[Bob in St. Louis]

Ok, cast your votes. 

[James Romeyn]

I voted sealed, with lengthy asterisk as follows.

Disclosure: I sell a high-end ($2990) distributed sub array, "DEBRA" (distributed-EQ bass reflex array) described at my two websites.  My extreme self-serving bias is obvious and noted.

Dr. Earl Geddes, Todd Welti (currently of Harman Labs), and Duke LeJeune claim that the nature of the relationship between a bass waveform and the walls in a domestic room (as opposed to a larger "commercial" space such as a theater) is such that the bass waveform must bounce between two walls prior to the listener perceiving the waveform.  The length of one complete waveform cycle is greater than the space between the source and the listener.     

Further, a properly designed and implemented multiple/distributed sub array effectively cancels the resulting bass modes prior to their propagating in the first place.  This contrasts with every other method of bass mode cure, which is an after-the-fact band aid approach. (Rather than "sub", I prefer the term "bass module" because they purposely cross above 100 Hz to extend the mode-damping range.  I fully realize crossing separate bass systems above 100 Hz is audiophile heresy.  I'm comforted that persons as highly respected as Jeff Hedback and Nigel Mellor provide comprehensive evidence consistent with my claims in THIS landmark study of October 2011.)

If all the aforementioned is correct, then this follows: If all the enclosure types listed above are tuned appropriately, then the quantity of subs makes a significantly larger difference than differences between the types of subs.

The reason I chose sealed for this poll is because sealed systems tend to mimic Duke LeJeune's "Room Gain Complementary" tuning function as employed in DEBRA.  The average boundary gain (not modal effects, in addition to modal effects) of a domestic space is +3 dB per octave below 100 Hz.  Duke tuned DEBRA the inverse of the above gain.  A sealed system rolls off at 12 dB/octave, 1/2 the rate of a reflex system. 

With reflex systems, extreme suckout or overhang may result if the port tuning overlaps one of the room's bass modes, but not the case with my system's Room Gain Complementary tuning.   

Per Hedback/Mellor's report above, the nature of a dipole system (open baffle) loading a domestic space is such that the lowest perceived frequency can be no lower than the room's lowest mode.  IOW: input the room's dimensions into Ethan Winer's awesome Room Calc at his Real Traps website.  The resulting lowest modal frequency is the lowest possible frequency perceived with a dipole (open baffle) sub loading the room.   

My website lists ancillary benefits with a distributed sub (bass) array.

Just to return Duke's generous favor, he sells at least one bass array (possibly more) priced below mine.   

[JohnR]

the nature of a dipole system (open baffle) loading a domestic space is such that the lowest perceived frequency can be no lower than the room's lowest mode.

That simply is not true, as anyone with a microphone and a dipole panel can verify.

[Freo-1]

I have Legacy Signature IIIs, bi-amped with a Threshold S300 on the woofers (120 Hz) and below.  They sport 3 ten inch woofers in a sealed design.  The bass is among the best I've heard any speaker, regardless of price.  They get right down to the low 20's quite easily, and they are a proper CLEAN bass. No boomy response whatsoever.  The bass from theese is like you get in the concert hall.

[Æ]

I voted sealed, with lengthy asterisk as follows.

He only asked for your vote. We were doing just fine until you followed through with all that other nonsense.

[FullRangeMan]

OB, once listen it is difficult to regret.

[Bob in St. Louis]

OB, once listen it is difficult to regret.

I agree 100%. 

Since we've already got two threads debating this, I wish this one would stick to the voting as oppsed to more chit chat.

I was mainly curious to what people thought by seeing the results of a simple vote.

Interestingly, I wonder the difference of the voting results if this poll were taken in the OB Circle, or over on another forum altogether, like the "Cult of the Infinitely Baffled".

bob

[James Romeyn]

That simply is not true, as anyone with a microphone and a dipole panel can verify.

Acoustical Measurement Standards For Stereo Listening Rooms, Oct 2011, by Jeff Hedback, Nyal Mellor, assisted by Dr. Floyd Toole, Duke LeJeune, Dan Fitzgerald, and Bill Weir.  Pg 20:

"...Acoustical design considerations for different speaker types...

Dipoles

Dipoles are a quite popular type of speaker both in traditional electrostatic / ribbon / planar magnetic configurations and new school cone open baffles. Dipoles have a couple of characteristics that are worth bearing in mind with respect to the acoustical targets defined above and the application of proper
acoustic design to realize high end reproduction...

