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Surround speaker arrays. Advice please!
Old 6th September 2007
  #1
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Thumbs up Surround speaker arrays. Advice please!

We are about to upgrade the monitoring in our main mix room and my boss has asked me to investigate installing an array of speakers for the surround monitors in the back. In other words, the Ls signal will be spread across 3 monitors as will the Rs signal. How are you guys doing this? Are you using active monitors or passive? How are you getting the signal to each of the monitors/amps? Are you using a distribution amp coming off the DAW to split the signal or some other type of line mixer? I would love to hear how this is done out there in the world. Any hints, tips, gear choice suggestions (model #'s) would be most appreciated! We were thinking about getting the JBL LSR's for the room but I'm not sure that they support that as far as calibrating the room. As to room calibration, do you adjust the level to each of the three monitors individually or as one?

I know, lots of questions, but I also know this is where all the best minds are to answer these questions.

Thanks a ton!
Old 6th September 2007
  #2
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Chris G's Avatar
 

I had the JBL Lsr's and they sounded great, just way too many power issues and no help from JBL.

I finnaly settled on the BlueSky System One 5.1 setup with the Bass Management unit. The support is amazing and they sound awsome.
Old 7th September 2007
  #3
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It sounds like you're talking about 3 rear speakers. Ls, Cs, Rs

If this IS the case, then you're not talking about 5.1 but, instead, 7.1. The best management of these types of setup uses one individual output for each channel going into a monitor distribution/controler;

Buy Tascam DSM7.1 Pro Digital Surround Monitor Controller at Musician's Friend

If not 7.1, there are tons of 5.1 monitor controllers.
Old 7th September 2007
  #4
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Red face

Sorry, I must not have been clear with what I meant. We are mixing in 5.1, but each side of the surrounds we are splitting across 3 monitors for a total of six monitors in the back much like a movie theater. Each of the three monitors is getting the same Ls or Rs signal. So we will have a total of 9 monitors (L(1 monitor), C(1 monitor), R(1 monitor), Ls(3 monitors), Rs (3 monitors), and LFE.

Sorry for not being totally clear.
Old 7th September 2007
  #5
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How big is the room and what are the main speakers being used up front? JBL has a few passive options that are popular. You would wire the three speakers on each side in series, making sure the amp you use has enough power at that impedence to power all three.

http://www.jblpro.com/pages/cinema/surround.htm
Old 7th September 2007
  #6
If your mixingroom is big enough (I suppose it is the size of a theater wich could house around 600 people) then I'd get a full BAGEND system with infra subwoofer system.

If it is just a moderate mixingroom. Talk him out of this amount of speakers.


Muziekschuur
Old 7th September 2007
  #7
we use Genelec 1030As in arrays along the Left and Right side of the dub stage.
They are matched in size for the room and the front end. Depending on the room and what you are mixing ( we mix films with the full arrays ) it's nice to have the arrays, because in most theaters you hear a mushy Ls and Rs from a long array of speakers up over head and both in front of you and behind you. That's why I use an array. Remember when you create an array the complete Ls or Rs Array level must be at spec, not each speaker. And, the speakers have to be balanced to be equal loudness across the array.

When I mix broadcast or music , I use a set of 3 L,C,R, sub near fields and only 1 Ls and 1 Rs speakers positioned in the standard 110,45,90,40,110 position
Dolby Speaker Setup Guide - Speaker Placement

http://www.dolby.com/assets/pdf/tech...sic_Mixing.pdf



cheers
geo
Old 7th September 2007
  #8
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Quote:
Originally Posted by muziekschuur View Post
If it is just a moderate mixingroom. Talk him out of this amount of speakers.
Muziekschuur
My room is about 4000 cubic ft (which is quit small but good enough fo tv mixing). I have 3 Dynaudio M3 speakers for L,C,R and bought 3 pairs of Dynaudio BM6 for the rear channels surround. More speakers for surround helps creating diffusion.

Old 7th September 2007
  #9
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Quote:
Originally Posted by TheGolfer View Post
My room is about 4000 cubic ft (which is quit small but good enough fo tv mixing). I have 3 Dynaudio M3 speakers for L,C,R and bought 3 pairs of Dynaudio BM6 for the rear channels surround. More speakers for surround helps creating diffusion.
How are you getting the signal to the rears? Are you using some sort of distribution amp or line mixer? If so, who makes them? Like Georgia suggested, do you have an the each of the 3 monitors outputting the same volume and you calibrate the Ls or Rs signal cumulatively?

Good stuff, thanks alot!
Old 8th September 2007
  #10
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Quote:
Originally Posted by TheGolfer View Post
My room is about 4000 cubic ft (which is quit small but good enough fo tv mixing). I have 3 Dynaudio M3 speakers for L,C,R and bought 3 pairs of Dynaudio BM6 for the rear channels surround. More speakers for surround helps creating diffusion.
Perhaps, assuming you are in a large room with a high ratio of ambient to direct field sound. In a 4000 cubic ft room, however, you will almost certainly get a lot of comb filtering by running individual channels through multiple speakers. Bad idea in my opinion.

