$1000 to spend on 12" or 15" Subwoofer

sounds like the dimensions of a earthquake supernova MKIV.

buy a earthquake magma 15 driver, and a slaps radiator, add bash500 plate amp, and put in a 19" cube box.

doesn't even come close to your $1000 budget, way cheaper.

is that kinda what you had in mind?

Even with shipping from the states (if you can't get earthquake local) would still be way under budget.


The other option I can think of would be a HSURESEARCH.COM 12" driver (1203) and put in the same size cabinet, with a pair of 4" diameter x 24" long ports (you'll need to put an elbow on the port tubes to get that length)
That design came from Dr. HSU himself. 25hz tuning with both ports open for music, and 16hz (If I remember right) with one port plugged for HT. It's either that, or build a DIY version of the 'turbocharger' that lengthens the ports to a 16hz tuning for HT use.

earthquake is louder, hsu sounds better.

The options I'd consider

Check out the infinite baffle woofers at www.aespeakers.com

And the servo sub kits at www.rythmikaudio.com

Those are the 2 best options, IMO.

Hi,
It hasn't been mentioned yet, but the new Exodus Audio Subwoofer drivers are new design, well engineered with the latest technological advances and constructed to a high standard.

The 12 inch Shiva-X is currently on sale ($135.00) which would give you a lot of options. A fairly big sealed enclosure will get you right down there. It's an extremely low distortion driver that really delivers. You could even have 4 of these in smaller enclosures distributed around your room for a problem free installation as far as room modes (eigenmodes) are concerned.

The 18 inch Malstrom-X ($352.00 each) also has XBL/2 motor technology (like the Shiva-X) for low distortion, will take enormous power and has an Xmax of 33mm (one way!). Recommended enclosures are on a PDF at the Exodus Audio site. I think that two Malstrom-X drivers in 4 cu. ft. sealed cabinets would be just about as serious as you can get in the Subwoofer dept. Depending on what enclosures cost to make, this might just make your budget.

Here's a link/URL:
http://www.diycable.com/main/default.php?cPath=24_93

Good Luck on your project!

Best Regards,
TerryO

In order to keep enclosure size down, I would actually consider using the larger driver in a smaller enclosure, and using eq to get the rest. For example, the 18" Maelstrom in a small 2-2.5 cubic foot enclosure with an LT circuit would do nicely. While I'm normally fairly against this design, in this particular case, the woofer has enough xmax and power handeling to deal with the demands of an LT, would help extend response down where you want it, and still give very decent output.

A larger sub from Rythmik is also a great option, but I'm still a fan of multiple subs in a room. I hate to keep spreading my view and beating a dead horse, but there really has been so much good research on this topic, and I just feel compelled to try and convince a few people to stop spending large amounts of money on a single subwoofer, when much better results could be achieved with 3, even 2 if you insist, smaller cheaper subs.

pjpoes said:

A larger sub from Rythmik is also a great option, but I'm still a fan of multiple subs in a room. I hate to keep spreading my view and beating a dead horse, but there really has been so much good research on this topic, and I just feel compelled to try and convince a few people to stop spending large amounts of money on a single subwoofer, when much better results could be achieved with 3, even 2 if you insist, smaller cheaper subs.

Click to expand...

Agreed. If I were designing a new subbass for a grand exclusive of amps, I'd get three Peerless XLS12's and three Peerless XLS12-PR's. Put each in a 35cm^3 enclosure or thereabouts, and stick one in the corner, one somewhere far away from that one, and the third as far away from the other two and on a pedestal or atop a bookshelf such that it's above the room's vertical centerline.

