x1 sub with rcfl18p300?

Hiya Thanks for the input. The Qts of the RCF isnt MUCH higher-and is still certainly in the range to be used for BP6. Perhaps not optimal however-but regardless it models similar to SD18.

Ofcourse Power compression is more readily apparent with lower Bl drivers.

really! i didnt know about this new Xmax measurement! Certainly it must comply with DUMAX specifications????

Should i email all respective speaker companys to see who complies with DUMAX -and who responds ! ;-)

Hmm.. For me a Qts of 0,26 or 0,35 is a respective difference. BL is a major difference. In the old forum Rog dis-advised to use the RCF in 6th order bandpass. Wigge says it doesn't sound good in a X1. WinISD shows a warning, that it's not suited enough for calculating 6th order. So my conclusion would be not to use the RCF in a X1.

About the Xmax: I've e-mailed 18sound about it, as they are the only brand, that actually shows the used "new" calculation in the specsheets, off course I didn't get any response. Well, returning e-mail doesn't seems to be usual for a lot of companies anyway, so if it means something?

A lot of brands give a Xmax in the specsheet, that you won't be able to calculate back. So if possible always calculate Xmax yourself.

Among these brands (which I noticed for so far) are RCF, 18Sound, B&C, DAS, Beyma and even PD. They don't use it always tho. P.Audio seems to add a little bit extra now and then, not always and most time not as much as the others. SD-18 for instance gives the true Xmax (5 mm). Calculated the new way it would be something like 9 mm. Sounds much cooler don't you think.

Didn't spot it on Ciare and BMS yet. And didn't find the required information on the Voids yet. Neither on Eminence, tho my guess is that they are using the the old calculation. Otherwise some speakers would be really crap .

A way to explain the new calculation is the fact that some models have way thicker poolplates now and thus will have more control. Also the lost of control by exceeding Xmax will be slower.

The other explanation is off course the marketing department going nuts.

Didn't discover it myself tho, Contour pointed me at it. I just checked a lot of speakers.

If you can read Dutch:

http://www.speakerstore.nl/htm/xmax.htm

Cheers

Elliot-its inbuilt into winisd pro-when you enter parameters it tells you -its a REALLY simple formula-simpler than the above link.

"Max linear excursion, usually calculated as abs(Hc-Hg)/2"

Hc

Height of coil.

Hg

Height of airgap.

Mobiele-atleast if the real Xmech is high theres no problem with destruction ;-) And the Xmax semantics can be largely forgotton +-30% no worries.

Apparently Hvc defined xmax, * 1.15 for DUMAX Xmax-approximately.

 

hahaha - my JBL M151 have no overhang (don't believe are underhung) and are rated 6.4mm xmax

my Altec 421 have ~ equal winding length to gap height and play imo cleaner up to 0.12" peak than some 6mm rated stuff
Selenium uses a 10% distortion figure (relative to what???)

mush - mush!

<ramble>

All marketers should die (slowly and painfully). Speaker manufacturers should disclose complete Kippel, DUMAX and/or other non-linear metrics. As it stands at the moment, the PA branch is starting to go the way of car-audio, and it's not pretty. Most manufacturers are too affraid to show their products for what they are, even the much touted 18-Sound (who propogate their warez as the only real thing and not give out manly specs? hehehe, what a bunch of )

</ramble>

There is some method behind the madness of the pole-plate thickness, but this varies between designs and the only way to know, is to see BL/excursion and KMS/excursion curves (like Adire for instance) along with other metrics. Distortion plots at 10% of Pe in sensible usage situations with a clearly visible percentage scale would be a big plus too. This is how the industry wil advance  (but I'm affraid sound doesn't matter to bean-counters in the least so one wouldn't expect anything to happen...arghhhh)

*hernia alert, automated shutdown initiated*

Martin

Timber_MG wrote: <ramble> All marketers should die (slowly and painfully). Speaker manufacturers should disclose complete Kippel, DUMAX and/or other non-linear metrics. Martin

 

You know this will never happen. Most of the bigger companies have used their methods of measurements for decades. I've even seen Beyma starting the use the AES spec to inflate their wattage.

Best Regards,