stereo 4-way with 2 DR-PAs

bc

I'm wanting to run my PA 4-way stereo (or at least 3-way stereo with mono subs.) It's JBL SR4732s, 4715s, 4719s. From what I understand, the DriveRack PA will only give me 3 ouputs. Can I use one DRPA in 2-way to feed the subs, and feed another DRPA to get lows, mids, and highs? Is there propagation delay that might affect the alignment tunings? Any thing else I don't know about/haven't thought about?

Yeah, yeah, I know, I should buy a 4800 or something, but for that money, I can buy a couple more amps that I need!

Even better, could I run the first DRPA in stereo 3-way, cut the subs out the bottom, cut the tweeters out the top, feed the second DRPA out the mids (for the lo-mids. hi-mids, and horns) and go 5-way stereo? I'd love to cut those passive crossovers in the 4732s out altogether (no offense intended, JBL!)

Thanks for all your great posts. I've read many of them, but never seen this issue addressed.

Gadget

With 2 DRPA's you could run 5 way full stereo.. but why would you want to take the outputs from one DRPA and feed the input of another? I mean you could, but why not parallel the inputs of the two DRPA's?...As in a \"Y\" config...

No you cannot do 4 way with a DRPA.. I run 4 way stereo with a single 260 however... hi's and Mids run stereo, and lo mid and subs run mono. (they're omni directional anyway right?

No need to apologize to me about JBL bashing... I do not like JBL...and will not buy anything they sell...

I too don't use internal crossovers...I prefer to set up and tune my own EQU.. and here in lies the rub...the LR24 (this is the only one we have actually measured with SMAART... has a 7.5ms propagation delay.. so with the 10ms delay per output on the DRPA you don't have NEAR enough for the alignment of the tops...and the subs ...the 260 however, does, OR you could get Crown XTI amps to provide the necessary delay to the hi's and mids, and lo mids too perhaps...The XTi's have 56.375 feet of delay per channel...AND if you go to Northern Light and sound, you will find GREAT prices (like XTI 1000 for $375, and a XTi 4000 for about $724...

Read all the posts you want but you really should read the \"read me first before posting\" stuff and FAQ's in that section as I have assembled a wealth of info there...
Gadget

Dennis

If you run your subs off of an aux, you wouldn't have to feed one DRPA from another DRPA. As a variation on what Gadget suggested, run direct into one from L/R set for hi, mid, low and direct into the second one from an aux set for the sub(s). Setting up in this manner will eliminate the double latency factor that the second unit in the \"daisy chain\" would see.

Having said that, the correct call is to use a single processor that can handle the job by itself even if it does cost more. Man up and put it on your Mastercard.

Dennis

Dennis

Gadget

You said: \"and here in lies the rub...the LR24 (this is the only one we have actually measured with SMAART... has a 7.5ms propagation delay\".

How did you arrive at that figure and what was your set up? I came up with 1.52 ms straight through the unit with no filters and then with signal through the mid out, high passed at 300Hz with LR24 and low passed at 4.5KHz with LR24 I came up with 1.6 ms. I'm sure your test was a different animal but 7.5 ms would be considered by some to be unusable.

Dennis

Gadget

Jack Alexander(instructor in Illinois somewhere in Chicago I think) has long postulated that all DSP devices have this delay, He demonstrates it in his classes and the processor he uses ( was it XTA?) has a 5.9 ms delay... the delay I spoke of was measured using SMAART by Mike Kovach, a top notch system designer and engineer who has written articles for SMAART and is friends with Robert Scovill... http://www.rane.com/apps/rane/live7.html Here is the base article that Mike wrote:
http://www.dbxpro.com/forum/viewtopic.php?t=957
Actually you are pretty close... I should explain... you did good, Mikey came up with 1.62ms through the LR24 to the tops.. I have been Parroting (actually my name is Perrett... pronounced like the bird...so) this info for so long I have forgotten to add that that is (actually) 7.44ms on the subs with regard to the tops using LR24...Here:
http://www.driverack.com/drug/view_thre ... forumid=15
find the \"short doc\" in Mikeymans post... it will \"illuminate\" you

Gadget

Dennis

As I suspected, there were a few more details to this topic than your reply to bc indicated.

Dennis

bc

Thanks so much for all the replies, and for the promptness! I really appreciate it.

You're right, Gadget, it's a much better idea to just \"y\" into both DRPAs. I guess I was so focused on dividing up the frequencies, and not thinking about the other options and filters offered in the DRPA (old school crossover thinking) that I couldn't see the forest for the trees. Thanks.

I've always liked the way a lot of JBL speakers sound, but I don't know anything about them corporate-wise. Why don't you like them, if I may ask? Is there something I should know? Is it the quality, or how they do business?

