Quick question on multiple subs & low freq. extension

[Deefa]

Hi all, first post here.

History:
My old system:

80's vintage bass 15" reflex/horn loaded (kind of) bass bins, Yamaha S4115 Mid/Highs, big HF horns. (all 15" Fane, Yamaha & unknown drivers rebuilt, new diaphrams in Yamaha compression drivers) Also my DIY 2x15" reflex/horn sub in top middle.
Driven by DJ mixer -> behringger DEQ/DCX -> EP2500 (subs) & Perreaux 6200B (Mid/Highs) & 60W/ch Hifi amp for HF horns.

Sounds great for the investment (rebuilt drivers, EP2500, DEQ/DCX).
Used infrequently outdoors playing progressive house/techno/psyrance for up to 100 people.

System is physically too big now, and I have just picked up Wharfedale pro 2 x LX153 Mid/Highs and 2 x LX15B subs 2nd hand very cheap (basic info here: http://www.wharfedalepro.com/Portals...X_Brochure.pdf

The new subs are 'little', but put out decent sound compared to the old system. I found someone just around the corner who is selling the exact same subs for also pretty cheap.

Question:
Will I get any low frequency extension from having 4 of the subs, or just a 3dB volume increase? I'm hoping having a couple will give me another note or two lower,along with the volume boost - a single LX-15B is rated -3dB at 42Hz

I realise I will likely need another EP2500 or equivalent, as I will need to bridge the EP2500 and drive one side with it for proper power levels (subs will total 1400W RMS Handling @ 4 Ohm per 2 each side).

Feel free if you need to let out some hate on the Wharfedale pro brand, but it's an upgrade anyway you look at it from the 80's gear.

Thanks in advance, and this site/forum is a great resource!

[wintermute]

Hi Deefa and welcome to diyAudio

Tony.

[Keriwena]

In a perfect world (ie, you get a gig in an anechoic chamber), you'll just get the +3dB. In the real world, where cancellations occur, you might actually get a bit lower with more drivers. Or not.

For sure though, you'll have twice the excursion so you should be able to EQ a bit more bass extension.

[Mike Caldwell]

In general it's not the best idea to mix different cabinet designs together that are reproducing the same frequency range. The destructive interference from time alignment and phase issues off set the added gain of more speakers. The 15 inch horn loaded cabinets look like the classic JBL 4560 or a copy there of, not really a bass cabinet they were only tuned to around 60hz, using them in multiples the coupling would help get a little lower. In the day they were intended to be low mid/mid range box with a sub cabinet used under them.

Mu advice would be to stop buying every "good deal" you find any pair of speakers to just add them to what you have but to focus on upgrading your system with matching components/cabinets for the sub and mid/high cabinets.

I would resist the urge to add the Warfedale cabinet to what you have now........ If you do I would only use the top cabinets with your three 15 inch horns.

[Deefa]

Thanks for the replies so far.
Sorry I wasn't very clear in my post - the new cabinets are purposed to replace (or at least be a different system) to the existing random pile of speakers. (Which is quite a stack of cabinets to store, and transport - trailer required)
The Wharfedale Pro system is matched (as you would hope from the same manufacturers range) so buying the extra two sub bins will give me the option of supplying more or less sub volume depending on the gig, and I can fit the lot and my DIY rack box in our panel van).
Thank's for the ID on the JBL 4560 copies (one is plywood and great condition, the others particleboard and showing their age)
Deefa.

[Deefa]

I am now concerned about how I am moving from a longer-throw to a short-throw system.
I have not yet been able to take the wharfedale gear out into an unoccupied half space area to see what sort of usuable coverage I will get from the mid/high LX153 & LX15B combo, at full volume.
The testing I did in the backyard put the speaker cabinets about 2M in front of a brick wall, which may have influenced my perception of the sub output, listening at about 7 meters.

I had better try and get a proper listen with the new gear before deciding to buy another set of the subs.