Mystery Woofer (4 Ohm) - any ideas?

[D-MAN]

Ran across this at Parts Express. Not quite a K33E but close in some ways. Check it out.

Mystery woofer link

[boom3]

I'm not sure which mystery you're referring to. It seems the Qes is a tad high for a wide-band bass horn, generally, Qes should be below 0.25 or so. They would probably be fine in a Cornwall cab.

[jwc]

I have seen this oofer before and it crossed my mind as a replacement. However, didn't like the higher Fs. Also lower Les. Sensitivity and Freq response on the mark.

I bet the port volume of the Cornwall is too large for it. If you look at the recommended cabinet options for the 15 inch woofers, they typically recommend a 2 port option that is only about a volume of 150-300 square inches. The Cornwall port volume is 713 sq. inches.

I would be interested in hearing the results.

jc

[jwc]

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On 6/14/2005 3:31:25 PM boom3 wrote:

I'm not sure which mystery you're referring to. It seems the Qes is a tad high for a wide-band bass horn, generally, Qes should be below 0.25 or so. They would probably be fine in a Cornwall cab.

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Hey Boom, I'm a little slim on the Qes understanding. Explain to me why you think it should be less than 0.25

Thanks

jc

[djk]

This driver would replace a LaScala woofer just fine, it has a higher mass corner than a K33 and would be a bit more efficient above the Fc of the horn.

It would port flat to 38 hz in a 2.5 cu ft box with a B6 alignment and have about the same 2.83V sensitivity as a Cornwall, amps larger than 100W would cause power compression due to the short x-max.

Looks like a fine driver at a fair price.

[D-MAN]

Dennis, thanks.

I was wondering if it is a Klipsch driver of some sort.

Decent and new 4 Ohm vc 15" drivers are somewhat rare. I note that the steel frame is the normal Eminence type (heavier than the K33E stamped frame). The magnet size looks about the same (guessing 80 oz?). 450 watts is a good thing although 3/4 of it gets "compressed".

DM

[D-MAN]

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On 6/14/2005 3:31:25 PM boom3 wrote:

I'm not sure which mystery you're referring to. It seems the Qes is a tad high for a wide-band bass horn, generally, Qes should be below 0.25 or so. They would probably be fine in a Cornwall cab.

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Hey Boom, I'm a little slim on the Qes understanding. Explain to me why you think it should be less than 0.25

Thanks

jc

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Here is a excerpt from the infamous Khorn Throat Riddle "Correction" article. This won't really explain the whole thing, but the part I'm zeroing in on is what elements in particular makes for a good wide-bandwidth horn driver. Beware, though, the article is specific to the Khorn, which seems to be a rather unique "animal" in the horn world.

The Qes of the K33E is .41 (if I remember correctly) and the Fs is 34.5Hz so that also flies in the face of what was said below. But I think that he's saying that the bandwidth extension is in the UPPER range, not the lower. This is pretty confusing, for me at least.

I've heard that nobody really knows what a driver is going to do until it actually gets in the horn. May be some truth to that.

What I have heard about horn drivers is pick one with the Fs below the Flc of the horn. Large magnet for good control "under pressure" as the horn presents a resistance to the diaphragm to movement. Long excursion is better such as 5mm+ one direction. Qmech above 5.0. That's about all I know. This stuff is sort of nebulous at best.

DM

[D-MAN]

Since I started on the Horn "Rules of Thumb", here's some other references that I ran across:

I'll add more to this as I find them.

DM

[D-MAN]

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On 6/14/2005 5:29:08 PM jwcullison wrote:

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On 6/14/2005 3:31:25 PM boom3 wrote:

I'm not sure which mystery you're referring to. It seems the Qes is a tad high for a wide-band bass horn, generally, Qes should be below 0.25 or so. They would probably be fine in a Cornwall cab.

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

Hey Boom, I'm a little slim on the Qes understanding. Explain to me why you think it should be less than 0.25

Thanks

jc

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A general Horn Rule of Thumb:

Here's what I've got so far...

The Qts is used to calculate the Fhc (high frequency mass rolloff corner) of a particular driver as:

(2*Fs)/Qts = Fhc (in Hz) (per Keele)

What makes a good horn driver test:

Fs/Qes = horn test ratio in Hz, where:

73+ is good for horn loading

-72 is good for bass-reflex loading

(from B.Edgar SB 05/09 article)

Posted by djk in the 'Jubilee' thread in 2 channel:

A driver with a free air resonance of 100hz will work in a horn as low as 10hz if the Qts is 0.2 or lower, and the horn has the correct taper rate and mouth area.

(Fs/2)*Qts=Flc (after Keele)

I'm starting to "get" some of this stuff!

DM

[boom3]

Thanks for finding those refs. I have been recovering from minor surgery and wrapped up in a book project (non-audio). The Klipschorn seem to be special case it seems for just about everything. It does seem that there is a fairly fixed axiom that says folded bass horns are lucky to get a frequency ratio (nominal cut off to first crossover point of 1:10 (40-400 Hz in the older Khorn)