Is There A Big Difference Between Subwoofers From Different Manufacturers

@phusis , You bet. I have two issues crossing at 100 Hz. The subwoofers have to be in stereo and symmetrically arranged around the main speakers and to inhibit room interaction and match the main speaker radiation pattern they have to form a linear array that extends down to 5 Hz. Because there are 4 subs technically they do form a DBA, just with additional characteristics by design to match the main speakers. 

@lalitk , it in not prejudice or hatred , just an analysis of the problem of making subwoofers you can distribute and sell in this market. Pitifully few of us are going to spend $36K per sub on Magicos. Being cost effective and competitive means compromises a DYIer does not have to make. There are all sorts of drivers available for reasonable money. The problem is the enclosure. As an example most woofers are constructed with an MDF base in a box format. Cabinet grade plywood is twice as stiff but 4 times as expensive. A box is perhaps the worst shape to use for a subwoofer enclosure and a lot of bracing has to be done to get resonances above the frequency range of the woofer but these resonances can still be excited. The perfect enclosure would be a sphere as it is self supporting. Try crushing an egg cupping it in both hands applying even pressure. Unfortunately spheres are very difficult to make and work with. Next is a cylinder. It would be much stiffer than a box and could be machined in aluminum but it would be very expensive. Making it out of wood would require multiple laminations around a form with the seams staggered again a very expensive, labor intensive process. It might be cheaper to machine it in aluminum! There are other more complex forms that could be used such a  Decadron cylinder. 

As far as integrating subs into a system is concerned the same factors apply to all subwoofers. Many commercial subs Like some of the JL Audio units have room control and adjustable delays which is great but you have to adjust the delay by ear a very difficult way to do it but a $300 measurement microphone would cure that problem. A dedicated 2 way crossover is for all intent and purposes mandatory if you want the best performance. IMHO and that of many others using a low pass filter on the sub and crossing it in under the main speaker is a half baked at best solution.

@lalitk , what we are talking about applies to any subwoofer and describes characteristics that others can use to evaluate commercial subs.

@Phusis, Right now it is two per channel and going to 4 drivers in two cabinets for a total of 8.  All the drivers are set to form a linear array so they all work as a unit as most bass is center channel. They are however hooked up stereo because I cross up at 100 Hz. As for overdoing it the limiting factor is space. I would use 15" drivers but the enclosures would have to be so big it would be impossible to fit them in. 

@lalitk , I have played with several Rel subs but not in my system. Their version of sub integration is designed for the lowest common denominator and it performs like the lowest common denominator. Sorry for being harsh but this is the honest truth.

Many people think DIY projects are second rate at best. It depends on the intelligence, experience and skill of the people involved. The ability of companies to get subwoofers to market include a bunch of economic factors that do not apply to the DIY individual.

@larry5729 , it is painfully easy to beat Rel subs. The problem is the only commercial manufacturer to do it is Magico. A private citizen that is a competent wood worker can do it with their hands tied behind their back. You use balanced force design like Magico and make the enclosure even stiffer.

@parker65310 , I used DIvas for 6 years or so and I could never get subs to match perfectly. This was before DSP came along. I returned to ESLs and with DSP have no issues with integration so, I am sure with proper digital bass management it will be easy and a huge benefit. Like ESLs ribbons do not like making deep bass. They can do it but they do not like it.

@ieales , Rel subs are made as well as any commercial subwoofer. If you are comparing them with other subs on the market. They have two issues. I hate their method of integration and it is easy to get better subs if you build them yourself. I can do things that are totally impractical if you want your sub to come in at a reasonable price and take less than a century to build. I am not trying to pump up my ego either I mean this in all sincerity. I can do better than the subs I have now but the fellow that calibrated my projector (this is his real profession not a side line) related it was the best bass he ever heard. Frankly, I think they are ugly and a bit soft. It was a good performance for 20 years ago but I have learned a lot since then and am in the process of building a new set. Unfortunately, they are competing will things I have to do for the wife and the wife always wins. It is going to be a little while yet. I was hoping this Summer. Time Waits For No One. 

@punkrock67 , That is odd because most people that I know think the ported woofers are boomy and the sealed ones tight and controlled.

@phusis , I wish I could find the link but is slow mo's an 18" woofer under a strobe actually wobbling under light power. One side starts moving before the other and goes downhill from there. The excursions are not very far. 

I feel the most comfortable with 12" drivers and you can get to the same place by using multiples. I keep doubling the number until I get what I want. Next stop is 8.

I saw Marcus Miller and Mike Stern at the Blue Note in NYC last month and I could feel Marcus's E string vibrate. It is that kind of authority I would like to get at home. I have great bass, just not that great. I know there are some recordings that can do it like Supertramp's Crime of the Century or any number of Dave Holland Albums and Jaco albums not to mention Organ works. 

@akg_ca , right on akg. No argument from me. I build my own subs because nobody makes one that sounds good for a reasonable price and I do not need the second rate electronics they stuff into the enclosures,

@phusis , good dissertation. I particularly like your comments on excursions. Larger drivers do not need to move far to displace air. Longer excursions always mean higher distortion. The notion that larger drivers are "slower" is mythology to the max. There is a limit as larger diaphragms are harder to control. I hold the line at 15" but for my own subs I stick to multiple 12" drivers. 15" drivers require much larger enclosures which would dominate the room. 

Put your hand on the subwoofer. Any vibration you feel is distortion. Stopping it is not easy. Balanced force designs are a good start but this is not enough. Bass is very powerful and stopping all resonance in an enclosure is not easy. The only commercial units I know of that do it successfully are the Magico Q series. 

Digital crossovers with delay management and room control are a godsend for subwoofers. They make integration soooo much easier. Another big plus for subwoofer performance are balanced mono amps you can place behind or next to the subs with long signal cables and very short speaker wires. Damping and control of the driver are greatly improved.

REL's system was created to cheaply get subs into peoples system (they don't have to buy additional items). It is a relatively poor way to do it and it fails to take advantage of a subwoofer's best advantages. People using that system should know that there are additional benefits they can grow into and really improve the performance of their system.

Rules of the Road.

Subwoofers have to be in corners or against walls.

Subwoofers have to be in phase with and time aligned with the main speakers.

Crossover should be between 80 and 100 Hz

Multiple subs in a symmetrical array are mandatory (at least two)

Bigger drivers are better. 10" is the smallest that should be used. At least four 10" subs would be needed. Two 12s will suffice.  

@ryder , sure. If you compare a range of 12" subwoofers there is a lot of difference. The single most important factor in subs is the enclosure. It has to be stiff, non resonant and heavy. The best spec to compare is weight. The heavier subwoofer is likely to be better. What the enclosure looks like means nothing. The best subs on the market use a balanced force approach. They put two identical drivers opposite from each other in phase. The Newtonian forces cancel and the enclosure does not shake. Magico makes it's subs this way. KEF uses this technique in the Blade. 

I build my own. I can make them heavier and stiffer than any company would care to for cost reasons. There are probably over 100 sub drivers on the market and many of them are excellent and even better than the units used by the manufacturers again for cost reasons.