These are the MK2 version i believe (From 1987). It's common to re-foam the midranges on these, also common to re-cap the massive crossovers. Both of which I've already done to mine!
But upon removing the tweeters, i noticed a strange brown stain on the stickers that show the brand name... I couldn't help myself, and took one of them apart very carefully, and guess what? Ferrofluid! Nasty, crusty old ferrofluid to be precise.
I tried asking around, and of the many people that work on these towers, NOBODY i asked knew that those tweeters used ferrofluid. I even emailed B&O, and they were surprisingly helpful! But even they had no real idea on how much fluid went into those tweeters. So i'm looking to just swap them out with more modern ones.
Turns out, this isn't as simple as it sounds. I've had replies going from "just buy some cheap tweeters and slap them on, you might get lucky!" all the way to very scientific replies that i barely understood...
They are ferrite, silk-dome tweeters. No idea what brand tho, the midrange drivers can be made by Nokia, SEL or ITT. Depending on the position of the moon it seems... I have a suspicion that the tweeters are made by SEAS tho.
So, what are my options here? Just eyeball the ferrofluid and hope for the best? Or try to replace them with modern tweeters, without knowing a damn thing about the specs of the old ones?
As i'm typing this, i'm also going to send an email to the owner of Audiofriends. I've bought all my Penta repair stuff from them, perhaps they'll know the true specs of the tweeters.
Any input is appreciated!
But upon removing the tweeters, i noticed a strange brown stain on the stickers that show the brand name... I couldn't help myself, and took one of them apart very carefully, and guess what? Ferrofluid! Nasty, crusty old ferrofluid to be precise.
I tried asking around, and of the many people that work on these towers, NOBODY i asked knew that those tweeters used ferrofluid. I even emailed B&O, and they were surprisingly helpful! But even they had no real idea on how much fluid went into those tweeters. So i'm looking to just swap them out with more modern ones.
Turns out, this isn't as simple as it sounds. I've had replies going from "just buy some cheap tweeters and slap them on, you might get lucky!" all the way to very scientific replies that i barely understood...
They are ferrite, silk-dome tweeters. No idea what brand tho, the midrange drivers can be made by Nokia, SEL or ITT. Depending on the position of the moon it seems... I have a suspicion that the tweeters are made by SEAS tho.
So, what are my options here? Just eyeball the ferrofluid and hope for the best? Or try to replace them with modern tweeters, without knowing a damn thing about the specs of the old ones?
As i'm typing this, i'm also going to send an email to the owner of Audiofriends. I've bought all my Penta repair stuff from them, perhaps they'll know the true specs of the tweeters.
Any input is appreciated!
Here in the UK, Willys Hifi supply a refill kit that "comprises a high accuracy syringe pre-filled with Ferrofluid specifically formulated for high fidelity tweeter application."
https://willys-hifi.com/products/ferrofluid-refill-kit
The important additional information is that "There is sufficient in the syringe for 2 tweeters & a micro applicator nozzle is supplied."
That may make eyeballing unnecessary.
The tweeter is an Seas 25TNF H358 tweeter (that sits in a waveguide) if i'm right. The modern equivalent should be the E0006-06 T25CF001, but it's not the same tweeter, not a drop in replacement. I think a drop in replacement doesn't exist (but could be wrong) for this driver. If they are repairable, keep the originals.
Don't different tweeters vary in size quite a bit? The neodymium ones on my friend's old B&W towers also use FF, and those tweeters are tiny compared to mine 🙂
Thanks! Unfortunately, the ones specifically made for the penta's are unique in their own way. Like you stated, they sit in a waveguide that's part of the speaker enclosure itself VS the waveguide being part of the tweeter. I don't know if the waveguide on the more modern version is removable tho?
No doubt, but the 0.25 ml of ferrofluid per tweeter supplied with the kit is a useful indication of the maximum amount you need to add.
Swapping in new ferrofluid is super easy, and a heck of alot less expensive than replacing tweeters. What did you end up doing with those speakers? I provide ferro' in Canada, but I gather that you may not be in my country. There are numerous sources of ferro' in USA and Europe, I can direct you to local suppliers if you wish.
Andrew Drouin
www.SpeakerFerrofluids.com
Andrew Drouin
www.SpeakerFerrofluids.com