Altec 414 in sealed enclosure..

[vuki]

Hi,

I don't know what Po/C is used in Clio software...
I didn't know the exact Sd either, so I used some values I tought could be near the actual value.
When measuring with Clio's "added mass" method the only parameters one can change are driver's diameter and added mass. Every other parameter is measured/calculated by Clio. In my measurements I used exactly 20g.
I will measure it again with even more added mass to see what happens. I'll also use Sd=505cm^2 and report results.
Regards,
Vuki

[vuki]

Hi GM,

you're absolutely right! I made measurements using Clio's "added mass" methode, but I inputed wrong mass value (1/2 of actual mass). Sorry! So here is what I got in repeated measurement. It could be the other driver from the pair so fs and some other (non "added mass" related) values might be slightly different.
I'm really sorry I caused this confusion.


fs 36,7Hz
Qm 3,5
Qe 0,35
Qt 0,32
Mms 39,9g
Vas 198 l
Cms 0,48mm/N
BL 17,4N/A
L(1k) 3,2mH

Regards,
Vuki

[vuki]

Today I made new measurements and used Sd value 505cm^2.
It seems the temperature also plays a role - today it's hot in here - (yesterday 23C, today 26C)and Fs is 1Hz lower! Vas changes with different added weights from 170 - 178 l, so that's less than 5%. But, it seems to me that all these variations don't affect box calculation by significant margin. If I'm to do a box I would make it ca 120lit and than play with BR tuning between 30-45Hz to get nice in-room bass response.

Regards,
Vuki

[GM]

Greets!

OK, this set calcs between 17.9685-18.0957 N/A and Mms 41.35 -41.94 grams based on my reference. Now that we know 'c' is measured based on time of flight and 'po' is fixed at 1.18, falling well outside the apparent norm for whatever reason, I calc c = 344.7382/346.4808 m/sec for 23/26deg C, or 17.8865-17.9769 N/A, Mms 40.9767-41.392 grams, Cms = 0.0004777-0.0004730 mm/N. Still off a bit, but 'close enough'.

Right, for designing a sealed cab these differences aren't a big deal, but I've had such good correlation with theory and other's CLIO, MLS, and my own measurements that my 'picking' at you was mostly about giving you a baseline to increase your measuring proficiency for when you need it.

Anyway, thanks for the specs, effort!

GM

[vuki]

Thank you, GM!

[Barossi]

Hi,

thanks a lot! Yes, i would like to build a sealed enclosure for the Altec 414. I would like to use them for an active System with the active crossover: Behringer UltraDrive Pro DCX2496, digital loudspeaker management system.

The drivers are: 288, or 806a
The midwoofer: 2* Altec 414 sealed box from >60Hz
The Bass: Klipsch khorn

Crossover frequenties ~ 60 Hz / ~500Hz

Which enclosure volume will fit for the 414 from 60 Hz?

Or should i build an open baffle?

Greetings Barossi

[vuki]

Hi Barossi,

I think that anything between 50-80 liters would work. It depends on the desired Q, poweramp output impedance etc. But, regardless of the chosen volumen, the driver would be already at least 6dB down at 60Hz. Since you would be using Behringer perhaps that won't be a problem.

regards,
Vuki