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.

[Ricci]

What you want to do is maximize your amplifier power, your linear driver displacement and cone area within your budget of 450 pounds for maximum bang for your buck. You have a large space to fill and if you can live with large enclosures this is the way to go. It's hard to recommend anything particular since we don't know what is available there and what it costs. Just shipping one decent driver from here could eat up most of your budget. It's probably better to find something there.

Do you have RE Audio (SE15, SX18), Alpine (Type R 15), Peerless, ?????? See if you can get a pair of cost effective but decent 18's or 15's to fit in your budget.

[ironglen]

What about an amp coupled with a (likely used) horn enclosure as rock bands use? Not diy, but I've seen some of those around and as others stated, perhaps best suited for your ht site considering the spl needed along with price point (plus it would be durable).

[Parts]

Hi

I can get the RE Audio SE15 D4 Subwoofer here for around £200. But it does not look that sensitive?

I could also order the Dayton DVC385-88 15" DVC at $150 dollars not including UK delivery and import, and probably use that in a ported enclosure until I get round to building a Tuba HT 36?

I was also looking at plate amps, and Rythmic Audio models look better than the ones available in the UK from BK Electronics and Wilmslow Audio?

I could also get a Wembley B.Line 18-600 in 4 ohms for £200 plus vat?

From what I can see the Fitzmaurice design looks the most capable? The Dayton driver and Rythmic sub amp panel look tempting as does the full Rythmic kit?

I will investigate what other drivers and plate amps are available in the UK

[Parts]

A couple of other units have gained my interest, not sure what would be best, the biggest issue is the room size and creating a passive sub with a high sensitivity to keep up with the VC's 103db sensitivity while giving a decent output around 20hz. Not sure how to work out what enclosure would be best.

Adire Tempest 15" (5 litre displacement) (this may also be able to be used in the Fitzmaurice THT later?)

* Nom: 2 x 8 Ohm
* Power: 750 W
* Fs: 18.8 Hz
* Qms: 6.7
* Qes: 0.4
* Qts: 0.39
* Vas: 317L
* Sd: 779 cm^2
* Xmax: 16.4mm
* Re: 3.5 Ohms
* Le: 2.9 mH
* BL: 14.2
* Mms: 195 grams
* SPL: 89.1 dB @ 1W, 1m

And from Wembleyloudspeaker.com

B-line 600 18" bass driver,

Usable Frequency: 20-hz-2khz
Power Handling(cont. RMS): 600watts
Power Handling(Peak Average): 800watts
Nominal Impedances offered: 4/8/16 ohms
D.C. resistances: 2.8/5.2/11 ohms
Sensitivity (AV 1watt/1m): 100db
Sensitivity(Peak Usable): 106db
Qts: 0.24
Q. Max: 19mm
Vd.: 814cc
Vas.: 0.53m x 3
Magnet Assemblies: 9.7kg(21.4lb)
Voice coil material: Copper HML
Voice coil former: Aluminium
Voice coil sizes: 77mm x 25mm
3" x 1"
4 layer
Chassis: Cast aluminium
Net weight: 13kg(35lb)
Shipping weight: 16kg(35lb)
M.M.D.: 140grms
B.L. Factor: 21 tesla

With this plate amp from BK electronics,

http://www.bkelec.com/Modules/bsbpv500.htm

[Ricci]

Can you get B&C, or Peavey there? How much is a Peavey LoRider 18"? You should probably skip a plate amp and get a Pro amp. How much does a Behringer EP2500 cost there? How much is an RE Audio SX18D2 (probably too much)?

Sensitivity really does not matter all that much in the low bass range IMO.

[Parts]

Hello,

I have not found any Peavy drivers here in the UK, and eBay UK is probably the easiest place for drivers apart from the previous tempest 15" and B Line 18" mentioned.

I can get an RE Audio SX18d2 for around £300

I can get an EP2500 for £250, but would still need some sort of filter/crossover and adjustment to equal the user friendlyness of a sub plate amp?

If I was to go for the BK plate amp mentioned, what size of ported box would serve me best with the Adire Tempest 15" and what ported box for the B-Line 600?

edit, I can also get this for around £250 http://www.proaudioparts.co.uk/V18-1200.jpg

[Ricci]

Can you obtain the Adire Tempest 15"s and for how much? Those have not been made in many years. What is your main source unit? If it is a pre-amp or reciever it will usually have a low pass x over built in these days.

I recommend a pro amp over a plate amp even if it's a smaller one like the EP1500, but yes you will have to get a subsonic filter unless the 30hz one built into the amp ends up working for you (doubtful).

Can you get any decent Eminence or other pro 18's for around 125 or 150 each? I think you will be better off getting a pair of cheaper drivers than one expensive one.

[Parts]

Hello again,

The store only has two Adire 15" DVC's left at £155 not including delivery. Today I have been contemplating two Emminence Sigma Pro or similar 18" 8ohm units running together as 4ohm with the BK plate amp. I was wondering how big a box I could get away with either sealed or ported?

Building a single box with a single 4ohm 15" or 18" driver and the BK amp could always be supplimented with an aditional identical build later if funds permit. So probably the best option.

