Ripole subwoofer, help needed a little

[matsuru]

Hello there, i need a pair of subwoofers for bookshelf speakers, and though about building a ripole desing.This would come to a 15m2 student apartment and they will be only for music, so no bone crushing volumes used, the sound quality will be priority.

I thought about using Feedbackdestroyer as an EQ to controll some room modes.

After reading some posts, i think that Peerless SLS12 might work as ripole pair nicely, they said SLS series 8" 10" 12" might be one of the best drivers at least here in europe for this kind of setup. Besides i heard that a sub made out of SLS10 was better at music in a close box, when compared to xls-12 in a closed box, althought offcourse didn't play as deep but what played was integrated to mains very nicely.This is now important if this ripole won't work in the end properly, so i will just do common closed boxs.

SLS10, QTS 0.51 and for SLS12, QTS 0.47

http://www.tymphany.com/datasheet/printview.php?id=38
http://www.tymphany.com/datasheet/printview.php?id=37

4-Drivers, 2 at each box in a ripole confiquration, like they do at audioelevation http://www.audioelevation.de/attac_400.htm

do you think that for a output, 35hz at 85-90 db would be possibly?

Help, comments, critique or link to an existing project would be greatly appreciated!

[matsuru]

Oh yes, second thing that someone told me about SLS drivers on general:

"Personally I wouldn't use a driver that has 8mm of Xmax in this application. The suspension travel is all one has in a dipole, so the longer the travel the better.

My suggestion is use something that has no less than +/-14mm Xmax, and double that is better yet."

So is SLS actually good for dipole because it is cheap, and you can use many drivers for the money? I have space as a limiting factor here, so i think that four 12" as two pair of ripoles are the biggest i can go, or maybe just maybe four 15" as two pair of ripoles.

do i really need these kind of heavy load to achieve around 30hz dipole bass?

[Calvin]

Hi,

playing the sub in a small 15m² room a pair of SLS12 or a quad of SLS10 are very ok.

Forget what "someone" told You, because it will be hard to find a driver thats able to move more than the Peerless´s +-8mm linearly and without creating noise. Additionally such drivers usually need a huge magnetical circuit. So the dimensions of the dipole (width) will increase substantially. Additionally such drivers usually feature very heavy moving systems with high values of inductance and relative small magnetic field forces. A prime measurement to create a bad sounding device and one with a extended stray filed that disturbs every TV/monitor in close proximity.

The SLS festure an excellent set of parameters together with a very affordable price. I even would prefer them over the XXLS series, because -apart from the linear stroke and optics- they outperform their much costlier brethren and any other driver I came across yet.
Since space is small -and money too I guess- a dipole with a pair of SLS10 could already be sufficient. Anyhow, since the SLS12 doesn´t cost much more and doesn´t build much bigger I´d prefer to use this driver, as it should meet all Your requirements best.
Because of its greater diaphragm area and higher Qt the SLS12 can generate higher SPLs i.e has greater reserves or lower distortion numbers.
A dipole featuring a parallel connected pair of SLS12 could have the following dimensions using 22mm MDF-board.
W: 360mm H: 390mm D: 340mm
Chamber front: W: 80mm
Chambers rear: W: 96mm
The Fs of the driver drops to 20Hz in zthis configuration.
Using a passive filter/EQ -which I strongly recommend- the Fs drops to ~16Hz and the response is linear between 21Hz-195Hz (F-3dB, nearfield).
Impedance stays above 2.7Ohms
Max. linear stoke is reached at 9.5V@20Hz, 17V@30Hz and 28V@40Hz respectively 20W, 70W amd 200W@4Ohms
An active subsonic-filter is strongly recommended.
The SLS-drivers feature a progressive suspension that makes them nearly mechanically indesctructable, but with drivers working under free air conditions like dipoles, BR, BL-Horns, etc. a subsonic is a very sensible device.

jauu
Calvin

[AJinFLA]

Oh yes, second thing that someone told me about SLS drivers on general:
"Personally I wouldn't use a driver that has 8mm of Xmax in this application. The suspension travel is all one has in a dipole, so the longer the travel the better.

My suggestion is use something that has no less than +/-14mm Xmax, and double that is better yet."

That person knows what they are talking about.
For dipole subwoofers, it's very simple. Output is determined by swept volume (Sd x Xmax) and path length (between the acoustic short circuit). Path length is purely a function of the enclosure. So the only relevant driver related parameter is swept volume.
Using the Peerless drivers as an example, both the SLS12 and XLS12 will have roughly the same Sd. The difference is Xmax. 12.5mm vs 8mm (forget the superior lower distortion motor system for now). The XLS will sweep more volume. It (one vs one) is superior to the SLS for dipole bass. It will handily outperform the SLS in any given enclosure. Period.
If you can get 2 SLS's for the price of 1 XLS and don't mind a larger enclosure, then go with the SLS.
I've tried the SLS12 in a dipole, it bottoms and distorts so quickly, it's completely useless, unless used in large numbers. Which means more enclosure volume vs the same number of XLS drivers.
The only benefit would be cost. They are less than the XLS or XXLS.
If you can comprehend who Siegrfried Linkwitz is http://www.linkwitzlab.com and understand what level of knowledge and expertise he has, then you might understand why he chose the XLS drivers for his projects.
Ditto for John Kreskovsky http://www.musicanddesign.com (XXLS)
If you can't, then listen to the self anointed "Internet experts" who know far more than these two gentlemen and go with whatever they recommend. It's your money.


cheers,

AJ

[vadi]

Hi!

