Chorus II Tweeters

[superfinemind]

Good evening.  I just now replaced the original 1992 tweeters in my Chorus II’s.  There was oil or fluid on both of these, first on the face of the magnet, and also the card stock was soaked when I cleaned out the gap into which the edge of the voice coil fits.  Both test at 8.4 ohms after reassembly.  Is the dark brown liquid from deterioration of the phenolic material (which looked OK) or is this ferrofluid?  If ferrofluid, is it necessary for proper operation, or just in high power applications to absorb heat.  I’d not heard any mention of ferrofluid in Klipsch products up to this point, but I cannot logically see how it could be anything else.  Help..!!  😃

[amped]

From what I’ve read, the difference between the K79 and K79k of the chorus is the ferrofluid. I posted in the above link and yes it’s a brownish liquid. I also killed an original diaphragm coil. Be delicate. 

[billybob]

@superfinemind

[winglet]

It’s ferrofluid as you guessed.

 

K-79-k is the model stamped on the magnet.  K79 refers to the same tweeter.

 

Tighter voice coil gap and increased sensitivity necessitated klipsch using the cooling fluid.  

 

 

[geoff.]

9 hours ago, amped said:

I also killed an original diaphragm coil. Be delicate.  

 

I came here to issue the same caveat. I’m guilty of murder too…

 

There was some debris down in the voice coil gap and it crushed the voice coil when installing.

 

Another excommunicated vendor of aftermarket parts used to suggest folding over a Post-It note and cleaning the gap.

 

It’s a game of Operation, lol. 

[OO1]

@superfinemind   the Chorus II  , K-79  tweeter can be used  with or without FF , the Cornwall II and Chorus   shipped with a K-79 without Ferrofluid  , while the Chorus II shipped with a K-79 with Ferrofluid  .FF helps with cooling of the diaphragm  VC ,  caution , however ,  FF oils evaporate with age  .  

[amped]

2 hours ago, geoff. said:

 

I came here to issue the same caveat. I’m guilty of murder too…

Another excommunicated vendor of aftermarket parts used to suggest folding over a Post-It note and cleaning the gap.

 

It’s a game of Operation, lol. 

I don't recall killing anything but a multimeter confirmed the sudden death in one channel. I got a pair of Ti replacements from Klipsch.

 

I also have extra parts express FF for (2) K79k which I thought I'd have to do a second time but didn't. It's in its original packaging and easy to do.

My 1994 FF was still in a liquid state btw...

 

PM me if you want it.

[OO1]

3 hours ago, amped said:

 

My 1994 FF was still in a liquid state btw...

the FF may have been replaced by the previous owner   , FF has a shelve life of 10 years     

[Deang]

If you aren’t close to 100% certain of a thing, please don’t give advice. I would also start avoiding some of the “Klipsch” Facebook pages which are now often filled with poor advice and incorrect information. 
 

https://speakerrepairshop.nl/en/questions/ferrofluid/c-34#:~:text=Yes%2C applying ferrofluid will increase,ferrofluid and the correct quality.

[Marvel]

Soooo... is the above link correct or incorrect?

[Deang]

It is correct. There is also an imbedded link with further instructions.

 

I found the following in my notes:

 

“Ferrofluid provides mechanical dampening and dramatically reduces Qms [and thus Qts] of the driver and flattens its impedance curve in the Fs zone. If the ferrofluid is removed, then most T/S parameters of the tweeter will change. Qms will be higher and the driver may tend to peak near Fs before rolloff, even Fs may change. The crossover would also need to be redesigned since the impedance curve will have different shape and a big resonance peak.”

 

The following is not correct:

 

“I cleaned the fluid out of the gaps with folded sticky notes until it was clean enough (as recommended by Michael Crites) Installed the new crites diaphragms. No sweat. No ferrofluid necessary.”  

[Marvel]

You should put that link in the above post and have it stickied...

[amped]

4 hours ago, OO1 said:

the FF may have been replaced by the previous owner   , FF has a shelve life of 10 years     

Doubt it. Nothing looked messed with. Screws were untouched etc. Paper quality cards intact, etc. But I guess if you say so…

[OO1]

2nd paragraph     https://speakerrepairshop.nl/en/questions/ferrofluid/c-34

 

 What is the problem with ferrofluid over time?
Ten to twenty years after production, many of those tweeters will sound dull, have lost sensitivity, or have quit working altogether. This happens because the oil in the ferrofluid has evaporated, leaving a muck or solid in its place preventing the voice coil from moving freely or even blocking it. 

 

[Mikekid]

16 hours ago, Deang said:

It is correct. There is also an imbedded link with further instructions.

 

I found the following in my notes:

 

“Ferrofluid provides mechanical dampening and dramatically reduces Qms [and thus Qts] of the driver and flattens its impedance curve in the Fs zone. If the ferrofluid is removed, then most T/S parameters of the tweeter will change. Qms will be higher and the driver may tend to peak near Fs before rolloff, even Fs may change. The crossover would also need to be redesigned since the impedance curve will have different shape and a big resonance peak.”

 

The following is not correct:

 

“I cleaned the fluid out of the gaps with folded sticky notes until it was clean enough (as recommended by Michael Crites) Installed the new crites diaphragms. No sweat. No ferrofluid necessary.”  

Exactly as we did follow when we changed ALL to titanium diaphragms. Apparently I did it wrong? Oh well. They've been installed for years and never a problem...they all sound beautiful..so far.

[amped]

On 5/14/2023 at 7:23 PM, OO1 said:

2nd paragraph     https://speakerrepairshop.nl/en/questions/ferrofluid/c-34

 

 What is the problem with ferrofluid over time?
Ten to twenty years after production, many of those tweeters will sound dull, have lost sensitivity, or have quit working altogether. This happens because the oil in the ferrofluid has evaporated, leaving a muck or solid in its place preventing the voice coil from moving freely or even blocking it. 

 

Yup, read it. It had that generic feel with more words than facts.

 

My voice coil gaps had no solids. The brown fluid was still partially wet. I cleaned it out with the enclosed absorbent papers. If you read the instructions from the link you provide, it also says you can put a few drops of alcohol in the gap to clean it out. What if that goes wrong? I cleaned with absorbent paper until it came out clean and refilled with new FF. It goes in cleanly, as it's attracted to the magnetic gap. 

 

What did you find when you changed the ferrofluid in your K79k's ?

 

It's only true if it's on the internet...

Edited May 16, 2023 by amped
proof of liquidity

[Deang]

The point was simply that if it was there to begin with, it should be there when you’re finished. Now, if you have a problem with the link or note, just ignore the information and do whatever you want.

[amped]

19 minutes ago, Deang said:

The point was simply that if it was there to begin with, it should be there when you’re finished. Now, if you have a problem with the link or note, just ignore the information and do whatever you want.

Did that

[OO1]

1 hour ago, amped said:

 I cleaned  and refilled with new FF. 

good 

[OO1]

Deleted