K510 Jubilee little HF horn....

[sfogg]

For those put off by the size of the K402 horn on the Jubilee the Jubilee also has a smaller HF horn available, the K510. Both the K402 and the K510 are very interesting in that they have constant dispersion and at the same time are Tractrix flares. I didn't know that combo was possible till I read about this from Roy here. I would have loved to have tried the K402s but three of them up front in my room are wider then my room which would be a problem.

As such I became interested in the K510 and would be willing to give up some pattern control compared to the K402. For those worried about the size of the K402 the K510 is *much* smaller. I have been using much larger horns lately (511B, 805B, MR94) so when the K510s arrived I was shocked at how much smaller they really are. Since I don't have suitable 2" throat drivers yet and haven't found throat adapters yet I can't say anything about how they sound. As such the most playing I can do is take some pictures of it and post them here. After I get a 2" driver in I'll spend some time listening to it and making some measurements on it. For the first driver I'm going to try the Peavey 44xt which should be arriving next week. Don't know what to expect from that driver as I haven't seen hardly anyones thoughts of it that has used it in a home setting. I might order a B&C DE750tn to run on the horn as well to see how it compares. Klipsch has apparently used the DE75 (discontinued) on this horn as well.

First picture compares the size of the K510 to the Altec 511B. Both are 500hz horns.

[sfogg]

511B and K510 from the front....

[sfogg]

This is the K510 and the horn out of an Altec Model 14. That is also a Mantaray CD horn which is only a little smaller then the K510. However the Altec horn is only rated to around 1400hz. It is interesting as it has asymmetric dispersion in the vertical plane. It is something like 10 degrees vertical below the horn and 30 degrees above it. Altec did this to limit floor bounce. Used upside down up on the walls it could be an interesting horn for surrounds.

[sfogg]

This is the K510 compared to an Altec 288 driver. It either shows how small the horn is or how large the driver is depending upon your point of view....

[sfogg]

Lastly comparing the depth of the horn to the depth of the 288....

[TBrennan]

Interesting. I wonder how the 510 manages to plumb so deep?

I assume it loses pattern control at the lower end of it's range.

Can't find 1.4" to 2" adaptors?

[sfogg]

Tom,

I assume it gets so deep from the combo of the large throat and the Tractrix flare, just a guess though. It does loose pattern controller higher up then the K402 but I don't know how much higher up.

I've been looking for 1.4 to 2" adapters but haven't found them. I'd like to try the 288s on them since then I'd only be listening to the differences in the horns instead of comparing different horns and drivers. Can't find the adapters though. The Seleniums were discontinued and Partsexpress is out of stock.

Shawn

[TBrennan]

Shawn---Jammin Jersey shows they have the adaptors, JBL models, but the price is dear, $75 each. I think PAudio might make an adaptor.

[D-MAN]

How much did these cost, and how-and/or-who do we call to get a pair? Very intriguing - these are 2" throats?

The high frequencies are going to be limited in dispersion characteristics by the actual physical flare angles of the horn once the wavelength is small enough to fit inside (or across) the horn mouth (per Olsen). This happens in all HF horns, though. I'm not particularily bothered by that in this case, in that the horn in question is so short and the walls are fairly straight with a very wide flare. My concern is mainly the midrange dispersion characteristics and whether they actually go down to the Fc.

I'd love to give these a listen!

DM

[TBrennan]

Here you go Shawn, that 1.5" to 2" would probably do the trick.

http://www.loudspeakersplus.com/html/paudioadapters.html

[sfogg]

Tom,

Thanks, I might give the 1.5 to 2" a try but the discontinuity at the throat wouldn't be optimal. PAudio also has 1" to 2" so I could try some 902s on these. If I really wanted to go nuts they even have dual 1" to 2" adapters.... if only I still had the 7 902s.

Shawn

[sfogg]

"The high frequencies are going to be limited in dispersion characteristics by the actual physical flare angles of the horn once the wavelength is small enough to fit inside (or across) the horn mouth (per Olsen). This happens in all HF horns, though."

Non-CD horns tend to beam the HF the higher up in frequency you go. Some narrow vertically, some narrow horizontally... some do both. The dispersion/directivity is not constant. In other words if you measure the driver/horn directly on-axis compared to say 30 degrees off axis the FR will not be the same. The collapsing dispersion acts as an EQ on the driver to keep its response flatter above its mass rolloff point.