As luck would have it, I do have some XTI amps that I'm going to use to power these speakers, and am going to get some more to power the rest as soon as I can. Thanks for the tip about Northern Light and Sound, I'll check them out.

But these speakers aren't that big, or bigger than many other cabinets. If the delays in the DRPA aren't long enough to align these cabinets, what ARE they useful for?

I have read a lot of the \"read me first...\" stuff, and am going through it all as I can. I know I speak for a lot of people when I say we can't thank you (and everyone who has contributed) enough for your time and all of your hard work in posting all this. Thanks!!

And Dennis, I know what you mean about manning up and buying the more expensive processor, but: Welcome to the New economy. I don't charge anything anymore. If I can't pay cash, I get by until I can. Small steps, grasshopper.

Dra

Why doesn't Gadget like JBL? Well :? , you asked for it.

DRA

Gadget

Well, it is a number of things...not the least of which is their reputation as a speaker with a very harsh high end...

It's their attitude to small customers...In one case on an install, 2 brand new SRX722's that couldn't meet (or even come within a country mile of what they spec'ed...they are \"supposedly\" as \"81-20khz +-3db...so when they were totally incapable of even 12Khz @ 3db down JBL was contacted and offered no explanation... further, one speaker exhibited a strange HF ring and upon inspection had a totally different driver in it...Yes JBL provided 2 new drivers, but these were no better...this was measured with SMAART...

JBL also put out those terrible TR pieces of trash (maybe THE worst piece of crap I have ever heard in a supposedly \"Pro audio\" piece...ya, they pulled them after about a year.. but there are a ton of those pieces of S*@! out there and they are USELESS! I don't like their entire low line of speakers...

I feel they charge far too much for their product for what you get...

There's more... but...
G

Dra

Delay alignment? The DRPA is designed to align speakers / horns in the same cabinet and then to (usually) front loaded subs. Horn loaded subs usually require physical placement to properly align.
If you can swing another $200-300, have you considered a DR260 and a DRPA. You'll gain all the alignment you'll ever need, plus lots of other goodies.

DRA

Gadget

ya even with a front loaded sub if you need 4ms for the horn to woofer alignment and 7.44 ms of propagation delay on the subs you kind of run out of... gas..er delay...My Labs, horn loaded subs ended up at almost 18ms of delay...

G

bc

Yeah, the TRs were trash. And come to think of it, I know of a company the repairs all kinds of pro gear that has started refusing to work on JBL because they're such a pain in the a** to deal with.

Thanks to your suggestions, I'm now really looking at the 260. Gadget, I like your idea about mono subs and lo mids, and stereo hi mids and highs. That brings up an interesting question-at what frequency do things begin to cease being omnidirectional?

And if I did that, could I still run the tweeters off a separate amp channel to get to 5-way (still looking to get rid of that passive x-over!)? What is the upper frequency for the crossover in the XTI 1000? Or is there a HPF I could use in the amp that would go high enough? I couldn't find anywhere that was addressed in the Crown manual or website.

Thanks again for all your help. Amazing how much I've learned in two days. Thanks!

Gadget

Go to the 'Driverack Training Modules' above. go to the downloads section, and find the 'System Architect' download, on that page download the \"BANDmanager\" (you'll need net framework 3.5 first though) you can GUI right into the XTi amps, monitor the power and make all your adjustments in the computer...

Getting a 5 way system aligned is a BITCH BTW...4 way is bad enough..

Sound gradually goes from non directional to more and more directional the higher the frequency goes..there isn't a place where one leaves off and the other picks up...Suffice it to say 150hz and under is pretty much omni, but 200hz is also within the realm..I set up my LABsubs @20hz-55 hz, my Double 18\" or single 18's or single 15 (depending on rig) lo mids from 55hz to 150 hz and the 12\"( I typically go lower if I use the double 15\" Yorkville Elite 2204 tops)but on the 12\" tops from 150 to 1200 hz and the 2\" horns from there up...

On those JBL's its pretty common to tri amp the tops and leave the HF tweeter in the passive crossover because it doesn't draw that much power, and it's tough to get them aligned properly.

But yes you could run the tweeters off one of those amps, the crossover HPF can be set even up to just below 20khz if you wanted to...there are BW and LR filters and delay and limiters...It's pretty comprehensive...

G

bc

Thanks again for your great advice. I've read some of the stuff on the System Architect and Band Manager, but haven't had the chance to download it and play with it yet. It's good to know it can do what I need.

I figured 5-way would be more of a bear, but I'm leary of the crossovers in the 4732. I've run them 2-way with the passive tweeter in the past, but I've had pieces fall off the crossover; it's happened in the boxes I have now, and apparently it was a common problem for JBL. I guess it's a trade-off between the difficulty of getting it aligned if you go active, and dealing with the internal crossover if you go passive. It's always something...

Thanks again for all your help, I'll let you know how it all works out.

BC