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#389502 - 02/09/13 01:50 PM Re: Opposed Subwoofer Design [Re: Andrew]
casey01 Offline
aficionado

Registered: 07/03/08
Posts: 761
Loc: Toronto
Originally Posted By: Andrew
Originally Posted By: INANE
Curious what folks/Axiom think about opposed subwoofer design in general. Where you have two drivers in a single box on opposite sides of each other.


Ah...a topic near and dear to my heart. If I am not mistaken, Mirage produced the first commercial subwoofer with an opposed woofer design with the drivers operated in phase with one another. This first model was the BPSS-210 and was originally designed for use in systems with the first Mirage bipolar speakers, the M-1 and M-3. This was in the very early days of home theatre and most of the original subs were sold with 2-channel systems. The design benefits behind opposed driver subwoofers are improved room loading from the multiple drivers and an almost complete cancellation of cabinet vibration. These designs are not gimmicks, they most certainly result in improved performance when well designed. I believe the main reason that we don't see more of them on the market is that the second (or third) driver(s) add significantly to the cost. One thing to watch are designs claiming to have force cancelling drivers where one driver is actually a passive radiator. In this case there will be no benefit in terms of reducing cabinet vibration. Interestingly enough, as Ian and I have been working on design ideas for the "v4" series of subwoofers we have been discussing the possibility of one or two models incorporating a balanced or force cancelling driver configuration. As with everything we do the designs would be evaluated strictly based on their performance versus the current models. Now is as good a time as any to throw the question out there: Is this type of design something that would interest you? wink


Andrew, you beat me to the punch on this one in stating that Mirage was probably the first to incorporate this type of design, a natural in their case working hand in hand with their enormous bipolar models you mentioned and they did sound very good. One thing you didn't mentioned when HT started to come in to vogue, Mirage designed and built an excellent crossover unit that worked beautifully in conjunction with any sub, an item somewhat ahead of its time.

The only passive radiators I have seen and heard in a few models were incorporated in to small powerful subwoofers to attempt to reinforce the bass in ultra small cabinets. Despite the claims of deep, powerful bass in a small package, I was never impressed with any of these overpriced designs and I think the marketplace has shown it.

When it comes to subwoofers, I have always believed that you can't really defy the laws of physics, the bigger the cabinet, the better, deeper AND louder the bass with less distortion. Since it will give somewhat more flexibility in placement and provided it is competitively priced, the bipolar design is one that Axiom should strongly consider for the future, forget the passive radiators.

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#389505 - 02/09/13 02:24 PM Re: Opposed Subwoofer Design [Re: INANE]
SirQuack Offline
shareholder in the making

Registered: 01/29/04
Posts: 13318
Loc: Iowa
totally interested if affordable
_________________________
M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana

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#389509 - 02/09/13 03:00 PM Re: Opposed Subwoofer Design [Re: Andrew]
chesseroo Offline
connoisseur

Registered: 05/13/02
Posts: 4788
Loc: western canada
Originally Posted By: Andrew
Is this type of design something that would interest you? wink

And to that question i ask a question, which design idea would actually NOT interest the forum readers here?
_________________________
"Those who preach the myths of audio are ignorant of truth."

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#389540 - 02/09/13 08:35 PM Re: Opposed Subwoofer Design [Re: chesseroo]
fredk Offline
axiomite

Registered: 12/06/07
Posts: 7031
Loc: Canada
Originally Posted By: chesseroo
Originally Posted By: Andrew
Is this type of design something that would interest you? wink

And to that question i ask a question, which design idea would actually NOT interest the forum readers here?
I'm so glad you asked. I'm pretty sure not many would be interested in this idea:

... and I really don't want them to release something like this:


... because then CV will abandon his alligator pit and start digging for the new Axiom sub.
_________________________
Fred

-------
Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!

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#389541 - 02/09/13 08:44 PM Re: Opposed Subwoofer Design [Re: casey01]
fredk Offline
axiomite

Registered: 12/06/07
Posts: 7031
Loc: Canada
Originally Posted By: casey01
The only passive radiators I have seen and heard in a few models were incorporated in to small powerful subwoofers to attempt to reinforce the bass in ultra small cabinets. Despite the claims of deep, powerful bass in a small package, I was never impressed with any of these overpriced designs and I think the marketplace has shown it.

