Khorn K-77 vertical mounting?

[TBrennan]

PWK selected the T-35s he used because they varied quite a bit in response which gives rise to a disquieting thought. We read of many here repairing T-35s but the response of a repaired T-35 is unlikely to be the same as the original response.

I've been told by an astute fella that the main reason for the variance is the inconsistant application of the phenolic coating to the diaphragm. So without a reference driver and a willingness to try diaphragms until one "clicks" T-35 repair may be an exercise in jerking-off.

I wonder if one couldn't use an array of those Vifa horn-loaded domes, the H-26. Those are VERY sweet sounding tweets and are rated as 96db efficient, same as a Heresy. An array of 8 or so should match K-Horn efficiency and would have some directivity control. Maybe. But using 8 a side they're not cheap anymore. :-)

[ZAKO]

That brings us back to the JBL 2404......Theres a hole in the bucket the bucket the bucket...Well fix it fix it fix it my dear......

[djk]

"If i recall correctly, there is a mention to the discontinuation of the licensing agreement to manufacture Klipshorn clones in an edition of Dope From Hope."

No such deal existed.

Klipsch was always trying to sue Speakerlabs. Since the patents were expired they had no luck there.

Klipsch had a trademark on the name 'Klipschorn', so Speakerlabs used 'K-horn' in its ads.

After getting a trademark for "K-horn", Klipsch was able to sue for infringement (1976).

[formica]

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On 3/12/2004 5:33:28 AM djk wrote:

Klipsch was always trying to sue Speakerlabs. Since the patents were expired they had no luck there....... After getting a trademark for "K-horn", Klipsch was able to sue for infringement (1976).

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Thanks for clarifing that...

[D-MAN]

CWM,

The Klipschorn patent expired in 1965, well before Speakerlab was ever in existence. There was no patent infringement and also no agreements between the two "institutions".

I dealt with Speakerlab (being located in Seattle) back in the "old" days, and my best friend used to work there back then, too.

DM

[D-MAN]

P.S, I forgot to mention that there were NEVER any lawsuits instigated by Klipsch against Speakerlab.

Foundless rumor. Won't die.

DM

[djk]

"P.S, I forgot to mention that there were NEVER any lawsuits instigated by Klipsch against Speakerlab."

OK, have it your way. Klipsch took no notice of Speakerlabs infringement of trademarked and copywrited material, no letters were ever sent, and the USPTO is wrong about Klipsch filing for 'K-horn' in 1976.

[D-MAN]

I don't know where you got your information, but I got it from a former employee of Speakerlab in its heyday (the time when all of this supposedly occured).

There were NO SUITS filed.

DM

[ZAKO]

Back to vertical mounting of T35/k77......I placed mine on top of Khorn (with small baffel) For the last couple of days. Did both vertical & horizontal positions. Shifted both forward & back alignments. When using mild slopes I could hear time alignment problems. but when using steeper slopes 24db or 48db slopes all seemed to dissapear. HHHMMMM So is dispersion less of a problem? Or alignment? or both? .....I do like my JBL 2404 Tweets for greater bandwidth extension. Even though my ears cant hear that high. 2404 are cleaner sounding. Im asking myself why. John Warren might want to step in with his findings?

[D-MAN]

In the vertical position the horizontal dispersion should be about 50 degrees or less. In the horizontal about 100 degrees or so (I guess).

If you have low ceilings, of course, the vertical position will cause more reflections from the ceiling. Horizontal position results in more wall reflections, etc.

However, the bandwidth reproduced by the tweeter is the same in either mounting all other things being equal. Only the dispersion characteristics would change, along with the room reflections and resultant modes.

This part remains a matter of opinion, but I cannot hear any difference concerning "time-delay" whether parallel with the midrange mouth or even diaphram to diaphram alignment. But we all know that it is technically there. I just can't hear any appreciable difference with my particular situation. I am running my tweets in the vertical position.

DM

[ZAKO]

The T35/K77 is a defraction horn tweeter. the vertical position gives the widest dispersion 120 degrees. (Audiocyclopedia by Howard M Tremaine page 1114)

[D-MAN]

Maron,

I am interested in what you think about the JBL tweeters.

I have been researching the JBL vs. the Beyma tweeters in the "constant directivity" horn.

Considering my idea about restraining upper-frequency dispersion, what is your take on this?

I thought a "diffraction" horn uses a driver backwards in the throat phase plug; exactly like a "bull" horn. The EV T-35 is nothing like that. So what gives?

