Dm7 tweeter shellac

[Andy1]

Hi all.
Charles, you suggested that there is ferrofluid in the tweeters fitted to these speakers, but I cannot seem find any references which support this on the net. I thought the specs in the original manual would Clarify this if this were the case. ( it goes into detail about everything else) Am I missing something? Could I add ferrofluid to improve performance regardless?
I have also read that bypassing the fitted 2a fuse would improve the sound too, which I have done. Would bypassing the 500mA fuse, which I believe protects the tweeter be advantageous too?

[57charles]

Hi all.
Charles, you suggested that there is ferrofluid in the tweeters fitted to these speakers, but I cannot seem find any references which support this on the net. I thought the specs in the original manual would Clarify this if this were the case. ( it goes into detail about everything else) Am I missing something? Could I add ferrofluid to improve performance regardless?
I have also read that bypassing the fitted 2a fuse would improve the sound too, which I have done. Would bypassing the 500mA fuse, which I believe protects the tweeter be advantageous too?

Hello Andy - I'm afraid those tweeters were indeed ferrofluid cooled - and B & W manuals don't state this. Old B & W tweeters are well known for this ferrofluid drying out problem - not just the tweeters in DM7. I've owned DM7, DM6, DM12, DM14 and DM2 series 2 and all the tweeters dried out and none are servicable by B & W. Bypassing the fuse is a complete waste of time.

[Pharos]

Switch cleaners in the coil gap?

Be careful, Kontakt is very vicious and may well remove coil varnish, I would use Radiospares Computer cleaning fluid.

[Andy1]

Thanks gentlemen.
I going to enjoy these for a while and then order the parts and give it a go. The age of the tweeters does show.. (they sound good still, but I know they should sound better). There is a good video available from good hifi.netherlands re replacing the diaphragm. They talk about refilling ferrofluid too. If it goes the wrong way there will be some dm 7 spares on eBay shortly after... I'm not happy unless I'm tinkering