Tweeter expiration date

[Abdo]

Good morning,

I'd like to ask a question. I had a problem with two 804s BW tweeters. I had them repaired here in Brazil, and they were fine.
But since I recently went to the United States, I ended up buying two new ones; I have one spare pair.
I tested and compared them; they sound practically the same, so the repair here was done well. I even took it to a technician for measurement, and he said it was up to standard.
My question is, can keeping the tweeter stored for a long time damage it? Someone who claims to be an audio expert says it's best to keep it in use, as the membrane can deteriorate more quickly if it's not used. Is this true? What would you recommend?
In the photo, it was manufactured in January 2025.
Thanks

 

[solderdude]

Only when stored under very high temperatures or when the tweeters have ferrofluid in them I would not worry about storing them.

 

[DVDdoug]

I expect a speaker to "last forever" unless it's overdriven, or exposed to moisture or direct sunlight, etc.

I don't think I've ever seen a tweeter die of "old age".

I've seen woofers with rotted foam surround, but I don't even know if they are using that kind of foam anymore. And a long time ago when I worked on car stereos I saw rear deck speakers turned crispy from years of sun exposure.

I've also heard of ferrofluid "drying out" but I don't think that's normal. I don't know what the fluid is, but I'd expect it to be some kind of oil, not something that would evaporate. ...Maybe those stories aren't even true. Maybe the tweeter died for some other reason.

 

[Abdo]

Thank you so much, friends. That's why I like forums.

Because in this audio world, they make up all kinds of conversations, I prefer to get my questions answered here.

Because initially, my two speakers died and I managed to repair them. I even imagine that I accidentally sent some audio too loudly, which could have damaged both simultaneously.

Anyway, I have two repaired speakers that work well and two new ones that I'll keep for future use.

I love these speakers; I've had them for 17 years. They play very well, and I don't feel the need to replace them.

Thank you.

 

[respice finem]

My B&W tweeters had to be replaced after about 20 years (known ferrofluid problem). The replacement tweeters allegedly do not have this problem any more. Nonetheless, if I had to store them for a long time, I would put them in some airtight box.

 

[Roland68]

Good morning,

I'd like to ask a question. I had a problem with two 804s BW tweeters. I had them repaired here in Brazil, and they were fine.
But since I recently went to the United States, I ended up buying two new ones; I have one spare pair.
I tested and compared them; they sound practically the same, so the repair here was done well. I even took it to a technician for measurement, and he said it was up to standard.
My question is, can keeping the tweeter stored for a long time damage it? Someone who claims to be an audio expert says it's best to keep it in use, as the membrane can deteriorate more quickly if it's not used. Is this true? What would you recommend?
In the photo, it was manufactured in January 2025.
Thanks

Every rubber, plastic, and organic material ages, just like all types of adhesives; it can't be prevented.

UV, too high humidity, too low humidity, too little ventilation, too much ventilation, too high temperature, too low temperature, release of plasticizers (which can damage other materials if there is too little or no ventilation), stress cracks, hardening, etc. The list and mutual influences is truly long.

Ideally, replacing the tweeters every six months or annually would be beneficial. I would recommend storing the tweeters in a wooden/cigar box, in a dark place, at normal humidity and normal temperature, and not wrapping them in anything like paper, fabric, or foil. A cardboard box is also fine, just make sure it doesn't get wet.

 

[Petrushka]

Materials age, but well designed drivers should last a lifetime, if not abused.

Ferrofluid is subject to deterioration. I wonder why there is so little discussion of how this happens and whether there are differences among types.

Side note: I’ve cleaned and restored a bunch of sewing machines. The most common problem is oil that dried to varnish. I think synthetic oil is less likely to do this, but again, no informed discussion.

I’m pretty sure car engines last longer now because of synthetic oil. Volvo recommends annual oil changes. This was undreamed of in my youth.

 

[levimax]

I am not sure what ferrofluid is made of but I have had several tweeters where it became very thick and sticky and definitely affected the performance of the tweeter. It is possible to clean out and replace the fluid with new and I have had some luck doing so but it is always a risk and not always possible to take a tweeter apart. My guess is the life of ferrofluid depends a lot on how hot the tweeters are run. As far as storing tweeters a good assumption is they can last for years in storage but probably not decades.

