Home Theater Subwoofer

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I used to have grand plans for a Adire Audio Shiva, but I'm starting to get the perception that it wasnt really intended for home theater. Although I do like the price tag.

Anyone able to recommend some top of the line woofers? Size is no object, really. Oddly enough, bigger is better to many extents. Needs to cover 20 hz decently, provide at least a minimum amount of kick. Something to that serves to the weaknesses of two 21W8555-01's 0.5 Q box.

Oh, and what are acoustic's golden ratios again (just need the #'s)? Applies for both sealed and ported?

I was doing some further research, and I discovered this: Adire Adui's new 18 inch subwoofer driver <a href="http://adireaudio.com/cd/maelstrom.htm">the Maelstrom</a>. Heavy duty.

Anyone with actual expertise care to make heads or tails of it? Looks like its geared towards more profesional solutions than the Shiva. Size optimizations, thankfully, went out the window. I'm starting to considering it a worthy investment, possibly the driver I'm looking for.

Any commentary? Competitors I should checkout?
A vented shiva is my HT sub. It is one of the deepest subs I've ever heard. High xmax lets you reproduce that LFE channel without as much bottoming-out as sometimes happens with other products. The ACI SV12, Dayton Titanic and NHT 1259 are other popular choices, but I've found they all sound great, so go for the one you prefer.

Be careful with the Maelstrom. Large subwoofertstend to produce more "loose" bass, and to get decent extension into 20-30Hz range you're going to need a huge enclosure. Typically you will have better results with multiple 12" drivers than a single larger driver.

I know some members here would never buy a foam surround loudspeaker, but I have had no problems with the Shiva. It is more cheaply constructed than others, so it might not last forever. But as you said, the price is right. As a student I don't have a lot of spare money, most of my income goes directly into tuition. So the shiva was a great choice.

If you're stuck on a sealed enclosure you might want to try one of the other drivers, they tend to have slightly deeper bass. The NHT 1259 and Dayton Titanic 1200 are optimized for sealed enclosures.

The SV12 is also a good choice. A very large vented enclosure with the SV12 (extended bass shelf) yields almost no dropoff until 25Hz, reaching F3 at 17.5Hz. However, it would have to be very large.

Shivas offer better response in smaller vented enclosures than the SV12. They also have also dual voice coils, which gives you some more options in amplification than other drivers.

Essentially it's up to you. Any of those in a properly designed and constructed enclosure would produce quite impressive sound for home theatre purposes.
Ignite perhaps refers to me when he mentions folks having reservations about foam surrounds. In my experience the foam lasts at least 5 years at a minimum, averages about 10 years or so; I can't recall ever seeing a foam surround last more than about 12-15 years.
Most people don't look that far ahead, but I've found that I tend to keep things for a long time (I still have speakers I bought in the '70s, for instance--including some that have had to have woofers replaced due to...you guessed it...rotted foam surrounds). It's up to you.
He is also correct in listing other drivers in the same class, all of which will give similar performance. I'm sure you'll be happy, sound quality-wise, with any of them. I know Bryan is pretty smug about the sound of his new sub--which houses a Shiva. Note that I don't doubt the sound quality of a driver with a foam surround, only its long term reliability.
Another of my periodic philosophic ramblings...
Where, oh where did this silly notion ever get started that there is a division between home theater subs and subs intended for listening to music? I assume that some crafty marketing type realized that they could sell twice as many subs if they managed to convince people that they needed a separate one for each use. Unfortunately, once an idea like that becomes common, it's hard to eradicate it.
If you think about it, you'll see that the requirements are identical. High spl (assuming that the source material demands it). Accuracy. Flat response. Depth. And to a lesser extent, efficiency. Nowhere in that list is there a conflict between HT and music. A sub that does well in one category will do well in the other.
Design and build the best subwoofer that you can afford, then live with it happily for all uses.

Foam surrounds: they may wear out, but you can always replace them. So far, I've replaced surrounds on three pairs of speakers. Something I dont mind doing every 10 years.

