Alnico K-77 weak magnets

[stig1]

 Howdy, not a newbie, joined 2000 or 2001 as stig. Something changed and I lost post count etc. Oh well on to the tweeter topic.

 

I have 2 alnico k-77 tweeters with weak magnets in my collection of Klipsch parts.  They have ohm readings of 2.6 and 3.5. They are very weak volume wise. How do you recharge these things?  Thanks to anyone who has an answer.

[Travis In Austin]

@Stig that account is still active, maybe @Chad can help you get access back.

 

Extreme heat can cause change in driver magnets, have not heard of them getting weaker over time.

 

Some others can probably help you out on the driver question.

 

Travis

[OO1]

@stig1   the magnets would require to be re-magnetized  by a shop that has the equipment for such a job ,  but  1st hand you'll have to remove the diaphragms 

[billybob]

@KT88

[KT88]

Perhaps this thread is of help.

 

 

[stig1]

Thanks to everyone for the replies. KT88 the German video was interesting.

Would anyone know if there is a place in Seattle that can do this job. I live 150 miles from there.

Thanks

[JohnA]

Your DCR readings are very, very low.  My K-77s measure 7.5 and 6.3 ohms.  Perhaps your problem is not the magnets. 

[stig1]

JohnA, after reading your reply I went back and took another ohm reading. I have entered the Twilight Zone, they now measure 6.4 and 6.5. 

 Sadly the higher reading did not help the weak sound. They sound half as loud as my other alnico K77 when run with a 2uf cap for comparison. 

 

So it looks like I'm back to square 1. I don't really need them right now, was just looking at a future fix.

 

Thanks  

[cosmichippo11]

I am also interested in any replies to this question.  I just sent a email to the German shop mentioned by KT88b, but I have no idea if they will do a job for someone in another country, what the cost would be, nor whether they will be able to read the English message I sent (I did provide an AI translation).  We will see.  Has anybody found someone in the US to do it.  I contacted Great Plains Audio, but they wanted $200.

[OO1]

On 3/19/2023 at 3:30 PM, stig1 said:

 they now measure 6.4 and 6.5. 

I dont think you can re magnetize an Alnico  magnet with the diaphragms connected to the magnets ,  the original  EV T-35  diaphragms  are unobtanium ,    the aftermarkets are not the same quality ,

 

you can unsolder  the diaphragms , and transfer them to  ferrite square EVT35 magnets ,  you'll  need   a pair of blow k-77M  tweeters  , then comes  the delicate work because you'll need to solder on  an extension to the leads using flat copper leads    , 

[OO1]

3 hours ago, cosmichippo11 said:

 I contacted Great Plains Audio, but they wanted $200.

  you're better off locating a set of  blown  k-77-M ferrite square magnet   tweeters , and transfer the diaphragms , but the job is delicate 

[KT88]

On 3/23/2023 at 12:30 AM, OO1 said:

I dont think you can re magnetize an Alnico  magnet with the diaphragms connected to the magnets ,  the original  EV T-35  diaphragms  are unobtanium ,    the aftermarkets are not the same quality ,

 

you can unsolder  the diaphragms , and transfer them to  ferrite square EVT35 magnets ,  you'll  need   a pair of blow k-77M  tweeters  , then comes  the delicate work because you'll need to solder on  an extension to the leads using flat copper leads    , 

 

As far as I remember, diaphragm with coil were removed before remagnetization. I find that the sound of the K77M is much less musical, especially on string instruments. That is why I would try to restore the Alnicos.

[OO1]

Just now, KT88 said:

I would try to restore the Alnicos.

I agree with you  Heinz  ,  the Ferrite option is a cheaper option for those who cant afford to pay 200-250$ in expenses .