Combining Horn and Front Loaded Subs

eighty8

Hello,
I am working with Mark of BT Productions to help supply sound for a DJ show in Ohio. He is at work all day today so I thought I'd try and fill in the best I can to ask some questions that we had. We are planning on using his sound and setup: 2600, LA460, and horn loaded subs in addition to my QSC KW1801's because the promoter says that "there is not enough bass". Reading through previous posts I found a comment from Dennis that says front loaded subs and horned subs odviously do not work well together. Are there any software tweaks or DBX tweaks that we can run to match up the delays between the horn loaded subs and my QSC front loaded subs? We were planning to run all of his equipment through the 2600 and using my DBX PX to setup a matching delay to the QSCs as close as possible to his equipment just for this show. Also would additional subs cause noise or phase cancellation?

Dennis wrote:

I believe LA400s are designed to sit up right. Horn loaded subs do not play well with front loaded subs even if you had a means of setting proper delay times. EAW processor settings for LA400 suggest mid/highs should be delayed 5-6 ms....I personally think that is a bit much. A while back, I time aligned an EV Elmininator over Cerwin Vega L36 with proper measuring equipment and came up with a 3.5ms delay time for the EVs (standard ballpark guess for the L36 is a 5ms difference).

Thanks,
Eighty8

Dra

eighty8 wrote:

Hello,
We were planning to run all of his equipment through the 2600 and using my DBX PX to setup a matching delay to the QSCs as close as possible to his equipment just for this show. Also would additional subs cause noise or phase cancellation?


Thanks,
Eighty8

I'll assume you meant 260 (not 2600) and that you will run a full range signal from one output of the 260 (delayed) in to the PX? (since the PX has no delay)

DRA

eighty8

Dra wrote:

I'll assume you meant 260 (not 2600) and that you will run a full range signal from one output of the 260 (delayed) in to the PX? (since the PX has no delay)

DRA

DRA, I was not aware that PX did not have delay capabilities. I suppose I stand corrected. But yes that seems to be the scenario we are attempting as the PX does not have delay. And yes the 260 (I think I had an Atari 2600 on my mind for some reason when I posted this ).

Hopefully Mark can sign on soon and fill in the gaps.

Thanks
Eighty8

BTproductions

Well my partner just got a PA+ so that solves the PX issue. Ya the venue could use more than what 4 LA400's can put out or at least for our bass heavy needs with electronic music. The thought was possibly using his QSC subs in conjunction with the 400's which I know is a no no but with the thought of setting aside sound quality and going for shear output is there a way we can get a delay set somewhat properly and just make it work? I've grazed across reading stuff that talks about how to calculate or software that can help get these settings right. All speakers will be aligned with their leading edges together as to simplify further delay confusion.

That being said I just picked up 4 old EAW SB850's that I'll get to testing tomorrow. I got those and a QSC Powerlight 6.0 PFC for $1600. One of the cabinets is for sure not going to work as the subs somehow got spraypainted and the surround is cracked on the one. None of the drivers are EAW and there is no crossovers or anything inside the boxes besides wiring straight to the drivers from the 8 or 4 pin connectors. I'm guessing best case scenario I'll get two working cabinets out of these maybe 3 if I'm lucky. If those end up working then obviously we should be better off and adding more front loaded subs is no problem. If not then idk back to trying to combine and hopes for the best or having a lack of sound

Thanks -Mark

Dennis

Mark, do you own any version of SMAART?

Gadget

EAW specifies 5-6 ms delay when vertically or horizontally deployed with tops...that would apply to other front loaded subs as well...note that it would be the OTHER speakers that would be delayed to allow the sound to get out of the La400'S That equates to a 4.43' to 5.31 foot horn path...

You could let the LA400's handle the 30-55 hz and let the "lesser" low end speakers handle the 50-100hz area...

My Labsubs have a 10+ ms path length...and with propagation delay and all I use almost 15ms for them...

BTW the surround on the 18's in the 850s... if the speakers still move without rattling... can be patched temporarily with nylon and surround cement...I have had speakers last for some time with this method...so you want to run the 4 SB 850's on one QSC 6.0? 2 ohm load? You better have a BIG FAT line right up to a stout 240 volt power outlet...those will draw a whopping 30 amps or so @ 120 volts...or more!

G

BTproductions

I have no version of Smaart or anyother like software. I guess we'll just go with the 5-6ms as per EAW specs and adjust by ear if there's even anything noticeable??? I spent the past two days getting these old subs into the best possible working order. On pair had fiberglass insulation in it that I replaced with some blanket polyfill. I ended up with two fully functional subs with the correct drivers. There were the other pair that had "Oversound" drivers in them??? They have less travel and idk they possibly could have been used as mids cabinets??? Well I got one sub with working drivers out of those so that's three total. The amp won't be working so hard now but the venue does have 2 30A outlets for the stage. I assume it's 120v cause it's regular plugs and I've plugged regular 120v equiptment into it before. The 6.0 will get a 15ft 12ga extension cord. I'm not sure which will be louder the 18's or my 400's? I've turned the 18's up some and wasn't real blown away tho I didn't really push them in my neighborhood garage. I'm just gonna take it all and we're gonna do our best. It's a sloppy ordeal which is not how I like to work but in this case it's our only choice.

Thanks -Mark

Gadget

There is a poor mans way to rough in the delay...you will need a CD that has individual frequencies.. like the one available in the FAQ section.

http://binkster.net/extras.shtml

You will need to play the frequency closest to the actual crossover frequency... say 100 hz. this will be played through the tops AND the LA400's. reverse the polarity of one of the speakers, tops or subs which ever is easier. (+ to + and - to - on one and the opposite on the other)

Play the tone @ medium to higher volume and sweep the delay on the driverack till you get the MOST null at that frequency (the sound gets the quietest.. it may not be an earthshaking difference but listen for the null) you have just found the point of most cancellation.. IE 2 frequencies arriving 180 degrees out of phase and cancelling each other out. (remember to correct the polarity reversal afterwards)

I'm curious... why not rent something for this one off rather then buy something you may not use afterwards? Seems to me that you could have found some more LA400's to rent, or buy.. and you would have then had a system that plays well together... :?

Those would seem to be Brazilian drivers...and it's not usually a good idea to just throw any speaker into a box... the box needs to be designed around the speaker...or you will get poor performance and overexcrusion is a real possibility...

Gadget

BTproductions

Thanks Gadget thats a neat little trick. I'll be doing sound for this venue once a month so the investment in more subs especially at the steal I got everything for was not only the quickest way but also solves this for us down the road. Had I not come across those by chance right when I did then we wouldn't have had enough even with Dave's 2 18's. Those oversound drivers were the previous owners concoction and they suprisingly sound pretty much the same as the RCF drivers. I got two RCF drivers that need re-coned then I'll buy another pair and they will all match more less cause even the RCF's part numbers vary. There supposed to be LS18200N I think and some end with a k and one's an 800 instead of a 200 ect... Call it my project to get them matched best as possible and gonna replace the 8 and 4 pin connectors on the the back with speakons and get rid of the ridiculously long 100' 8 conductor wires I have to use for them right now.

-Mark