[*Scotty*]

Referring to the link posted to Permanent Magnet Selection and Design, page 11 section IX " Modern high coercive force magnetic materials do not significantly degrade over time...... Most magnetic material will encounter degradation from corrosion,heat,or mechanical impact long before their magnetic properties would degrade because of time....."
 As most of our loudspeakers used in a home environment are safe from these hazards we will probably suffer degradation to our listening experience from the effects of time on our hearing before the magnets used in our speakers give out.
Scotty

[medium jim]

Referring to the link posted to Permanent Magnet Selection and Design, page 11 section IX " Modern high coercive force magnetic materials do not significantly degrade over time...... Most magnetic material will encounter degradation from corrosion,heat,or mechanical impact long before their magnetic properties would degrade because of time....."
 As most of our loudspeakers used in a home environment are safe from these hazards we will probably suffer degradation to our listening experience from the effects of time on our hearing before the magnets used in our speakers give out.
Scotty

+1

Jim

[Saturn94]

Thread officially derailed....

Back on track....hey AJ,  where's those demos....lol.

[jackman]

"Go out out of alignment" is very different from "demagnetize." Going out of alignment is caused by some sort of external shock, such as being dropped hard. (Or, I suppose, the weight of the magnet acting on the frame, if the frame is a thin cast variety; I've never personally seen that problem, though. Demagnetization, in the case of Alnico magnets, happens with ordinary use, as the thread to which you linked also states. That flaw, IMO, makes Alnico unsuitable for high-fidelity loudspeakers when we have two much more stable magnet technologies in ferrite and neo. Fortunately, the SAM1 didn't use drive units with Alnico magnets, so it's not an issue for those fine speakers. I presume the SAM2 doesn't use drive-units with Alnico magnets, either.

Alnico is unique among the major magnet technologies used in loudspeakers in the ease with which it demagnetizes.

The Mark Dodd* designed Dual Concentrics (mid-1990s D-series and Saturns for "home;" NFM, Studio and System series  for "pro") are vastly superior to the old Alnico-magneted ones. A cutaway of a Dodd-designed Dual Concentric is my avatar.

So if you see, say, a System 10 DMT II, run to go hear it. An old Arden or Berkeley or whatever...sure, it's better than most current speakers because at least the midrange polars are not so bad (but not something well-designed using modern parts, like the SAM1) but it's more a curiosity than anything else.

Mr. Dodd, who designed the "Tulip" phase plug for Tannoy that was such a massive improvement over their old "Pepperpot" design, was later poached from Tannoy by KEF/Celestion, where he designed "Tangerine" phase plug used to such great effect in the concentric mid/tweeter used on, inter alia, the SAM1. IMO, Tannoy has not yet recovered from the loss of Mr. Dodd to KEF.

D'S,
Great post.  In the old days when companies did not have a choice, alnico was a necessary evil.  Because of the reasons you stated, there are better magnet materials for modern high end speaker magnets.  Your fact based, well thought out responses are a breath of fresh air around here.

Alnico is still a good choice or guitar amplifier speakers because it has a very distinctive sound.  It would not be my choice for a high end home speaker.   

[neekomax]

I presume the SAM2 doesn't use drive-units with Alnico magnets, either.

So, the M2 woofers use these, I take it?

No. Nor the M1. Hence my concerns about tour. More weight = more shipping drama chances. The M1 tour pair took a pounding. These aren't typical 2 way 5-6" monitors either, by a long stretch.

Also, DS, thanks for the informative post!

[DS-21]

Referring to the link posted to Permanent Magnet Selection and Design, page 11 section IX " Modern high coercive force magnetic materials do not significantly degrade over time...... Most magnetic material will encounter degradation from corrosion,heat,or mechanical impact long before their magnetic properties would degrade because of time....."

That kind of stability is out of scope of the discussion. The problem is not that Alnico sits there and degrades. Alnico's flaw that makes the stuff unsuitable for high-fidelity loudspeakers is that flowing current through a voicecoil it demagnetizes an Alnico structure around it.

And yes, Tannoy uses Alnico (along with that Pepperpot phase plug, which does not perform as well as their more modern Tulip phase plug) in their most expensive speakers, because their most expensive speakers are overwhelmingly targeted to (mostly Far Eastern) retro fetishists.

[medium jim]

That kind of stability is out of scope of the discussion. The problem is not that Alnico sits there and degrades. Alnico's flaw that makes the stuff unsuitable for high-fidelity loudspeakers is that flowing current through a voicecoil it demagnetizes an Alnico structure around it.

And yes, Tannoy uses Alnico (along with that Pepperpot phase plug, which does not perform as well as their more modern Tulip phase plug) in their most expensive speakers, because their most expensive speakers are overwhelmingly targeted to (mostly Far Eastern) retro fetishists.

I guess you know what the half life of an Alnico magnet is?

Jim

[DS-21]

I guess you know what the half life of an Alnico magnet is?

No, I don't. I and many others know something higher-level, though. We know that the "half life of an Alnico magnet" is irrelevant to its suitability as a permanent magnet in a loudspeaker. So whatever its half-life is, an intelligent person has no reason to care unless s/he is heavily invested in Alnico futures or something like that.

What does actually matter here is the fact that Alnico degrades in the presence of an electromagnetic field. Such as that caused when one puts power to a voice-coil. For loudspeakers, it's obviously better to use a magnet that doesn't degrade like that.

[medium jim]

No, I don't. I and many others know something higher-level, though. We know that the "half life of an Alnico magnet" is irrelevant to its suitability as a permanent magnet in a loudspeaker. So whatever its half-life is, an intelligent person has no reason to care unless s/he is heavily invested in Alnico futures or something like that.

