Building a DJ rig

rec

I am building a DJ rig and want to make sure that the DRPA is the right tool for the job.

I will have dual 2-way cabs on each side for my tops (BFM DIY speakers OT12's)
4-subs (BFM T30 subs)
here is the site if anyone is interested http://www.billfitzmaurice.com/

Is the DRPA the best candidate for this application or would I be better off using a different DBX component?
Thanks

Gadget

It should be fine. 2X4,, stereo with fullrange tops. Or if your bi-amping them 2x5 0r stereo 2x6...Which version are you using? the 12 tweeters or the single? We have built the table tuba, and the auto tuba's. The Auto tuba makes a great cinema sub!

The 260 is a far better piece, and if you get the DRPA you should get a UPS to prevent the thump if the power goes down...

Gadget

rec

Gadget, I am building the OT12's with the 12 tweeter array in them.
I do have a UPS
What benefits would I get fromthe 260 over the DRPA?

Gadget

Here's a list I made up that's on the other web site.. and there's MORE!

Hi
Well, I have both. I will only use the DRPA in a disco/type system where advanced functions are not necessary. Here is a list as best I can remember of the 260 VS DRPA.
The differences have been covered on this user group about a year or so ago. But since it's not that easy to find something ;-) Most important advantages of the 260 are:
GUI control and firmware updater
output relays (saves a lot of headaches!)
muting buttons per output channel
dual mono settings
more PEQ's
longer delay-times
full function input mixer
outputs freely configurable
much more flexible auto-eq functionality
It's really quite a difference.
Almost forgot one of the most important advantages of the 260 over the pa, at least as far as I'm concerned: full functional security! You can also freely configureany of the 6 outputs to do anything you can imagine within the confines of the units functions, and true dual mono operation which the DRPA cannot do

Where the PA only has a simple lockout (which can be by switched off by anyone who can read the online-manual), with the 260 different security levels can be assigned to any function.
Anyway, with the DRPA, the RTA (Real Time Analizer) and Auto-eq can only be used in combination with each other (within the auto-eq wizard).

The 260-user can switch on and off the pink noise on the input mixer, view the analizer with any signal (even on the computer-screen via the GUI-control) and then decide wether or not to use the auto-eq function. Much more flexibility.

So for my money(and I just purchase another one)its the 260...When you get it make sure you have version 1.01 or use the updater and load the new program before you do any of your own programing.

rec

wow major over load, but great info
I will have to do some more reading and make a decision
THis will strictly be for DJing and I am not a musician so no chance of band usage.
Thanks again for your help
Rich

rec

Gadget, can you help me understand what 2x4, 2x5, etc means?
what does each number refer to?

Dra

# of inputs x # of outputs
Inputs:
2 = stereo
1 = mono

Outputs:
2 = full range stereo
3 = stereo hi's + mono low's
4 = stereo hi's + stereo low's
5 = stereo hi's + stereo mid's + mono low's
6 = stereo hi's + stereo mid's + stero low's

DRA

rec

ahhhh! as the light bulb goes off above my head
thanks

rec

Gadget/Dra
I could use some amp advice, hopefully you dont mind me asking on this forum.

I currently own a QSC 1850HD that I was going to run in bridged mode to run my subs (either 2 at a time or 4 for the bigger venues)
My tops will be the BFM OT12's mentioned above with the tweeter arrays

I need to buy a second amp and have been thinking about the QSC PLX 1804 for my tops

What do you think about this amp choice
Am I making a mistake running bridged mode on my subs?
Thanks
Rich

Gadget

Hi,
Well that's a good amp, but how about considering a Crown xti instead. I know for about $750 you can get the Xti 4000 from Northern Sound and Light and have more power and features...for about the same price.

It's fine to run bridged with 2 but you'll need to run stereo with 4 as long as the impedance of the individual cabinets is 8 ohms each...if the are 4 ohms you will have to run stereo for 2 ohm loads...

G

rec

I think I am going to try and stick with a budget amp for now
I am leaning towards the QSC GX5

I have a question though: Can any of the features that a lot of amps have built in hinder the operation/performance of the the DRPA.

I am speaking of the cross overs, limiters, etc...

