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Author Topic: Crossovers in Booth Monitors
Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 06-16-2002 05:02 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
I keep reading about crossovers and booth monitors...why do some people seem to use these terms interchangeably?

Why would the booth monitor contain crossovers?

Aren't they usually in the processor or the loudspeakers? I've also seen them as add-ons for the amps.

But...in the monitor? What gives?

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 06-16-2002 05:04 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
It all started with the THX crossover monitor. In fact it is probably the best place to put it since it eliminates one of the potential places for ground loops to sneak up and bite you
QSC and USL also have a cross over monitor

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 08-25-2002 05:40 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
I wish I had known that the CP-650 did not have built-in crossovers (like the CP-45). I just got Component Engineering MS-100 Monitors, so I am not in the market for a crossover/monitor.

Could you please post some recommendations for rack-mounted crossover networks?

I am using JBL 4675-8LF speakers and QSC 1400 amplifiers.

I do not like the little boxes that plug into the back of the amps. They are ugly and they can be bumped out by accident.

~Manny.

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Richard Fowler
Film God

Posts: 2392
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 08-25-2002 07:05 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
Smart 624 bi-amp crossovers have a nice feature of a passive backup if the main system fails...it is unbalanced so some thought in harness make-up has to be considered. The QSC DSP boxes can be mounted to an accessory rack panel to create a crossover set-up. The cans where always a pain due to tampering and connection problems in humid situations.
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-25-2002 09:01 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Add on crossovers...

Ultra Stereo's XTA-300s are VERY tough to beat in terms of matching to a JBL 4675C or equivalent...their passive bypass mode is better than most people regular crossovers.
http://www.uslinc.com/products/xta.htm

I also use RANE crossovers (2-way and 3-way)
http://www.rane.com/

Below is the rear view of a pair of RANE 3-way (AC23B) crossovers wired into a rack we recently assembled


Next is the front of the rack (with a Dolby CP-650 w/EX)...the AC-23 does has it's share of knobs! Continiously adjustable delay on any two of the three sections is a tough one to beat for fast accurate alignment.

Lastly, is a picture of the rear of the rack...at the bottom is a QSC SF-3 (sub filter) that is similar to their rear mounted crossovers (the XC-3) which are also quite good.

Personally, I don't like having the crossover in the processor...it makes the wiring of the monitor unecessarily cumbersome. Furthermore, not all crossovers are made equal. Just because you like a processor doesn't mean they make a good crossover.

I like crossovers on the amplifier or in the monitor...no extra work is involved. If I were you, I'd problably just get the USL XTA-1s and be done with it...never had one fall out and who is looking the back of your racks to judge prettiness?

And since DIGITAL is in...there are DSP solutions available too. Items like QSC's DSP-3 and DSP-4 which will also go on the back of the DCA amplifiers. (though they can work standalone). DSPs clearly offer the most flexibility in terms of features and customizing the crossover (and other functions).

Check out the DSP-4 at
http://216.149.53.76/products/amps/dsp/dsp4.htm

Or the less expensive (though a bit noisier but has phoenix connectors) DSP-3.
http://www.qscaudio.com/products/amps/dsp/dsp.htm

Steve

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"Old projectionists never die, they just changeover!"


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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 08-26-2002 01:55 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Bah!

The only need for a booth monitor is to monitor....nothing more other than it can be a good troubleshooting device to check for audio distortion, and to see if you have a clean signal coming out of the processor and/or power amps.

Hey, Steve....did you wire those racks? A real beautiful top-notched job! Wow! I am very impressed by the quality of wiring and workmanship in those pictures!


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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-26-2002 05:46 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Paul, yup, those were my wiring jobs. Thanks for the compliments.

As to the booth monitor, I agree as to it's funcion. However, you are already running a set of low-level lines to it for minitoring anyway...as such it is an acceptable area to have the crossover. (likewise on the amplifier).

I tend to not like combining components since a good monitor maker may not be a good crossover maker and if a single piece dies, it shouldn't take down the system. Then again, I'm normally wiring racks in bulk so saving time is also a concern.

Steve

------------------
"Old projectionists never die, they just changeover!"


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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 08-26-2002 06:26 AM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
Steve:

Thanks for those GORGEOUS photos. I'm fastidious about wiring but that is an awesome example of what to shoot for in terms of tidiness.

Thanks also to you and Richard for the info and the links.

~Manny.

