Sanity check

[planet10]

The ApexJr Super 8 has BL measured as 2.287 lb/A.

To use Martin's model i need BL in N/A

with 1 lb-ft = 1.356 Nm and 1m = 3.281 ft i'm figuring

1 ft/A = 4.45 N/A

ie this driver has a BL of 10.175 N/A ??

dave

 

[kelticwizard]

Got a link so I can look up the Thiele-Small parameters on that?

BoxModel will straighten this out.

 

[kelticwizard]

Here are your Thiele-Small parameters via BoxModel.

Bl is 9.18 Tm which I believe is the same as NA.

The numbers in the dark blue I wrote in, (I estimated 200 sq cm for the Sd), and the numbers in the light green underneath BoxModel calculates.

Neat, huh?

 

[planet10]

Here are the measured parameters picked out of the pdf at ApexJr

dave

 

[sreten]

The ApexJr Super 8 has BL measured as 2.287 lb/A.

To use Martin's model i need BL in N/A

with 1 lb-ft = 1.356 Nm and 1m = 3.281 ft i'm figuring

1 ft/A = 4.45 N/A

ie this driver has a BL of 10.175 N/A ??

dave

Should be just a case of converting pounds to newtons,

(1kg = 2.2 lbs = 9.8 newtons)

2.287 lb/A = 1.04 kg/A = 10.2 N/A.

sreten.

 

[planet10]

Thanx Sreten... i've long lost handy access to all those convrsions in my head, and the others were the only quick factors i can find... now that i see 1 kg=9.8 N it all comes back... thanx for the forhead slapping moment

dave

 

[sreten]

You still got the right answer, near enough, sreten.

 

[joensd]

Here´s a handy tool for converting quite a few units which I recently found on the net :

 

[fireman]

Hey Dave, what are you up to with this woofer ?

I meant to build something with this baby a few months ago. Time and money had me put the project to rest for a while. If I get the promotion I applied for, I guess it'll will have to wait 'til I move to my new workplace. Hopefully, I'll then have a real workshop where I can work on my speaker projects.

 

[planet10]

Here´s a handy tool for converting quite a few units which I recently found on the net :

Useful if you are running Windows....

I downloaded an OS X ap called Balance Pro... but didn't find the lbs > Netwtons conversion till just looking now.

http://www.MacDev.ca/

dave

 

[planet10]

what are you up to with this woofer ?

Been thinking about a push-push TL designed to push back into a corner... maybe slap a battery powered clock at the top as a disguise...

Initial numbers are coming up with an awefully small box thou.

dave

 

[fireman]

Useful if you are running Windows....

I downloaded an OS X ap called Balance Pro... but didn't find the lbs > Netwtons conversion till just looking now.

http://www.MacDev.ca/

dave

Thaat's a nice little program ! I had not looked around much but this is definitely a keeper.

 

[MJK]

Dave,

MathCad will take any off-the-wall set of units that you can dream up. You do not have to be consistent with any units, length can be entered in mm and miles in the same worksheet. If you enter BL in lb/A it will immediately be converted into a consistent set of mks units. No challenge is too great for MathCad!

 

[planet10]

MathCad will take any off-the-wall set of units that you can dream up. You do not have to be consistent with any units, length can be entered in mm and miles in the same worksheet. If you enter BL in lb/A it will immediately be converted into a consistent set of mks units. No challenge is too great for MathCad!

Good reminder... at this point i've just plugged it into my spreadsheet version of your tables... the 10:1 taper line is too small for our purpose (and may not even have room to mount the drivers :^)

I also need to extrapolate the existing tables to accomodate higher Qs & Fs (1/2 the drivers i've worked with since implementing the tables don't fit into the range).

dave

 

[kelticwizard]

Why do I get the impression that ApexJr used the "include half the surround" method of calculating Sd?

The excursion is not that large-about average. How come the huge surround?