In a CD horn the FR will be more even directly on axis and say 30 degrees off axis. The horn has controlled directivity/dispersion. The tradeoff there is CD horns require external EQ to keep FR flat above the mass rolloff point.

Since I tri-amp with digital crossover/EQs handling this EQ is easy.

"My concern is mainly the midrange dispersion characteristics and whether they actually go down to the Fc."

I'll be testing the low end on the horn/driver. Roy says they are 500hz horns though so I don't doubt that they can get down there.

"How much did these cost, and how-and/or-who do we call to get a pair?"

Klipsch commercial/theater sells it as the Kpt-904-hf which includes mounting equipment and the B&C DE75 driver. They probably have a combo with their K69 driver as well. They are 2" throat horns.

Shawn

[sfogg]

BTW, one other thing I noticed after looking at this pictures. In the pics the K510 looks asymmetric. I actually went and got them again to double check that. They aren't. The stiffening ribs in the horns are off center. I am assuming that is to alter the potential resonant frequencies of the horn itself to two different frequencies per side instead of two of the same resonances which would couple and be higher in level. Nice attention to detail!

Shawn

[DrWho]

That's gotta be painful to have no way to hook them up at the moment...I'm looking forward to your impressions

[D-MAN]

All I would want is the horns, only. B&C drivers? Bah!

As for "beaming", in a single-throat exponential or in this case, tractrix, a close-relative with an even tighter flare, yes, I would expect that it would have a tendancy to narrow in dispersion pattern as dictated by the general proportions of the horn walls flare. That is not a CD design, although its rapid, wide flare and very short length would promote a fairly wide dispersion angle even at extremely high frequencies. I would be surprized if the horn in question actually displays a disagreeable tendency to beam.

Ameliorated in some designs, though partitioning, or multiple flares, etc. but never truly rendered moot. It is a matter of physics, and for one tradeoff, there is always another.

Here is the quote from Olson:

It will be seen that up to the frequency at which the wavelength becomes comparable to the mouth diameter, the directional characteristics are practically the same as those of a piston of the size of the mouth. Above this frequency [smaller wavelengths], the directional characteristics are practically independent of the mouth size and appear to be governed by the flare.

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This means that the smaller the mouth, the wider the dispersion for frequencies lower than the l=m ratio, and the narrower the smaller wavelengths become until they match the flare.

DM

[TBrennan]

" I might give the 1.5 to 2" a try but the discontinuity at the throat wouldn't be optimal."

Yeah, but since the discontinuity is small and a step up rather than a step down it might be inaudible. Anyway they're cheap.

Now you could take a burr-grinder to the exits of the 288s and open them up that 1/10th of an inch.......nah.

[sfogg]

"As for "beaming", in a single-throat exponential or in this case,
tractrix, a close-relative with an even tighter flare, yes, I would
expect that it would have a tendancy to narrow in dispersion pattern as
dictated by the general proportions of the horn walls flare. That is
not a CD design"

Again, this is a horn with CD. It also happens to be a Tractrix horn. Roy has confirmed this. Look at the polar patterns posted for the K402 for example. They show a horn with constant directivity/dispersion.

The quote from Ohlson is talking about the low frequency dispersion of the horn. In a nutshell it would basically point to where a horn would loose pattern control.

It hardly applies to what happens on the high end at all. The high end is where a CD horn differs from non-CD horns.

Shawn

[D-MAN]

Please re-read the quote you clearly didn't get it the first time. Also, the parameters/characteristics I stated above are all consistant with the commonly-called "CD" horn.

However, the term "CD" as applied to horns is a misnomer, or more of a marketing tool, but I digress.

The attachment is an excerpt from the JBL paper on CD horns, and outlines some of the properties/characteristics that I mentioned previously.

DM

[D-MAN]

Here is the actual JBL paper in pdf format.

DM

AES_v31_n6_p408.pdf

[sfogg]

"Please re-read the quote you clearly didn't get it the first time."

If you think that I'd suggest you are the one that needs to re-read it a few times. That quote is describing where a horn looses control over its pattern. Per that quote that occurs when the wavelength of the sound gets larger then the diameter of the horns mouth. When the wavelength of sound being reproduced becomes smaller then the diameter of the horns mouth the horns flare itself is what more governs the directional characteristics of the horn. Since you apparently have missed this lower frequency sounds have longer wavelengths then higher frequency sounds. In other words the quote is describing what happens near the bottom of a horns bandwidth, not up top.

Shawn