Of course, multiple subs with drivers like the above-mentioned Maelstrom-X is better still!

who says the maelstrom-x is better, why? Because it has an XBL^2 motor, more xmax, greater power handling, more linear BL curve? Ok I know, sure sounds like a better driver. However distortion is higher at lower levels. This would imply that, for the same price as that one driver, multiple lower xmax drivers of decent size (15-18") would actually give better performance, just at the expense of compactness. In all seriousness though, if you read through Dr. Geddes work on this subject, you will see that the quality of the driver is pretty much irrelevant. I mean, lets not take that to an extreme and go buying the cheapest crappiest drivers we can, but spending extra money on drivers with uber motors is a waste too. If your goal is the greatest amount of output with the lowest extension from the least drivers, then uber woofers are great. If your goal is the very best sound quality and bass smoothness, regardless of size, cost, etc, then those are not a good option. If you want to keep a relatively compact size, I would seriously consider the Mach 5 audio MJ 18" subwoofer, as its a pretty good value, all things considered. If you want the very most compact package you can do, those peerless woofers are great choices, and the Dayton Reference series are another similar high quality option. I have a Dayton 12" reference woofer, the HF type, and just took some measurements today so I can begin work on the bandpass box for it (It was in a sealed box, collecting dust since lightening hates my amplifiers). The Le was much lower than specified at .45 mh instead of 1.75mh, which impressed me. So much that I decided my WT3 must be wrong, went to my LCR bridge, same thing, went to my ATB PC Pro, same thing (roughly speaking that is), so sure enough, it has a very low Le which is always nice. The frequency response is amazingly smooth out to far higher than needed.

If you want the ultimate subwoofers (In my opinion), I would consider a B&C 18TBX100, BMS 18N850V2, McCauley 6174, and possibly the new BMS 18" driver with much greater xmax. Put these into any number of box types for some of the cleanest lowest distortion bass around. Again, you are better off building 3 small cheap subs than 1 big huge sub. I just saw a home theater install pic that showed four 18" sonotube subs all sitting right next to each other across the front wall, behind the screen. The owner was surprised that moving them around a little made such a huge difference in sound. The sight of that made me cringe, simply moving those around the room would have improved things so much. He had so much going for him too, at over 6 feet tall and ported on the top, he had sound sources at different heights. He could flip the subs so that two have the woofers on the bottom, and two on top, would have been a great setup. Oh well, he will never know what he is missing.

pjpoes said:

who says the maelstrom-x is better, why? Because it has an XBL^2 motor, more xmax, greater power handling, more linear BL curve? Ok I know, sure sounds like a better driver. However distortion is higher at lower levels.

Click to expand...

I say it's better. For the record, I have three XLS12's (830500), and three XLS12-PR's, as well as a Maelstrom-X. The Peerless drivers, while excellent, are currently sitting in my closet.

I'm not sure where you get that the Maelstrom has higher distortion at lower levels than the XLS12. At all levels, the Maelstrom sounds cleaner than the XLS12. In my experience, which encompasses too many but certainly not all of the good drivers out there, the only other driver of which the same can be said is JBL's W15GTi, which is the car-fi variant of their dual-opposed-coil Vertec pro subwoofer.

pjpoes said:

This would imply that, for the same price as that one driver, multiple lower xmax drivers of decent size (15-18") would actually give better performance, just at the expense of compactness.

Click to expand...

You're misreading what I wrote. I wrote that multiple XLS12's would be a good system, but multiple Maelstrom-X's would be better. (I did not write, but I think it's safe to assume in context that it's implied, "set up in the same manner." Don't get me wrong, my experience after experimenting following reading Dr. Geddes and others has put me firmly in the multiple subs, randomly placed camp. I think that in most rooms, multiple XLS12's would be a better solution overall than one Maelstrom-X. (I'm currently running a hodgepodge of subs in my main system: sealed Maelstrom-X, a Tannoy B475 - 18" ~160L cab vented pro cabinet -, and a sealed JBL W15GTi. The nearfield system only uses one JBL W15GTi, but I either use that system when sitting at my desktop computer or as background music. I firmly believe that multiple subs are key to good in-room performance for non-nearfield systems.)

pjpoes said:

In all seriousness though, if you read through Dr. Geddes work on this subject, you will see that the quality of the driver is pretty much irrelevant.