Are there any woofers with very high Xmax (higher than XLS) that make no noise?

[Calvin]

Hi,

oh my gosh, just another one who lost :-)

At the time SL constructed his dipoles the XLS was probabely the best possible driver for a dipole, but it isn´t any more and I´m very sure he´d use other drivers nowadays.

The XLS has two major drawbacks for use in ripoles:
- 1. too low Fs. Since a Ripole lowers the Fs even more You´ll end up with an Fb ~13Hz!!
- 2: too low Qt. Since there is no Q-raising mechanism as in CBs or BRs the optimum value for Qt should be in the range 0.5-0.7
Additionally such a low Qt (SLS~0,2) demands heavy equalization of the freq-response, because of low linearity. A pair of parallel connected XLS is 4,5dB lower in SPL @20Hz as a pair of SLS in the same cabinet. So its superior throw isn´t of real use down here.

The SLS on the other hand are nearly perfect with regard to those parameters. Also they feature lighter moving systems, which prooved to be sonically advantageous in dipoles. Having tried those drivers as well as many others, I can just repeat that they work better in ripoles than any other and clearly better than the XLS. Much more practical (in a lot of cases You could even cross over passively!) with higher linearity, Fb at the right point, and much less need for equing.

In short: When sounds matter.....try the SLS....when prize matters...try the SLS....when practicability matters..try the SLS.... When prize doesn´t matter use multiple SLS....Point!

Oh BTW. Not having a Website doesn´t mean You´re plain stupid.

And as AJ said: Don´t listen to those self appointed Internet Experts....and I might add:......who haven´t had any experience yet with ripoles but lost in building working stuff

jauu
Calvin

[454Casull]

http://www.linkwitzlab.com/faq.htm#Q34

How has lighter Mms proven to be sonically advantageous in dipoles?

[AJinFLA]

How has lighter Mms proven to be sonically advantageous in dipoles?

Its on Calvins vast website Calvinlabsanddesign.com
The technical dissertation and extensive blind listening tests are there for all to see.
There you will also find his AES papers, the Calvin-Riley crossover used in most pro speakers, the Calvin Transform used to extend bass response in large numbers of commercial subwoofers, his decades of dipole research and speaker systems, his studies on ripole vs monopole vs cardioid inroom response and on and on it goes. Check it out.
He's the real expert here. Buy whatever he says. Put on a nice pipe organ track, crank the volume and listen to the wonderfully musical cracking, of an 8mm xmax dipole drivers voice coil, crashing against the backplate. Enjoy!


cheers,

AJ

[AJinFLA]

Help, comments, critique or link to an existing project would be greatly appreciated!

Matsuru,

to answer your question, here are a few: http://www.linkwitzlab.com/proto.htm#PW1
"Craw built as an H-frame dipole" http://www.musicanddesign.com/craw.html
http://www.euronet.nl/users/temagm/audio/dipolesub.htm

A so called "Ripole" is no more than a compact dipole. That's it.
It's in room behaviour will be exactly like the velocity source that it is. No more, no less.

cheers,

AJ

[Calvin]

Hi,

@AJ
We agree in disagreeing...so far so fine. It´s just a pity that You didn´t have the class not to respond on a personally insulting level.
We have an interesting phenomenon in forums like this one. Everybody who runs a website is automatically regarded a competent person, somebody who doesn´t is not. I won´t disclose why I don´t run one, but to be cynical about that without knowing my experiences or expertise is rather insultive and stupid than funny.
At least was and am I able to give matsuru clear construction details with predictable results instead of just quoting others´s websites.
Where´s Your solution to matsuru´s prob Mr. AJ? Did I miss it?.....oh no, I just forgot....You don´t have any experience at all with the ripoles. So how the **** do You think You are the person to critisize others experiences, products or projects in such a rude way?
And yes, the ripole is a compact version of a classical dipole...so far You´re right. But You just missed out on how this difference in size effects the drivers and what it is used for.

@rest
I know that theoretically the mass of the moving system of a driver shouldn´t play any big role within the working freq-range.
Over the years experience showed (and it´s not my experience alone) that drivers with high moving masses -for their size class- never gave really good sounding ripoles. The ones with light to mid-weight sytems were always preferred. So this answer is a matter of experience and taste not theory and numbers.

jauuu
Calvin