400 hz Spherical Tractrix for K55?.....inexpensive

[ClaudeJ1]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=9718926801&rd=1&rd=1

Has anyone heard these or purchased them. Look like a good deal to me if the shipping from Germany doens't kill the bill.

Claude

[TBrennan]

According to Bruce Edgar (who knows more about tractrix horns than anybody since Voight) tractrix horns must be crossed higher than their rating, for instance he uses 350hz horns for a 500hz crossover.

To quote Bruce "the problem is that the tractrix horn response just does not extend to the flare point-----the 300hz horn that I make turns on around 400hz"

So if using tractrix horns this most be taken into account, maybe the maker of the horn in question has, I don't know. I used to use 550hz Edgar saladbowls and Bruce advised that I cross then at 700hz or so.

[Deang]

Here's a 350Hz Tractrix horn that 'turns on' at 350Hz -- At least, that's where the -3dB point is with a K-55 attached. I've read in a few places that any horn should be crossed over a 1/2 octave above its cut-off, but it's never been with any explanation as to why.

[Guest " "]

Horns produce a knocking sound as you approach the horn's resonate frequency.

Quite different type of sound then the ringing often refered to.

So you need to check if the recommended crossover frequency for the horn has already taken this into consideration.

Also need to consider optimal crossover frequency depending on the slope of your crossovers. The more gentle the slope, the closer you are likey to get to the resonate frequency.

[TBrennan]

"Horns produce a knocking sound as you approach the horn's resonate frequency."

Do you mean the driver itself running out of excursion and the diaphragm clacking against the phase plug?

[DrWho]

Do you really want the directivity of a spherical horn? [^o)]

[bodcaw boy]

99% of the horns i have designed and built and tested (mostly of the tractrix tribe and about 300-400 of them) have met the designed cutoff. not all horns have to be crossed over at a high freq than cutoff. it really depends on the transition from resistive to reactive and by looking at that you can decide where you should crossover and what minimum slope to use.

have a blessed day,

roy delgado

[freddyi]

interesting stuff - FWIW 400 vs 511 in this graph

http://img130.imageshack.us/img130/4305/lskn8.jpg

[3dzapper]

Freddi, Thanks. It's obvious from that graph why those that like repressed upper midrange/treble (blah v blatt) prefer the Altecs.

Rick