Film-Tech Forum ARCHIVE: Home Theater and Cinema speakers

This is topic Home Theater and Cinema speakers in forum The Afterlife at Film-Tech Forum ARCHIVE.

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Posted by Antonio Marcheselli (Member # 373) on 07-18-2003, 05:46 PM:

Hi everyone!

I'm so convinced I've already wrote this message in this forum but... Brad, did I violated some forum rules and you deleted my message? I'm confused...

However, I need your opinion. Perhaps I'll have the chance to buy three old JBL speaker, three LF model 4638 and three horns with driver, do not remember the model, the larger horn.
The system will be amplified by QSC amplifier, biamped and equalized by 31-band graphic equalizers.

The room will be adequately treated for good acoustic.

My question is: how does this kind of speakers sound without a screen in front of them?
I saw that many of you have private screening room equipped with cinema speakers, I would like your opinions!

Thanks for your time!

Bye
A

Posted by Brad Miller (Member # 2) on 07-18-2003, 06:01 PM:

Two things.

First, nothing has been deleted.

Second, if you actually thought you had violated some rule, why in the world would you post it again without emailing me? Doesn't seem like you put too much thought into that.

Posted by Antonio Marcheselli (Member # 373) on 07-18-2003, 06:17 PM:

Because I read again the forum rules before posting again... [Big Grin]

Bye
A

Posted by Dave Macaulay (Member # 813) on 07-18-2003, 11:31 PM:

The "home theatre" gurus will tell you it's a bad idea to use commercial theatre speakers, explain why, and show you the amazingly excellent "home theatre" speakers they sell that can cost many, many times what commercial cinema speakers cost.
They are in some ways correct. Cinema speakers are generally large, ugly, and meant to be a relatively large distance from the listener, so there are some imaging and directivity problems using them in a relatively small/short/wide room.
In some ways these speakers are made to be loud and efficient and not specifically to have perfect sound.
Good home theatre speakers will have better imaging and coverage at the distances encountered, and usually have a smoother frequency response. They will be less efficient (as a rule larger speaker = more efficient) and will not be capable of being as loud - but a big JBL speaker made for a typical commercial cinema would be overkill in a home theatre and deafening if used at its potential. Overkill doesn't hurt though, and you will have lots of headroom for dynamic sound tracks! (the ever popular "too much is barely enough" theory)
There is however nothing wrong with using cinema speakers at home. They have decent frequency response. Depending on the room, the directivity pattern of the horn might be a problem but few people would notice... the sound will still be pretty good.
There isn't a huge difference between using these systems behind a screen or not, final EQ and aiming will be about the same.
Using commercial cinema speakers should sound a LOT better than the "home theatre in a box" systems.
If you have a critical ear you would notice quite a difference in a high-end home theatre setup... but the cost difference is staggering. Even without the "smoke and mirror" stuff like $500.00 AC power cords or $200.00/metre speaker wire (actual prices!) a fancy home theatre sound system costs many thousands.

Posted by Antonio Marcheselli (Member # 373) on 07-19-2003, 06:44 AM:

Dave,

Thanks for your opinion! The problem is that I do not trust anymore the "Hi-Fi" stuff. You buy speakers for thousand dollars and you discover that they are made by crap and sound crap.
I had a "home theater" subwoofer, considered a very good sub by the "hi fi" gurus. Was unacceptable for me. I'm trying to realize a hi-end home theater setup, and perhaps I'll have some chance to buy at good price JBL speakers. But someone suggest me to avoid large horns but I was not so convinced by his reasons!

I realize that large horns and 15" woofer are not very suited for near listening but I also believe that to have the same sound quality and power I should pay much much much more money in the "hi fi" world!

Bye!
A

Posted by Jeff Taylor (Member # 443) on 07-19-2003, 12:01 PM:

Antonio: While I ditto the remarks about the usual run of "boxed" home theater sets, I have experimented with my QSC and JBL commercial stuff, and finally settled on a Sony/Bose setup for home theater. I just couldn't sell my "decorator (read wife)" on using it in the den, and the Bose setup with five satellites and a powered sub is really quite good and so damn inconspicuous and convenient. When I want to have some fun, however, I occasionally use my data projector in the basement screening (only when nobody's home) room with the QSC's and JBL's, and it is spectacular--too much for everyday use, though.

Posted by Antonio Marcheselli (Member # 373) on 07-19-2003, 07:31 PM:

Jeff,

I know, this is why I'm preparing a car box for Home Theater purpose, I'm not assembling it in my house!
bye
A

Posted by Darryl Spicer (Member # 711) on 07-20-2003, 01:33 AM:

just a word of warning. Do not use these high powered large magnet speakers near any tube type CRT television. You will screw up the purity of the tv screen with the extreem magnetic fields

Posted by Ron Lacheur (Member # 1126) on 07-20-2003, 05:28 AM:

Using commerical JBL speakers in a home setting is great, but more suited towards front projection setups where the speakers are hidden behind the screen and the projector is mounted on the ceiling or in a cabinet.

