Altec 3-way active

[Elitopus1]

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 testers.

And yes the 414 does make a good mid. Good luck with your project

[GM]

Let me take a shot at it, so, here goes....

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

[bowtie427ss]

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.

[Elitopus1]

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

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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

[bowtie427ss]

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.

[GM]

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.

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

[bowtie427ss]

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..

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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.

[Elitopus1]

All the factory coned Altec's I have had have had a very loose suspension. I know my 414 are pretty loose but could benefit from a good surround cleaning. It would probably lower the Fs slightly closer to where they should be. Of course I don't know where exactly they are right now because I don't have a woofer tester

And thanks for clarifying that guys

[GM]

Pano had a costly bit of a nightmare with a pair of 416As, which he only posted a glimpse of here. It was quite an eyeopener for us and judging by what you and a few others have posted since then, Bill has apparently 'gone the extra mile' to hopefully keep it from happening again.

GM

[jocelys1]

Greg /Bowtie...thanks for your views. It is quite an eye-opener and plenty of lessons learnt. Let me try answering some of the questions.

I was told these were untouched vintage units sitting in a warehouse the past 20/30 years, not sure how long back.

This was the specs from a single unit, of which I have four, will post the remaining spec's as well. I'm using the pair that match closest.

I'm writing from India, so, GPA is out of the question.

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The close miked response from all four.

Can the units be remagged without removing the assembly ? That's good news indeed.

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Elitopus, a friend who has plenty experience said the same thing - run them till 6K, but looks like the units I have can't really reach 6K.

On the flip side, could my measurements be incorrect ?

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Here's the TS specs of all four:

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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.

Bowtie, the spider, surround and cones are VERY stiff, with age or a suspect recone I cannot say. I've been running them in an OB, limited to -6dB at 80Hz , the past few weeks to get an idea of what they can do. Have a pair of woofs below that. They still sound fantastic.

So, I'll measure them again in a day or so.