DRPA/Crown/JBL setup

cam

Newbie here: I have a Yami 01V96 board to the DRPA, 3 Crown XTi 4000's, 2 JBL SRX 718's and 2 MRX515's. I want to run 2 Crown XTi 4000's ( one for each sub ) and 1 XTi 4000 in Stereo to the 515 tops. I have a 4 wire speaker cable, one to each Sub then patch from each Sub to the Tops

Do I need to config the 2 4000's as Bridged MONO and how do I set it up in the DRPA??? I can't find that type of config in the DRPA....

Thanks in advance for you input!

Cam

Gadget

Changing the DRPA to a \"bridged setup (even if it has it in there) changes nothing... you'll need to have a couple panel mount (NL4MPR) running the bridged sub outs (two red posts, or an NL4FC with pins 1+ and 2+ sent to the panel mount 1+, 1- for the subs, then the tops amp L/R black red to the panel mount pins 2+, 2-, or two NL4FC's with 1+, 1- going to the panel mounts 2+,2-.

A 2X3 cofig should suffice, you have power enough for only a xover in the 110-120hz range (625 watts to the tops.. little headroom, so a higher xover point is warranted...

Use like xover types for the sub to tops, I like LR24, use a steep falloff for the sub HPF I like BW18...
gadget

cam

Can you explain the \"power enough only for a cross over in the 110-120 range?\" Are you talking the low end of the high cross over? Should it be higher than 110-120 Hz?

I've already been using the cables from 1 4000 bridged at 4OHM for the 2 718's... adding the 3rd 4000 as I'm very short on Sub power with 1 4000.

That's my curent xover types now..LR24 etc

Thanks gadget!!!!

Dennis

Gadget was referring to the crossover point between the subs and the mid/highs which includes not only the \"low end of the high crossover\" but also the \"high end of the low crossover\" which in the future we will identify as a point or points where we low pass the subs and high pass the mid/highs. His point was the mid/highs are underpowered at 625 or 650 Watts so to compensate, The low crossover point is raised to 110-120. If you had 800-1000Watts per mid/high cabinet, you might do a low crossover point around 90(ish). The crossover points on the subs and on the mid/highs don't have to match. They can overlap.

Dennis

Gadget

Dennis, perhaps you could elaborate on Why it's ok, and in what cases, to overlap the crossover point on the sub/mf-hf point.
Gadget

Gadget

My point was, it is necessary to (in 4 wire NL4 connections)configured the way you want...split the feed from the amps so that the bridged 4000's feed the 1+ and 2+ from the amps to the 1+ and 1- to feed the subs...AND, IF, you wanted to use the NL4's on the subs as a through to the tops, you would need to feed 1+ and 1- for BOTH channels of the tops amp to the sub on 2+ and 2-... then you would need to change the 2+ and 2- coming out of the sub (remember we have sent the sub signal on the 1+ and 1-), to the 1+ and 1- of the tops, and those cables would then have to be marked as such, because they would have to be used there and there only...

Dennis gave good explanation of the power issue..
G

Dennis

Ok Gadget, so maybe I didn't think it through in this specific application and the overlap would defeat the purpose of the higher than average crossover point.

In general, overlapping the low crossover point will create a coupling zone and when time alignment is done at that crossover point, coupling will occur. End result is more low end response.

Almost everything we do in live sound is a compromise and to address that, I am going to quote a couple lines from Bob McCarthy's \"Sound Systems: Design and Optimization\": \"Since the wavelengths at the high end are the smallest, they will have the least margin for phase offset. Therefore, controlling the high-frequency overlap will be crucial. Mid-range and low-frequency overlap can be accommodated to a larger extent since the wavelengths are long enough to minimize cancellation.\"

Dennis

Gadget

Thanks Dennis,

I've seen it done, and never really saw the benefit in it. I think perhaps when Bob says:

Mid-range and low-frequency overlap can be accommodated to a larger extent since the wavelengths are long enough to minimize cancellation.\"

What he is indicating is that \"it can be accommodated\" but it doesn't necessarily have to be a good idea...The overlap of frequencies in the crossover region has been shown to create irregularities in that region. A PEQ can help if you have some deficiencies in that area ... say from spreading the crossover point a little... A perfect example was a band I saw tonight...Behringer powered tops and two different powered subs...no crossover... as I walked the room I found a power alley, and about 7 very distinct fingers in the low to lo mid frequencies...of course the subs were improperly placed, but one would have been ok in the right place...but the sonic hash had the bass and kick nearly indistinguishable. There were multiple problems here, but the point I'm trying to make is that we go to great lengths to try and minimize the interaction with:

The walls and floors(ceilings too but from coverage patterns a lesser problem).

Each other.

The boundary's especially with concern to the 80hz frequency.

I've read pros and cons for additive overlap and I have to say the preponderance of information is that it is more destructive than useful.

And that is my opinion...
Gadget

Dennis

I don't think of anything as a \"one size fits all\" solution. I included the quote from Bob to illustrate that the crossover overlap can possibly work or not depending on the system and room. It would be something you might try in a given situation and if it didn't work, move on to another solution.

