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Imperial PA (Read 8154 times)
Corey
Ex Member



Imperial PA
09/13/05 at 03:30:46
 
Okay is this all I need?

- Laptop

- Squeezbox 2 with mods

- Mixing board

- Valve amp

- Drivers/enclosure

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Corey
Ex Member



Re: Imperial PA
Reply #1 - 09/13/05 at 03:32:14
 
Actually SS should probably be used.
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jj420
Ex Member



Re: Imperial PA
Reply #2 - 09/13/05 at 03:46:51
 
good start, though the last item on your list should actually come first as it will likely be the longest/most complicated step of the whole process.

have fun.
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Braggi
Ex Member



Re: Imperial PA
Reply #3 - 09/13/05 at 16:16:20
 
Corey, you should know that the costs associated with PA go on forever and the payback might never make up for it. I'm sure DirtDawg could chime in here. I think he is one of the few that actually earned his living doing sound.

I've been trying to build a little PA on the cheap for some time and I'm amazed at how often I have to cough up another $100 here or $200 there for cables, adapters and misc. whatnot and it's just a hobby for me. If I really needed to earn a living from this I think it would be hopeless.

Even if you get a PA put together most of your gigs will be backyard stuff for friends you'll never get paid for. Go to some small concerts and take a look at the rack cabinets full of gear. Every little skinny box in the rack means another $300 to $1,500 and the time spent to learn how to use it. It's a frustration for me, but there are some rewards. (Somewhere around here I put the rewards. Didn't I?)

All kidding aside, be very careful what you sign up for. Go buy the Yamaha Sound Reinforcement Handbook and read it cover to cover. If you understand most of it and you're willing to spend a lot of money then go for it. Another good book is Jeffrey Forsburg's Building Pro Speaker Enclosures. It will humble you. There's a lot to consider before comitting yourself to this path.

If you just want to do some DJ stuff, remember that most DJs don't make enough money to pay for the music they buy. That aside, a DJ system can be a whole lot simpler than a full PA for sound reinforcement and you will be the life of the party. You just won't have time to actually enjoy the party because you'll be getting there early, setting up, running the show, then staying late packing it all back up in your truck. Oh, you do have a big truck, don't you? A good idea is to find a DJ without a system and rent him or her yours. That way you actually can get some money for your work.

If you buy your gear inexpensively, you can always sell it on eBay and get most of your money back. That's what lots of other people do.

OK, still going for this madness?

I am.   Smiley
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Corey
Ex Member



Re: Imperial PA
Reply #4 - 09/13/05 at 18:24:08
 
Everybody has their panties in a bunch saying the Imperials are not portable!

Shocked that. They are. I am just engineering in my mind the little trailer to pull behind my truck.

Corey
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Corey
Ex Member



Re: Imperial PA
Reply #5 - 09/13/05 at 18:27:19
 
Have rollers on 2 sides of each enclosure. So after you get them off the trailer by tipping them up you roll them on the upright rollers. You also have rollers on one long side. So you can clear doors by laying them down, lower c of gravity and more stable.

I am looking at the PA Coaxials from www.commonsenseaudio.com

Corey
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Braggi
Ex Member



Re: Imperial PA
Reply #6 - 09/13/05 at 18:52:49
 
[quote author=Corey  link=1126582246/0#4 date=1126632248]Everybody has their panties in a bunch saying the Imperials are not portable!
[/quote]

Hmmm. There many PA cabs that weigh over 300 lbs. Not sure what you're responding to here, but Forsburg has some good ideas for "caster boards" in his book. Wheels on cabinets will vibrate so are best made removable. A heavy duty hand truck with a strap might be a good idea but you'll need help getting up and down stairs.
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gildcm
Ex Member



Re: Imperial PA
Reply #7 - 09/14/05 at 12:41:44
 
I use my Imperial for PA use and I attached casters to the bottom of tha cabinet. So pushing it around is not a problem.

