questions regarding TUMULT vs. the big boys...

[kramskoi]

Where is Mr. Dan Wiggins when you need him? And by the way, he is one smart s.o.b.!

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... Thanks to all.

 

[Buckeyefan 1]

Kram,

I'd suggest cutting and pasting this question over at AVS. There's a few guys that could really help you out. Ed Mullen for one.

http://www.avsforum.com/avs-vb/forumdisplay.php?f=113

http://i19.photobucket.com/albums/b152/tpc3416/Canadian Audio/2006AutoShowB009.jpg

http://i19.photobucket.com/albums/b152/tpc3416/Canadian Audio/2006AutoShowB002.jpg

I did demo a few Paradigm Servo's this past weekend. Pics above. They sounded beautiful with music, but didn't have the same depth the larger dual SVS boxed subs had. There's something to be said about a large, ported design. For the longest time, I was a proponent of big amp, large driver/sealed subs. It's not the case with me - but I've yet to hear an IB design.

 

[WmAx]

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

Sorry, this is not a proper question. The issue has more to do with overall bandwidth and the final room transfer function effects, than anything having to do with the anechoic target function.

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

Servo systems, as a rule, make more difference on poor quality drivers which have poor linearity. On a high quality driver which has a high quality motor and mechanical linearity, a servo will not produce an appreciable difference in typical operation. You would have to drive the subwoofer into ranges where it was deviating from linearity significantly; with moder high quality drivers such as the Tumult, this is an extreme condition in which you would not normally use the driver.

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.

If you are most interested in the 'best' sound for your prefernces, you will do as I do: you will use an efficient, flat response bass alignment with low distortion within the bandwidth that you desire. You will then use a DSP based system to adjust the transfer function to have the 'sound' that you want by adjusting the rolloff rate and the curve shape. You can replicate the signature of any alignment with this technique.

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.

Depending on the size of the cabinet needed for this, you will need to pay careful attention to the modal resonances within this cabinet and the acoustic control methods used internally so far as they relate to the bandwidth in which it is used.

-Chris

 

[kramskoi]

Sorry, this is not a proper question. The issue has more to do with overall bandwidth and the final room transfer function effects, than anything having to do with the anechoic target function.



Servo systems, as a rule, make more difference on poor quality drivers which have poor linearity. On a high quality driver which has a high quality motor and mechanical linearity, a servo will not produce an appreciable difference in typical operation. You would have to drive the subwoofer into ranges where it was deviating from linearity significantly; with moder high quality drivers such as the Tumult, this is an extreme condition in which you would not normally use the driver.



If you are most interested in the 'best' sound for your prefernces, you will do as I do: you will use an efficient, flat response bass alignment with low distortion within the bandwidth that you desire. You will then use a DSP based system to adjust the transfer function to have the 'sound' that you want by adjusting the rolloff rate and the curve shape. You can replicate the signature of any alignment with this technique.




Depending on the size of the cabinet needed for this, you will need to pay careful attention to the modal resonances within this cabinet and the acoustic control methods used internally so far as they relate to the bandwidth in which it is used.

-Chris

Thanks Chris. I assume, for DSP, you're advocating something like the Bassis from Marchand. A tremendous device for the sealed box no doubt, but unless they can offer one at 1/2 the price, it's a no-go for me. The linkwitz transform looks like the only other option. I would prefer to "set it and forget it" and not have to resort to parametrics to boost the low end. I can decide later on if the Bassis is truly needed. From my view, too many options can lead to "paralysis by analysis". I appreciate that some will prefer this though, and it's purely a matter of taste. I would only be interested in Q values below ~.58

I understand the use of DSP, as you explain it, to find the proper room-transfer function but with a budget of 1500.00, that won't be a luxury i can indulge. The driver and amp come to 1200.00+, which leaves less than 300.00 to have the cabinet built. Woodworking and microelectronic skills would make this project easier, but as i have neither, i must travel the hard road.



Thanks very much for your input.

 

[WmAx]

Thanks Chris. I assume, for DSP, you're advocating something like the Bassis from Marchand.

Behringer DCX2496. Superior, far more powerful device. Much cheaper, at about $250.

-Chris