When it comes to subwoofers, I have always believed that you can't really defy the laws of physics, the bigger the cabinet, the better, deeper AND louder the bass with less distortion. Since it will give somewhat more flexibility in placement and provided it is competitively priced, the bipolar design is one that Axiom should strongly consider for the future, forget the passive radiators.

Casey. My understanding of subwoofer design is that you use the passive radiator to eliminate the internal volume of a port (making the sub a little smaller) and to completely eliminate the issue of port chuffing. The cheating of physics in small commercial designs is probably a design compromise where the designer wants a smaller cabinet more than deeper bass and so reduces cabinet volume beyond just that which the port makes up.
_________________________
Fred

-------
Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!

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#389553 - 02/10/13 02:17 AM Re: Opposed Subwoofer Design [Re: Andrew]
INANE Offline
connoisseur

Registered: 02/04/04
Posts: 1660
Loc: Omaha, Nebraska
Originally Posted By: Andrew
Now is as good a time as any to throw the question out there: Is this type of design something that would interest you? wink


Well, ya laugh

I have been looking at the Epik subwoofers because their prices are relatively low. I've also been considering the DIY route again (all my subs have always been DIY). Regardless this design does intrigue me.
_________________________
-Ben
HT v2.0 !
HT v1.0

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#389575 - 02/10/13 07:13 PM Re: Opposed Subwoofer Design [Re: fredk]
cohesion Offline
local

Registered: 03/27/12
Posts: 208
Loc: Maple, Ontario, Canada
Originally Posted By: fredk
Originally Posted By: chesseroo
Originally Posted By: Andrew
Is this type of design something that would interest you? wink

And to that question i ask a question, which design idea would actually NOT interest the forum readers here?
I'm so glad you asked. I'm pretty sure not many would be interested in this idea:



Actually that one looks pretty good to me - but only if it comes with an Axiom logo instead of what's there!

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#389594 - 02/10/13 11:01 PM Re: Opposed Subwoofer Design [Re: INANE]
Boltron Offline
veteran

Registered: 11/18/11
Posts: 170
Loc: Toronto
I will be purchasing a second sub to replace a smaller polk soon I hope. I can't wait to see/hear whats in store. Size however is a constraint for me, I am hoping the next gen subs will not be bigger than the EP500 (or else the wife will notice ;))
_________________________
For every expert, there is an equal and opposite expert.

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#389868 - 02/19/13 05:57 PM Re: Opposed Subwoofer Design [Re: INANE]
GregLee Offline
veteran

Registered: 03/12/03
Posts: 131
Loc: Waimanalo, HI
Maybe this is like the Sony SA-WX700 "push-pull" sub? I think they're no longer made. They were inexpensive, and I bought one. Mine broke (as did many of them, I gather) after a year or so. I still have it sitting in a corner of my listening room, waiting for me to replace a condenser, in hopes that would bring it to life. I was pleased with it, while it worked, but I couldn't give you a good critique.
_________________________
Greg
VP180, M80s, M22s, QS8(4), CSW S305s, EP500, Pioneer SC-1522
M2i, M3(2), Pio vsx-1017

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#389977 - 02/22/13 12:24 AM Re: Opposed Subwoofer Design [Re: GregLee]
INANE Offline
connoisseur

Registered: 02/04/04
Posts: 1660
Loc: Omaha, Nebraska
Originally Posted By: GregLee
Maybe this is like the Sony SA-WX700 "push-pull" sub? I think they're no longer made. They were inexpensive, and I bought one. Mine broke (as did many of them, I gather) after a year or so. I still have it sitting in a corner of my listening room, waiting for me to replace a condenser, in hopes that would bring it to life. I was pleased with it, while it worked, but I couldn't give you a good critique.


What I'm talking about is not push-pull. That Sony resembles an isobaric design. In a dual opposed the drivers would be push-push.

I'm seriously considering buying a pair of inexpensive (aka cheap) drivers and building a very basic enclosure just to see what gotchas I might come across.
_________________________
-Ben
HT v2.0 !
HT v1.0

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