Transporting it is the problem. Laying the cabinet on its back it takes up the whole back of my truck and I can't put any other equipment in the back. I have to borrow a friends trailer to transport the rest of the equipment. Which is the sound equipment for a rock band.

It can be done but you need a truck and trailer or a big box van to haul all your equipment.
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« Last Edit: 09/14/05 at 12:42:29 by gildcm »  
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J_Rock
Ex Member



Re: Imperial PA
Reply #8 - 09/14/05 at 20:42:22
 
I think we can assume safetly that Corey relizes he would need a large vehicle to fit Imperials in guys...Its pretty obvious.  

I think the main question is what do you want to do with these imperials?  Do you want to do the DJ thing, the rent out thing, or the sound renforcement thing?  The equipment is very different for each "thing."
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stvcmty
Ex Member



Re: Imperial PA
Reply #9 - 09/14/05 at 23:41:50
 
Regardless of the intended application, always get an amp that is one model larger than what you can afford.

Headroom is important.  Small amps never seem to have enough power, no matter what application they end up in.

I got some 850 watt amps as starter amps for my mains, thinking they would be good monitor amps later, but even as monitor amps they are under powered for larger shows.

If I were going to build a pair of imperials for PA use (DJ or Live sound,) I would load them each with a Gold Wood 15120 and a Peavey Black Widow HE.  I would run the woofers in each cabinet in parallel.  To drive them, I would use a QSC RMX5050, so 1800 watts to each imperial.  I would find or build a horn that would go down at least to 800Hz, and use a 2” compression driver for it.  To make sure I wasn’t lacking in power for the horn I would use a CE2000 to drive the horns, and an active crossover between the imperial and the compression horn.

That would be a sizeable investment to start, but if that was the ultimate goal, it would be less total money to start there, than to start with other stuff.  Starting with other stuff would leave me with the other stuff when I had my full system at a later point.

That is just my thoughts on an imperial PA.  Getting the speakers and the amps right is the Imperial part of the PA.  Everything else is either source, stage gear, or interconnects.

Stv
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DirtDawg
Ex Member



Re: Imperial PA
Reply #10 - 09/15/05 at 14:45:14
 
[quote author=Corey  link=1126582246/0#0 date=1126578646]Okay is this all I need?

- Laptop

- Squeezbox 2 with mods

- Mixing board

- Valve amp

- Drivers/enclosure

[/quote]


What can I say........... uhmmm ....... No.
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serenechaos
Ex Member



Re: Imperial PA
Reply #11 - 09/15/05 at 18:04:55
 
More like,
not even close...

Robert  :)
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DirtDawg
Ex Member



Re: Imperial PA
Reply #12 - 09/15/05 at 19:31:28
 
Actually the question, " Is this all I need? " recurs often. I think you did that part just right.
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Corey
Ex Member



Re: Imperial PA
Reply #13 - 09/16/05 at 17:04:29
 
                               - Laptop
                               - Squeeze box 2
                               - ZBox
                               - Mixing board:

From mixing board:
- HF Active crossover into HF horn power amp(Crown) driving the compression drivers on top.

- QSC power amp driving the Peavey BW and the JBL knockoffs full range.

                                       
Corey
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« Last Edit: 09/16/05 at 17:51:56 by lynch »  
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stvcmty
Ex Member



Re: Imperial PA
Reply #14 - 09/19/05 at 00:02:42
 
Driving the woofers full range is a tough call.

If they don’t beam at higher frequencies, then driving them full range will give them a more open sound.

If they beam, then they will need to be low passed by the crossover.

I just threw out the amps I would like.  There are better ones for more money [Crest, Crown IT series], and there is other high power ones for less money [Behringer EP2500].

When looking at amplifiers, lately I have tried to find ones that will give me the power I want into the load I have without running them at bridged mono.  When an amp is bridged, current becomes a concern, as well as heat dissipation.  [Compare running 2 CE1000’s bridged mono to running a single QSC RMX5050 in stereo with 4-ohm loads].