Click to expand...

I think if you read it more subtly, you'll see that Dr. Geddes has expectations that are not in line with so much of the crap that's actually available to DIYers, because he only uses gear that is considerably better than most such kit. He once called a 15" woofer with like 1.8mH of Le and an 8Ω nominal impedance a "high inductance driver," after all. Where does that put something like a (stock) TC3k or the Mach 5 stuff? That's rather different than saying a TAD and B&C compression driver are both so competent that no sonic differences exist after response and level correction.

Also, keep in mind that a sealed or PR box (which is all most DIYers can do, because of lingering biases against bandpass boxes and the measurements required to get one right) will have more stringent requirements than Dr. Geddes' BP boxes.
(I should add that I've never heard a good bandpass. I'd experiment now, but I'm so happy with what I have I don't see any compelling need to. BP's would be bigger than my sealed subs, and with multiple Crown XTi-series amps that provide plenty of crossover/EQ horsepower and lots of power, the efficiency bonus isn't a large issue either)

pjpoes said:

I mean, lets not take that to an extreme and go buying the cheapest crappiest drivers we can, but spending extra money on drivers with uber motors is a waste too. If your goal is the greatest amount of output with the lowest extension from the least drivers, then uber woofers are great. If your goal is the very best sound quality and bass smoothness, regardless of size, cost, etc, then those are not a good option.

Click to expand...

On a dollar per displacement basis, the Maelstrom-X is really not expensive. I don't think there's another subwoofer with a non-obscene amount of inductance and similar volume displacement that's cheaper. The SoundSplinter RLp18, for instance, is actually a fair bit more expensive.

(I must admit that I had some distaste buying a product from a firm whose name implies that one should expend any thought at all on something as silly as audio wires beyond making sure one has enough of them and they reach where they did to reach, but the driver is truly excellent.)

pjpoes said:

The Le was much lower than specified at .45 mh instead of 1.75mh, which impressed me. So much that I decided my WT3 must be wrong, went to my LCR bridge, same thing, went to my ATB PC Pro, same thing (roughly speaking that is), so sure enough, it has a very low Le which is always nice.

Click to expand...

Sweet. The XLS's and XXLS's also always seem to measure significantly lower in Le than spec'ed in professional and amateur third-party measurements, as well.

Right now I think the Dayton Reference stuff is the better value. The Peerless is a better built and better looking woofer - only talking about old Danish production, but I'd imagine the new Chinese ones are better or at least equal - but measurements show the Dayton's to be similar in performance and of course they're cheaper.

pjpoes said:

If you want the ultimate subwoofers (In my opinion), I would consider a B&C 18TBX100, BMS 18N850V2, McCauley 6174, and possibly the new BMS 18" driver with much greater xmax.

Click to expand...

The Maelstrom-X is likely better than all of those for home use, and similarly priced. (At current rates, it's about $20 more than the 18TBX100. I don't know how much the BMS driver will cost. The B&C 21SW150 has probably similar real-world volume displacement and certainly looks much cooler. (I was planning to buy one as my next sub upgrade - looks spectacular in a ~4 cubic foot box with appropriate EQ to bring up the low end) It is, however, considerably pricer. The McCauley 6174 and Aura NRT18 (or whatever the current designation for the old 1808 is) are both going to cost as much as two if not potentially three Maelstrom-X's, with likely inferior performance.

All that said, I don't think many people will be able to fit multiple 5 foot sub cabs in their rooms, so it's a bit of a moot point. Also, most people don't have mains good enough for that much bass capability. I think for most people a few 10's or 12's in ~1 cubic foot enclosures is a really, really good solution.

