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Replacing top of Khorns with 400-16K mid horn


Randy Bey

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I have a thought about just taking the top half of the Khorn off, setting (OK, screwing down) a "manly" Altec horn+driver on top, and running them both full range, leaving natural rolloff as a crossover.

Insane? I hope not.

I think a nice pair of 16 element Altec horns and a good 1" driver would do an acceptable job.

Questions would center around logistics: How big is that big horn, would it fit on the woofer bin or would it need support?

Is the crossoverless idea worth considering or is there efficiency matching to deal with?

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Randy---Running Altec 1" compression drivers full range will blow them or cause diaphragm clacking. However they sound very good with a simple 1st order at 500 cycles. Altec multicells have quite a cult but the 511B horn is meant for the 1"ers and sounds very good and it's LOTS cheaper. The 1.4" 288 drivers meant for the multis might work without a highpass but I doubt it. Mike Bates runs his 2" throat TAD 4001s without a highpass and reports good results, I hope he never blows a diaphragm, replacements run about $600 each. I've never heard multi-cells and 288s in the home, only at the pictures. One very astute and experienced horny I know says multicells sound kinda bad in the home, high frequency fingering being a problem. I don't know but before I spent big bucks on multis I'd hear them first in a home or small room situation. But I imagine 288s in the home would be VERY low distortion devices. You can find dimensions of the various Altec high freqeuncy horns at www.soundpractices.com and www.audioheritage.org/

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  • 5 weeks later...

I replaced the top of my Khorns and have incorporated the Altec 288ks drivers and the Altec 805b horns. The throat size on the horns and drivers are 1.4. The 805s were a horn that came in the Altec A4s. The dispersion of the horn is 40° vertical and 80° horizontal. So they have a nice distribution not too great vertically where you do not want to have reflections from the floor and ceiling. The other horn I considered was the 1005, but this horn is a ten cell and was just too big. The 288ks are 16 ohm with alnico magnets. Each weigh in at 30#, 7.6 in diameter and are very sensitive. Although the 288ks are rated a 500cps they were measured and easily go down to 400cps.

For the tweeters, I replaced with the ElectroVoice T-35's. I also use the Al Klappenberger crossover.

With the mods the systems sound wonderful. I bought the Khorns new in Jan 2000 and stock they lasted a month. Stock they were way to edgy. I listen to lots of Jazz and with these mods you can almost feel the "spit" from Miles Davis horn and John Coltranes sax.

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I think it is ill advised to run the midrange / treble horns without a cross over. A single capacitor, well chosen, may be sufficient.

But, take care of your drivers.

It is possible to run a bass unit without a cross over "full out". This is because the windings are robust. Also, the natural inductance of the voice coil acts as a crossover.

The situation is reversed with the treble unit.

The winding are delicate.

The infrasonics of some recordings at high levels from a powerful amp can distroy bass drivers and will probably certainly distroy the windings of a treble driver unit.

Gil

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  • 2 weeks later...

i shoehorned community bi-radial horns into the top section of my 60's vintage k-horns, with jbl 375 2" drivers (the 30 pound ones!) the horns barely fit- they span the entire width and height of the top section. put ev t-35's on top of the box, set back so their voicecoils are aligned with the 375s. used the stock crossovers.

I N C R E D I B L E difference in the sound. extremely detailed with astounding imaging. i've closed my eyes and had out of body experiences without any mind altering substances!!

needless to say, i recommend the change!!! but ya gotta use crossovers or you'll fry your mids/tweets!

------------------

mr.bob

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