Stv
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DirtDawg
Ex Member



Re: Imperial PA
Reply #15 - 09/19/05 at 13:14:50
 
To full range or not to full range? There are tradeoffs to consider, as mentioned by stv.

If you run them full range they will probably sound more "live" and open, at times, but less controlled, great for drums, not so good for acoustic guitar and voices. The 15's will start to beam noticeably around 800Hz and serious (objectionable) combing in relation to the horns starts from 2K-ish range and up to where ever the 15's roll off significantly. Beaming is more of problem outdoors, combing is worse indoors. Beaming becomes much less noticeable with a PA on the short side of a long skinny room, except up close, of course, but you probably don't want to be very close to them for your ears' sake. Combing in the same room is much worse. If you are going for a HiFi sounding clean, flat, non resonant response, you need to cross them before they start to beam. That solves both problems, except for any combing caused by the 2 - 15's side by side. To fix that you need to cross much lower, like 150Hz range depending on how far apart they are, but combing in that range seems to be less noticeable to most people. The best way to detect and correct for either is to use pink noise (download to laptop) and move around a little.

When running an amplifier in mono mode you don't get more power. The main advantage to bridging for mono is in impedance matching and sometimes increased (percieved) headroom. Pretend for a moment that amps are perfect and you have 2 X 500W @ 8 ohms (stereo), in mono you will still have 1000W (2 X 500) but, the amps impedance is 16 ohms now. With 4 - 8 ohm drivers using stereo you can put 2 drivers across each side in parallel, and get 2000W total, in mono you usually can't drive a 2 ohm load so you put your drivers in series/parellel giving you 8 ohms again and the output is 2000W. If you try to run 4 ohms in mono (or 2 ohms in stereo), unless it is specifically designed with that possibility in mind, which many are nowdays, you will either be hitting the thermal limits of the amps, which means it takes a nap if you're lucky, or severely compresses the signal to protect itself.
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« Last Edit: 09/19/05 at 13:25:01 by DirtDawg »  
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Corey
Ex Member



Re: Imperial PA
Reply #16 - 09/19/05 at 17:12:58
 
What do you recommend fro a x over to do both jobs, like in one box?

I am only familiar with car audio xovers like Audiocontrol 24XS etc.

Corey
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DirtDawg
Ex Member



Re: Imperial PA
Reply #17 - 09/19/05 at 22:32:30
 
[quote author=Corey  link=1126582246/15#16 date=1127146378]What do you recommend fro a x over to do both jobs, like in one box?
[/quote]

I'm not clear what you mean by "both jobs". I have used Crown, Rane, Yamaha, Ashley, even the cheapest, DOD crossovers, and Rane, Yamaha, Ashley, and UREI equalizers (a 1/3 octave EQ on each channel is handy Smiley) with good results.
Bargains are out there, and I would grab any one of these brands if I could get it for a song or two*, but I wouldn't buy anything new without first checking out the Behringer DCX2496 Crossover.
I haven't used these, but to me it seems like a tremendous value. I've heard hot and cold about this unit on other forums. Maybe some of our resident smart guys who has one can weigh in on this idea. Are you building a 2-way, 3-way, 4-way?


http://www.behringer.com/DCX2496/index.cfm?lang=ENG

* A DOD would have to be very cheap, like <$40 to be a bargain in my opinion.
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« Last Edit: 09/19/05 at 22:36:00 by DirtDawg »  
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stvcmty
Ex Member



Re: Imperial PA
Reply #18 - 09/20/05 at 00:24:33
 
Running an amp bridged mono into a 4ohm load [2 8ohm loads in parallel] produces more power than running it stereo into 2 separate 8ohm loads.

I would never buy an amp that was not 2ohm stereo stable unless the price was 50% less than normal retail.  The flexibility that 2ohm stereo stable amps give is worth paying more for them in the short term.

The distinction I was making is using a single RMX5050 would be better than using 2 CE2000’s.  The reason is dampening and wasted power.

I really like the Behringer CX3400 crossover.  Combined with a decent 31band graphic EQ, it can take care of just about anything.