Basically most high xmax drivers tend to have higher distortion than lower excursion woofers. Zaph did an article one this, but I have read this elsewhere and also measured this to be true myself. In talking with Dr. Geddes, he gave me the impression this was also his experience in his research. In talking with even Dan Wiggins, it has been my impression that he believes this, but...He thinks the distortion difference is inaudible, and that since the distortion is lower at higher output levels, its a better driver still for the average person. He wrote to me once that while he could design and build a driver with 3mm of xmax and a massive cone with his uber motor, that would have minute amounts of distortion, the box requirements and driver size would mean that nobody would buy it. People want drivers that allow them to have the smallest possible packages with the least amount of woofers, and get the most output. That doesn't mean they are the best, just the best for filling most of peoples requirements in a driver.

Taste is so subjective that you can't really argue taste here. If you like the sound better, then for you, they are better. Distortion doesn't always sound bad, in fact, adding certain types of distortion can often improve the sound people here subjectively. Low feed back amplifier designs usually have higher levels of distortion and noise, but people find they sound better. I had an amplifier once that had pots to adjust the level of feedback. My experience with this amp was that less feedback made a tighter crisper sound, while more feedback made things sound smoother, but more woolly and loose (Which was the exact opposite of what I expected).

I have no data from a Maestrom X unfortunately, but I had a Brahma from back in the day, and have measurements of its distortion spectrum as compared to the Dayton Reference, TC3K (My special one), and Eminence Omega 18" LF driver. The Brahma had the highest distortion of the three at levels between 70 and 90db's. The TC3K was second highest, but also remained the cleanest at peak levels over 110db's (Which is why I kept it), while the Eminence had the lowest distortion from 70~85db's, but very quickly rising after that (We are talking in the sub bass range, it was lowest at all levels above 200hz or so).

Zaph's Article: Woofers with lower Xmax sound better

I've seen Krutke's article. It's pretty old. He was reacting to the same types of drivers that I have always found to sound horrid, such as most of TC Sounds' non-LMT overhung drivers. (The TC2+/TC1k were pretty good, but everything else I've ever heard from them has been awful. I have not heard the TC2k, which has potential on paper.)

I think JK has something wrong. It's not the throw, per se, that's bad. It's the high inductance that typically accompanies it. Yeah, a stock model TC3k is going to sound and measure awful, because it has a peaky BL curve and sky-high inductance. Likewise, a Dayton Reference or Peerless XLS/XXLS, with low Le and a solid motor/suspension design, scores well.

I'm curious, in your test how well did Le correlate to your measurements? Likewise, how did the presence or absence of shorting rings correlate to your distortion measurements?

The Adire Brahma was a considerably higher inductance beast, and didn't even have a shorting ring. (Note that measurements of pre-Faraday and shorting-ringed Adire Tumults, which were basically über-Brahmas, have shown the latter to be clearly superior performers at all levels.) The Maelstrom-X is a very low inductance driver, and has Faraday shielding in the motor.

I would love to see Klippel data for the Maelstrom-X, because I expect that it will entirely vindicate what I and others have said about its quality.

inductance is relative to motor strength

The absolute value of inducatance is not a good indicator, just as the absolute BL value is no meaning without comparing it to Rdc of voice coil (so-called BL^2/Re value). All these values are scalable with respect to Rdc. Actually, the importance of inductance is determined by a lot more factors.

In subwoofer application, the transition point from a back-EMF dominating frequency band to a inductance-dominating band indicates where the motor structure begin to lose firm control of cone motion. Maybe a better word is equilibrium point and for most woofers it occurs between 60hz to 120hz. At frequencies below this equilibrium point, back-EMF dominates the impedance value, and above this point, back EMF is so low, that is becomes more like current drive. Coincidentally, that minimal impedance frequency point is way higher with smaller woofers, or woofers with smaller xmax. All these come into play when some people would prefer to use multiple small woofer to get the SPL up vs one large woofer. There is no doubt that a woofer with a higher equilibrium point would sound better controlled.

