tweeter "drying out"

[dasdoing]

So this is the tweeter of an old G1 KRK Rokit speaker.
I noticed it producing distorsion in the crossover range, the other speaker with a newer tweeter doesn't have.
theses tweeters all seam to die like this. I lost one before the same way.
Is there anything I can do?

 

[JSmith]

Is there anything I can do?

Assuming you mean the ferro fluid has dried out, then I believe you can attempt a repair by replacing the fluid with a similar grade;

Generally what happens over time is the fluid dries out to a solid at the bottom of the tweeter gap, so the coil is then stuck, which is likely the distortion you are hearing. Might be a heap easier just to purchase a similar replacement tweeter.



JSmith

 

[dasdoing]

Assuming you mean the ferro fluid has dried out, then I believe you can attempt a repair by replacing the fluid with a similar grade;

Generally what happens over time is the fluid dries out to a solid at the bottom of the tweeter gap, so the coil is then stuck, which is likely the distortion you are hearing. Might be a heap easier just to purchase a similar replacement tweeter.



JSmith

I am talking about those fissures in the surface

 

[dasdoing]

edited the foto to make it more visible

 

[ernestcarl]

So this is the tweeter of an old G1 KRK Rokit speaker.
I noticed it producing distorsion in the crossover range, the other speaker with a newer tweeter doesn't have.
theses tweeters all seam to die like this. I lost one before the same way.
Is there anything I can do?

View attachment 151904

Haven’t seen cracks like that before. Could it be that these are made using a (organic?) compound that rapidly degrades over time? Maybe the environment — e.g. temperature, humidity and the like contribute to it’s “drying out” as well. Don’t have solution thought out other than finding something else with similar sound characteristic that has better longevity.. maybe.

 

[dasdoing]

Could it be that these are made using a compound that rapidly degrades over time?

that's probably it. it sure isn't dry air since I live in the tropics

 

[dasdoing]

finding something else with similar sound characteristic that has better longevity

probably the best option other than substituiting the whole speaker

 

[Count Arthur]

It looks like the coating on the fabric dome has deteriorated.

I wonder if Brazil's climate, warm with very high humidity, is having a detrimental effect; when I visited Rio a few years back, it was only 27 celcius, but 95% humidity.

Maybe choose something with metal dome tweaters.

 

[dasdoing]

so it seams recoating is possible https://www.audiokarma.org/forums/i...rs-w-measurements.559836/page-2#post-13115270

 

[dasdoing]

it's the resin that evaporates. see left/bottom part where some areas are darker?
it is probably UV light doing that.
now finding out what kind of resin is used for this seams impossible. nobody seams to know

 

[Count Arthur]

If you're willing to experiment, and for it not to work. I would try something like a polyurethane varnish: https://www.amazon.co.uk/Rustins-POSC250-250ml-Satin-Varnish/dp/B001GU4BQW/ref=sr_1_2?crid=WLL7UNGWAIA9&dchild=1&keywords=polyurethane+varnish+satin+clear&qid=1631101066&sprefix=polyurethane+varnish+satin+,aps,161&sr=8-2, given the humidity, I'd be inclined to use a solvent based varnish, rather than water based.

I imagine that the primary function of the coating is to make the fabric of the dome air-tight, although it probably also serves to stiffen the dome. As such, it may be difficult to get it to match the dome's original properties exactly.

 

[dasdoing]

If you're willing to experiment, and for it not to work. I would try something like a polyurethane varnish: https://www.amazon.co.uk/Rustins-POSC250-250ml-Satin-Varnish/dp/B001GU4BQW/ref=sr_1_2?crid=WLL7UNGWAIA9&dchild=1&keywords=polyurethane+varnish+satin+clear&qid=1631101066&sprefix=polyurethane+varnish+satin+,aps,161&sr=8-2, given the humidity, I'd be inclined to use a solvent based varnish, rather than water based.

I imagine that the primary function of the coating is to make the fabric of the dome air-tight, although it probably also serves to stiffen the dome. As such, it may be difficult to get it to match the dome's original properties exactly.

thanks,
I can experiment a little because I have a third tweeter that "died". I suspect it could even come back to live.

 

[ernestcarl]

thanks,
I can experiment a little because I have a third tweeter that "died". I suspect it could even come back to live.

Do tell us if you succeed with your repair experiment!

I was thinking of using something quick and dirty like a kiwi or nikwax waterproofing spray, but Count Arthur's suggestion sounds much better.

 

[dasdoing]

Do tell us if you succeed with your repair experiment!

I will

 

[dasdoing]

there is this "gel" (how they call it) they use on the borders of woofers here in Brazil. I guess I try this. they say it also hardens a little. My newest tweeter is way harder than the oldest one that died.
one product I found is an acrylic emulsion

 

[Count Arthur]

acrylic emulsion

Emulsion paint is typically what you'd use on walls, plaster, and the like, I wouldn't think it would be particularly good as a coating for fabric or paper, where you are "doping" the fabric or paper: https://en.wikipedia.org/wiki/Aircraft_dope

 

[dasdoing]

Emulsion paint is typically what you'd use on walls, plaster, and the like, I wouldn't think it would be particularly good as a coating for fabric or paper, where you are "doping" the fabric or paper: https://en.wikipedia.org/wiki/Aircraft_dope

So what if I use this stuff made for aeromodlism?

 

[Count Arthur]

Honestly, I've no idea.

However, be aware that most aircraft dope is designed to shrink as it dries, so that it pulls the fabric taut, or tissue paper in the case of model aircraft; that might be a disaster on a soft dome tweeter.

 

[dasdoing]

sorry, my camera is not good at close distance

tweeter after some cleaning

went with the acrylic emulsion marketed for speaker surroundings

product aplyed and some drying with the hair dryer....dry to the touch. aplyed very little

meassurement with mic about 2cm from the tweeter
Do I need to say which is before?
huge success

 

[McFly]

Nice work - Have you measured a brand new/known good tweeter to reference your repair to?