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View Full Version : Few specific questions about pro cinema gear install:



kenratboy
01-07-2010, 06:41 PM
I apologize if these questions have been asked before.

While I know some of you are doing some VERY large LCR's (like 4722's, or 3732's!) - I am more interested in maybe:

--3678 (3, screen channels, any reason these would not be PLENTY big and have the same sound quality for a moderately-sized HT?)
--8320 (2-4, surround channels, again, these should be MORE than plenty)
--4645C (1-2, not much more expensive than the 3635, and I like bass!)

Few practical questions I have:

--What is the minimum distance one can be from the screen channels? I was under the impression these speakers needed some room to breath (something to do with the crossover and time-alignment for commercial cinemas, which are designed for 20, 30, 40' minimum)
--It seems the Crown DSi series is choice for powering the subs (plenty of power, and most importantly, the EQ is built in), any reason to look elsewhere?
--How do I make a residential pre-amp interface with the DSi series amps? I do not see RCA or XLR inputs.
--What would be the best way to power the screen channels and surrounds (more DSi amps, or something else)?

Sorry, that is a lot of stuff, but trying to fit the pieces together in my head.

Thanks,

Ken

mikebake
01-07-2010, 07:22 PM
What size room?

kenratboy
01-07-2010, 07:30 PM
What size room?

I guess I am working backwards as to what the SMALLEST room I could use these speakers in would be. To throw a number out there, 20x25x10. The 'money seat' (aka, my seat) would probably be ~12' from the screen (could be closer or further depending on the needs).

Speakers could either be placed on the floor with the horns just below the bottom of the screen, or maybe a perforated screen.

This would be a take-no-prisoners dedicated-HT system. No pool table or listening to music. Movies.

Is that what you needed?

Thanks!

EDIT: even in a THX install, these speakers are certified for 45,000 cu. ft. (vs. my 5,000 cu. ft.) and distances up to 40' (vs. my ~12'). I imagine these should be able to rip ones head off.

Eaulive
01-07-2010, 08:09 PM
You're going to be grossly overkilled with those but I will let the movie theater guys chip in, it's not my area.
As for the crown DSI, they don't have XLR or RCA type connectors but an Euroblock (phoenix?) connector. It accepts balanced or unbalanced inputs, you just go with stripped wire, no connectors. That's the standard preffered setup for fixed installs.

No special interface required.

kenratboy
01-07-2010, 08:12 PM
I know it would be gross overkill, but it seems there are people that are not only pulling it off with good results - but are using FAR larger screen channels that I am.

Maybe I should just get a 4645C + DSi amp just to get it out of my system. I have had a 4648A-8 for almost 10 years (from the Tent Sale), so I don't even think of it as being that big anymore.

How deep would my 4648A-8 go if I were to get a DSi amp and set it up properly? Could I get anything below 30 Hz.?

rlsound
01-08-2010, 11:55 AM
You could pick up 2 4675-8 and get another 2360/2446 HF for the 4648 you already have.

Then you would have 3 x 4675C upfront. 2x 4645C should be more than plenty, make sure you process the subs using the B6 tuning and those subs should be ruler flat down to 20-22HZ

8320s should cover the room nicely, though you might want to put 3 on the back wall and 2 on each side.

You could use any HT receiver as the processor, provided it has preouts ( rca is fine, especially if your going to a euroblock connector )

This system is for a front projection system only. You will not be able to use a regular TV with this system. I recommend building a stage and putting the LCR up on the stage at the preferred height, and put the subs on the ground, if on concrete, a thin rubber pad between the sub and ground.

kenratboy
01-08-2010, 05:23 PM
The 3678's (seem) to be gross overkill, and the dual-woofer LF systems seem to be even more over the top. Then again, the 4648 would be a sweet center channel/structural support for the room!

rlsound
01-08-2010, 07:44 PM
No such thing as overkill.

You can always install a large system into a small room, but never vice versa.

Just calibrate it to the standard and youll have a very dynamic setup.

Don Mascali
01-09-2010, 04:26 AM
Too much, is just enough... :thmbsup:

I have an 18'x20'x8' room with 2-4645C up front. Since I need to store the 2-4695's w/2241h that I use for portable DJ someplace, they are in the back corners. All are 700wpc each by P7000 pro sound Yamaha's.

They can provide visceral impact in H/T and set up properly the system sounds pretty good on music.

4345
01-09-2010, 07:52 AM
I use a pair of 4642A's powered by a Crown K2 for Subs and 3 AS series speakers with 2206, 2381 and 2447J's. Sound is great. However, I do not use them at full capacity. It is all about fun anyway. So, why not go a little overboard.

Don Mascali
01-09-2010, 10:25 AM
4345 said "However, I do not use them at full capacity"

I should hope not, The old JBL product warning comes to mind,
"Severe hearing damage will occour, long before the mechanical limits of the transducer are reached"

I have the same type of system and like my Yamaha R1 motorcycle, just because it will do 190 MPH doesn't mean it isn't alot of fun to ride at 70MPH.

:applaud:Ain't it great...

rlsound
01-09-2010, 11:37 AM
4345,

Very nice setup!


Don hits the nail on the head, when you have this much power ( whether it be watts or horsepower ), use your common sense.

Tweak48
01-09-2010, 01:50 PM
I'm running a pair of JBL 4670D (http://www.jblpro.com/pages/cinema/4000.htm)'s in a two channel system in a 42X25 room. They sound very good at 15 to 20 feet and beyond. I would not recommend much closer than that.

The 70 watt tube amplifiers have no problem driving them to satisfying levels.



http://audioheritage.org/vbulletin/attachment.php?attachmentid=11525&stc=1&d=1134261187http://audioheritage.org/vbulletin/attachment.php?attachmentid=11526&stc=1&d=1134261202

kenratboy
01-09-2010, 02:19 PM
Great pictures, I love it!

My concern is not as much about overkill, as having such large gear, and such a great distance from the various drivers, the sound starts to fall apart simply due to the physics (for example, if you had the HF horn 4' away from the woofer, they may not blend together well).

This is what was appealing about the single-woofer solution (3678), seems due to the proximity of the two drivers, and the fact you only have one woofer - getting things to blend in a smaller space would be fine.

In theory, pretend you had one of the MASSIVE speakers in your home (4732, for example). The drivers are so far apart, would they not blend well if you were only 10, 15' away? I know for home speaker design, the distance from the woofer to tweeter is a engineering, and not a design choice.

Thanks, I am learning a lot!

demon
01-09-2010, 02:44 PM
hello ken!

your plans are very interesting. everytime im asked about "proper speakers, good value" i think about jbl cinema gear. i think that these are raw diamonds, that can sound extremely nice with a little time spent setting them up.
since you didnt buy anything yet, i hope youre not afraid of getting distracted a little: "drews clues" on this website describes a DIY system wich could suit you very well. its an inspiring read thats for sure: http://www.audioheritage.org/html/perspectives/drews-clues/drews-clues.htm


In theory, pretend you had one of the MASSIVE speakers in your home (4732, for example). The drivers are so far apart, would they not blend well if you were only 10, 15' away? I know for home speaker design, the distance from the woofer to tweeter is a engineering, and not a design choice.i have such a situation right in front of my nose currently. in my case its FAR better than i would have ever expected (i know his sounds suspicious. ha!). best would be if you can visit as many projects similar to yours before you get out and buy something. can be alot of fun, too. dont know if you already did that, of course!

cheers,
mikey