Dismantling of 2441 driver on video!

[panos29]

Here is a guy dismantling a 2441 driver and replacing the plastic throat with a new bronze one. My question is the obvious, since after this operation the magnetic circuit of the alnico magnet is going to be open, my understanding is that the magnetic force is going to collapse or loose part of its strength. Am I right or this operation is normal and can be performed with no loss of magnetizing strength?


Here is the video:
https://www.youtube.com/watch?v=wvWSg2tpFLk

[gasfan]

Here is a guy dismantling a 2441 driver and replacing the plastic throat with a new bronze one. My question is the obvious, since after this operation the magnetic circuit of the alnico magnet is going to be open, my understanding is that the magnetic force is going to collapse or loose part of its strength. Am I right or this operation is normal and can be performed with no loss of magnetizing strength?


Here is the video:
https://www.youtube.com/watch?v=wvWSg2tpFLkThere is no "circuit", it's a permanent magnet. It's not an electro-magnet in which case the field is maintained until the circuit is broken resulting in total collapse.

[panos29]

I really think you are mistaken, if you search in this forum you will find in so many threads that if you break the magnetic circuit by removing the plate of the driver the alnico magnet looses a big part of its power.

[macsic]

Interesting, but where to find this bronze tube?

[panos29]

Interesting, but where to find this bronze tube?

The guy posting the video is trading these on ebay.pl

100 euro per pair, not that bad, but there is the catch of magnetization strength loss, maybe it can be installed through the front?

[richluvsound]

More10 has done this upgrade ....

demag the driver , dismantle it , replace throat and remag to original spec .... :applaud:

[panos29]

More10 has done this upgrade ....

demag the driver , dismantle it , replace throat and remag to original spec .... :applaud:

This is the obvious, what if there is no availability of mag-demag utility in a country?:bouncy:

[richluvsound]

This is the obvious, what if there is no availability of mag-demag utility in a country?:bouncy:


Send it to me and ill help or send it to Italy or Berlin ..... :D

[Kay Pirinha]

Hi,

and what might have been the necessitiy for replacing the plastic throat? Can it degenerate?

Best regards!

[panos29]

Hi,

and what might have been the necessitiy for replacing the plastic throat? Can it degenerate?

Best regards!

There are alot of people with cracked throats

[Kay Pirinha]

Ok, I as a noob didn't know that. But I didn't recognize a broken throat in this video?

And if a throat is already cracked, wouldn't it be easier and not that dangerous to remove it from the front and replace it without dismantling?

Best regards!

Btw, here's an example for a cracked throat:


https://www.youtube.com/watch?v=rE029iX1TU4

[neskor]

Send it to me and ill help or send it to Italy or Berlin ..... :D
Where in the UK we can do remag?

[Kay Pirinha]

And who in Berlin does it?

Best regards!

[richluvsound]

And who in Berlin does it?

Best regards!



Contact Guido , he's used them

Rich

[Earl K]

Guido at ; Behringer-Electric (https://www.behringer-electric.de/)


Yes there is indeed a circuit in place with these old alnico drivers ( created by the cast pot and the top-plate ).

It is common practice ( or used to be ) that when storing alnico magnets that a "Keeper-Circuit" was put in place.

See ( click the pic ); https://upload.wikimedia.org/wikipedia/commons/thumb/0/08/MagnetEZ.jpg/220px-MagnetEZ.jpg (https://en.wikipedia.org/wiki/Magnet_keeper)

Googling Magnet Keeper (https://www.google.com/search?q=Magnet+Keeper&rlz=1C1CHBD_enCA823CA823&oq=Magnet+Keeper&aqs=chrome..69i57j69i60&sourceid=chrome&ie=UTF-8) will lead one into the heart of this topic ( unfortunately I couldn't find an expected percentile-loss number > when breaking the magnetic circuit ).

:)

PS:
It's a crying shame that this web-site doesn't have a definitive article ( in our reference section ) outlining the dangers of breaking the magnetic circuit ( as shown in that ill-informedYouTube video ).

Maybe Robh3606 could contact Greg Timbers to see if he would write one for this Web-Site.

I'm sure if G.T.s name was attached to this information there'd be little to no push-back .

[Kay Pirinha]

Thanks to both of you :)!

Guido is the guy who built a pair of 4435's in 2004, isn't he? Unfortunately he appears to be inactive for more than three years now :(.

Am I right that a remag job has to be done prior to a recone? And are ferrite magnets susceptible to lose their magnetic force the same way as AlNiCo's, even without opening the magntic circuit?

Best regards!

[Earl K]

Thanks to both of you :)!

Guido is the guy who built a pair of 4435's in 2004, isn't he? Unfortunately he appears to be inactive for more than three years now :(.

Am I right that a remag job has to be done prior to a recone? And are ferrite magnets susceptible to lose their magnetic force the same way as AlNiCo's, even without opening the magntic circuit?

Best regards!


Some info HERE! (http://www.audioheritage.org/vbulletin/showthread.php?4031-The-Great-Alnico-Ferrite-Debate)

I would remag first // then recone ( though I don't know if its mandatory or just recommended best-practice ).

FYI, I've had drivers remagged here in Toronto ( by a long defunct outfit ) + I was told to take out the diaphragms before dropping them off .

:)

[Kay Pirinha]

Thanks, Earl, these are great infos :)!

I can imagine why remag has to be first: We'll measure the magnetic field in the - empty - gap and adjust to the right value. Correct?

Best regards!

[Kay Pirinha]

I was very pleased as I found out that Guido Behringer runs his business just about 50 km/30 miles from my hometown. Guess I'll visit him soon :D.

Best regards!

[dn92]

Send it to me and ill help or send it to Italy or Berlin ..... :D

Appart that after March 29th shipping cost to you won’t be the same...

There is also a good address in France that could be able also to do the replacement, with no Customs fees for shipping inside EU.

[panos29]

Here is a new video by the same guy on how to take off the old throat from the front without dismantling the driver!

https://www.youtube.com/watch?v=rMsfvY6F9Gg

[Kay Pirinha]

Ok, much more clever than opening the magnetic circuit :applaud:!

I don't get his use of these valve clearing gauges, though:dont-know: . Wouldn't it be sufficient to glue the jig directly into the old throat?

Best regards!