One big subwoofer or two weaker subwoofers?

Mavilla: Try filling the interior volume of the sub with a varied density of foam ( or polyester fiberfil as a second choice ) and turning the crossover point as low or almost as low as it will go. This should get you a lot closer to something musical rather than something that goes "boom boom". You can fine-tune the quantity i.e. how "tight" or "loose" you want the bass by varying the amount of stuffing in the box. This shouldn't cost you more than about $10 or so to try and will probably make you a whole lot happier. Don't forget to try various placements for the sub once you get things dialed in reasonably close to where you want them with the stuffing.

El: As far as motor structure and mass goes, my Brother's 5" mids and 9" woofers both have 3" voice coils. The 9's have less than 30 grams of moving mass. How's that for "transient response capability"? From what i can tell, this is equivalent to having a fully massaged "big block" bolted into a shopping cart : )

Even with this much "motor structure" and lack of reciprocating weight, these drivers don't demonstrate the high "force factor" aka "slam" that many larger and heavier drivers are capable of. The bass is very tight and punchy, but it just doesn't have the "weight" or "impact" that one can achieve by using a larger driver. Even though my Brother is using two 9" woofers per side, he knows that he's missing bottom end. That's why he's also running two larger sub-woofers per side : ) Sean
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PS... Many folks confuse large quantities of bass and / or bass over-hang with deep bass extension. Since it is easier to obtain greater output at higher frequencies than it is to go deep and maintain high levels of linearity, many manufacturers substitute "bloom" for bottom end. Once one gets rid of the "artificial boost", you can really hear the lack of extension. I am going through this right now with my Father and his system. After rebuilding / modifying his system, he thinks he's missing deep bass. Since we effectively made his cabinets larger, which extends bass response, there is NO way that this is possible. What he's doing is confusing the lack of upper bass "bloat" for deep bass extension. While he's VERY happy with the improvements in bass definition and tonality, the lack of 80 Hz bass makes him think that the system is "lean". That's why i'm working on a 15" sub-woofer for him now : )

Sean, don't you think that TWO 15"ers in stereo (i.e. one per channel) would do the trick for yr Dad?
- You would still have definition (not the single-note pulsating muddiness)
- There would be better spl so, bass will be more perceptible
Cheers

Sean...Those small drivers with big voice coils wouldn't be Dynaudio by any chance. I have a set of Dynaudio MTM boxes with 5inch "woofers" that have 3inch voice coils. They bark furiously, but no bite. Very nice close up in a small room.

Size matters.

My next direction is going to be in a really good subwoofer. I am beginning to think that this is one area where i will probably try a number of home auditions before deciding.

Long live the local brick-and-mortar shops!

Greg: My Dad's system is actually quite solid down to 35 Hz and rolls off below that. Given that he doesn't listen to pipe organ music or electronica, he'll simply have to get used to "natural" sounding bass. It may take some time, but after living with stupendously bloated "thud" for years on end, and thinking it was both "good" and "extended", it may be tough for him to deal with initially. As i've already commented though, he is well aware of the phenomenal increase in bass resolution and transient response, so i'm thinking that there is hope : )

As far as the sub goes, that will be used for HT purposes only. This specific model was rated as being -1.5 dB down at 25 Hz and is quite large. Due to using this strictly for special effects on movies, placement of the sub becomes less critical. This is in comparison to if the sub was used for stereo purposes, which would require some semblance of low frequency imaging. The speakers that he's running for mains are actually too large for the given installation in my opinion. Adding two large sub-woofers with the requisite box size required for good performance would be too much for this room and there just isn't enough space to do so. Given that his mains already have an 8" and 10" per cabinet that share the low frequency load, he's not "hurting" in this regard.

Besides all of that, i'm paying for the sub, amp and cabling, so he can't complain about "only having one sub" : )

El: The mids, tweeters and woofers that my Brother is using are Morel drivers. Given that Morel purchased technology from Dynaudio, one can see the similarities in driver design.

Having said that, i agree with your assessment. That is, even with minimal mass and big motors, these drivers just don't move air / respond like a "big boy" can. This is why i've got six 12's, four 10's, six 8's in my HT system and eight 12's in my main two channel system. Even with all of that, i can hear others saying "What ?!?!?! NO 15's, 18's or 21's ????" : )

UncleJeff: If you do some research, i think that you'll find that you'll have better luck building a sub from a kit than anything that you can buy at a brick and mortar shop for anywhere near the same amount of money. Having said that, most sub kits are PHENOMENALLY easy to put together, so don't let a lack of mechanical / electrical aptitude scare you away from attempting such a project. Sean
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PS... The pair of subs that i've got lined up for my next "project" make use of a single 12" and two 15's in large, low Q sealed cabinets. I may use these with my Ohm F's, which should help increase max spl and clean up their transient response a bit. Obviously, active crossovers would be used since passive's do horrible things to the amplifier / speaker interphase : )