I agree with the oversize issue. I'm considering going for daul SV12's or dual Shiva's in a mechanically-parallel ported system, optimized for a nice sinfully low cutoff frequency, depending on how hard it is to implement dual drivers. Anyone know of good sites for information on dual drivers?

From the raw cuteness point, not really knowing what acoustically it does, I'm thinking of doing what <a href="http://www.libinst.com/LspCAD.htm">lspCAD</a> calls a Bandpass Box Type 4, with two subwoofers on independent side chambers firing into a center chamber, with all three chambers being ported.

I'm a little pissed that I'm going to end up with 8 ohms resistance. The <a href="http://apexjr.com/Apexsenior.htm">amp</a> I was planning on buying for it only runs 250 watts RMS at 8 ohms. Fooey. Would that make it worth abandoning the dual driver plan?

Oh, and does the shape of the port matter? I've seen a couple "mailbox" / "mailslot" designs cropping up utilizing a slot across the top of the box.

[Edited by Myren on 10-31-2001 at 05:24 AM]

The current best bang for the $$$ in high excursion drivers is the BP1503. This an extremely good driver and the price is right. It won't plumb the lowest depths like multiple Tempest's or PE DVC 15"s. But it will reproduce clean and astounding high output down to 18Hz when used in a proper box.

Next in line $$, is either the Tempest or PE DVC 15". Although not identical these have very similar performance characteristics.

Current foam surround technology has a life span of roughly 15 years according to the driver mfgrs, and it's more linear than rubber = less distortion.

All of the drivers listed above use a carbon fiber layer epoxied to a formed paper cone (=very stiff). As a result there are almost no issues with the cone becoming nonlinear/less pistonic when driven hard.

IMO bandpass designs don't provide flat response or good sound quality. Go with either a sealed or ported design

Regarding the large drivers = loose/ slow bass that's bunk. If the T/S parameters of a 12" and 15" driver are the same, the drivers are just as fast/tight. This is true for 18" units as well.

Round ports are much easier to tune/adjust and they can be used with flares. Flares drastically increase the air flow from ports = decrease potential of chuffing/port compression. As a result 3" flared port moves as much air as a 4" straight port. This situation is the same for larger flared port sizes to.

Finally a single 15" will displace almost as much volume as 2-12"s, and the cost is much less.

The old saying 'there's no replacement for displacement' still hold true.
Just thought I'd comment on the Shiva. I made a ported sonosub using a single driver, which is linear to below 20 hz, and is about 6db down at 16hz. I partnered it with the AVA-250 sub amp from Adire, and I've yet to surpass the half way mark for the output because the amount of bass can easily overpower all other channels without even being up 1/3 of the way. I also use it for music, where it integrates seamlessly with my mains. If you want abnormally high SPL's, then make sure the rest of your equipment, including (especially!) your listening room is up to the task.

Yes, the Shiva does have a foam surround, which will rot out eventually, but not for many years to come, and by then, I'm sure I'll just go ahead and build a new sub with a new driver, because odds are driver technology will have changed quite a bit within the next decade. So unless you want to build the last sub you're ever going to build, the Shiva is an excellent driver regardless of its foam surround. As for me, its safe to say there will be many more subs and loudspeakers to come, so I'm not too concerned as to whether or not my whopping $450 in parts will hold up for 10 years. It's as good as it gets for me right now, and was well worth the investment.

And I definitely agree with Grey. There shouldn't be anything that defines a sub as one for home theater or music. If its what it should be for music (well rounded), then it should perform equally as well for HT. If it doesn't, then it's not a good sub.
Perhaps size doesn't change the tightness of bass. But the Maelstrom does have quite different T/S parameters. It begins to drop off in response very quickly, and frankly needs a HUGE enclosure. I was playing around earlier with using an ACI SV10 for a small sub for a small system I have. Instead I've decided to use my current shiva for it and build a sealed 4.5cu ft Tempest. With a bit of equalization I can give it flat in-room response well below 20Hz. I was a little dissapointed with the "tightness" of the vented shiva. It had rather high group delay nearing 20Hz, so that's to be expected. I hope this sub will be really tight.
Given the massive enclosure, is the Maelstrom a worthwhile driver? Again, I'm actually almost hoping for a large subwoofer, something to match my computer's supercooler. Need to fill in that under the bed space (elevated bed).