So now let us see what can move the equilibrium frequency point up.

First, bigger magnet. Bigger magnet increase BL value with everything else unchanged. Higher BL values increase the back-EMF and push it's equilibrium point to inductance to a higher value.

Second, lower moving mass. Lower moving mass would also increase back EMF at higher frequency point.

Three, Faraday ring. Only faraday rings are thick enough to contribute at frequencies below 100hz. Copper sleeves is not thick enough to reduce inductance below 100hz.

So the opposite of all above can cause the equilibrium frequency point to move down. But what else can cause it to move down? The widening of magnetic gap. Certain high excursion drivers try to stuff as much wire in the gap in order to increase the "L" value in BL. But increase in L value also increases inductance, so it appears the equilibrium point should remain unchanged. But in reality, widening gap reduces B value, so it is more like use a smaller magnet now. As a result, it causes the point to move down. In addition, the more wires, the heavier cone, .....

One may ask why cone control (or having an EMF dominating impedance in subwoofer) is so important. Because the engergy inside the enclosure wants to escape. If a woofer does not have firm control of the cone, that cone can move in response to that energy and give the energy a passway to outside. It defeats the purpose of having a tank-like enclosure. A woofer with firm cone control creates a different dimension of clean sound. Here I emphasize "dimension" because another dimension of clean sound is from low distortion and these two are completely orthogonal. It is always good to have both, instead of only one of them.

BTW, those who are more familiar with T/S equivalent circuit of a woofer may already understand this. The cone mass is represented as "capacitor" in that equivanet circuit, which has a 180 degrees phase difference with voice coil indutance. In addition, lower cone mass yields a smaller cap value and therefore higher impedance. And unfortunately, the voice coil inductance will counteract with that and cause the impedance to look smaller and make it appear as if the woofer has a heavier cone. That is another way to look at the impact of inducantace.

Re: inductance is relative to motor strength

rythmikaudio said:

In subwoofer application, the transition point from a back-EMF dominating frequency band to a inductance-dominating band indicates where the motor structure begin to lose firm control of cone motion. Maybe a better word is equilibrium point and for most woofers it occurs between 60hz to 120hz.

Click to expand...

To put things in perspective, Peerless 12" XLS and XXLS have that equilibrium point at 160hz or so vs a 15" TC 2k at 60hz. That is a huge difference. Effective inductance is four times when the equilibrium point is cut in half.

I also think another read of Krutke's article is worthwhile if all you took away from it was the issue of high inductance and higher distortion. He also mentioned the rise in response contributing to the third harmonic distortion, and being audible still. That whole part is still true of the Tumult as far as I know (based on its response measurements I have seen), and most other top end subwoofers I have seen or measured.

As I mentioned, I have talked with some of the designers of these drivers, and my discussion with them has always indicated that the trade-offs made by high excursion drivers, even those with lower distortion motors, was detrimental to sound quality. The impression I got was that designing a driver to have long excursion, produce deep bass in a small box, and have more linear travel at higher excursion area's required that you give up better sound at more reasonable levels as a result of increased distortion and noise.

I really think that the biggest improvement in these drivers has been more in reducing mechanical noise than in the area of distortions.

What, would you say, is a low enough excursion driver? I.e. how little excursion must I have to be really safe? If I am building a sub woofer to play 20Hz and 30Hz tones, should I go for 10" Seas drivers with +/-6mm (12mm p-p) linear excursion?

Would you say that 12" Peerless XLS (25mm p-p) is better or worse than a 12" Shiva-X (54mm p-p) or Acoustic Elegance AV12-X (46mm p-p), for playing at low to moderate levels?

Is it any different if my aim is to reproduce perfectly from 20Hz to 100Hz, instead of 50Hz to 500Hz?

soundengine355 have a high budget...

Since you have such a high budget, I'd contact John from Acoustic Elegance. I'd use one AV15-H which has one of the lowest Le available and a respectable 46mm of xmax p-p.