Posted by Antonio Marcheselli (Member # 373) on 07-20-2003, 05:57 AM:

The projector will be installed on the ceiling, far frm the speakers. Unfortunately the room in not big enough to install the speaker behind the screen... I'll have a non-perforated screen and the speakers around it.

I also have a 4688 JBL subwoofer, I've already tested it, it is fantastic...

Here is the frequency response... But the source (DTS HT test disk) is limited 20-80

The room has the main resonance at 23Hz, I was tempted to let it where is it!!!

Bye
A

Posted by Rob van Ede (Member # 1457) on 07-20-2003, 06:07 AM:

i think the directivity of large horns is very good when used at home: Wall and ceiling interactions are much less, so acoustical treatments are less necessary. The downside is that your sweet spot will be small and you have to point the horns to your sofa, which may look a bit odd.
No idea why 15 inch woofers are bad for using at home. I use them in my large basshorns in a 3 x 4 meter room and there are no problems. You shouldn't use them to high because they get beamy, that's all. They can move a lot of air without actually move that much themselves and that means low distortion. I've seen people blowing out a candle in front of the port of a HT subwoofer. That must mean a lot of distortion....
Large speakers don't mean you have to use a large amplifier. The sensitivity of those JBLs may be 10 to 20 dB higher than of most HT speakers, so you won't need all that power. A HT receiver will be happy driving them. It will sound better than most HT setups.

Rob

Posted by Darryl Spicer (Member # 711) on 07-20-2003, 11:40 AM:

the important thing on the amplifier issue is that you don't under run the amplification. If you do sometimes it will introduce distortion. It is best to run at or above the specified wattage of the speakers being used. Now I am not saying that you would pump up the volume to hit the max with your main volume control. My feelings about home theater systems is that if you are using home theater sources such as video projection and sound sources use home speaker systems that are geared for that. If you are a film collector who is installing theater type equipment, film projectors and processors then I would concider theater type speaker systems. Movies are mixed a little differently when they are produced for video souce aplications like DVD's and such. More attention is given to the mid-range area of the mix process and evaluated using home theater sound systems geared for homes.

Posted by Antonio Marcheselli (Member # 373) on 07-20-2003, 07:24 PM:

I will use MPX300 amplifiers for all channels, they're just 200W for channel, just a bit more than my needs!
I agree, I will not install cinema speakers because I have to use them at full power but because I can have the sound with few power and with few stress by the speakers (=low distorsion, excellent freq. response, see the graph above!).

What do you say about sound's quality?

Bye
A

Posted by Rob van Ede (Member # 1457) on 07-22-2003, 10:53 AM:

After Equalization, it will sound much better than most whimpy HT speaker systems.
Amps with more power than max input power of drivers: that is true for (passively filtered) high-power applications, where the amp might clip, sending square waves to the tweeter and destroy it.
When using these speakers at home, with active crossover, they will rarely see anything over 10 Watts of input power. Those compression drivers could probably handle that with a passive, first order crossover! I would not worry about using a too small amp.

Rob

Posted by Paul G. Thompson (Member # 655) on 07-24-2003, 07:09 PM:

I tired some Altec A-7's once....after I strapped the crossovers down as low as I could on the high end and stuffed foam rubber down the throats of the horns, they sounded better. I abandoned the idea of using theatre speakers as home entertainment speakers after that attempt. My Sansui SP5000 speakers sounded much better. Smoother high end, and a much better low end.

I have a pair of Altec 1205's which seem to be a portable version of the A-7's, (same woofer, crossover and driver the A-7 used) but they are also "too bright". They sound excellent in a small bar room dance hall. But as far as home use, forget it. Too much of a hassle to make them sound good at home.

Posted by Christopher White (Member # 1844) on 08-17-2003, 05:08 PM:

I am running a home theater setup using commercial amps and speakers right now. I have a Denon AVR-5803 surround receiver. The front three speakers (JBL 3677) are powered by a QSC DCA 1644 (I use 3 channels with one spare). Side surrounds (6 JBL 4330) are powered by a QSC DCA 1222 and the rear surrounds (2 JBL 4330) are powered by the internal amps in the Denon (170 watts each). I have these speakers mounted behind a perferated screen from Stewart Filmscreen (14 foot wide, 16:9 aspect ratio with side masking for 4:3 and top/bottom masking for 2.35. I am very pleased with the results. I am in the home theater business and this set up sounds better than JBL's home theater designed Synthesis systems at a fraction of the cost. Mind you, the room this is in is considerably larger than typical home theater rooms so anything much smaller might be overkill. But if you have a large room I think commercial cinema amps and speakers are the way to go.