I am not sure of the AV amps sub capabilities, and was thinking the BK sub amp had a lot more options for simple set ups levels phase etc. I can also use this later in another project for domestic use if needed.

To be honest I am getting more and more tempted with the BK amp, seems simple for plug and play IF I can find a reasonable 4ohm bass driver and simple box to build. (I can always get more complicated later if the Bang for Buck project works?)

[Ricci]

Can you link to the BK amp? How much is it?

A pair of Eminence Sigma Pro's sound like a solid and efficient plan. If you can afford a pair.

[Parts]

Hi again,

This is the BK module, which seems quite versatile and useable in a few more situations (such as in a stereo system).

http://www.bkelec.com/Modules/bsbpv500.htm

As this is 500w into 4ohm a 4ohm driver/load would be preffered.

I can get Eminence/Fane/Precission Devices/Wembley/B&C/Beyma/Void/P Audio Pro type bass drivers here in the UK.

Wembley loudspeakers can do this 18" B-Line 600 with a foam suround for me for £200 + VAT + delivery, but they recommend a 750w amp. http://www.wembleyloudspeaker.com/pa...line-600.shtml

These guys have a reasonable looking selection of car audio drivers http://www.audioassault.co.uk/Subs/15%22_Subwoofers

I am still looking for other dealers in the uk.

The bass management of the Yamaha amp is a little crude, but works, I ran it out to an integrated amp, connected to a work colegues 12" Fusion sub in a carpered box and managed to get some low end fill.

The Yamaha has two RCA outputs for paired subwoofers, so I could run a stereo (or bridged) power amp with gain controls directly.

I guess I am back at square one, what drivers are suitable and with what sealed box and ported box sizes?

Sealed box is another area I would like to know a bit more about? I notice the Eminece Kilomax can be used in a sealed box without the need for a rumble filter, what designs would NOT require a rumble filter?

I did notice a lot of excesive cone movement with the 12" Fusion car sub in its ported box?

Cheers
Steve

[Ricci]

The BK amp does look nice if a bit expensive.

You should probably go with a ported box. You have a large space, a limited budget, sensitive large mains, and a limited amount of power (500w). Sealed subs can be great but they are not efficient, sometimes require EQ and require very large amounts of power and driver excursion to do the low bass right. A ported cab will give you higher efficiency and make better use out of xmax limited drivers and moderate power with the tradeoff of a much bigger enclosure and the need for HPF's.

I noticed a pair of Eminence Kilomax 18's for 350 shipped on UK Ebay. Is this out of your range? There were also some Infinity Reference 12" drivers for about 55 ea and some JBL GT5-12's for about the same. You could get 4 of either of those and wire all of them to 4ohms. A pair of the RE SE15's or the Tempest 15's would be good as well. After you pick some drivers we can help you with the enclosure for them.

[Parts]

I am going to leave the amp for now, I am now considering a Behringer EP4000 after I build the bass cabs with whatever drivers I end up with, seems popular. And I am now under the impression it will give me more driver choices and such.

I think the AV sub out into a power amp driving a 12" Fusion car sub was promising it seemed to go well, well at least indicate such an implementation may work. I could at least build one or two cabs, use an old amp, and upgrade the amp, then later when I am more experienced evaluate my sub requirement better?

I have found JBL GT4 15" drivers at reasonable cost, two for the same price of a single Eminence Sigma Pro 18"! (though stock is not varified)

Considering this was intended to be "bang for buck" I am wondering how well this driver would do for the basis of my first project? Considering the price I could do a single cab, or get two drivers and build two subs, or build a twin, or four?

Would two wired in parallel in the same cab be preferable to two seperate cabs? Does this increase sensitivity? As they are 4ohm I guess two twin 15 cabs running from the left and right outputs of an EP4000 would be optimum? And that four 15"'s in the same cab would be a waste?

The Yamaha has parallel (IE two) sub outs, one of our other amps (Pioneer) has the ability to run a front and rear sub.

I wonder if a big sealed box would work? Would I need a rumble filter or have to worry about cone excursion with a sealed? JBL seem to recommend sealed as the best option?

[Mike P.]

Two ported JBL GT4 15's would definitely out perform a Sigma Pro 18". Wired in series they would take 300 watts and need a rumble filter at 22 hz. Sealed would still require a rumble filter. If bass is what you want, ported is the way to go.

[SteveCallas]

How far will the seating be from the subwoofer and where in the room is this movie setup located? I hate to keep sounding like a party pooper, but in a typical home theater we have room gain, boundary gain, and tend not to sit more than 12' from a subwoofer. You won't have any room gain in the range this subwoofer will cover, you may not have any boundary gain depending on where your setup is located in the room, and the further away your seat is from the sub, the more lossy the output. Typical sized home theaters make up for that distance loss with room reflections, but your room is too big for that.

If you go with dual ported subs, can you place them right at the sides, or right behind your seating area?

[brandonnash]

I second the near placement option steve is talking about. I have a hard to drive room and have found that placing my sub behind my sofa keeps good dynamics and extension. The tactile experience doesn't hurt either.

Other than difficulty in the build, why not just go for one of the tuba subwoofers? The drivers they use are not that expensive and the 36 or 48 looks like it would do that room nicely and not cost that much.
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