can i install 4 ohm or 16 ohm woofers in my khorns?

[funkyhambone]

i would like to take the woofers out of a pair of khorns and replace them with the old blue stephens trusonic woofers. i have both 4 ohm and 16 ohm stephens. can i just swap them out? does something need to be done to crossovers? is damage a possibility? i have AA crossovers in the khorns.

[twistedcrankcammer]

i would like to take the woofers out of a pair of khorns and replace them with the old blue stephens trusonic woofers. i have both 4 ohm and 16 ohm stephens. can i just swap them out? does something need to be done to crossovers? is damage a possibility? i have AA crossovers in the khorns.

You did not say what year Cornerhorns you are working on, but with th AA crossover, you use the 4 ohm Stephens Truesonics. A 4 ohm driver is seen as 16 ohm resistance in the horn loaded Cornerhorn. I changed mine out for the 4 ohm Alnico magnet Electro Voice EV 15W-K drivers.

By the way, I want that window in your avitar!![Y]

Roger

[funkyhambone]

the khorns i removed the stephens from were early 50's. i want to put them in my 1982's with the AA. so you just swapped them without any adjustments? did your sound change dramatically? these stephens are about twice as heavy as the k-33's. i have wanted to do this for a while but thought some adjustments might have to be made.

[capo72]

You should be able to compare your final resistance measurement without pulling any woofers. Check your current final resistance at the input of your AA. Then unhook the K-woofer from the AA and hook up the Stephens and measure final resistance at the input again. This should give you a rough idea of the change in your final impeadence. I would try that before going through the work of swapping out the woofers. Good luck.

Jeremy

[twistedcrankcammer]

the khorns i removed the stephens from were early 50's. i want to put them in my 1982's with the AA. so you just swapped them without any adjustments? did your sound change dramatically? these stephens are about twice as heavy as the k-33's. i have wanted to do this for a while but thought some adjustments might have to be made.

The Electro Voice and the newer style K-33E that are in your Cornerhorns are both called 4 ohm speakers. If you actually check the woofers with a dc resistance ohm meter, you will get a resisitance reading of anywhere from 3.4 to 3.7 ohms. It should be a direct swap as well for the Stephens Truesonic 4 ohm speakers. You should be able to have the 16 ohm Stephens reconed to 4 ohms as well if you like the change you get. (I have someone to recomend for that if that is the case).

As for the weight of your Stephens Truesonics, and the Sound; Remember that Paul Wilbur Klipsch himself always preached about the efficiency of a speaker, and how this reduced distortion?? Now realize that these very old woofers used Alnico magnets instead of todays Ceramic magnets. one pound of Alnico AKA rare earth magnet has the same magnetic field of 5 pounds of Ceramic AKA Ferite AKA Mud Magnets used on todays woofers, even the more desirable "Square" magnet K-33E are mud magnets. I don't know what the specific magnet weight is on your Stephens, but on my Electro Voice EV15W-Ks, they have 5 pound Alnico magnets, or the equivelent of 25 pound Ceramic magnets, and guess what?? this makes them more efficient.

Sound?? I switched back and fourth several times just to make sure. (I did it at my brother in laws who also owns Cornerhorns and a 24ft by 32ft listening room. It was obvious that I had picked up some bass, but what was even more obvious was that I could play the Alnico speakers clearly at levels that the K33-Es were flapping and bottoming out at.

Roger

[djk]

Ah.....the alnico myths.

Early magnetic structures were horrible, especially the welded pipe style found in early EV, Altec, and JBL speakers. Themagnet structures were so in-efficent that they need huge magnets to work. JBL came up with a cast return structure that would have the same flux density with only a one pound magnet as the older welded pipe structures using five pounds of alnico.

Alnico vs ferrite.

In general, ferrite needs to be about 2.5 times heavier than alnico for the same flux density. This varies with the type of plates in the magnetic structure. If a full cup return structure is used (like a JBL cast type), the weight can be much closer to alnico. Stamped plates are used for low cost as they are much cheaper than cast and machined (like JBL), thus more inexpensive ferrite is added to the magnet structure instead.

The only thing not done in cheap ferrite structures is to have a shorting ring. Alnico is conductive, ferrite is not. JBL uses an aluminum (or copper) shorting ring in all their ferrite structures, Eminence does the same on request.

An interesting comparison would be a JBL 2441 vs 2447, they both can use the same diaphragms. The ceramic 2447 is actually over one pound less in total weight, and has higher gap flux too! Of course the old neo magnet version of the 2447 (2451) is only 10 lbs, and the new (2452) is 4lbs~5lbs (estimate as there is no data sheet spec).

Square vs round K33E.

Original ceramic Eminence drivers had square magnets as they could only shear the plate stock into square plates. This is poor utilization of the magnet weight. When they were able to punch 3/8" plate they went to round magnets. Bob Crites has a clone built to square plate specs using round plates.

[twistedcrankcammer]

Ah.....the alnico myths.