Look at the response graphs for a GW15120 on parts express.  Its response falls really fast, so it should not be terribly bad about beaming/comb filtering if it is used with something else in an imperial.

The difference in the front radiation sensitivity between a Peavey black widow HE and a GW15120 would also help to prevent comb filtering.  The main purpose of the GW15120 in the imperial is back loading into the horn.  The Black Widow HE is strong enough to back load into the horn well, but it is also sensitive enough so the front radiation keeps up with the horn.

One thing I would not do, run the imperial as a 3 way cabinet.  Both 15” speakers need to be fed bass, they are in the imperial’s compression chamber to feed the horn.  I could see having an active roll off for one of the drivers between 90 and 150hz, but the other one would need to either be full range, or crossover to the Compression Driver/Horn.

Stv
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DirtDawg
Ex Member



Re: Imperial PA
Reply #19 - 09/20/05 at 02:59:35
 
Quote:
Running an amp bridged mono into a 4ohm load [2 8ohm loads in parallel] produces more power than running it stereo into 2 separate 8ohm loads.

I would never buy an amp that was not 2ohm stereo stable unless the price was 50% less than normal retail.  The flexibility that 2ohm stereo stable amps give is worth paying more for them in the short term.


stv,
You and I are not in disagreement. We are both saying the same thing 2 different ways.
Corey, keep in mind the fact that many of the bargain priced top brand amps out there are not the newer models with 2 ohm stereo or 4 ohm mono capabilty, so just be sure which model # you are looking at before you buy.


Quote:

One thing I would not do, run the imperial as a 3 way cabinet.  Both 15” speakers need to be fed bass, they are in the imperial’s compression chamber to feed the horn.  I could see having an active roll off for one of the drivers between 90 and 150hz, but the other one would need to either be full range, or crossover to the Compression Driver/Horn.



Absolutely right and I would send the same signal to both 15s and not worry too much about combing between them. You can't overlap the 15s and the horns and expect to get a flat response, so get that range out of the horns. I didn't see a polar response graph on either driver, but you have to decide how much beaming from your 15s you can tolerate, anyway. My tolerance is zero, so I would cross any 15 over at around 800-1500 Hz, but that's possibly @n@l if you only need 30degrees mid dispersion.
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stvcmty
Ex Member



Re: Imperial PA
Reply #20 - 09/20/05 at 03:36:34
 
http://www.partsexpress.com/pdf/290-397b.pdf

For the Goldwood, scroll down to page 3.  It doesn’t give polar response, but it does show the gold wood peaks at about 125hz and falls quickly above that.

The horn will load the rear of the driver, getting bass from it, but the front radiation will be seriously drowned out by a higher sensitivity driver.

I think this site has the GW15120 on clearance, http://www.cheaplights.com/catalog/01_info.php?sec=411
I ordered the 411-WF1558 from them and it was a gold wood 1558.

Stv
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stvcmty
Ex Member



Re: Imperial PA
Reply #21 - 10/01/05 at 23:25:58
 
I don’t think I can recommend a QSC RMX5050 now.

I went to guitar center today to trade in some speakers, and before they would take them, they had to test them.

They used a RMX5050, and I was not impressed.  I have used a CE1000 bridged mono with the speakers I was trading in, and that combination would bring down the house.  They bridged mono the RMX5050 against the pair of speakers, and it sounded bad.  At low volume it distorted.  I thought the person testing them didn’t know what he was doing, but I checked the source, the board, and the crossover, and they are all correct.  The RMX5050 went into protection mode for no good reason several times.  The guy thought it was my speakers [it wasn’t, I tested them this morning, and they work fine] so he tried hooking up a set of JBL speakers, and they sounded just as bad.

It may be that it was a display model, but my “hands on experience” with the RMX5050 is not so good.  The online reviews I have read of the RMX5050 are good, but there is a difference between reading about something and experiencing it.

Then we tired testing the speakers I was selling on a CE4000, and everything worked fine.  So if I had to pick a high power amp, I would go with a CE4000.

