Hey all...

I've just been having fun trying to find DUMAX reports for some of the most common subs that get stated as being 'SQ subs' just to see how the heresay holds up to cold hard facts Does anyone know anywhere where you can get DUMAX's for modern subs? I could only find a few, most of the ones around are for pre-2001 subs

Anyway, have a nosey, its very interesting, heres a few popular models :

JL 10W7 : Lovely flat motor strength and suspension strenght vs excursion Yum


IDMAX : Motor isnt horrendously linear but thats one hell of a flat responding suspension


DD 9500 : Got some wicked motor strength going on in there... but the motor strength vs excursion is a bit... :?


Brahma : I love XBL^2 Flat as a ruler response through pretty much all of its usable range... theres a reason i'm going to stick to XBL woofers from now on (from either Adire or RE or anyone else who does 'em )

dumax isn't everything, but for low frequencies and high output linearity, it gives yo uan idea of how the driver will hold together.

I know its not everything, but its nice to actually see some hard proof of the claims manufacturers make Lots of companies claim 'low distortion output at high volumes', but its nice to see which ones are actually doing it

Have you got DUMAX's for the RE XXX Ben? I couldnt find one, i'm just interested in seeing how it compares with the Brahma, with the XXX having a higher BL

Dumax tests are bogus, moving a cone with air pressure does nothing to show how a woofer can control cone motion under it's own power.

Virtually no-one in the Pro Audio arena gives them any weight. You can build a driver so it looks killer on Dumax, but sucks ass in the real world.

If you want to know how a woofer performs, listen to it!

Phil

Doesnt it? Its only telling you the linearity of the motor BL field and the suspension, whats not easy to understand about that?


Then i suggest you're hanging round with the wrong 'Pro Sound' guys, most pro sound guys and DIYers that i know of think of them as a useful tool for cutting the crap...


Indeed you can. But it doesnt work the opposite way the same : If a driver sucks ass in the real world, its very likely it'll suck ass on a DUMAX report.

It seems interesting that, by and large, the only groups who complain about DUMAX style reports are the companies and people who's drivers dont look so crash hot when tested on one...

BTW, i've used the DD's, W7's and Brahma's, and have heard IDMAX's, and the way they sound when listened to actually fits the picture the DUMAX paints... the W7's and Brahmas DO keep their SQ at high volumes, and the DD's DO have massive output power but slowly dropping control as the volume increases I know you'll have a go at me for saying that, but i sell all three brands of drivers, love DD woofers to bits, and have no axe to grind

Dumax reports ARE NOT bogus.
sure their application in the real world is different to that on paper,
but if a woofer is moved by air, it'll create electricity through the coil.
it'll create the same electricity (minus some losses) as the amount of amplification required to move the cone the equivalent amount.

even if the magnitude of the electricity varies due to being powered by air, the delivery of the electricity across the excursion range will be the same anyway.

these charts prove the theory of long gap, short coil subs. and show the shortfallings of long gap long coil subs.

BL isn't EVERYTHING, i mean having 30Tm of peak BL, is useless when it drops to 15 after less than 10mm of excursion!

Phil, that's a great point, but how many good woofers are around which aren't on display, OR aren't demonstrated to their full potential. i mean, if someone had a brahma on a demoboard, what's the chances that the store employee will throw 1000WRMS at it to demonstrate it's linear xmax?

leaving you to search for a woofer installed in a vehicle... and what's to say that's tuned properly, or has the same transfer function properties of your vehicle?

any piece of info which might help us to determine the differences between woofer is beneficial IMO

The loads on a cone/coil are dynamic not static.

Taking measurements at rest are meaningless, compared with a cone/coil moving 50-80 times a second.

Phil

Phil just doesnt like dumax because DD didnt come out on top

That has nothing to do with it.

Phil

Sure

You can't tell you that moving a cone back and forward with compressed air, can tell you anything about how it behaves real world with 2000Wrms.

The Dumax does nothing to factor in the massive inertial and dynamic loads that occur in a speaker coil/cone that stops, accelerates in the opposite direction then repeats this procedure 40-160 times a second.

Phil

What ever in a Dumax report is not that important at all. Most important for a sub woofer it must sound stressless and be able to blend perfectly with your front split. That is what SQ sub is what about. Not on a paper of how good they are.

I personally have heard lots of good sub. But most of them was never tune in line with the front split.

I do have this problem blending them in perfectly, it take time and lots of listening from home system sub. How a note of a string goes right down to the bottom. It must joint in perfectly.

Is there a Dumax report for a 91XX series DD woofer? They're the SQ optimized ones aren't they?

DD don't use Dumax as it is a flawed test. Measurements taken on static loads have nothing to do with real world dynamic loads.

Have a listen to a 91xx if you want to know how it performs!

Phil

Id like to see a dumax test on a 3512, thats the only dd woofer ive heard before. I think the dumax report would reflect my opinion of how it sounded.

That said the dumax reports dont really mean a whole lot in regards to car audio as there are more important factors in the sound than the actual woofers distortion (sound quality wise, for spl who cares about distortion :S).

Dumax reports are alot like any enclosure calculating program you could say, they give a good impression of how the speaker should sound everything being perfect, but in the real world it can be very different.

The sub enclosure is as important as the woofer itself, this is often overlooked also.

Another problem I see all the time, someone will tell me the sub is "boomy" or "muddy" whereas the real problem is often the crossover point, phase, level and lack of midbass.

Phil