"Who would have thought that when it came time to cash in your chips, this old "diseased maniac" would be your banker?" -- Lex Luthor in Superman: The Movie.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 08-26-2002 07:49 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
I have always like as few devices as possible to eliminate noise and possible ground loops. As such I do like the DCM and THX combined monitor crossover
For almost all other jobs I use the Smart crossover



These racks use my favorite crossover the Component Engineering and the the processor in one is a CP65 the other is a Mod6 and the crossovers are Smart

This is during construction of the Fairview Complex in toronto and both these booths are 70mm equiped



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Richard Fowler
Film God

Posts: 2392
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 08-26-2002 08:33 AM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
War of the rack builders ......from a guy who neatly delivers 100 - 120 systems a year
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com

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Sam Hunter
Jedi Master Film Handler

Posts: 779
From: West Monroe, LA, USA
Registered: Jan 2002


 - posted 08-26-2002 09:07 AM      Profile for Sam Hunter   Email Sam Hunter   Send New Private Message       Edit/Delete Post 
WOW!
Steve thats some great work! I used to work for a Motorola RSS and one of my duties was systems installations of radio communications networks and control systems and I really liked performing neat and orderly installations. Its refreshing to see quality work like this. Believe me I have seen many a rats nest as I'm sure all you guys have.

P.S. Hey Gordon, Didn't mean to leave you out man. Your systems looks great as well!


------------------
Samuel Hunter Sr.

Death to DLP (Video)


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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-26-2002 03:55 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Thanks guys...I was actually just trying to show the crossovers...the racks happened to come along for the ride. The top picture showed the beginning of a string of racks (with different processors and amps...we try to be accomodating)...these racks ended up in the Cinema Center in Selinsgrove, PA.

I have found that hums and noises are funciton of what you use and how you install them.

Steve

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"Old projectionists never die, they just changeover!"

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Oscar Neundorfer
Master Film Handler

Posts: 275
From: Senoia, GA
Registered: May 2000


 - posted 08-27-2002 06:57 AM      Profile for Oscar Neundorfer   Author's Homepage   Email Oscar Neundorfer   Send New Private Message       Edit/Delete Post 
I know this topic is on monitor/crossover issues but...

Steve,

Your racks look great! What kind of wire are you using, especially the different colors of wire?

Also, how are you labeling the wires? Are you using a label under transluscent heat shrink in various colors? Are these computer generated labels, p-touch labels or what. I have been trying to find a cheap, very easy, and flexible labeling system. Anyone got any favorite labeling methods?


Gordon,

Your racks look great, too! I really like the open frame racks, although that is not what we offer here at SMART. If I were doing racks for my own use, I would use the open frame variety.

Sam said, "Its refreshing to see quality work like this. Believe me I have seen many a rats nest as I'm sure all you guys have."

Yeah, Sam, I agree.

I would like to see a topic with pictures like this to show how it SHOULD be done. If anyone has a picture of their favorite rack wiring job, please post it, or maybe better, just provide a link to it so we don't clog up too much of Brad's bandwidth.

I am sure "normal" people would think I am crazy, but to me this kind of job quality is like a work of art, and is something I enjoy seeing in a way similar to my enjoyment of a nice painting or sculpture.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 08-27-2002 07:47 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
Oscar the sides were still off while it was being moved that was a Hammond RKF serries knock down rack
As for labeling I make up sheets of lables on the laser printer and put it under heat shrink usually
Also 3M makes rolls of numbers and letters as well

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-27-2002 04:32 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
>>"Your racks look great! What kind of wire are you using, especially the different colors of wire?

Also, how are you labeling the wires? Are you using a label under transluscent heat shrink in various
colors? Are these computer generated labels, p-touch labels or what. I have been trying to find a
cheap, very easy, and flexible labeling system. Anyone got any favorite labeling methods?"<<

Once again thanks...

The different color wire is a mixture of Belden and West Penn wire. I use "snake" cable to come out of Dsubs (6-jacketed, shielded pairs). West Penn wire #291 comes in all of the colors. Belden #9451 also come in all of the colors...I much prefer Belden over West Penn.

As to labling...I am a minimalist. The colors speak for themselves...

Left = Red
Center = Blue
Right = Green
Ls = White
Rs = Yellow
S/W = Brown

I didn't invent them...Dolby has been using those colors since the CP-50 and onwards on their test points (with red and green on each and every forward scan solar cell).

The additional channels...
BSl = Violet
BSr = Orange

Left-Center = Grey
Right-Center = Black

The colors are used thoughout from cell to speaker. Makes things easy to trace.

The speaker wire gauges will determine what section of the speaker it feeds...larger going to the more LF section.

When it comes to labels...I tend to use 3-M's label tape. Also P-touch for the fronts of the equipment. Depending on the job, sometimes cables are tagged too.

I'll probably give Brady's and Panduit's label makers a bit more of a closer look.

I generally wire my racks so things are self-explanitory and adequate service loops (though I don't make them loops to avoid potential inductance) are "stashed" thoughout to allow for future changes (really helped out when "EX" happened a few years ago.

Steve

------------------
"Old projectionists never die, they just changeover!"

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