Stv
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stvcmty
Ex Member



Re: Imperial PA
Reply #22 - 10/02/05 at 00:09:02
 
Why must so much of sound come down to the differences between spec sheets and real life?
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Braggi
Ex Member



Re: Imperial PA
Reply #23 - 10/05/05 at 04:09:04
 
I'm pretty happy with my CE1000. It's noisy if I don't use a balanced preamp though.
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stvcmty
Ex Member



Re: Imperial PA
Reply #24 - 10/05/05 at 05:14:25
 
I run 2 CE1000’s, but some times, I need more power, which is no fault of the amplifiers.

The RMX5050 is one of the largest cost effective amplifiers I have seen, which is why I was interested in it for a while.

The largest pro sound amplifier I have seen is a Crown IT8000.  4000 watts per side into a 4ohm load.  It just ends up being about $1 a watt.

After my experience with the qsc, I will be staying with crown amplifiers.  The CE1000 is a safe bet, always.

Stv
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DirtDawg
Ex Member



Re: Imperial PA
Reply #25 - 10/05/05 at 05:14:46
 
Most of the DJ rigs I've seen are not balanced, at least not really because, so many effects rack toys unbalance at the inputs. If you're running very many live mics, you need to go balanced all the way to the power amps, or you will hear every lighting ballast up a block away or more. ???
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DirtDawg
Ex Member



Re: Imperial PA
Reply #26 - 10/05/05 at 05:20:03
 
[quote author=stvcmty  link=1126582246/15#24 date=1128485665].....  It just ends up being about $1 a watt.
Stv
[/quote]
It sounds pretty cheap when you put it that way. Grin
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stvcmty
Ex Member



Re: Imperial PA
Reply #27 - 10/05/05 at 05:33:24
 
Not when it is an 8000-watt amp and tuition is $12,000 a semester…

Balanced gear is good.  Having a separate hot and cold line is nice, because the signal ground can be lifted to get rid of hum.

Speaking of balancing, hum, PA’s and grounding, is there any safe, easy way to setup a temporary star ground for a show?

Stv
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DirtDawg
Ex Member



Re: Imperial PA
Reply #28 - 10/05/05 at 06:49:38
 
I always ran a separate ground from my board to my power mains rack, kind of "star" like. Everything grounded to the mixer, and out thru a cable separate from the snake. If I needed to lift a ground I would use an "adapter" ( 1 foot mic cable without the ground connected, spray painted orange ) at the mic end. I had a doctors bag ( actually a tenor sax case that weighed over 100lbs, nicknamed "The Dreaded" ) of impedance transformers, adapters of all kinds, and isolation transformers and all knids of cool stuff for hums. Nobody ever got shocked after I did the ground on the board, except for a couple of guitar players, but it was thier stuff, that bit them.
Here's a cool link full of info:

http://www.rane.com/note110.html

And another

http://www.gbaudio.co.uk/data/ground.htm

Oh, sorry, I forgot the "easy" part.    :)
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« Last Edit: 10/05/05 at 06:50:26 by DirtDawg »  
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Papi_Bill
Ex Member



Re: Imperial PA
Reply #29 - 10/06/05 at 14:25:41
 
skip the dod and behringer crossovers, and  buy a dbx driverack pa. used at around $300 on evilbay...get the calibration mic too while you're at it... in one rack space you get up to 3 way stereo x/o with alignment delay, graphic and parametric eq, feedback suppression, compression, subharmonic synthesis (not sure if that would be useful with imperials though!) and limiters on each output. Oh yeah, the box will "auto eq" the room using pink noise and the calibration mic....
you would need to buy at least 3 or 4 of the above mentioned items for a reasonable pa anyway.... save space time and money and get one of these....  dbx makes grea stuff... I have one in use with my w/o pa...and the second on my bass rig for now until I build some monitors.
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« Last Edit: 10/06/05 at 14:27:19 by Papi_Bill »  
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Braggi
Ex Member



Re: Imperial PA
Reply #30 - 10/08/05 at 05:11:21
 
I'm grateful for all the cool information shared on these boards.

