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-   -   Quick question on multiple subs & low freq. extension (http://www.diyaudio.com/forums/pa-systems/207143-quick-question-multiple-subs-low-freq-extension.html)

Deefa 20th February 2012 07:41 AM

Quick question on multiple subs & low freq. extension
 
Hi all, first post here.

History:
My old system:
http://i222.photobucket.com/albums/d...ungeSystem.jpg
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 20th February 2012 08:03 AM

Hi Deefa and welcome to diyAudio :)

Tony.

Keriwena 20th February 2012 12:06 PM

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 20th February 2012 01:15 PM

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 20th February 2012 09:42 PM

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 22nd February 2012 01:06 PM

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.

2lok 14th June 2012 09:47 AM

One of your biggest restricting factors, will be the behringer amps, they are OK, but most certainly no the most accurate or capable. In order to get those true lower,ul need to look at investing in amp that response ability is better on the lower end of the spectrum.

Another point, is your processing, perhaps you current units just don't have a ability to reproduce the lower sound, normally because of an inferior pre amp. GET YOUR SOURCE RIGHT 1stly! Process it Correctly, your restrictions already start at the DJ mixer,Eq, Crossover/Speaker Management. and if they bad there, they will be worse after going through an EP's preamps.

That being said,behriger is decent and can give you good sounding sound.

So if you double up on bins, u will get perhaps a +1,5dB volume increase ( if even,AS real as it get) but you will get better excursion and higher spl at lower volumes, and naturally becasue the driver will reproduce the lower frequencies better at lower volumes(because it working less), you might get what your looking for.

In accord with the type of music u described your looking for a <63hz exageration to get that real balls punchy low end? if thats what you want?

Buying the 2 bins will help to achieve that better,but then u also gota get a another EP2500 for sure.

I would recomend you strive towards ( if you want 2 more binbs)
3 x EP2500 ( Or eqiuvlent ) (2 in Bridged (mono) (lp Cut - Off) 1 in stereo (Hp Filter on))
Behringer does have some straight forward configuration on the back which is nice,but sometimes people forget about that, which can cause an issue.
1 x Deq2496 ( As u have it )
1 x Dcx2496 (as u have )
Mixer, dont know what you have but stick to the Pioneer & Allan and heath range,in terms of preamps they excellent, if you want to pro, go for sound-craft or Yamaha.

With that size pA run cleanly and correctly you will easily do 150-200 people in a decent sized room, perhaps 300sqm. Pole mount tops and lift for coverage and let the bins do the rest of the work!

If i ranted on here to much, dnt hate!

AndrewT 14th June 2012 10:48 AM

Add Sd with it's own amplifier, will give more air displacement @ bass frequencies.
Stacking Sd beside each other, will give more air displacement @ bass frequencies.

More air displacement @ bass frequencies = more bass SPL.

Back to the +3dB in post1.
Adding a speaker and powering it independently, thus a doubling of Sd and a doubling of Power input, will result in +6dB of bass SPL over a limited range of frequencies.
That will not necessarily result in an extension downwards of F-3dB or F-6dB or etc.


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