I would like to build a large AV subwoofer, but need some advice!

[Parts]

Hello all,

My first post, and I am UK based, so first a big hello to all.

So.... I would like to build a large subwoofer, this is to be used in a large poor acoustic/room around 80ft by 60ft with a suspended ceiling and some reflective surfaces, it is a large workshop within a large warehouse where my and a coleague have decided (and been allowed to) to put some kit together for movies. (Since having kids there were sacrifices for us both at our homes )

The speakers in this system are Cerwin Vega Mk1 V-152's with a sensitivity of 103db, and I feel they cut off around 40-50hz, we have tried a couple of small domestic AV subs and I feel such cannot match the main speakers. Amp is an ageing Yamaha A1 or such (huge with front flap)

This is on a budget, so I am thinking of a big driver and a subwoofer plate amp (or a bridged budget PA amp and passive crossover/filter), money is tight so good bang for buck, with the possibility of future upgrading may be beneficial.

I have been advised a Precision Devices PD-186 18" 97db sensitivity 4ohm 600w bass driver may be a good choice, and was thinking of adding a 500w (4ohm) subwoofer plate amp from Wilmslow Audio.

If the above driver and amp are good starting points, I guess the next step is what sort and size of enclosure? Any advice on these choices and my options?

I have plenty of cabinet materials, 1" chipboard, 18mm MDF, 2"+2" batton, screws and dampening, it will be fitted to castors and size is not really an issue in a large warehouse with double doors to the listening area. I guess a simple to construct large not too complex cabinet with cross bracing and no time spent on aesthetics may be in order.

What I would like is clean and even powerfull bass with decent LF extension around the 20Hz area, sensitive enough to provide a reasonable match to the 103db sensitivity Cerwin Vega's, and teh parts have to be easily to purchase within the UK.

I would also like to get this done before the end of the month as the current sub (a small Kef item) will probably die soon if my collegue has his way.

Any opinions or ideas on which direction a newbie should take?

On a side note, a couple of guys have offered me car audio sub woofers, one of them a 12" Fusion item in a large carpeted box with green trim, and some have said adding a plate amp to such may suffice?

Thanks,
Steve

[Mike P.]

Welcome to the Shack!
We can model the PD sub to see what kind of performance you can expect, However we need to know at what frequency the plate amp from Wilmslow Audio has a rumble filter. The models below are with 500 watts input nd assume a rumble filter at 18 hz. The PD2150 would be a much better choice considering the size of the room.

On a side note, a couple of guys have offered me car audio sub woofers, one of them a 12" Fusion item in a large carpeted box with green trim, and some have said adding a plate amp to such may suffice?

Not if the goal is 20 hz extension in a room that size.

[SteveCallas]

For that giant sized room, a bass horn that focuses on 25hz+ might be the best option. Member Ricci has some recent experience with a bass horn from a GTG in which more typical HT subs were also demo'ed. Perhaps he wil chime in - I think you'd be better served doing 25hz+ with authority in that large of a room than trying to dig deep.

[Parts]

Thanks for the quick replies all,

Edit, this is the WA panel amp spec,
This british-made, 500 watt active Sub Bass Module is our highest powered, delivering 500 watts RMS (1000 watts peak) and isideal for use with drive units that have a high power handling capacity. Airtight construction means it is simple to incorporate into your cabinet with no need for a sealed box.

This amplifier module is supplied with an IEC lead.

Features
Phase shift continuously variable 0-180?;
500w RMS into 4ohm
Airtight construction
High-level input with gain control
Low-level input with gain control
Variable upper roll between 40-240Hz
Filter bypass switch for use with sub out from processors
DC & short-circuit protection
4mm thick aluminium front panel

Specifications
Frequency response - 10Hz-240Hz
S/N ratio - 100dB
THD - 0.05% typical
Low-level sens - 150mV
High-level sens - 1.5V
Weight - 5Kg
Dimensions (HxWxD) - 254x254x95mm

I am open to suggestions on drivers, but again availability and cost inc post within the UK are factors, as I have an intended budget of £100 to £200 for the bass driver.

Eminence models are easy to get, as is the Fane Collosus 18XB and a Beyma model , but as I have no experience or knowledge at what large sensitive bass drivers are available for building subs I am guessing at what may be most suitable. Some examples of what I may be able to get around £200 and less are, (though they are all PA models)

Beyma 18G50 18" 8ohm
Fane Collosus xb18 600w
Eminence Omega Pro 18"
Eminence Kilomax 18"
Eminence Sigma Pro 18"
Precision Devices 184 18"
Precision Devices 186 18"

Cheers,
Steve

PS with this being my first atempt a simple box ported or sealed is probably more suitable than a horn I guess?

[Mike P.]

PS with this being my first atempt a simple box ported or sealed is probably more suitable than a horn I guess?

Between ported or sealed, ported would be the way to go. Horn building can get complicated. Just curious what the PD2150 would cost? Also it doesn't appear the amp has a rumble filter, I suggest you contact the seller and find out for sure. A rumble filter is a must for your application.

[Parts]

Hi BK Electronics also do amp panels subwoofer modules at a reasonable price, though again no rumble filter that I can see is mentioned, anyone know if these have or not?

The PD 2150 I have seen for arounf £460 in the UK, which is outside my budget unless I sell something LOL

[Mike P.]

Out of the list of subs you posted here are top 2 in terms of low end output. The PD sub needs a rumble filter at 20 hz and the Kilomax needs a rumble filter at 23 hz.

[Ricci]

How much do the drivers cost that you are considering over there? How much is the plate amp? What is your budget? I assume that since your space is so big that you are not concerned with how big the subs are? Horns can get difficult so ported is the way to go.

[Parts]

Hello Ricci,

I have to say that after reading a few forum threads here and elsewhere I am having doubts about my original plans.

I had planned to spend around £200 or less on a bass driver, and maybe £250 or less on a plate amp.

After reading about the Rythmik Audio and looking at that site, and looking at the Tuba Home Theater elsewhere I am starting to think there may be better options.

The Rythmic will cost a bit to ship and import, but it has made me wonder (their plate amps look better than the two UK offerings), as had looking at the Dayton Drivers at Parts Express (do they ship abroad to the UK?)

The problem is I am not sure what drivers are available in the UK, nor what to be looking at. I am thinking a basic box ported, but would like even response down quite low with a similar sensitivity or the capability to match well with my 103db senitive main speakers.

And yes space is not really too big an issue, though I will have to store it elsewhere in the warehouse when not in use. Horns are tempting (IE the THT), but initial build would be preferably a ported box utilizing 1" chipboard as I have a few sheets of that and 18mm mdf. A driver that could do well in a ported enclosure and horn me be worth considering?

Steve

[SteveCallas]

You're not going to match the sensitivity of your other speakers unless you use multiple subwoofers, build a bass horn, or use pro drivers and only focus on >30hz.