Is there any simple day to do dual drivers? What do I need to adjust for the parameters for dual drivers? Any good websites with info on dual drivers?


When the need/want is for extreme SPL's, then BIG high excursion drivers are the way to go. And yes 18" drivers need BIG enclosures. You might also look at the BPD1803. Slightly more $$ than the Maelstrom but it is currently shipping. And it's capable of quite a bit more output given the 45mm P-P Xmax

However something to consider are drivers like the Stryke HE-15-$425, or BluePrint BPD 1503-$229. Both of these have a much greater Vd than the Maelstrom. And either of these is capable of literally house shaking output, when driven by the proper amplifier in relatively modest sized box. Now I'm sure there are those that will say that the bass from those drivers won't 'tight' be given T/S parameters. But having used both of these, I can say that in a correctly designed enclosure, the bass is some of the finest available regardless of cost.
I certainly agree with thomas

The BPD1503 has the best bang for your buck.

However this driver has a 'treated foam surround'. Will the surround rot just as much has untreated foam reqardless if its treated/ will it just last longer than 'ordinary' foam surrounds/ or is it so good that it won't rot at all if handled properly?
I've been trying to look up information on the BPD1503 for the longest time now. Google is - for the first time every - not giving me much success.

I would really like to investigate the BluePrint BPD 1503, but I'm keep turning up nothing on it. I swear, when I build my sub, if it has a BluePrint in it, this problem will be rectified. :) :D Anyone wanna help me on this quest by pointing to at least a spec sheet somewhere?

The Stryke HE-15 is alittle over my budget. $300 is the most I can afford to pay for a the driver unit.

I'm beginning more and more to consider dual shivas. It would make an almost perfect enclosure for me. Nothing fancy, just too complex, and as per ThomasW's suggestion. But for $100 a pop, I'm starting to doubt whether I can go wrong with dual shivas.

Course, the fact that dual shivas would have to be 8 ohms is kinda a pain in the butt. That may actually kill the dual shiva plan.

Also investigating SV 12, Tempest, and PE DVC 15". Once more, for the record, a big enclosure is 100% AOK. No problems with having a massive enclosure here.

I kinda abandoned the Maelstrom, upon so many people suggesting so many woofers that were better. I trust you people about three hundred times more than I trust myself. I thank all of you for your advice.

On the subject of power sources, could someone please offer a two line or more comment on <a href="http://apexjr.com/Apexsenior.htm">this amp</a>, the one I'm probably going to buy unless someone gives me a good reason not to. I'm afraid I dont know enough fo the small print of amplifiers to figure out if it has some huge gaping flaw their not telling me.

Briefly on the subject of flares, wouldnt it be possible to flare a mailbox style port? Just route away some of the edge, give it that same curved flare feel. Are there extra calculations involved with flaring? If its simple, please mention. I know you dont count the port against the internal volume, so the flare shouldnt affect internal volume. I'm assuming the flaring count in the port size? Anything else?

Whew... that was a bit longer than I had intended. Thanks again everyone, I dont know what I'd do without you.
The Apex amp or anyone elses version, Adire, PE, etc will be fine for a Shiva, Tempest, PE-DVC 12"-15" etc, design..

However it is not adequate for a high excursion driver like the BluePrint 1503 or HE-15. Those drivers when mounted in a box have low efficiency and need 500+ watts/VC to really light it up.

The best low buck amps for the new high excursion drivers are something like the Samson S-700, the QSC PLX3402 or another equally powerful pro amp. Since the BluePrint drivers are SVC, it's best to get an amp that can be strapped into mono, unless the plan is for using 2 drivers.

