questions about Tumult vs. the big boys... (1 Viewer)

[MaRtIn^dB]

Where is Mr. Dan Wiggins when you need him? And by the way, he is one smart son of a...!

He pretty much laid to rest the myth of woofer speed/transient response vs. woofer size. After reading his technical paper and the "think-tank" battle on car sound & performance forums, i think i'm sold on his Tumult 15d2 driver. A sealed and L/T'd 1200 watt low Q enclosure.

However, there is no place i can go to demo any of the high end sealed subs in the $2K+ range so i guess it all comes down to the various online forums.

I would like to hear from "anyone" who has experienced the sound of the sealed 15" big-boys...ACI maestro, Revel b15, Kleiss s15a, Velodyne, Paradigm, etc.

Anything subjective or objective, listening impressions, performance data...anything!

Finally, a few more questions i'm pondering:



1. The musical differences in a critically damped sub (Q=.5) versus a bessel alignment (Q=.577)

2. The recommended f3 point for a sealed enclosure with a Linkwitz transform as it relates to room
gain in a THX-select environment (1,800 cu. ft.). This room can be fully sealed.

3. The viability of a servo-circuit unit integrated into the sub.

4. The comparative levels of performance between the Tumult and those units mentioned above.



My biggest fear is that this unit will overpower the room, hence the low Q alignment. But how low is the question. I would absolutely prefer a musical signature to this subwoofer, letting sheer displacement take care of HT. I have (3) 8" inch drivers moving the room currently so i don't fully know what to expect from this high end 15" driver. I do know that it models extremely well in winisd pro and Dan has made a very strong case for the XBL^2 topology, not to mention his "observations" on low inductance and transient response, which has put my mind at ease concerning the woofer speed myth.


This guy has really accelerated my learning curve of loudspeakers.


Now if we can just get the drivers released...smile Thanks to all.

 

[Ryan Schnacke]

Dan has a good point about low inductance. But in that paper I thought he really failed to make a coherent argument for neglecting moving mass. Some bad math, lotsa hand waving and ... Look Ma, I'm breakin' laws of physics! His own use of the age-old dragstrip analogy goes a long way to discount his arguments.

“Or to put it in an analogy, does the 1/4 mile time of a vehicle depend upon where you start? No, the distance over which you measure is still 1/4 mile. So whether you start in front of your house and go straight 1/4 mile, or motor on down to the dragstrip and go 1/4 mile it doesn’t really affect the car’s 1/4 mile time. "

Yeah, that makes sense if you’re going disregard position from the equation. But that’s not what he does. He uses this argument to disregard the motor strength (BL) and mass (m). That’s the equivalent of saying that the 1/4 mile time of a vehicle is completely independent of how powerful your engine is and how heavy the car is!

Even his experimental data was ... disappointing. I could go on and on. I did, actually - wrote up my critique of this paper. But when I was done it was 3 pages long. And until now I haven't heard anyone reference that paper, so I decided not to post it just to stir up a pot of flames.

 

[MaRtIn^dB]

hello and thanks Ryan for posting. I'm not sure if you caught the thread on the forum i mentioned above but this is an exerpt of how it ended:

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"So Rob, I think you have successully driven an AGREEMENT between me & Dan Wiggins. If we define transient response as the "complete" time domain response, including overshoot, ringing & damping, mass will certainly have an effect (through Q, Fs). HOWEVER, if we use Dan's definition ... restricting transient response to the RISE TIME of the step (or impulse) response ... we see that mass (inductance) has NO EFFECT !!! I think I can completely agree !!!

Dan, what do you say ??? You gotta like this !!!

RobM, you are a genius. My hat's off to you"
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I assume that may be you've found this 3 page (incidentally) meeting of the minds and if not here is the link to it:

*since i'm under the 15 posts rule, i cannot provide the link****sorry

I won't pretend to have any expertise in this area, but it did settle a long raging debate between my ears on woofer speed vs. size!

It is "highly" instructive (to me anyway) and well worth the read!...Thanks again

 

[steve nn]

I would agree, but my assessment does not reflect any negativity towards what a smaller driver can offer.

 

[Ryan Schnacke]

Martin, I seem to have missed out on that conversation. At some point I have to limit the number of forums I keep up with or I'll spend all evening on the 'puter. Sounds like that thread is worth a read though. Please post a link once you've got the min posts.

"if we use Dan's definition ... restricting transient response to the RISE TIME of the step (or impulse) response "

I had to read Dan's "Woofer Speed" paper several times before it occured to me that he was really only arguing what the layman would call "reaction time". It even makes sense with his dragstrip analogy. The mass of the car and power of the engine have nothing to do with the reaction time of the "driver".

Sorry to sidetrack your topic.

 

[AlbertD]

I have a 6 year old Infinity HPS1000 sub. It has a 15" downward firing driver and is in a large sealed cabinet. While it is not ported it does have two 15" passive radiators though. It goes to 17 Hz and is tight, taught, crisp, and blends in great with all the speaker systems I have paired it with. Infinity, then Dunlavy, and now Triangle. I have had occasion to listen to other subs from quite a few companies (have many friends that have HT systems and I belong to a local audiophile group) I'm not any kind of expert, but I believe in a sealed design simply due to the fact that my sealed sub sounds better (to me) than any other design or brand I have heard. I am not a fan of small cubes or small enclosures either. To my ears there is just something missing. All of the subs that I have heard that I do like were ALL in larger enclosures. All the subs that I didn't care for were either in small enclosures or ported. But this is just my opinion.