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Replace ferrofluid in tweeter


Replace ferrofluid by yourself - a manual on the basis of a B&W DM500 and DM600 series (ZZ05460) tweeter.

The coil of modern tweeters is sometimes damped with ferrofluid - this is to improve the sound quality. Over time, however, the ferrofluid hardens and must be replaced. Here you find a roadmap for replacing ferrofluid in a number of pictures.


An overview of what we will encounter during the repair ....

You need:

  • Ferro Fluid suitable for tweeters (not the cheap one for educational purposes)
  • A screwdriver fitting the screws of your tweeter
  • White masking tape
  • Cotton swabs (with alcohol) - sometimes needed


The tweeter (ZZ05460) in the picture below is completely disassembled.
It is important that you perform this repair in a clean / dust free environment. At least clean your work surface with a wet cloth before you begin. Don't perform this repair in a dusty garage!
Replace ferrofluid in B&W ZZ05460 tweeter: all the items needed for the replacement


Remove the tweeter from the speaker cabinet. The way in which may vary, but in this case the tweeter is simply unscrewed. Behind the tweeter is usually a foam ring that closes the tweeter airtight - keep it well because you'll have to put it back after the repair. If you are not sure how the tweeter should be connected after the repair mark the wires and make some pictures for your reference! In rare cases, the tweeter's soldered to the wiring and you'll need a soldering iron.
Replace ferrofluid in B&W ZZ05460 tweeter: remove your tweeter from the speaker cabinet


Clear the diaphragm from the magnet. In many cases, the diaphragm is screwed onto the magnet. Sitting in the magnet the diaphragm usually has small holes fitting into 'pins' on the magnet. This way the diaphragm is centered. Be careful with the diaphragm, as opposed to the magnet both the dome and the coil are very vulnerable. Make sure that the coil (on the rear side of the diaphragm) is clean. This is usually the case. Is the coil not clean (there are remains ferrofluid to be seen on the coil) rinse it gently with a cotton swab with some alcohol on it. Place the diaphragm in a safe place before proceeding.
Replace ferrofluid in B&W ZZ05460 tweeter: remove the diaphragm from the magnet


Below the diaphragm there is a gasket in a number of cases. Take it off and put it away, until after the repair.
Replace ferrofluid in B&W ZZ05460 tweeter: the magnet - notice the air gap in the magnet


You are going to remove the old ferrofluid. You will use white masking tape. Tear a piece off.
Replace ferrofluid in B&W ZZ05460 tweeter: you can use masking tape to remove the old ferrofluid from the air gap


Fold the tip of the tape with the sticky side on the outside.
Replace ferrofluid in B&W ZZ05460 tweeter: fold the masking tape - the sticky side is on the outside


Repeat this several times until you have a solid piece of tape with the sticky side on the outside. This tape will remove the old ferrofluid in the air gap in the magnet.
Replace ferrofluid in B&W ZZ05460 tweeter: fold the masking tape several times to create a thin sticky tool


Put your piece of masking tape in the air gap of the magnet and move it around circularly. The old, mucky, ferrofluid will stick to the tape.
Replace ferrofluid in B&W ZZ05460 tweeter: use the masking tape to remove the old ferrofluid


The tape is filled with 'dirt', take a new piece. Move the (clean) tape around as long as ferrofluid comes out. If you put in a new piece of tape and it comes out totally clean you're fine.
Replace ferrofluid in B&W ZZ05460 tweeter: the old ferrofluid will stick to the masking tape


Apply new ferrofluid in the air gap. Do not fill the gap completely, leaving about 1-2 millimeters open. This way, the voice-coil will fit the gap later without the air gap 'overflowing'.
Replace ferrofluid in B&W ZZ05460 tweeter: apply ferrofluid to the air gap - do not fill it up completely


Place the gasket back onto the magnet.
Replace ferrofluid in B&W ZZ05460 tweeter: fresh ferrofluid in the gap


Place the diaphragm carefully back. Make sure the holes in the diaphragm are exactly over the pins on the magnet, so your tweeter is correctly centered and the voice-coil is in the air gap of the magnet. Set the diaphragm using the screws again.
Replace ferrofluid in B&W ZZ05460 tweeter: carefully place back the diaphragm


Place the tweeter back into the cabinet. If there was a sealing ring, place it back before connecting the wires. Connect the wiring correctly in accordance with the marking (s) that you made earlier.
Replace ferrofluid in B&W ZZ05460 tweeter: install the tweeter back into the speaker cabinet


© Good Hifi VOF 19-06-2016