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How to correctly tune crossover


Įrni F. Siguršsson:
Hi there. I work part time at a concert hall, where mostly local garage bands play, but it's also used for lectures, movie nights (theres a 200" screen and a projector in there) and more (It is at a center for 16-25year old people)

Got a picture of the hall here, but unfortunetly it doesn't show the PA.

Also got a screenshot of a Google SketchUp file of the hall (attached fo post)

The stage is 7m wide, and under the middle we have two Peavey MaxSys™ 215 (discontinued) subwoofers. We have old JBL AS4732 ( speakers that has been put into a new housing (to hang them horizontally, the two cones one on each side and both hi-frequenzy drivers in the center)

The tops hang in about 2,5M and point slightly down and slightly inwards (it is on my plan to lower them a bit, since they are actually pointing directly at FOH, which is infront of the door at the back of a hall, at a riser that is the same hight as the stage. This is causing blind spot (mainly read as "no vocals") closest to the stage. The hall from stage to back is about 9meters causing blind spot (mainly read as "no vocals") and the tops are hanging almost in line with the front of the stage

There are drapes hanging around the stage, behind the panel (so there is about 50cm from the drapes to the wall at the back of the stage, in attempt to reduce monitors from bouncing back into the hall.

The PA is ran with two Peavey amps (can't remember model name exactly, but I think its CS1200 for the tops and CS1800 for the subs) and a Be***r crossover (I know, great!) model CX2310. The crossover is behind a locked plexi, and only I have the key, so I want to tune it correctly and lock it like that. While I'm at it I also want to turn the amps down enough, so it should be nearly impossible to make it too loud (both too loud for ear health, and loud enough to cause damage to the gear). I currently don't have any processing for the mains, but I could try to sqeeze out a 31band graphic (probably only behringer) when I next get a budget for improvements (which doesn't really happy often, and we just bough a lighting control and LEDPars) if it would be any improvement.

Now for my question: Is there a "scientificly correct" way to adjust the crossover frequenzy off the hall, and sub-top ratio somehow ? I have a measurement mic, and a fellow of mine owns Smaart (but doesn't know all to well how to use it), so I could get him over to help me do some measurements. Please let me know if there is any more info you want, I can try to take some more pictures, and finish my drawing (putting the front PA up)

Marsellus Fariss:
Your gig reminds me of my first house gig 15 years ago except you have decent lights.

Cross over: You should find the specs sheets for your subs and tops and start by following what they recommend. I figure the 12"+2" tops will suggest a 80-100hz crossover point. Start there and adjust using your ears. The tops will behave different since they're in different cabinets but they are good drivers.

I would highly highly suggest you get a 31 band graphic for your house. You are very limited without one unless you have a digital console that will do it on the faders like the M7CL and LS9. Get an old Asly or White or even just a DBX or used Rane will cost as much as the cheap Behringer your thinking about. Hop on Ebay and start surfin' I snagged a Klark DN360 (the mother of all FOH EQ's) for under $300 last year but you can find much much cheaper.

Also You should look into a DSP for the house rig. It will let you do marvelous things things that will make a big difference. It will have good limiters in it you can set which will work better then simply rolling the gains back on the amp. Also it will do crossover points, give you lots of EQ for tuning the rig and let you time align everything which helps a lot when things get loud. Once again check the marketplace here and Ebay. I bought an older XTA last year for under $300 and it's let me do all kinda great things that really help. If you have a laptop you should keep the software up so you can work with the unit during a show for educations sake. See what happens when you time align to the backline in the middle of a show. Move the crossover point during a show. Set the limiters to the requested volume. 

Seeing that you are where I was when I started my first house gig I'd like to suggest a few things that will help you greatly in your travels as they did me and still do 20 years later.

Get the Yamaha Sound Reinforcement Handbook and read it twice. Come to think of it I should dig mine back out and read it again. Almost of the info in it is still valid today and it's a wealth.

Go to bigger venues and ask a lot of questions. Ask if they'll let you stand out of the way and watch and ask a few question. It's invaluable and I still do it when I'm at shows working or otherwise. Go get on as a loader for any big shows you can at a big club theater or arena around you. You'll usually be working for comp tickets but sometimes it pays and it's a great way to get a foot in the door. You'll just be pushing heavy cases in but you can learn a lot watching.

Learn to make cables. You'll gain really valuable skills sets and save a ton of money in the long run.

Good luck out there. 

Įrni F. Siguršsson:
Thanks Marsellus, funny with the light, this picture is actually just three 650w par cans and a smoke machine :)

I tried getting a budget for a processor for the PA but there wasn't any :/ But I'm not done trying.

I always every once in a while retune the crossover, trying to get it better than before, all I can do is practice :)

I've been doing exactly what you're recommending, trying to get to watch bigger shows and it's gotten me far, I got myself into a position as a monitor mixer for a 3-day metal festival last summer (all I got was food and bedroom) and I've been hired (for money) this summer. Also last summer the FOH guy, who just finished his Masters in Acoustics Engineering and has been hired for a big concert/conference center opening this summer as the lead sound technician, kind of offered me a job there (the downside is I have to move out of town, but I'm probably going for it)

I've been thinking of getting the Yamaha book, I've been seeing it pop up a lot on the forums, going to order it when I finish what I'm reading now (Master handbook of acoustics)

I know how to make cables ;) Just made a splitter tail with multipin for a snake the other day and done a few snakes before that.

Thanks again for everything!


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