn't seem colored or constrained. And their subs have a satisfying amount of "slam" to them. I don't like any of the DSP stuff often included in receivers, mainly since it adds all kinds of distracting reverb and other junk to the sound --especially in the surrounds. I feel the DSP stuff also masks out other audio details in the mix. For my own listening choice, I figure if the soundtrack was meant to have a bunch of reverb or other effects added to it, the sound designer would have added it to the mix. So I just run the straight Dolby Digital, DTS and Pro-Logic programs on my Yamaha receiver. And then when I listen to CDs, I hit the "Effect Off" button to defeat the Pro-Logic circuit and get straight 2 channel sound.

Pink noise generators in receivers are great. But I think most manuals and remote controls make such tools difficult for a lot of people. So many folks will just live with how ever the factory defaults sound instead of balacing the stage and surround channels properly. Every room is different and will have different needs on speaker settings.

Posted by Mark Gulbrandsen (Member # 72) on 03-16-2003, 11:08 PM:

I've used the smaller Paradigms for surrounds in small movie theatres with excellent results. They were really cheap and provided an excellemt response. Can't ever remember having to replace one either......

At home I had sold off my high end system(kept my Dynaudio speakers though!) and bought a Sony DD ES Reciever with all the bells and whistles. Biggest mistake I ever made! So it sits and just gets used for switching the video signal to my HDTV set. I am really a 2 chan fan anyway.... So now I'm back to high end stuff but this time having built everything myself and saving thousands in the process. I now have a better system than I started out with!

Anyone interested in building your own high end gear should go over to www.diyaudio.com and sign up for the forum and check it out!!
Mark

Posted by Mark Gulbrandsen (Member # 72) on 03-25-2003, 07:13 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. They don`t have to handle as high levels and dynamic range like cinema speakers anyway.
"
_____________________________________________________________

I completely disagree with the assesment above. Rooms at home have an equal effect acoustically vs. the size of the room. Its usually easier to make minor acoustical correections at home than in a theatre though. For instance, my listening room suffers from side wall reflections, but its easier to correct for it and the panels do not need to be as thick to do the job. EQ'ing at home is not necessary if one buys really top of the line speakers in the first place. Take just about any of the Dynaudio speakers for instance.....they all have pretty flat response within their capabilities, so selecting a speaker that it similar to any of these would get you a pretty flat at home response assumming you don't have too much absorbtion built in like thick carpeting or such. Also, it is absolutely necessary to be able to reproduce as much dynamic range at home as it is in the theatre, and actually, at home you would want even more dynamic range capability thaneven the finest movie theatre sound system is capable of in order to reproduce the new generation of high resolution audio CD's. These disks have dynamic range capabilities approaching the loundess of a jet engine.....Fortunately Dynaudio's tweeters,and at least one other I know about can do this with ease, as they are capable of repeated 1kw pulses, and cruise at lower power levels needed for these life like reproduction levels.
Mark

Posted by Manny Knowles (Member # 1171) on 03-26-2003, 10:40 AM:

So -- what would be more cost-effective for someone like us with RTA and experience in setting up theatres?

The best speakers in the whole entire universe?
Or...So-So speakers and an equalizer?

Bye.

M.

Posted by Mark Gulbrandsen (Member # 72) on 03-26-2003, 07:09 PM:

In my experience its better to build, or buy the best speakers you can afford first. Check the used market after deciding what you want as you can save a ton!. Just be sure they have not been abused. Then at a later time spend the bucks on the best electronics you can afford. Use the building block method and start at the speaker end. My Dynaudios were purchased new, but I built my Pass Labs Aleph 2's and Pass Labs preamp, and they are better built than the factory stuff is. There are many advantages to building your own electronics if you are into that sort of thing. I saved over 8K just by building my own electronics.
Manny, Check out www.diyaudio.com
Also, http://www.dynaudiousa.com/main2.htm
Mark

Posted by Rob van Ede (Member # 1457) on 03-28-2003, 11:56 AM:

I would say build the speakers yourself using good (pro) drivers and buy a good processor to tune the system. This way you can make directional speakers (horns) so you don't need to worry about sidewall reflections and use the processor to eliminate standing waves that every room has.
I've built two such systems with horns and digital processor for home use and the results are excellent.

Rob

Posted by Steve Anderson (Member # 364) on 03-28-2003, 04:27 PM:

Manny, use this link to go to Digital Eyes
http://www.digitaleyes.net/details.cfm?info=OVA5867DVD
Avia Guide To Home Theater $34.97
I looked up Video Essentials and they said out of print.

Hope this helps

Posted by Manny Knowles (Member # 1171) on 04-01-2003, 09:56 PM:

I don't understand why there would be no need to EQ because isn't the whole point of EQ'ing to counteract the effects of the room?

How does the manufacturer know what kind of room I've got?

What are the parameters of a room that would not need to be EQ'd?