Thomas
Old 11th September 2007
  #11
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Quote:
Originally Posted by mondojml View Post
How are you getting the signal to the rears? Are you using some sort of distribution amp or line mixer? If so, who makes them? Like Georgia suggested, do you have an the each of the 3 monitors outputting the same volume and you calibrate the Ls or Rs signal cumulatively?
No distribution amp. You can plug them in parallel directly from the amp (Bryston 4B for me) or from speaker to speaker . Georgia is right (as usual), you do calibrate the Ls and Rs signal cumulatively. one pair is located on each side wall a little in front of my mixing position, the second pair is located on each side wall a little behind me, and the third pair is on the back wall. Also no loudspeaker is pointing directly at me except LCR . A bigger room will always sound better but I am not doing music and direct monitoring with only one rear pair is not a option for me. If you want also direct monitoring for music Georgia's set-up is more flexible. I would recommend you hire a specialist to check your room before doing anything. It will pay at the end!

Old 26th December 2007
  #12
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bit mangler's Avatar
 

Quote:
Originally Posted by TheGolfer View Post
No distribution amp. You can plug them in parallel directly from the amp (Bryston 4B for me) or from speaker to speaker .
Wont you have an impedance mismatch if you connect multiple speakers across the amp outputs?
Old 27th December 2007
  #13
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minister's Avatar
Quote:
Originally Posted by bit mangler View Post
Wont you have an impedance mismatch if you connect multiple speakers across the amp outputs?
not sure where you're getting an impedance mismatch....

amps can operate in stereo, bridge, or parallel mode. in stereo, each channel remains independent. in bridge, both channels are combined and on one control and the signal is twice the voltage. in parallel, you have one input and two independent outputs. so for a surround array, you get a 4 channel amp run in parallel and the Left Surround comes in and then goes out 2 separate channels controlled by separate pots. Same for the RS.

I think Georgia uses Dixie cups and thread between her surrounds. the Dixie cups for that Southern Rock sound.
Old 28th December 2007
  #14
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Quote:
Originally Posted by bit mangler View Post
Wont you have an impedance mismatch if you connect multiple speakers across the amp outputs?
As long as the impedance per speaker is the same and each channel of the amp receives the same amount of speakers, there will not be an impedance "mismatch."

However, there will be a much higher impedance load on the amp; thus reducing its power output to the circuit. We will use the JBL 8330A speakers listed previously as an example. These speakers have an 8 ohm nominal impedance rating. If you connect 3 of them in series, the resultant load would be 24 ohms per each side of an amp. Using a Bryston 4B-SST amp, rated at 300 watts into 8 ohms, the circuit would now be receiving roughly 100 watts at 24 ohms. That would equate to roughly 33 watts per speaker, thus grossly under-powering the 8330A.

One solution to this problem is to increase the number of speakers to 4 per side. Of course, this solution is highly dependent upon the size of the room. If we take 4 speakers and divide them into two pairs, we can then wire each speaker per pair in series and each pair in parallel to the amplifier. This would allow us to maintain an 8 ohm load at the amp. The entire set would then receive the rated 300 watts, with 75 watts per speaker. While this is still under-powering for the 8330A, it would at least start to get you closer to the goal.

Still yet another solution is to just have two speakers wired in parallel to each side of the amp. The Bryston is rated at 500 watts across a 4 ohm load. Each 8330A would then get 250 watts.

As you can see, the problem with wiring surround arrays like this is not really with impedance mismatching, but more with power output and amplifier matching. In order to accomplish the setup as listed above, you would need to either get a more powerful amp, start wiring speakers creatively, or both. Also don't forget other factors such as the resulting change in Damping Factor with changing the amplifier load. Of course, with cinema surrounds this may or may not be that big of an issue.

Please keep in mind that I am certainly not instructing you how to design your room in any way. I am just fully explaining the pros and cons of many different methods.

-Nate Bishop
Old 28th December 2007
  #15
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Thanks for the explanation Natethumbsup
Good point about the change in the damping factor but like you said , in this application there shouldnt be any issue.
I was thinking about a scenario where a 5.1 based facilty would be able to able to do a theatrical mix.Ofcourse I understand that there are so many factors other than the speaker array.
Old 30th December 2007
  #16
we use powered genelecs so we simply mult the outputs of the Ls and Rs to multiple speaker inputs post EQ.

cheers
geo


PS: Tom, the hard part is getting a good knot in the dixie cup strings to connect that 3rd cup to the initial two without affecting frequency response at the knot and thus causing freq loss and potential standing waves between cups.
Old 30th December 2007
  #17
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Quote:
Originally Posted by georgia View Post
PS: Tom, the hard part is getting a good knot in the dixie cup strings to connect that 3rd cup to the initial two without affecting frequency response at the knot and thus causing freq loss and potential standing waves between cups.
Cal'ing the Cups is a b&*$#!!
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