Gadget

Since they are digital features they wouldn't seem to affect each other.. I wouldn't suggest stacking comps or limiters though plus those features a re better on the Driverack anyway...
G

rec

That makes sense now that I think about it

thanks

rec

Here is my plan

2 Channel DJ mixer to DRPA

DRPA MID Outputs QSC 1850HD to 4 BFM OT12's Full Range Cabs (2 on each channel)

DRPA LOW Outputs to QSC GX5 to 4 BFM T30 subs (2 on each channel)
Running GX5 in parallel mode

Looks like this would be 2x3 mode
Is this a reasonable way to set things up?
Thanks

rec

I need to make a corection
The OT12's will only be play mids and highs......not full range
sorry

Gadget

Yes thats reasonable.. but what are you proposing as the HPF/LPF and points and slopes...What speakers are those? Please provide a link will you?

Gadget

rec

They are custom built speakers, see the following site

http://www.billfitzmaurice.com/

Omnitop 12
Tuba 30 subs

I think the recomended LP filter is around 100htz
I need to find out what is recommeded for HP

I am ignorant to what slope is (still learning)

Dra

Slope is exactly what it sounds like. The slope of a hill. The slope of a car ramp. The slope of a x-over / filter. The big the number the steeper the slope.
How fast you fall off a mountain is determined by the slope.
How fast frequencies fall off is determined by the slope.

The \"knee\" is the \"bend radius\" at the starting point of the slope, and is the area where the filter \"get's up to speed\".

The slope number indicates the db's per octive that are reduced. a 6db slope started at 100hz will yield:
-0db @ 100 (technically -3db because of the knee, but for this explanation forget that)
-6db @ 50hz (an octive is from any hz to double that hz, 500 - 1000, 3000 - 6000, 40 - 80, etc)
-12db @ 25hz
-18db @ 12.5hz
etc

The letters: LR, BW, etc are the knee types and are sometimes defined as \"orders\" and decribed the number of \"layers\" the filter has to change the \"transition\" speed of the knee.

DRA

Gadget

Yup, well said Dra... but I would move the xover to 120 hz though since you don't have enough power for the tops, and the 12\" will sound better on mids that way...

Set up an all custom 2x3 (or 2x4) in the wizard ...I'd go 35hz BW 18 HPF (minimum) with a LPF of around 120 hz LR24 Set a HPF of 120 hz on the tops...
G

rec

Dra
explained nicely, thanks

Gadget
You dont think the qsc 1850HD is enough to run two tops per side at 4ohms??
Thanks for the recommended setting by the way
Rich

Gadget

Nope...
It will have to do but consider this@ 600 watts @4 ohms(EIA) stereo that's only 300 watts per speaker...that leaves no headroom...the rule of thumb is 2-3 times the RMS rating of the drivers.. (Crown says up to 4X) Plus the lower you cross the speakers the less clarity in the lower midrange region...
G

Dra

I will say that the 2x / 3x / 4x rating Gadget is giving is good for R&R and, in general, for top cabs for DJ (rap) work. But for subs, I learned the hard way that 2x is about the limit when deal with rap and it's tendency to play 30 - 40 hz content at high levels compared to the rest of the song's content. Add the fact that many songs, while they have \"beats\", they are more increases of pulse as opposed to rests between beats. No time for the speaker rest and cool itself. I over heated (blistered) a pair of 400w coils with an 800w amp with limiters ON in just a couple of minutes. That stunk, literally.

DRA

Gadget

I think...and your NOT going to like this..but... you cooked them WITH the limiter...The average power went up as the limiter kept squashing the peaks and the power supply went into over load, and you \"averaged\" them to death...Had you left the limiter off you would have had more power, and you would have had a clear indication when the limit was reached... you also sacrificed a bunch of power when engaging the limiter...As I have said, the QSC RMX 2450 drops to about 1600-1800 ( I think the figure was 1680 but it was a while ago...so) watts with the limiter engaged, and the balistics of the limiter circuit are less than adequate...IMHO...

G

Dra

I can't be certain, but I don't think the limiter was engaging. I wish I knew for sure. I never heard the popping sound I had been experiencing at higher volumes and in those situations the limiter was engaging only occasioanlly. But again, not certain. That's the depressing thing.

DRA

Gadget

I do not/would not use the limiter...on the amp...use the one on the 260.. thats way better...

Dra

That's what I meant. The limiter on the 260.