 

[Abdo]

Every rubber, plastic, and organic material ages, just like all types of adhesives; it can't be prevented.

UV, too high humidity, too low humidity, too little ventilation, too much ventilation, too high temperature, too low temperature, release of plasticizers (which can damage other materials if there is too little or no ventilation), stress cracks, hardening, etc. The list and mutual influences is truly long.

Ideally, replacing the tweeters every six months or annually would be beneficial. I would recommend storing the tweeters in a wooden/cigar box, in a dark place, at normal humidity and normal temperature, and not wrapping them in anything like paper, fabric, or foil. A cardboard box is also fine, just make sure it doesn't get wet.

Thank you,
See the photo of the original box. I think it's best to keep it inside.
Where I live (Sao Paulo/Brazil), the humidity is very good, always around 40 to 50%.
So I think keeping it in a dark, humidity-free cabinet is a good idea.

 

[Heatransfer]

Obligatory link to a tweeter ferrofluid replacement project... WITH MEASUREMENTS.

DIY: Tweeter Ferrofluid Change - with pre- and post- frequency & distortion changes. And on-line amiability among hobbyists.

A blog for audiophiles about more objective topics. Measurements of audio gear. Reasonable, realistic, no snakeoil assessment of sound, and equipment.

archimago.blogspot.com

Imo: should last 10-15 years, which is probably within a reasonable expected service life... And perhaps longer if the speakers aren't driven hard, shorter if frequently driven hard in warm environments. Swapping tweeters every 6 months seems excessive and wasteful.

 

[CT Man]

Good morning,

I'd like to ask a question. I had a problem with two 804s BW tweeters. I had them repaired here in Brazil, and they were fine.
But since I recently went to the United States, I ended up buying two new ones; I have one spare pair.
I tested and compared them; they sound practically the same, so the repair here was done well. I even took it to a technician for measurement, and he said it was up to standard.
My question is, can keeping the tweeter stored for a long time damage it? Someone who claims to be an audio expert says it's best to keep it in use, as the membrane can deteriorate more quickly if it's not used. Is this true? What would you recommend?
In the photo, it was manufactured in January 2025.
Thanks

I had to replace my B&W Matrix 3 Series 2 tweeters after about 25 years. It seemed to be a fairly common issue.

At the time B&W was stocking the part (I think for about $30) but their QC was not what it used to be. Twice they failed to pack the tweeters correctly, they bounced around in shipment, and they were visibly damaged. Finally a manager supervised the packing and the tweeters were well-protected for shipment. The speakers sound great after replacement.

Now the only Matrix 3 S2 part they list is the crossover, but it's not in stock. See below.
https://bowerswilkins.encompass.com/search?searchTerm=Matrix+3

 

[Petrushka]

Obligatory link to a tweeter ferrofluid replacement project... WITH MEASUREMENTS.

DIY: Tweeter Ferrofluid Change - with pre- and post- frequency & distortion changes. And on-line amiability among hobbyists.

A blog for audiophiles about more objective topics. Measurements of audio gear. Reasonable, realistic, no snakeoil assessment of sound, and equipment.

archimago.blogspot.com

Imo: should last 10-15 years, which is probably within a reasonable expected service life... And perhaps longer if the speakers aren't driven hard, shorter if frequently driven hard in warm environments. Swapping tweeters every 6 months seems excessive and wasteful.

That’s interesting. That response curve exactly matches what I get using HouseCurve, after replacing the coils and ferrofluid on a KEF tweeter. New tweeters are unavailable, and I figure the curve is smooth enough to fix with DSP.

 

[bmc0]

I've also heard of ferrofluid "drying out" but I don't think that's normal. I don't know what the fluid is, but I'd expect it to be some kind of oil, not something that would evaporate.

Any fluid will evaporate, but some do so extremely slowly at normal temperatures/pressures. Life of ferrofluid in tweeters depends on the particular carrier fluid used as well as temperature. My understanding is that modern ferrofluids are expected to last at least a decade or two in normal conditions.

Ideally, replacing the tweeters every six months or annually would be beneficial.

