Can we ignore for now and solve the Bass /Mid xover bit...:S
Can we ignore for now and solve the Bass /Mid xover bit...:S
Let me take a shot at it, so, here goes....
The 414 pair has original Altec cones. It cannot go very low though. I measured close range and this is what it does. By 2K there's a drop of almost 10dB.
Here's the TS spec.
* This data was exported from DATS the Dayton Audio Test System
*
* Manufacturer: Altec Lansing
* Model: 414-16b
* Piston Diameter = 260.4 mm
* f(s)= 55.85 Hz
* R(e)= 11.81 Ohms
* Z(max)= 58.32 Ohms
* Q(ms)= 1.862
* Q(es)= 0.4726
* Q(ts)= 0.3769
* V(as)= 126.8 liters (4.478 cubic feet)
* L(e)= 2.834 mH
* n(0)= 4.458 %
* SPL= 98.59 1W/1m
* M(ms)= 25.49 grams
* C(ms)= 0.319 mm/N
* BL= 14.95
* K(r)= -2.44e-005
* X(r)= 1.237
* K(i)= 8.388e+006
* X(i)= -1.153
Thanks for posting those measurements. I also have a pair of 414-16b. Running them full range in a small box (2cuft). I bring the horn in around 6-7khz with a first order xover. Looking at the curve there I can see that the gentle slope on my horn driver must allow it to cover where the 414 rolls off. I need to get me one of those woofer testersOriginally Posted by jocelys1
.
And yes the 414 does make a good mid. Good luck with your project
Last edited by Elitopus1; October 28th, 2016 at 10:20 AM.
Hmm, based on numerous measured 414s of all vintages, These are 'deader than a door nail'. Fs, Qts is as much as 2x too high and Vas up to 2x too low, indicating the magnets need to be completely drained, re-zapped and/or the spiders are wrong and/or 'frozen'.
That said, in recent years we've learned that Altec, hence GPA, had apparently consolidated its product line to the point where re-coned out of production units had specs similar to yours, so these could be re-cones unless you know their full history that they're OEM and not been 'rode hard and put up wet' one too many times.
GM
Last edited by GM; October 28th, 2016 at 03:05 PM.
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
GPA offers current manufacture alnico 414's. Their T/S specs are pretty close to what one should reasonably expect from a healthy vintage example. But, you really need to measure at least a couple parameters to know that your vintage examples are within spec. Absolutely agree with GM, something is amiss with jocelys1's examples.
http://www.greatplainsaudio.com/down...ec%20Sheet.pdf
FWIW, Bill(GPA) can service the 414 magnets without disrupting the moving assembly.
Not all vegetables make good leaders.
GM and Bowtie: Pls educate me a little on these T/S specs and why they are abnormal. Is the freq response graph also abnormal? Thats what I was most interested in.
I thought the 414 was much stronger up to around 4khz. My 414 speakers sound very balanced with the horns crossed at 6-7khz.
In the meantime I'll go look at the GPA specs again and see what is different
- - - Updated - - -
One thing I noticed is the OP's Fs is 55hz and the GPA 414 Fs is 25hz. Big difference. Its like the surround goop has hardened on the OP's 414's
I would agree with, and defer to GM, that the magnets have been discharged/weak.
Also the Qts is a red flag, classic Altec woofers are revered for their low mass cones and low Qts(almost always under .25) making them well suited for use in all manner of bass/mid-bass horns.
It's about the only thing that can be wrong without exhibiting other obvious symptoms.
Have the suspect woofers been in Switzerland, near Geneva? Watch some time lapse images of the earth's magnetosphere when they have the LHC fired up and compare them to images when the LHC is not running. Scary times. I doubt alnico holds it's charge very long in those parts.
Not all vegetables make good leaders.
It seems like one of our regulars here had a magnet charge issue with a pair of 416's a while back.
Anybody remember who it was, or how we might easily find the thread?
It'd be interesting to compare that OP's symptoms to jocelys1's listening impressions, they don;t go low etc..
- - - Updated - - -
A question or 2 about jocelys1's posted specs.
DID he test both woofers of the pair?
If so, are the posted numbers an average between the two?
Was there much deviation between the two?
The spiders aren't real beefy in these to begin with. It seems like if they had frozen or become abnormally stiff, it would be difficult to get consistent numbers as each sweep would likely loosen them up a bit.
Not all vegetables make good leaders.
Good to know, thanks!
Noticed that in my haste I didn't write up my previous response correctly, so edit is in bold red.
GM
Last edited by GM; October 28th, 2016 at 03:03 PM.
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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