1. Dipoles radiate equally forwards and backwards.
2. Dipoles have cancellation nodes perpendicular to the baffle axis. Due to this they do not excite room modes along this axis and have reduced interaction with the side walls.
3. Dipoles have a lower reverberant field for a given SPL at the listening position (3.8dB less) relative to a monopole due to their increased directivity. The distance to which the direct sound dominates spectral balance is further as a consequence of this; this also means that single figure T60s can be higher for dipoles relative to conventional speakers.
4. Dipoles are velocity rather than pressure sources. This means they couple to room modes differently. A pressure peak is a velocity low and vice versa.
5. Dipoles cannot pressurize a room below the frequency of the lowest modal resonance. This is a consequence of their velocity source nature. In small rooms the lowest modal peak can be in the 30Hz range which makes a subwoofer a consideration. In addition Dipoles have a ‐6dB per octave cancellation below the so‐called dipole peak. This means that very large baffle sizes and displacements are required to reproduce low frequencies at high SPLs..."

(emphasis added to quote)

[JoshK]

He only asked for your vote. We were doing just fine until you followed through with all that other nonsense.

Tell us what you really think.  :rolleyes:

Anyway....I've heard all the theory and hoopla, but I've never heard OB bass even sound good let alone better.   I get the science, I've yet to hear it in practice.   And I am one that doesn't like the bass of big planars.

[Æ]

Tell us what you really think.  :rolleyes:

Anyway....I've heard all the theory and hoopla, but I've never heard OB bass even sound good let alone better.   I get the science, I've yet to hear it in practice. And I am one that doesn't like the bass of big planars.

I'd love too, but I better not, it might get me into trouble.
Anytime someone mentions Geddes, blah, blah, blah, I begin to feel nauseous!

How very true, planars don't have very much bass at all. That is why so many of them have their own built in woofer/subwoofer to augment the lower octaves.

[JohnR]

5. Dipoles cannot pressurize a room below the frequency of the lowest modal resonance.

I think you're misinterpreting that quote, Jim. The "cannot pressurize a room" thing is referring to the notion that at DC a dipole has a net zero change in pressure in the room. So, no "room gain." That doesn't mean that below the room's fundamental, there is no bass. As I said, it is simple enough to verify for yourself.

[James Romeyn]

I think you're misinterpreting that quote, Jim. The "cannot pressurize a room" thing is referring to the notion that at DC a dipole has a net zero change in pressure in the room. So, no "room gain." That doesn't mean that below the room's fundamental, there is no bass. As I said, it is simple enough to verify for yourself.

Thanks. 

So "cannot pressurize" means only no room gain below the lowest room mode, but there is still audible output?  Is that right?      

By definition, is not output below the lowest mode, compared to the mode, diminished by the quantity of the lowest mode (all quantities in dB)?  IOW, if the lowest mode is +9 dB, output below it is -9 dB (vs. the reference of about 150 Hz, the frequency at which the room's effect changes). 

I don't have a dipole sub.  But I suppose I could make one as follows: Two identical reflex bass modules, back-to-back, invert polarity of the rear module (driver spacing would be about 22") 

 

[JohnR]

So "cannot pressurize" means only no room gain below the lowest room mode, but there is still audible output?  Is that right?      

Well, it's certainly measureable... since my fundamental is 23 Hz, it's not clear that "audible" is very significant, but regardless, the bass doesn't just suddenly drop off a cliff. At least in my room, I've not seen any kind of effect like that at all.

By definition, is not output below the lowest mode, compared to the mode, diminished by the quantity of the lowest mode (all quantities in dB)?  IOW, if the lowest mode is +9 dB, output below it is -9 dB (vs. the reference of about 150 Hz, the frequency at which the room's effect changes). 

I'm not really sure what you mean...
 

I don't have a dipole sub.  But I suppose I could make one as follows: Two identical reflex bass modules, back-to-back, invert polarity of the rear module (driver spacing would be about 22")

I'd not considered what would happen if you used ported boxes for that, although I've been meaning to try it with sealed for a while. Well, mostly I want to simulate a cardioid, which can be done with a time delay on the rear driver. Anyway, if the ports are on the same baffle as the drivers, then I think it will probably work? Otherwise not.

[Bob in St. Louis]

What do you guys think, should I add TL and horn to the list?

Bob

[Quiet Earth]

I chose vented because I like single ended triode amplifiers. So far, vented has been the best choice for me.

I voted sealed,

Disclosure: I sell a high-end distributed sub array, DEBRA

Debra is a "Distributed-EQ Bass Reflex Array". I don't understand the connection between what you sell and how you voted.

[bummrush]

Also my speakers are Clements with transmission line where would that fit in? Some kind of sub category I guess.

[mgalusha]

I voted sealed but that is my preference. Perhaps the poll title might have been which type of bass do you prefer. I've heard outstanding examples of all the choices and depending on the room and owners preferences I believe some are better for certain situations.

[eclein]

I voted sealed but I've never heard anything but vented and sealed.....this will be interesting...Bob why did you ask for the vote??? Curious...

[charmerci]

What do you guys think, should I add TL and horn to the list?

Bob

I would assume they would both fall under vented. But really, I'm not that sure technically.

[Bob in St. Louis]

Bob why did you ask for the vote??? Curious...

Due to the discussion on this page: http://www.audiocircle.com/index.php?topic=101044.0
Seemed like a good time to have a poll. 

Bob