Altec GPA 414-8B Thiele-Small

[HeartFixr]

I have been trying to get accurate T/S measurements for this speaker before I purchase and the search has been elusive. I received T/S data today from GPA that is at variance from other sources. The speaker seems to have good characteristics but before I build a cabinet, I would like accurate data.

From GPA 414-8B
RE 7.28 ohms at 25'C]
FS 25.6 Hz
QTS 0.22
QMS 7.53
QES 0.23
SD 78.54 in2 (0.051m2)
XMAX 0.15in (4mm)
VD 11.79in3 (0.19L)
VAS 9.29 ft3 (263.1L)
No 1.85%

Posted at 41Hz Audio website
FS 29Hz
QTS 0.254
VAS 379.62L


Trying to get good measurements on this speaker has been daunting. Has anyone actually measured it and would care to post their data?? Any references for the T/S measurements?

Any help would be appreciated.

[Alien_Shore]

I have a pair of 414-8C that I've measured if you want those just say.

[Earl K]

I have been trying to get accurate T/S measurements for this speaker before I purchase and the search has been elusive. I received T/S data today from GPA that is at variance from other sources. The speaker seems to have good characteristics but before I build a cabinet, I would like accurate data.

From GPA 414-8B
RE 7.28 ohms at 25'C]
FS 25.6 Hz
QTS 0.22
QMS 7.53
QES 0.23
SD 78.54 in2 (0.051m2)
XMAX 0.15in (4mm)
VD 11.79in3 (0.19L)
VAS 9.29 ft3 (263.1L)
No 1.85%

Posted at 41Hz Audio website
FS 29Hz
QTS 0.254
VAS 379.62L


Trying to get good measurements on this speaker has been daunting. Has anyone actually measured it and would care to post their data?? Any references for the T/S measurements?

Any help would be appreciated.

I realize you figure you are doing "Due Diligence" here ( before box building ) but in my opinion you're fixating on some trivial differences between GPA's published & others TS parameters .
- One shouldn't ever build a box solely on the strength of published data / one needs to measure for ones-self what is in hand .

The thing to do is to take the TS collection ( that you've accumulated ) and start working with an enclosure/speaker modelling program to see what you can come up with ( for all the various permutations & combinations ) .

I highly doubt that GPA has released a driver that is unusable ( due to it having slightly different TS parameters when compared to it's predecessors ) .

[nullspace]

I have a pair of GPA 414-8B, and measured the theile-small #s. A couple caveats: (a) the drivers were tested without any break-in and (b) the testing environment was sub-standard (to say the least) -- drivers lying face-up on my dining room table. My conclusion was that my pair are well within mfg tolerances and GPA's #s are representative. When it came time to use #s for modeling a box, I still used GPA's #s since I think they're at least as representative of the 'true' T/S #s of my drivers as are my clearly flawed measurements.

Here are the averages for my pair:
Re - 6.54
Fs - 32.9
Qms - 7.74
Qes - 0.30
Qts - 0.29
Le - 0.90
Vas - 237.8
Bl - 13.23
Mms - 39.12

Regards,
John

[HeartFixr]

Excellent and good points all arounds. Like trying to count the number of angels on a pin head.
Appreciate the help.

[HeartFixr]

I did measure Thiele-Small parameters and then received the data from GPA.
Re 7.28 ohms
Fs 25.6 Hz
Qts 0.22
Qms 7.53
Qes 0.23
Sd 78.54 in2 (0.051 m2)
Xmax 4mm (0.15inch)
Vd 0.19 liter (11.78 in2
Vas 263.1 liter (9.29ft3)
effective diameter 25.5 cm
Volume displacement 4.8 liters

Hope this is of help to other demented obsessed hobbyists like me

HeartFixr