Thanks to all!
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Corey
Ex Member



Re: Imperial PA
Reply #31 - 10/08/05 at 06:03:48
 
P Bill,

I am from a small town and have had the idea of starting a DJ company since the Imperials came out since that "Hell..." thread during XMAS time. I made it a point to check out my competition the last two years and can confidently say each of the dozen services available in my area sound terrible.

I started this thread with the idea that I may get some ideas on what may sound good. When you recommend a driverack pa. is it because it offeres superior sound quality or because it is conveniant? I ask only because if a seperate Rane etc. can give me better SQ I will go that route. I must say this thread has evolved into much more amplification info. than I would have thought. Great info. guys and thanks for getting me started.

Now that I know what is involved a consultation with Steve will be that more useful.

Corey
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Papi_Bill
Ex Member



Re: Imperial PA
Reply #32 - 11/09/05 at 06:31:29
 
the driverack is sonically superior IMHO. also you have less cables and potential for ground loops and all those headaches.
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Corey
Ex Member



Re: Imperial PA
Reply #33 - 11/11/05 at 23:07:42
 
Are there horns efficient enough to run on 5 watts in a 4 horn line array for 8 ohms nominal?

I am talking smaller venues like 20 X 30 size bars and 1 room clubs in small towns etc.

Then run a pair of Imperial SO's with an increbible amount of power.

Umm.. what do I want for Christmas.? A tablesaw!  ;D

Wow, we guys have a simple life. A tablesaw makes us happy while the women want fricken diamonds! Well some do.  I guess I shouldn't stereotype!

Corey  :)
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stvcmty
Ex Member



Re: Imperial PA
Reply #34 - 11/27/05 at 00:48:22
 
I get the Musicians Friend catalog, and a new one arrived.  I was flipping though, and there was a review of the DBX Drive Rack PA.

http://www.musiciansfriend.com/srs7/g=live/content/doc_id=89558

Reading the review, and then reading the user manual, what it does makes sense.

Just to see what similar functionality would cost, the closest I could find would be a Behringer Ultra Drive PRO DCX2496, and a Behringer Ultra Curve Pro DEQ1496.  The two total ends up being $550.

The DBX Drive Rack PA is $500.

I have not heard the DBX in person, so I cannot say how it sounds, but after reading the review, it sounds promising.

Stv
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Braggi
Ex Member



Re: Imperial PA
Reply #35 - 12/01/05 at 02:59:01
 
Hey STV, thanks for sharing the link on the review. Sounds pretty glowing. I'd be skeptical, but I read some posts on the ProSoundWeb from a guy who replaced his Behringer crossovers with DBX and he was positively glowing about how much better the SQ was. Assuming he wasn't the same DBX employee who wrote that review (just kidding) it's probably good stuff and I'd suggest the DBX over the Behringer. All the ProSoundWeb guys dis Behringer a lot. One guy says he'd love Behringer mixers if he could keep them working. Says they're always in the shop.

OK, enough. When I can afford it, and assuming I can justify it, I'll be getting a DriveRack.
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Michael E
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Re: Imperial PA
Reply #36 - 12/12/05 at 01:41:35
 
[quote author=Corey  link=1126582246/30#33 date=1131750462]Are there horns efficient enough to run on 5 watts in a 4 horn line array for 8 ohms nominal?

I am talking smaller venues like 20 X 30 size bars and 1 room clubs in small towns etc.

Then run a pair of Imperial SO's with an increbible amount of power.

Umm.. what do I want for Christmas.? A tablesaw!  ;D

Wow, we guys have a simple life. A tablesaw makes us happy while the women want fricken diamonds! Well some do.  I guess I shouldn't stereotype!

Corey  :) [/quote]
Which horns ?
you can work it out...
Sensitivity + power = SPL
SPL - audience distance = SPL at audience

jblpro.com 'tech papers' 'sound system design'

Mike.e
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