Early magnetic structures were horrible, especially the welded pipe style found in early EV, Altec, and JBL speakers. Themagnet structures were so in-efficent that they need huge magnets to work. JBL came up with a cast return structure that would have the same flux density with only a one pound magnet as the older welded pipe structures using five pounds of alnico.

Alnico vs ferrite.

In general, ferrite needs to be about 2.5 times heavier than alnico for the same flux density. This varies with the type of plates in the magnetic structure. If a full cup return structure is used (like a JBL cast type), the weight can be much closer to alnico. Stamped plates are used for low cost as they are much cheaper than cast and machined (like JBL), thus more inexpensive ferrite is added to the magnet structure instead.

The only thing not done in cheap ferrite structures is to have a shorting ring. Alnico is conductive, ferrite is not. JBL uses an aluminum (or copper) shorting ring in all their ferrite structures, Eminence does the same on request.

An interesting comparison would be a JBL 2441 vs 2447, they both can use the same diaphragms. The ceramic 2447 is actually over one pound less in total weight, and has higher gap flux too! Of course the old neo magnet version of the 2447 (2451) is only 10 lbs, and the new (2452) is 4lbs~5lbs (estimate as there is no data sheet spec).

Square vs round K33E.

Original ceramic Eminence drivers had square magnets as they could only shear the plate stock into square plates. This is poor utilization of the magnet weight. When they were able to punch 3/8" plate they went to round magnets. Bob Crites has a clone built to square plate specs using round plates.

djk,

I really can't speak to wheather or not your comments on motor structure are correct or not, but I have researched and talked with several magnet manufacturers, and they all clame that Alnico has 5 times the gauss of ferrite, as I was checking into making a Neodinium magnet EV15W-K. All of the manufacturers list Alnico as 5 times Ferrite, and Neodinium as 10 times the field strength, but this would also depend on N42, N50, etc. It is also widely known that Alnico is much more sensitive to heat degridation than the other two.

I don't know enough to state any claims to the contrary on your motor structure statements, but I sure would question your statement of only 2.5 times as powerful. Alnico ceased to be used for cost purposes and scarcity more than anything else, but the fact remains that my EV15W-Ks have more bass and play louder than my K33-Es, which I will gladly demonstrate for anyone who wants to come to Ohio.

Roger

[mike stehr]

Gauss

[djk]

Material BHmax cost/$lb cost $/BHmax

Material	BHmax	Relative Cost ($ / pound)	Relative Cost ($ / BHmax)
Flexibible	1	$1.00	$0.60
Ceramic	3	$2.00	$0.50
Alnico	5	$20.00	$4.30
SmCo	20	$100.00	$6.00
NdFeB	40	$50.00	$1.40

I guess if you repeat something long enough it becomes true?

Maximum Energy Product (given the symbol BHmax, and measured in Gauss-Oersteds). This is an indication of what volume of magnet material is required to project a given level of magnetic flux.

AC-8B and AC-12 types of ceramic magnets have a BHmax of 4.0 (MGOe) Alnico 5 (the grade commonly used in speaker magnets 30 years ago) have a BHmax of 5.5, this same ratio may be seen in the cost/BHmax chart above.

" It is also widely known that Alnico is much more sensitive to heat degridation than the other two."

That is completely wrong, Alnico is one of the best in the heat department, NdFeB is the worst. The problem with alnico is is demagnetizes when it's magnetic field is modulated by the field produced by the voice-coil.

"I don't know enough to state any claims to the contrary on your motor structure statements, but I sure would question your statement of only 2.5 times as powerful."

When used in the same kind of magnetic return structures the AC-8B and AC-12 only require about 1.375X the amount of Alnico 5. Since ceramic is so inexpensive we may choose to use a much simpler magnetic structure by increasing the amounts a bit higher (up to 2.5X). As the case in point shows, the JBL compression driver actually showed an increase of flux density with a decrease in total weight compared to the alnico. "

Alnico ceased to be used for cost purposes and scarcity more than anything else, "

Somewhat correct, although EV switched their woofers over to ceramic over 10 years before it became scarse/expensive.

"but the fact remains that my EV15W-Ks have more bass and play louder than my K33-Es, which I will gladly demonstrate for anyone who wants to come to Ohio."

I could have Eminence design a ceramic magnet woofer that would knock the socks off the old EV15WK. The coil on those old EV woofers are short, short, short. That combined with a machined top plate made them efficient. A machined top plate with XBL^2 gap geometry and a ceramic magnet smaller than the 5-1/2 lbs of alnico EV used would be all it would take. A shorting ring would be nice for low magnetic modulation, alternately a bucking coil (as used in field-coil drivers) could be added to the top plate (like some Eighteen Sound).

P.S.

"All of the manufacturers list Alnico as 5 times Ferrite"

They're trying to sell you something that costs 10X as much and requires secondary machining operations ($$$ for them). They are also comparing AC-1 ceramic (BHmax=1.05) vs alnico 5 (BHmax=5.5), and not comparing with AC8B and AC-12 (BHmax=4.0).