Peerless XLS vs XXLS (as dipole)

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Hello,
Any comments on using Peerless XXLS (830843) instead of XLS (830452) in twin dipole (like orion etc)?

AJinFLA posted in this thread that is might be suitable, but certainly no specifics were discussed.

Whilst retaining a high x-max, XXLS has increased Qts from 0.17 to 0.44. This is still below 0.5, but I'm quite aware SL for example recommends a low Qts. Eg compared to SLS, XLS has a long throw, and its very low Qts can be compensated with severe equalisation. Now the XXLS has a long throw, but additional differentiation comes from XXLS having higher Fs (25 instead of 18.9 for XLS) and a huge Qms(9.03) (why, I don't know).

Clearly I would need to use less equalisation: but this would be an easier speaker to drive, and given it is for music use, very low frequencies are not important. Question being: what disadvantages would I have using XXLS, and would it be a less musical speaker (given crossing to a W22 requires it to perform bass in addition to 'sub' duties)?

Would be very appreciative of any comments! Thanks :)

[I did post this on a board where a few dipole builders post, but not heard anything so far - I expect I'll be shot by one of the people who I know post on both]
 
Aluminum XXLS?

Would you consider the new aluminum XXLS ( 830951 ) that has a Qts of .3, and Fs of 20.8 on top of Tympany's claim of "completely eliminate distortion".

http://www.tymphany.com/datasheet/printview.php?id=320

In the states, Madisound has the 10 inch listed for the same price as the 830843, but not the 12 inch version yet, so it appears to be available.

Anyone else use this new driver and have any feedback?

Tom
 
You may want to look at my page of eqing gradient woofers. http://www.musicanddesign.com/Gradient_woofer_eq.html

The XXLS will work fine, particualrly if you can accept a cut off of 25 Hz, the driver fs. The Qts is sufficiently close to 0.5 to allow use of the eq methods for woofer with Qts greater than 0.5.

The use of low Qts woofers can be advantageous as long as a Qt = 0.5 target is desired. All that is required is shifting the poles to the desired cut off with 1st order shelving filters. The problem with this type of eq is that with a low Fs, low Qts driver, like the XLS, the lower frequency pole is around 5 hz. This means that the eq'ed response will have a 2nd order roll off from the system cut off to this pole. That seems like a good thing until it is realized that with a gradient woofer the excursion goes like 1/f ^3. Thus a 3rd or higher order roll off below the system cut off is advantageous from the point of view of protecting the woofer from over excursion. The trade off is greater group delay.
 
Hi,

Nothing wrong with "huge" Qms, I'd regard it as rather good.

Qts of 0.44 is a far more sensible starting point than 0.17
IMO, and more than makes up for the slightly higher Fs.

:)/sreten.
 

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Hi guys, all three of you were very helpful with that...

Nice to have confirmation I hadn't missed something small but fundamental in considering that speaker: I'm just making final decisions on the possibility of the aluminium driver suggested. John, I'd noticed your use of these drivers, that was one thing enouraging me to pursue replacing SL's choice.

I'd seen the aluminium (830951) before, and like the idea of continuing metal cones (seas excel) down to the bass dipole. The problem is I'm working on a twin dipole and the aluminium driver comes only in 4ohm flavour, so x2 I've 1.5 for Zmin. I need to work on 10" not 12" driver, and I don't think a single 10" will shift enough air (and don't want distortion as this speaker will play above the 'sub' range).

The aluminium therefore needs a much more tollerant amplifier :/

By contrast, the break up is 'better' (as was pointed out to tme off-forum), and it might even allow for a less steep crossover despite the extended frequency range I'm going to need this to cover before W22s take over. Without financial consideration for amplification, I would certainly have four aluminium 10" on order!
 
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