@68pete I definitely will keep all updated. Looking forward to hearing some really nice improvements in about a month.
Ferrofluid
Hey guys. So I have been texting someone from Germany I met online as he also has a pair of B&W 800 Matrix speakers. He mentioned that he treats his tweeters every so many years with Ferro fluid. It was kinda hard to actually text about it online with someone I just met from another county. I did google it and looked on utube for some videos and there are some. It’s seems it should be done about every 10 years or so. And u actually have to take the tweeter out of the cabinet disassemble / remove the voice coil clean out the old Ferro fluid and add new Ferro fluid. It’s seems to be some kind of a magnetic liquid used in speakers especially tweeters for better clearer sound, highs, voices etc. It really looks like a job for the experienced in rebuilding speakers. Has anyone heard of this or had it done ? I’d really love to know from folks who had experience with this. My speakers are from the 90s and even though they still sound phenomenal I’d really like to know more about this. I do plan on keeping my speakers for the long term. Thanks to all in advance.
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@tattooedtrackman sent me a woofer, a mid, both tweeters and his crossovers from his B&W 800 Matrix. He had a crack in his woofer, a nice dent in his mid and complained of harshness in his tweeter. I repaired the woofer and removed the dustcap for the mid and took out the crimp. Then measured the tweeters. One measured as though it had dried ferrofluid, the second measured as though it was just drying up. I went to remove the ferrofluid and noticed that on 1 tweeter the voice coil gap was a bit off. I removed the ferrofluid. It was overfilled and drying up. I rotated the voice coils and put them back together. FS was cut in half with the old fluid removed, but one was still off a bit, but they still measured a bit better than when I got them overall. I then upgraded Every Cap in the crossover, redesigned the tweeter section to close a sizeable hole between the mid and tweeter and sent them back. Mike’s initial impression was that everything was better, but it wasn’t long before he was feeling that there was a harshness out of one side that wasn’t on the other. He pulled the tweeters and crossovers and sent them back to me. I disassembled the tweeters, the voice coil magnet gap just wasn’t right on one of them. I took a spacer and moved around the gap trying to get in back in round. I soon felt comfortable that there was a clear improvement. I went ahead and measured out just enough ferrofluid to say that it was enough and replaced the coils. this time continually rotating and remeasuring until I got a very close match between tweeters. I then changed added a bit more resistance and changed the inductor coil on the tweeter crossover.. Even though the same 18db per octave slopes were used, the design was a fair bit different than the original. B & W used 18db bessel slopes. The mids were rolling acoustically at 24db per octave, with the hole between mid and tweets, crossover point was 10db down. I lowered the crossover point by 200 hz and I changed the slope on the tweeter from bessel to butterworth. The butterworth slope along with the slightly lower crossover point gave us a linkwitz alignment at 2200 hz. So, the hole was gone, what was a hole is a smooth transition response. Mike has only had these back for a few days, but that is what was done. I really believe all problems were taken care of. |
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