Altec 416-8b woofers

[Mercury3]

Hey everyone,

I started to post about these woofers in my other posting for a MLTL design but decided a separate thread devoted to these woofers might be better.

I've four of these woofers and recently tested them with DATS and was quite disappointed. All four woofers tested off from what the specs are suppose to be. Two were pretty bad with the other two not as bad:

fs: qts:
40hz .56
39hz .54
30hz .3
27hz .26

I've a 416-C to test against so I know the DATS is giving me pretty close readings.

Its my thought the magnets need recharged which would explain the high qts but not the high fs.

I spoke with Bill at GPA and I've sent all four in to be reconed and have the magnets recharged. For the benefit of others I'll post the results when I receive them back.

In hind site had I known the Alnico Magnets can become weakend if over driven (what I suspect has happened to these) I might have selected the "C" model over the "B"

At any rate even if I don't end up using these 416-b's I couldn't bring myself to sell them without having them fixed first.

Does anyone have any thoughts on how much power one can safely run on these without fear of weakening the magnetic field strength? More the reason I see for running two per channel vs one. I'll be running mine with a PassLabs XA30.8 which can hit about 150 watts pk. so be about 75 per woofer pk. I do realize amps can do a lot more when driven to clipping but I don't abuse my equipment. I do however like to crank it up a bit every now and then.

Any thoughts appreciated and I'll post the results when I get these back from GPA. That way any others considering the same have access to this info. I suspect there are a whole lot of 416-b's out there with weakened magnetic fields.

Mark

[Elitopus1]

I?m curious to know the answer to this also. I drive my AlNiCo drivers with high power SS amps and don?t want to push them too hard either.

I?m curious which would happen first, mag loss or VC damage. Assuming a normal Altec/GPA VC is being used.

[LOUDER]

If it was I, and it's not I would've sent Uncle Willy just the two way out of spec 416's so we all could have seen what the difference of a remagging does since you have the test equipment. Remember the value goes down once you don't have the original cones. Plus it will save you some money. If the remagging works get the other two remaged since he'll have all four anyway's.

[bowtie427ss]

I do realize amps can do a lot more when driven to clipping but I don't abuse my equipment.

I just have to know, are you implying/insinuating that driving an amplifier to clipping is abuse?

[Mercury3]

I just have to know, are you implying/insinuating that driving an amplifier to clipping is abuse?

Would "abuse" be the wrong term? I'm a bit slow are you being sarcastic?

Anyway in home audio I would think so.

- - - Updated - - -

If it was I, and it's not I would've sent Uncle Willy just the two way out of spec 416's so we all could have seen what the difference of a remagging does since you have the test equipment. Remember the value goes down once you don't have the original cones. Plus it will save you some money. If the remagging works get the other two remaged since he'll have all four anyway's.

Good idea but I figured I prefer if they all match. I think we should be able to tell when I measure them all once I get them back. I'm a little concerned to find out.

[Elitopus1]

I’m curious how close the woofers test after GPA is done with them.

Re amp clipping: I always drove my pro amps into light clipping doing small shows for the band that I was in. And even at home when I had less efficient speakers. No amp or speaker damage ever occurred. If you drove the amps into heavy clipping I would think the speakers would be damaged first, as your nice sine wave turned into a squarish wave.
The amp should be able to handle a square wave. Hell, I’ve heard you can weld with an Ashly amp.

Lol, just thinking about it. I used to turn my amps up into clipping and then turn them down slightly.

[Mercury3]

I?m curious how close the woofers test after GPA is done with them.

Re amp clipping: I always drove my pro amps into light clipping doing small shows for the band that I was in. And even at home when I had less efficient speakers. No amp or speaker damage ever occurred. If you drove the amps into heavy clipping I would think the speakers would be damaged first, as your nice sine wave turned into a squarish wave.
The amp should be able to handle a square wave. ****, I?ve heard you can weld with an Ashly amp.

Lol, just thinking about it. I used to turn my amps up into clipping and then turn them down slightly.

I think that make sense in terms of Bowtie's remark. Hence some clipping may not be considered abuse. Given you're reply then yes I probably have done the same. I should have worded my remark differently. It may be almost normal to drive an amp to some clipping during dynamic passages. I was thinking more in terms of grossly over driving the amp.

[Todd W. White]

Just remember that ALL Alnico magnets lose magnetism over time, not just from being overdriven. It is also possible that the two that are so far off might not have original factory cones in them. There are a lot of counterfeits out there. Further, all speakers can be negatively affected by heat and humidity, as well.

Also - Some Thiele-Small parameters are derived from mathematical formulae using information acquired during direct measurement of a loudspeaker. In the late 1980s, while working with Mr. Jerry K. Hubbard, then head of Altec Lansing's Acoustic Laboratory, he and I discovered that a few of the original derivations were actually in error. If you were measuring using the original parameters published by Altec, that could explain some of the variances you found.

The Thiele-Small parameters published on the page below have been checked and corrected, where necessary, using the mathematical formulae given to the author by Mr. Hubbard, and include most of the newer models produced by Altec Lansing since the original publication of Technical Letter No. 267B.

Altec Thiele-Small Parameters

[bowtie427ss]

If you drove the amps into heavy clipping I would think the speakers would be damaged first, as your nice sine wave turned into a squarish wave.

Clipping, in and of itself does not damage speakers. They could really care less about the shape of a waveform.

The only thing that you can input to your speaker wires that will damage your speakers is too much power. The ways you can arrive at this are many, and one certainly includes poorly designed amplifiers that generate large high frequency harmonics when driven to hard clipping. Blame that excessive power on those harmonics for any damage incurred, not the clipped off peak of a waveform.

For those who want to eliminate their clipping paranoia, please see the good folks at Audio Classics for a Powerguard equipped McIntosh and never worry about clipping again.

- - - Updated - - -

Would "abuse" be the wrong term? I'm a bit slow are you being sarcastic?

Anyway in home audio I would think so.

Mostly just mincing words. We are probably largely in agreement at the end of the day.

But, on the surface i consider occasional clipping less abusive than say letting your $1k+ phono cartridge run off into the dead wax.

In a well sorted system either incident should be able to occur hundreds and hundreds of times with no visible, audible, or otherwise measurable damages.

[Mercury3]

Thanks much for the reply Todd,

I used the DATS to test them and I have no idea how precise it is. I think is must be close because I have a 416-C which tested almost exactly to specs listed on this green chart.

I'm anxious to test mine once I get them back but after speaking with Bill at GPA I feel confident they'll be good to go. I think it's probably about the best we can do with 40 year old woofers. I'm grateful we have someone out there like him keeping these alive.

One thing I'm unsure of if I need to break them in a little before I test them.

Thanks Bowtie,

Yes perfect sense I agree. I like to crank it up every now and then but at my age nothing like I did back 40 years ago.

I have bad tinnitus which prevents it. I think resulting from my time in the military as well as my first job right after high school in a very noisy welding/metal shop. Around 1974 time frame I can remember safety being big on wareing goggles / face shields but there was little if any emphasis on hearing protection.

Mark