What does actually matter here is the fact that Alnico degrades in the presence of an electromagnetic field. Such as that caused when one puts power to a voice-coil. For loudspeakers, it's obviously better to use a magnet that doesn't degrade like that.

Rather interesting hypothesis.  No I have no interest in Alnico Futures, rather that I merely posted the 3rd common type of speaker (magnet) and never espoused it as being superior or otherwise ( I did mention that there is a cost factor).  Funny how things escalate...that is why I apologized (inferred) by the Bird Walking Comment

Jim

[*Scotty*]

Unless the speaker's magnetic motor structure that the alinco magnet is installed in can be dis-assembled and the alinco slug removed to allow the periodic re-magnetization, sooner or later you will have an expensive doorstop instead of a functioning loudspeaker. I thought that some sound reinforcement loudspeakers that utilized alinco magnets were made to be dis-assembled to facilitate the re-magnetization process on an as needed basis.
Except for the fact that there is a demand for alinco equipped loudspeakers, the material itself is functionally obsolete and has been superseded by better performing magnetic materials.
Scotty

[jackman]

No, I don't. I and many others know something higher-level, though. We know that the "half life of an Alnico magnet" is irrelevant to its suitability as a permanent magnet in a loudspeaker. So whatever its half-life is, an intelligent person has no reason to care unless s/he is heavily invested in Alnico futures or something like that.

What does actually matter here is the fact that Alnico degrades in the presence of an electromagnetic field. Such as that caused when one puts power to a voice-coil. For loudspeakers, it's obviously better to use a magnet that doesn't degrade like that.

Ouch!  Another great post.  You contine to do a great service to AC by providing logical explanations to the wild conjecture, witchcraft and nonsense continuously spewed by some of the more prolific posters.   

[Donald]

Thread officially derailed....

Back on track....hey AJ,  where's those demos....lol.

Agree. Maybe all of this magnet talk should be started in another thread. Back to the demo's.

[neekomax]

Erm, I have no idea what the netiquette is regarding threads and how on topic they're 'supposed' to stay, but as the OP, I'd just say that I personally would rather learn about nifty shit like different magnets and what makes one better than another, then limit ourselves too closely to talking SAMs and only SAMs. I mean, they DO use magnets, right? 

As has been pointed out by jackman, the ratio of actual information and substantiated opinion to hearsay and mystical Shakti Stone voodoo is a bit low in general in HiFi Land, so I'm grateful for all the science I can get.

OTOH, if OT sidetracks are against the rules of the circle or something, no worries....

I love my SAM 1s. There, we're back on topic. 

[Letitroll98]

Thanks for getting things back on track Neeko.  Regarding netiquette for OT I think you're pretty much on target.  After 18 pages of SAM-1 if the members stray a little OT, but stay in the general ballpark of the OP,  I'm not inclined to be heavy handed.  I mean, we are here to enjoy ourselves, right?  If someone starts spouting about the Kennedy's or something, maybe I'll step in, but magnets in speakers in the speaker circle, not so much.  That being said, I think we've beat that poor alinco horse as much as the old girl can take, especially since there's nary a trace of the stuff in SAM speakers.   

[medium jim]

Neekomax:

Since you are interested, I post the following link:

http://www.audiocircle.com/index.php?topic=52321.0

Jim

[neekomax]

Neekomax:

Since you are interested, I post the following link:

http://www.audiocircle.com/index.php?topic=52321.0

Jim

Thanks dude, will read.

[medium jim]

It is from the AC and is a short but accurate and informative read.  You're welcome.

Jim

[James Romeyn]

What you need is a Mid Atlantic rep willing to offer auditions to those interested.  It would be a tough job, but I'd be willing to volunteer.  You have my address to send a complimentary demo pair....

    

This does not relate to your obviously humorous post.  We had at least a few persons request free complementary guitar seasoning devices.  One guy in particular called at least three times, and finally made threats simply because we wouldn't give him free stuff.  One time he ordered his secretary to call us.  Another guy more recently presented himself as some type of consultant to multi billion dollar companies and promised all kinds of free consulting advice if we'd just send him free stuff.

Oh, AJ, add me to your list of requests for free demo pair...Design looks highly original and very nice!   

[pslate]

Getting back on track, Roscoeiii was over last night for a spell, and we had a good time putting the SAM-2 through its paces. I think it was unanimous, the SAM-2 kicks serious but, and really takes things to a whole other level. Incredible. Very cool to have someone over who was so knowledgeable, homeboy has a deep repertoire of cool test tracks. The SAM-2 imaging is quite good, with the ability for those images to hang in the air holographically. Things like wind chimes are scary real. The SAM-1 is not like that, but has other great attributes of course. Who is going to  get the second pair

[Saturn94]

Getting back on track, Roscoeiii was over last night for a spell, and we had a good time putting the SAM-2 through its paces. I think it was unanimous, the SAM-2 kicks serious but, and really takes things to a whole other level. Incredible. Very cool to have someone over who was so knowledgeable, homeboy has a deep repertoire of cool test tracks. The SAM-2 imaging is quite good, with the ability for those images to hang in the air holographically. Things like wind chimes are scary real. The SAM-1 is not like that, but has other great attributes of course. Who is going to  get the second pair

When you say "the SAM-1 is not like that", are you referring to imaging properties or instruments like wind chimes sounding "scary real"?

I ask because I think one on the SAM-1's strengths, at least in my setup, is imaging much like you described.  Of course I've not heard the SAM-2, but looking forward to doing so at CAF.

Why do I have this feeling that my visit to the Soundfield Audio room is going to cost me? 

Btw, I take AJ's lack of response to my offer means the answer is "thanks, but hell no!"