 

[Torin Krell]

Roughly 40 year old Energy 22 speakers (Energy Pro22, Energy 22 Reference, Energy Reference Conn) are also known to suffer from tweeter problems related to thickening ferrofluid, and sometimes other issues. This can result in changing frequency response or total failure. Supplies of new replacements are no longer available and rebuilds by the few (one?) remaining specialists are expensive. When my Energy 22 Reference speaker tweeters started misbehaving (on my secondary system) I simply picked up another (nearly immaculate) pair that was fully working for just $90 through facebook marketplace.

 

[RayDunzl]

I've also heard of ferrofluid "drying out" but I don't think that's normal. I don't know what the fluid is, but I'd expect it to be some kind of oil, not something that would evaporate.

Regarding aged oil...

I found an old old unopened can of Quaker State Motor Oil (from the 70's or 80's hiding on the bottom shelf of Dad's (RIP) "stuff" cabinet.

I figured I'd recycle it.

Punched a hole in the can and turned it up.

Nothing came out.

It had gelled.

I don't think I have an old enough sample of Mobil1 synthetic with which to compare, though I've been using it since 1979..

 

[thewas]

I don't think I have an old enough sample of Mobil1 synthetic with which to compare, though I've been using it since 1979..

He had:

 

[SamIAmSam]

Every rubber, plastic, and organic material ages, just like all types of adhesives; it can't be prevented.

UV, too high humidity, too low humidity, too little ventilation, too much ventilation, too high temperature, too low temperature, release of plasticizers (which can damage other materials if there is too little or no ventilation), stress cracks, hardening, etc. The list and mutual influences is truly long.

Ideally, replacing the tweeters every six months or annually would be beneficial. I would recommend storing the tweeters in a wooden/cigar box, in a dark place, at normal humidity and normal temperature, and not wrapping them in anything like paper, fabric, or foil. A cardboard box is also fine, just make sure it doesn't get wet.

"Ideally, replacing the tweeters every six months or annually would be beneficial". That strikes me as a whole lot of overkill. IMHO - it might properly read "Ideally, overhauling the tweeters every fifteen years would be beneficial - and even then, only for tweeters that employ ferrofluid".

Experiences; I've been an audiogeek for more than forty years, and have owned perhaps 30 pairs of loudspeakers. I currently own a number of older model speakers, including KEF Cantatas, KEF 104/2 (with ferro') a big old pair of 80's Pioneer party speakers for summertime outdoor get togethers, some Soundstage mini monitors for rear shop speakers, a pair of Celestion Ditton 44's as shop mains, a pair of small Mission speakers (with ferro' in the tweeters) as a PC setup, a couple of small powered studio mini-monitors for camping party's and, of all things, a pair of Magneplanar panels, for of all places, the bedroom (a very patient wife)...
I recently sold a pair of Magnat 'All Ribbon 10s' (a move which has been regretted ever since) which also used ferrofluid. I'm the Canadian source of ferrofluid, so am somewhat biased toward ferro'.

 

[respice finem]

"Ideally, replacing the tweeters every six months or annually would be beneficial". That strikes me as a whole lot of overkill. IMHO - it might properly read "Ideally, overhauling the tweeters every fifteen years would be beneficial - and even then, only for tweeters that employ ferrofluid"

It doesn't hurt IMHO to check their performance every few years, instead of preventively replacing them.
For the less "technically savvy" users, even a smartphone app and a few seconds white noise should suffice.
When they can't play 16+ kHz any more, it's probably time...

 

[Abdo]

I'd like to revisit this topic, because out of curiosity,

I used a multimeter to measure the tweeters. I don't know much about multimeters, but I did a simple test.

The two repaired tweeters both read 3.8 on the multimeter, while the new ones both read 2.8.

So, I don't know if this is a problem or not. Is there any way to do a more accurate test to check if everything is okay with them?

Thanks.

 

[respice finem]

The multimeter, or a simple "battery test" won't tell too much, because even with very dense ferrofluid, the coil remains conductive and even the membrane will move a bit. For the spara pair, you will have to mount them into your speakers, or a frequency limited "test bench" setup to really test them (by measuring acoustically). The tweeters must not be fed signal below their rated frequency range, bass would blow them immediately.