Real advantage of Alnico motors?

[Dr.db]

Hi,

I´ve started my JBL journey years ago with old alnico horndrivers and finally ended up with the equalent ferrite versions, because most of the used alnico´s had significant magnet loss over the years...
Many on this forum say a 2445 motor will sound exactly like a 2440 with the same diaphragm installed.

Now my question:
Why do company´s such as JBL and TAD use the more expensive and heat fragile motors on their woofers again these days??
What is the advantage in real life of these?
For example TAD has the very expensive 1601b woofers with alnico motor and the 1603 ferrite version. Both share the identical cone/spider. There is no significant difference in Flux densitiy or BL strengh etc... But a hefty 400$ more for the alnico version....
So is it high-end vodoo marketing or a real benefit?

[JeffW]

http://www.audioheritage.org/vbulletin/showthread.php?4031-The-Great-Alnico-Ferrite-Debate

[Dr.db]

Thanks a lot, that is a great link!

So far I´ve understood that a modern, well designed Alnico motor should be in advantage.

The demagnetization of an Alnico motor has to be taken care of!
In case of the JBL 1500AL this is the case.
What about the TAD 1601b and 1602 etc.... there designs are decades old!

[speakerdave]

? . . . What about the TAD 1601b and 1602 etc.... there designs are decades old!

The 1601b and ferrite 1603 use the same high-temp voice coil. What is the reason the 1603 exists if, as GT says, the costs of Alnico and ferrite motor production leveled very soon after the political situation around cobalt was relieved?

I've used the 1601b and 1601 with a 1603 cone kit. They sound the same.

I've used the 1602. It sounds different and is much preferred. Actually Don mentioned that very thing. The 1602 was phased out because of the warranty cost in studios where some customers, e.g. rappers, were not happy with the bass unless their pant legs were flapping. Are we seeing history repeated with the arrival of the 1501Al-2 and JBL's refusal to make the earlier versions of the cone and reluctance to make the -2 cone kit available?

I argued once that based on TAD's description the 1602 is underhung, therefore there is not enough coil to create the demagnetization problem. However, Guido says based on the published specs underhung is mathematically impossible. I'm not in a position to question Guido's 'maths' but I reserve judgement because published specs can contain errors. Either way, I really like the sound of the 1602, and I think at reasonable (ear preserving) volumes it should be OK even if Guido is right. I should note that the 1602 has a cone coating the others do not have.

Then there is the problem of finding that lovely long-discontinued woofer.

[Earl K]

Here's a very interesting shot of a TAD 1601b assembly ( from the blog of a master Japanese re-coner who does/did work that others wouldn't touch ) .

Of some note, the Alnico magnet structure is not the typical internal single ring type.

Clearly this 1601b is over-hung .

:)

[Dr.db]

The 1601b and ferrite 1603 use the same high-temp voice coil. What is the reason the 1603 exists if, as GT says, the costs of Alnico and ferrite motor production leveled very soon after the political situation around cobalt was relieved?


Allright, so TAD offers the 1603 ferrite version because it takes more abuse than the alnico motor.
Why hasn´t TAD implemented the same technology as JBL in the 1500AL to make their 1601b stay stable without demagnetization ?

The 1602 looks pretty interesting and has a very low fs. But it has the same foam surround problems as the JBL 2235h and I think it´s a lot harder to find service-parts for TAD speakers...

BTW, what enclosure size did you use for the 1601b ?


@Earl: Thanks a lot for this hard to find pictures!!

[Mr. Widget]

Why hasn´t TAD implemented the same technology as JBL in the 1500AL to make their 1601b stay stable without demagnetization ?
Why hasn't TAD designed a new woofer in over a decade, maybe two?

I have no idea, but over the years TAD's catalog of drivers has been steadily shrinking. No new drivers have been developed and production is very limited. Quality has been maintained and is still excellent+, but watching one wonderful driver after another become discontinued has been disappointing.


Widget

[Dr.db]

That´s true, even their tweeter is obsolete now...