You ask him to custom built it, to add the Appollo upgrade on it, which will add two massive aluminium faraday rings to further reduce Le and increase power handling.

Then I'd purchase two PR18-2500 from him, ask him to add as much mass as the PR can handle.

You maximum enclosure size give about 100 liters internal volume net. So that would be great with dual PR18 with a custom AV15-H.

That finishes my realistic suggestion. Then to go overboard...

To go further, you'd need to ask John to add a sensing coil to that massive custom AV15-H and contact rythmikaudio to custom build a servo amplifier for that custom AV15-H... but I'm dreaming a bit there !

This zaph article is pure rhethorics and basically says that a good designed low xmax driver sounds better than a badly designed large xmax driver, which is no wonder at all and no indicator about soundqualities relation to xmax or individual cases, where distortion measurements render such arguments useless but entertaining.

MaVo said:

This zaph article is pure rhethorics and basically says that a good designed low xmax driver sounds better than a badly designed large xmax driver, which is no wonder at all and no indicator about soundqualities relation to xmax or individual cases, where distortion measurements render such arguments useless but entertaining.

Click to expand...

Most people will not look into this type of details. Let me just share a few points:
1) We all build solid enclosure to "contain" internal standing wave retransmit through enclosure walls. A typical knocking test is suffice. Now try that on your cone and you can see how solid our cone is. Cone is part of transducer and part of enclosure. It needs to follow the input signal and yet at the same time effectively resist the standing wave acting on it just like any other part of the enclosure (otherwise, it defeat the purpose of having a solid enclosure). The ability for the cone to resist standing wave push is related to the back EMF to inductance ratio. I don't need to say more. Larger excursion drivers simply have weaker back EMF to inductance ratio (for the most broad frequecies). Traditional test procedure cannot test this because it completely replies on steady state signal. It is like determine a car's performance using straight road. We should try a couple of turns. Most people will not do that because it is very subjective impression for these experience. So what do engieers do? drop it from the test.

2) In the T/S parameters, the equivalent circuit represents the cone mass is the driver's impedance is a capacitor, which has an opposite phase of inductor. As a result, they substract from each other and that is not good at all. Let us say the indutactance have 1ohm reactance and distortion is 10%, that is 0.1ohms of distortion. Let us say the mass reactance is 0.9ohm and is pretty linear. Because they substract from each other, the net reactance is now only 0.1ohm. No other thing can cancel that 0.1ohm distortion, so what is the distortion percentage now? It is 100%. When you look at the inductance by itself, most people say it is no big deal. Sure. Now add the motional impedance of speaker.

Thank you for sharing your knowledge. That was a very interesting post !

What do you think about my idea ? Your current sensing coil on a AE AV15-H ?

I purchased an amplifier from your company in the past. After 4 years it's still going strong. I think your Servo line of subwoofers are the best value available for Servo controlled subwoofers, if not the best Servo controlled subwoofers at any price.

simon5 said:

Thank you for sharing your knowledge. That was a very interesting post !

What do you think about my idea ? Your current sensing coil on a AE AV15-H ?

I purchased an amplifier from your company in the past. After 4 years it's still going strong. I think your Servo line of subwoofers are the best value available for Servo controlled subwoofers, if not the best Servo controlled subwoofers at any price.

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Glad to hear that. The idea of AE AV15-H is pretty good. But I need to get the right power amp for that project.

rythmikaudio said:

Glad to hear that. The idea of AE AV15-H is pretty good. But I need to get the right power amp for that project.

Click to expand...

Yeah, sorry, I always dream about the perfect subwoofer driver...

Also, if you put an Apollo upgrade on it, might need an even bigger amplifier since thermal power handling will increase again and we will get less distortion...

You like strong aluminium cones, those new AE aluminium cones can hold a person standing on it. Last generation was alot weaker. I don't know if they are stronger than yours OTOH.