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BHearon
01-13-2013, 07:41 AM
I know that this has been posted before but finding consistent data is frustrating. Altec 414-8B uses a ferrite magnet and the 414-8C uses an Alnico magnet. The Thiele-Small measurements are different but finding which is which is confusing. GPA has not been very responsive in sending this information. Google search has directed me to different sites with varying data. SPL sensitivity for the 414-8B is slightly different from the 414-8C (or not depending upon the source).
Any help would be appreciated. Hard to design a box enclosure without accurate Thiele-Small data.

speakerdave
01-13-2013, 08:39 AM
Which version do you have? The 414-8b has an Alnico magnet. I've seen it debated whether the c is Alnico or not, but the data sheets do say Alnico. That does not mean they are not different, of course. Have you posted this question (or done a search) over at the Great Plains Altec user's forum? They are deeply passionate about Altec there, and your question will enthuse them for days.

The best thing would be to test your own woofers and use those numbers.

The Woofer Tester 2 from Smith and Larson is recommended over the WT3 from Parts Express. That is NOT a successor product from S&L but is rather an imitation product which many users have found does not work well.


I know that this has been posted before but finding consistent data is frustrating. Altec 414-8B uses a ferrite magnet and the 414-8C uses an Alnico magnet. The Thiele-Small measurements are different but finding which is which is confusing. GPA has not been very responsive in sending this information. Google search has directed me to different sites with varying data. SPL sensitivity for the 414-8B is slightly different from the 414-8C (or not depending upon the source).
Any help would be appreciated. Hard to design a box enclosure without accurate Thiele-Small data.

BHearon
01-13-2013, 10:18 AM
I don't own it yet but an trying to get the data. On eBay, GPA has listed both 414-8B with Alnico mag weighing 20 lbs (price $330) and 414-8B with ferrite magnet weighing 22 lbs (price $240). What is the difference between them and the 414-8C? I spoke with GPA and he said the only difference was the magnet and the T/S data would be the same Alnico vs ferrite. There is quite a bit of difference between the T/S data for the 414-8B vs 414-8C. Since the T/S data is so different between the B vs C, I want to know before I start building the cabinet.
Great idea on posting this on Hostboard.

Thanks

Earl K
01-13-2013, 02:51 PM
According to GPA, (http://www.greatplainsaudio.com/) the new production ferrite and AlNiCo 414s share the same T/S#s. Here's what they sent me:

RE 5.80 Ω (23◦ C)
FS 26.6 Hz
QTS 0.21
QMS 5.84
QES 0.21
SD 81.71 in.2 (0.053 m2)
XMAX 0.15 in. (4 mm)
VD 12.26 in.3 (0.2 l)
VAS 10.49 ft.3 (297.0 l)
ηo 2.52 %

I have a pair of the AlNiCo, but haven't yet had a chance to see how close mine match the published specs. I do have a box built, though...

Regards,
John

Measuring the drivers was on my to-do list for the long holiday weekend, but since it's a timely topic I managed to get them done today. Here is the average for my pair:

Fs 32.385 Hz
Re 6.8 ohms[dc]
Le 308.76 uH
L2 999.405 uH
R2 19.09 ohms
Qt 0.315 -
Qes 0.325 -
Qms 7.82 -
Mms 30.765 grams
Rms 0.7996765 kg/s
Cms 0.000806 m/N
Vas 295.295 liters
Sd 510.71 cm^2
Bl 11.4663655 Tm
ETA 2.905 %
Lp(2.83V/1m) 97.44 dB

These were made with ARTA using the added-mass method. When measuring drivers on their back pointed up (so I can just lay four nickels on the cone), I find that both Fs and Qts tend to measure on the high side. And, these are fresh out-of-the-box -- no break-in. So, FWIW, YMMW, and all that... but GPA's published #s appear to be about right to me.

Regards, John



Taken from here ! (http://www.diyaudio.com/forums/multi-way/200801-414-8a-alnico-8-ohm-t-s.html)

:)

BHearon
01-24-2013, 07:12 PM
I finally heard back from GPA today with their T/S measurements.

Re 7.28 ohms (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 11.78in3 (0.19L)
Vas 9.29 ft3 (263.1 L)
No 1.85%
These measurement are different than any that I have seen elsewhere. Any comments or suggestions as to which I should believe?

cerondipity
04-09-2015, 06:11 AM
I know that this has been posted before but finding consistent data is frustrating. Altec 414-8B uses a ferrite magnet and the 414-8C uses an Alnico magnet. The Thiele-Small measurements are different but finding which is which is confusing. GPA has not been very responsive in sending this information. Google search has directed me to different sites with varying data. SPL sensitivity for the 414-8B is slightly different from the 414-8C (or not depending upon the source).
Any help would be appreciated. Hard to design a box enclosure without accurate Thiele-Small data.

Old thread but others will follow for the information so let us get it straight without debate-

I have owned all of the 414 incarnations and the "A" ("Z" designation without the rear magnet trim cover), "B" and "C" are all Alnico with slightly different Theil-Small parameters like QTS, FS & DbW efficiency. The "E" series is the one with the ferrite magnet. They have a much larger magnet and do not have the 'two step' rear magnet housing of the "B" and "C" versions. The major change was in efficiency and FS from the higher efficiency "A/Z" version to the slightly lower efficiency DbW/FS "C/E" version which despite a different magnetic material shared similar specs, noted by GPA.