John Warren Posted March 10, 2005 Share Posted March 10, 2005 Soft iron saturates at about 1.2 Tesla. If the original design is near saturation, the flux density in the gap will not exceed about 1 T. Adding more magnet will only increase stray field which will debit the performance. Look at any JBL spec sheet, the gap flux density is between .9 and 1.2T. That's the limit. Quote Link to comment Share on other sites More sharing options...
djk Posted March 10, 2005 Share Posted March 10, 2005 Maron: There are now some BeTi foil domes at a reasonable price, this may be something to look at. John and Maron: Most of the JBL compression drivers can hit 1.9T, obviously not the same stuff EV used. I used to have some of the Focal tweeters with the FC poles and they ran 2.1T, sounded quite nice too. They had a horn version in their pro line, but I have not heard it. They are no longer going to sell to DIY so its kind of moot. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted March 10, 2005 Share Posted March 10, 2005 DJK & JOHN....When I die Im going to have both your brains transplanted into my skull. Quote Link to comment Share on other sites More sharing options...
BEC Posted March 10, 2005 Share Posted March 10, 2005 djk, If you can let me know where I can get some bare 1 inch Be Ti domes, I might be able to get some EV coils installed on them to try. Bob Crites Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 10, 2005 Share Posted March 10, 2005 BeTi, is that Beryllium and Titanium? My this is becoming rocket science. I was holding my tongue, but John W and others have already spoken about the flux density et al. I knew there was some reason that more magnet wasn't necessarily better. On slightly related topic, what is it about the K77 that makes it better than the standard EV driver of same design? Did Klipsch order hundreds, individually test them to certify as K77 or ?? I have a couple of EV units that look just like K77 that I bought from MCM electronics years ago for probably $39 NIB. Wonder if BEC would like to 'test' them just for fun? At the time I was making some all in one speakers for PA use that ended up remarkeably similar to a Cornwall box. Michael Quote Link to comment Share on other sites More sharing options...
Hardhead Posted March 10, 2005 Share Posted March 10, 2005 On 3/10/2005 11:24:16 AM colterphoto1 wrote: hat is it about the K77 that makes it better than the standard EV driver of same design? Did Klipsch order hundreds, individually test them to certify as K77 or ??---------------- Yep, that's just what Klipsch & Associates did. As part of the sales contract with EV, Klipsch overbought, cherry-picked the ones they wanted, and sent the "rejects" back to EV for credit. The "Klipsch" medallion or stamp on the back of the K-77, etc. tweeter means quality and consistency. The tweeters that didn't pass aren't necessarily bad per se or worse sounding than the ones that passed Klipsch's tests; they just didn't fit within Klipsch's testing parameters. Quote Link to comment Share on other sites More sharing options...
Thumpelstiltskin Posted March 10, 2005 Author Share Posted March 10, 2005 ---------------- On 3/10/2005 1:27:15 PM Hardhead wrote: On 3/10/2005 11:24:16 AM colterphoto1 wrote: hat is it about the K77 that makes it better than the standard EV driver of same design? Did Klipsch order hundreds, individually test them to certify as K77 or ??---------------- Yep, that's just what Klipsch & Associates did. As part of the sales contract with EV, Klipsch overbought, cherry-picked the ones they wanted, and sent the "rejects" back to EV for credit. The "Klipsch" medallion or stamp on the back of the K-77, etc. tweeter means quality and consistency. The tweeters that didn't pass aren't necessarily bad per se or worse sounding than the ones that passed Klipsch's tests; they just didn't fit within Klipsch's testing parameters. ---------------- Michael, There may be another difference between the t35/k77. Bob Crites once said (04/04) the Klipsch K-77 "has a large thick phenolic (I think) spacer under the magnet effectively insulating the magnet from housing. It is the only variant of the alnico T-35 as far as I can tell...." I wonder what the spacer does? Is that possibly the reason for an Alnico K-77 not messing up the picture on a CRT? Quote Link to comment Share on other sites More sharing options...
John Warren Posted March 10, 2005 Share Posted March 10, 2005 ---------------- On 3/10/2005 1:27:15 PM Hardhead wrote: The tweeters that didn't pass aren't necessarily bad per se or worse sounding than the ones that passed Klipsch's tests; they just didn't fit within Klipsch's testing parameters. ---------------- There is an "old" saying in the aircraft engine business that applies here ..."you can't inspect quality into a part". Quote Link to comment Share on other sites More sharing options...
John Warren Posted March 10, 2005 Share Posted March 10, 2005 ---------------- On 3/10/2005 6:29:30 AM djk wrote: John and Maron: Most of the JBL compression drivers can hit 1.9T, obviously not the same stuff EV used. ---------------- You are correct sir. I was thinking of the motors used on the direct radiators which seem to be around the 1T range. The "run of the mill" 99.9% Fe will saturate a little over 1.2T, 99.99% Fe is closer to 1.6T. To get to 1.9T (or even 2.1T!!!) specialty alloys are used (Permendur will saturate at 2.4T). For those that are following this, the saturation level is determined by examination of the second quadrant of the B-H curve. The B-H curve shows the extent that the magnetic domains in a paramagnetic material align themselves in the presence of a magnetizing field, H. The extent of the alignment is B (the flux density in the material). As H increases, the domains eventually reach a saturation level such that further increases in the magnetizing field produces no additonal increase in B. The saturation level is also a function of temperature. The higher the temperature the lower the saturation. Magnetic domains are described by quantum mechanics. Bottom line, it's pointless to add magnetic material to a motor if it's saturated. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 11, 2005 Share Posted March 11, 2005 John W sez "Bottom line, it's pointless to add magnetic material to a motor if it's saturated." Thanks for summarizing John, the rest made my head hurt! Michael Quote Link to comment Share on other sites More sharing options...
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