Regarding flares, so that you aren't driven insane by calculations just use a straight port for the box model. And understand that the port with flares will flow air more easily. The length for ports with flares, is the same as the length with out flares.

Regarding pricing, 2 Shivas's cost $230+ shipping, combined they will displace approx 3L. A single Tempest is $140+ shipping, and displaces 2.5L. See why the Tempest is a better buy? Now to further complicate this, the BluePrint 1503 costs $230+ shipping and displaces 6+L.

So how to decide? Well I'd say 12"'s aren't a smart buy, but 15"s certainly are. Now this my sound funny given my big IB sub, but Tempests and 15" BluePrints weren't available when it was constructed.

2 Tempests or 2 DVC 15"s are slightly more expensive than a 1503. They have a lower Fs and therefore can play a bit lower in a when placed in a large cabinet. And they are more efficient so a monster amp isn't necessary.

The 1503 has 20% more displacement than a pair of either of the 15"s mentioned above. So with large amp it will play louder and it can be put in a relatively small box. (I understand you have room for a big box, but remember these things occasionally need to be moved.

Just so you understand how much output can be obtained from a HE-15 or BPD-1503. I have a 2500 sq ft brick ranch style house, with a 1500sq ft basement. The AS-15 cabinet with either driver can literally shake the entire house so much that things fall off shelves......

One final item, the high excursion drivers must have parametric EQ, not 1/3 octave. There are good ones available for sub use only, that can be purchased for $100-$150
Wow... thanks a million Thomas, that last post really tied a lot of things together in a really nice way.

I'm starting to look at total costs more. I could probably go for a BluePrint 1503, but dual tempests would probably be over budget.

As for powering a blueprint, I really am liking the idea. Looks like a sure winner. The problem is powering it. I noted both the amp I listed and the Samsung S-700 ThomasW recommended were both 350 watts at 4 ohms. I'm hoping to get by with <a href="http://apexjr.com/Apexsenior.htm">the previously (and now) listed amp</a>, seeing as how its $200 and fits nicely within budget.

Dual tempests sounds great, but driving it would be a bitch and it'd actually cost a bit more than the blueprint. I'd like to stick with blueprint.

I'm trying to keep driver and amp around ~$450. $600 is really redlining it, but I could be convinced if there was a solution that was just that much better than everything else.

Glad to be of assistance.....

The plate amp will work but, understand that you won't be able to use the full potential of the BPD-1503 with the relatively limited power. 350 watts may sound like tons of power, but the high excursion drivers are inefficient.

Also I believe this is the same amp for less money


One drawback to both the Apex and PE amps is that they have a built-in fixed bass boast. This can be defeated if you have a little skill with a soldering iron. Here's a thread where the 'mod' is discussed.


You might consider looking around for used pro amps. Frequently these can be found relatively cheap. Make sure it can be strapped into mono

[Edited by ThomasW on 11-04-2001 at 11:56 PM]
Real pro touring gear is Crown, Crest, Ashley, etc. This stuff has a tank like build quality and the used gear is usually a very good buy.

Samson and QSC are sort of 'semi-pro amps'. Not super stout for full blown touring use, but more than up to the task for the average home user. The Samson units are supposed to have the quietest fans. Dan Wiggins of Adire likes the quality and power of the QSC amps. People I know using them complain about the cooling fan noise. Not a problem if the amp can be placed in a closet, or a different room

There are other 'semi-pro' units like Mackie, Carver, etc. Many of these brands have a checkered history of reliability issues. Carver in particular doesn't like driving low impedance loads. Mackie has had major QC problems. One road manager had a palate full of new Mackies delivered prior to a show, 52 units, and all were DOA

You'd need to check and see which specific amps can be bridged. Most of the mfgrs have this info on their websites.

[Edited by ThomasW on 11-05-2001 at 08:10 AM]
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