An opinion we might share regarding mid/high cabinets is once we find correct EQ, crossover, and time settings, we \"set it and forget it\".

An opinion we might not share regarding subs is that they should be re-time aligned in each venue to compensate for the room's characteristics. Without even seeing the band last night I am going to stick my neck out and and say I think their problems could have been corrected with a DR260 and SMAART. Repositioning the subs would be a second option. Quite often in a venue, there are not a lot of options for speaker placement.

You said \"What he is indicating is that \"it can be accommodated\" but it doesn't necessarily have to be a good idea...The overlap of frequencies in the crossover region has been shown to create irregularities in that region. A PEQ can help if you have some deficiencies in that area\". If the overlap isn't going to work and you have combing issues, they are probably in the time domain which can't be corrected with a PEQ.

I recently did an installation in a club that was 40' x 80'. The system had only one sub. It was a dual 18\". It had plenty of power but I had a terrible time covering more than half of the room with low end. I finally overlapped the crossover point and the system woke up and gave me even coverage through the whole room. Will this work in every situation? No, of course not. It is just another tool in the tool box.

Dennis

Gadget

As I said those were MY opinions...I have nothing against what you are offering EXCEPT the populace here is primarily newby to novice. We do kind of cater to that crowd and the information overload foe these people is ...well daunting... we tend to try and \"keep it simple\" That technique you speak of is often used but remains controversial within the pro audio community...

What I was speaking of with regard to the subs.. I wasn't saying TIME aligning to the room ...I never do that, I do align the mains to the backline...I do align the speakers..and mains within their relationship to the subs. In complex situations I have even employed delay to increase intelligibility of spoken word within a space with a 1.5-2.5 ms reverb time...But what I was speaking of was (boundary cancellation) the location of one sub about 3.5 feet from the boundary... that is a classic no no for live music with Kick drum as that is the cancellation length for the first harmonic of the kick drum...(here is the link to just one of the things provided in the FAQ section to help those that want to know)
http://www.peavey.com/support/technotes ... lation.cfm

The rule of thumb for subs is more than 8 feet or against the boundary(wall)...

Thanks Dennis for your contributions here. I was in no way discounting your opinions, just offering mine as perhaps a counterpoint...All sound is subjective and what is one mans nirvana is anothers sonic chaos...Stick around, it's good to have you here!
G

Dennis

Good point(s). Sorry Cam, you are probably wondering what any of this has to do with your JBLs and Crown amps. I get carried away. I am now going to my kitchen and pouring myself a large cup of \"shut the **** up\" and then lurk in the background.

Dennis

cam

First, thanks for all your input and patience! And if we get off track a bit I don't mind at all... I'm way on the left side of the learning curve, so anything helps... bare with me on this basic stuff!! LOL!

So let me ask this, I see now I am underpowering the 515 tops... is it possible to run one 4000 bridged 4 OHMS, to the tops, then the other 2 4000's, each bridged at 8 OHMS to each sub.... and still run 1 4wire cable per side?

I know the tops would be overpowered so to speak but wouldn't I acheive more headroom that way as opposed to running the 4000 in Stereo and underpowering them??

How would I connect from the DRPA to the amps, then to the panel, then to the subs, with my 4 wire cable... can I please trouble you to explain in as much detail as you care to share... :? ???

Edit 1... Is this correct?... L/R out of the LOW on the DRPA to IN of Chan 1 and 2 of 4000(A)m then LINK to IN of Chan 1 and 2 of 4000(B)......

OR

L of DRPA to Chan 1 of 4000(A) and R of DRPA to Chan 1 of 4000(B)????

Gracias!

Gadget

Firs off you never did tell us what you were going to do... are you using panel mounts like I suggested? it makes a difference...and yes...you can it.
G

cam

I'd like to run the panel mount as you suggested...

Gadget

This again would require a special cable that is marked for the tops.. from the subs, and HAS to be hooked up only one way... OR you could rewire the second (thru) connector on the subs...if you re-wire the sub, you would wire 2+ 2- from the input(from the amps) to the 1+1- of the thru jack in the subs... this would then HAVE to be marked on the jacks on the subs, and used that way...

Yes it would be better to have the power...that is 1600 watts per speaker available...
Form the JBL website:
[/quote]

MRX515 Power Capacity 400/800/1600 watts

Dennis...

I am now going to my kitchen and pouring myself a large cup of \"shut the **** up\" and then lurk in the background.

No need brother... no need, just keep up the good work!


G

cam

Good lord Gadget!! I asked and received! Thank you!! I need to buy a couple brewski's for this! Thanks again Cam

Gadget

Oh well...a picture IS worth a thousand words is it not 8)
G

Gadget

****Note****

The top amp ... in the picture should have the wire going from the channel 2 red+ terminal to the panel 1- terminal.. all else is the same...

Geez I jave tried and tried to get the new photo to load... but it won't...

It's been a LONG day...

G

Dennis

If you were to disconnect pins 1+/- on the loop thru connector of the SRX718 and then insert a jumper wire between 1+ and 2+ as well as insert a jumper wire between 1- and 2- on the connector of the MRX 515, you could use a standard NL4 cable for the sub to mid/high jumper cable and not worry about which end goes where.

Dennis