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Old 30th March 2004, 08:41 AM   #1
Coolin is offline Coolin  Netherlands
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Default Will removing ferrofluid change response?

I understand removing the ferrofluid from my tweeters will improve sound quality. Will the response be tilted up when doing this?( more high frequency). Or just more resolution all over.
Damping will be reduced, how will this sound? Any way to compensate for this mechanicly? I have already used some "puzzlecoat"
They are fairly sensitive (97 db with horn) 1" non compression dome horn drivers. I dont know if this is relevant for the results. I dont have any spare ferrofluid so trying it is non reversable until i can get a hold of some. I also dont know what the viscosity is.

Coolin
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Old 30th March 2004, 11:05 AM   #2
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Default You what?!

Change the response? Definitely. Improve it? I doubt that very much.

Since ferrofluid is part of the magnet system of the speaker, removing some of it will weaken the effective strength of the magnet. This would probably cause a peak in the midrange, a drop in efficiency at high frequencies, and a dramatic increase of possible resonances. The whole point of ferrofluid is for damping of resonances and to be able to use a smaller magnet than otherwise possible. If the manufacturer could save money and make the tweeter sound better by not adding ferrofluid, then they would've already thought of that.

CM
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Old 30th March 2004, 11:46 AM   #3
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Quote:
If the manufacturer could save money and make the tweeter sound better by not adding ferrofluid, then they would've already thought of that.
That's what some actually did already !!!!

Some Scandinavian tweeters are deliberately marketed as having no ferrofluid (e.g. Seas No-Ferro) and they are said to sound BETTER than their ferrofluid counterparts.

But changeing a driver's properties by removing the ferrofluid might give somewhat unpredictable results (it is designed with the ferrofluid taken into account after all). The best would be to find out if someone has already done it on the very same model and what the outcome was.

Regards

Charles
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Old 30th March 2004, 02:37 PM   #4
Coolin is offline Coolin  Netherlands
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Default Guys, please only respond if you have experiance..

I know that the theory would seem it would be a bad idea but there are experienced people that have tried it and said it was an improvement.

With regards to the magnetic strength issue, Jon Risch has said it has very little effect.

I can imagine you loose detail because of the friction in the fluid.
There are many post over at AA regarding this issue but only a few who have tried and recomend it.
Im looking for more who have done this here.

Also i have read somewhere that some Scan speak top models dont use it iether.........

Later, Coolin
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Old 30th March 2004, 10:41 PM   #5
Kjetil is offline Kjetil  Norway
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I know the people at Kharma does the removal of the ferrofluid themselves, manually, on Focal tioxid tweeters. I think it would be very hard to predict how the response is affected, but one approach could be to buy an extra tweeter to experiment with.

I also think it would be very much harder to do on a soft dome tweeter than on a ceramic or metal dome tweeter.

Remove the membrane from the test-tweeter , and use some very accurate pipettes (from medical use or something) to remove some ferrofluid. Reassemble and measure. Write carefully down your results, both measurements and ammount of removed ferrofluid, and repeat the process. Remove some more fluids.. measure.. write down.. on and on..

You should maybe keep a small ammount of the ferrofluid left in the tweeter , I'm really not the one to tell you how much.

Experiment if you can afford it. When and if you can keep a smooth response with a minimal ammount of ferrofluid left or nothing at all, go for a modification of both tweeters you will use in your speakers, and remove exactly the same ammount of ferrofluid from both...

Note that even if you make it work with an improved result, the ferrofluid do have a purpose in a tweeter designed to be ferrofluidfilled. There will be no warranty if you burn your tweeters, so if you're to experiment, make sure you can afford some blown tweeters...

An approach could also be to buy some tweeters with no ferro-fluid (like the top models from Scan-Speak in denmark)
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Old 31st March 2004, 07:10 AM   #6
Eva is offline Eva  Spain
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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 would change. Qms will be higher and the driver may tend to peak near Fs before rollof ['honky' sound], even Fs may change. The crossover would also need to be redesigned since impedance curve will have different shape and a big resonance peak

A tweeter designed to rely hardly on ferrofluid dampening may be unusable after ferrofluid is removed
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Old 31st March 2004, 10:14 AM   #7
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When and where was it established that removing ferrofluid would be a good idea in the first place? Just because some highly regarded tweeters are designed without any ferrofluid, surely it doesn't mean that other tweeters should have their's removed?

CM
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Old 31st March 2004, 11:18 AM   #8
Kjetil is offline Kjetil  Norway
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Quote:
Originally posted by CeramicMan
When and where was it established that removing ferrofluid would be a good idea in the first place? Just because some highly regarded tweeters are designed without any ferrofluid, surely it doesn't mean that other tweeters should have their's removed?

CM

As said, regarding the focal tioxid tweeters, Kharma personel does this to great success. The Equisite series and the Ceramique 3.2 RFM, perhaps the very best 2-way system ever built by man, uses these manually modified tweeters... but wether it's a good idea or not to attempt this as a DIYer is an entirely different matter. I am sure the people at Kharma have high expertise and the funds and equipment to do this in a proper manner, but my point being that there can, in some cases, be beneficial to remove the fluids if one knows what to do and how to do it (wich, neither of us really do i guess..) However, I would still say there's a 99% chance at least to get a better result by buying a tweeter that meet ones goals, than by modifying one that doesn't...
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Old 12th September 2006, 10:15 PM   #9
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I'm resurrecting this thread to ask if there are any more current comments or experiences. In particular, I'm wondering what to expect from my Vifa D27TG35 tweeters if I were to remove the ferrofluid from them.
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Old 13th September 2006, 06:48 AM   #10
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Troels removed the fluid on a Monacor tweet.. with some interesting results.
http://www.troelsgravesen.dk/C17_II.htm

He documents the results near the beginning of the article.
Photos of hte process at the end.

Quote:
Originally posted by Tosh
I'm resurrecting this thread to ask if there are any more current comments or experiences. In particular, I'm wondering what to expect from my Vifa D27TG35 tweeters if I were to remove the ferrofluid from them.
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