No fluid at all! Ribbons are much faster. Catchy nickname btw.
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The main function of the fluid is to cool the voice coil of the driver by transferring heat to nearby structures. The fluid can also act to damp the motion of the coil/diaphtagm. The main downside is that the fluid will dry out in about 15 to 20 years. With some drivers, the gummy remsins of the gluid can be cleaned out and replaced eith hew fluid. I have not done this so I don’t know what that entails, but you can look it up by googling speaker ferrofluid. |
Ferrofluid can help flatten the impedance curve and reduce Fs and diaphragm excursions, but each design is different and handles those potential issues differently, so it’s use isn’t universally advantages. I changed out the FF on my 30 year old Seas domes a few years ago, and it made an audible improvement after. |
It’s fallen pretty much out of favor. The biggest advantage today is higher power handling, which for home listening is usually not a big concern. I doubt most home tweeters ever see more than 3 W honestly. One big disadvantage is that it dries out and gums up the magnet cavity and voice coil requiring replacement AND cleaning. Like @knotscott said, if your tweeter was designed for FF you definitely need to maintain it as intended. Here’s a good article on the subject.though I don't necessarily agree that all tweeters should have some. Like every other type of technology buzz word, take it with a grain of salt and evaluate the finished product, not the buzz words. |
Thank you for your thoughts on this, I was only aware of the fluid drying out. Never realized it was a maintenance item, not surprised to hear pros and cons of no fluid or with. @erik_squires Sir you are magical at your explanations I quite enjoy this forum and you are one of the reasons I keep reading. Thank you again to everyone. I wish for everyone here on audiogon, a happy, healthy and musical filled 2025. |
@dickface - Obviously your mileage may vary, but search DIYaudio and you’ll find lots of discussions about cleaning out old tweeter voice coils with dirty or gummed up ferrofluid. That’s the only reason I know about this. I don’t know however how much better a certain brand or model of modern FF using tweeter is vs. the early days, but certainly some top brands still have a couple of models which rely on it, and they also tend to be high power versions, which given how efficient the modern tweeter is, really are for very high output systems. |
You don’t see "ferrofluid cooled tweeter" advertised much anymore, except in cheaper speakers. Being a big Tannoy fan - this topic is intresting to explore in the 2000s era Tannoy lineup, where they used ferrofluid tweeters in the "tulip" DC drivers (lower lines and pro lines) and no-fluid compression chamber / horn tweeters ("pepperpot" DC - dry coils) in the upper half of their top Prestige line. I have a few of both kinds, and though ferrofluid tweeters are defnitely out of fashion now, those Tannoy ferrofluid tweeters still do GREAT. Haven’t had a problem with one yet, and their treble response actually tends to be a bit smoother and more extended than the pepperpot one. However, the latter DC lends its magic in the midrange, and with its massive efficiency. At some point I'll have to check on them and clean / replace the fluid, but frankly that seems pretty easy. The magnetic gap will hold it in place. |