DM

[ZAKO]

Diffraction horns are narrow mouth horns. THe flair provides proper cut off of frequency, while the narrow mouth provides a slit source in vertical plane. the device works on the principle that sound leaves slit that is small in comparison to wave length of the emitted sound and acts as a point source of sound . Consequently the sound will emerge, flowing around the sides of horn into a cylindrical waveform (horizontaly) the term diffraction stem from the fact that the wave form diffracts out of the narrow opening. Since the mouth dimensions are small in the horizontal plane, the flare must increase quite rapidly in the vertical direction to provide the proper cut off frequency. The fact that the horn flares in the vertical plane does not mean that the dispersion is greatest in the vertical plane. witch varies with frequency. Because of relationship of slit width to wave length, as frequency is increased, less diffraction takes place becauseof the opening up of the slit.

[ZAKO]

If you look at the JBL 2404. In the center you will see a diffraction SLIT then it will form into BABY CHEEKS. On the Bema it looks a bit different. There are other BABY CHEEK types with out diffraction slit.(Eminence APT-200, Selenium DH-200, CTS , EV-350. IT would be nice to collect them all & run some tests. Im trying to get a pair of TAD 703 be diffraction tweets. These are the cats meow. Go from 5k to 50k. From what ive heard these should really be the true replacement for the high frequency end of the Khorn. IM not going to get into the mids too mutch But I have a short list on that. As far as tweets we havent touched on the BULLET types yet. An inner ciecle of friends are getting into these as SUPER TWEETS out to the speed of light.

[WMcD]

To answer a couple of questions.

A bullhorn type of horn is called a "re-entrant" horn. It is type of co axial folding done in three dimensions. The first path is to the front, then the is a 180 degree turn to the back, and then a 180 degree to the front. We see the last expansion with a tapered cone in the center.

Diffraction horns typically have a mouth which is rectangular rather than round or square.

Here we get into some effects of wave mechanics. Plus we have to understand what we want, and why.

1) If the narrow aspect of the mouth of the horn is very much less than a wavelenght, the diffraction effect tends to spray the sound over a wide angle in that plane. But then as frequency increases, there is less of spray and the horn becomes directional.

2) The effect of 1) is that the horn is omnidirectional (broad) at low frequencies (in that plane) and then the beam narrows.

3) The result of 2) is that when you're sitting on axis, the horn has "gain" or increased output at higher frequencies. This is good if the output of the driver is falling off. It is a type of equalization. OTOH, it also means that there is not a constant pattern with frequency.

4) I've written ("that's not writing, that's typing") about this before. Don Keele did the best original explanation about trying to get a horn to have a pattern which has uniform beaming which does not change with frequency. These are constant directivity horns which are, in the middle section, mostly conical, meaning straight walls.

5) Don's credo on this is "What's so Sacred About Exponential Horns." An AES preprint which I'd be happy to mail to anyone.

6) This work is very consistent with the horn being a type of radio antenna converted to the audio range. It says that if you want a narrow spread, then the antenna has to be relatively large. This means that if you want a narrow output spread in the vertical, the mouth size in the vertical has to be large. There is more to it than that because we need a narrow cone angle in the vertical too.

7) Now this is contrary to common logic. You look at one of the midrange drivers in a Klipsch product and the vertical dimension of the horn is typically less than the width. You'd think that the vertical output is narrow; much as if the driver is a light bulb and shines through the narrow height of the mouth.

8) The common logic in 7) is not true at all in fact. The small height of the mouth is not big enough to have a uniform spread at all frequencies. There is a diffraction effect, the beam is varying in width. But the gain is good. Also the horizontal spread is fairly uniform.

9) If we need to keep the vertical much more narrow than the horizontal, then we wind up with a middle section, and mouth, which has some odd geometry. More than can be described with words. The structure is trapezoidal and overall. Importantly, the vertical aspect at the mouth has to be very large.

But that also means that at the back of the midsection, the end toward the driver, we wind up with a tall vertical slot.

10) The slot at the back of the midsection is itself a good thing and a bad thing. We have to continue the horn back to the driver. The good news is that we can make a small diffraction horn in this area (driver toward the trapezoid) to feed the trapezoidal horn going toward the mouth. The bad news is that the slot intersection must be so small that it uniformly sprays, at all relivant frequencies, into the big trapezoidal section. (Again, can't be described well without pictures.)

10.5) In fact, the Keele set up requires an addition wide flare at the mouth. Putting it all together, we have a design where there are three horns put together in series along the sound path. The diffraction horn; which feeds the trapezoidal one; and then the big flare at the mouth.

11) There is a bottom line to this. Looking at the above, we wind up with a bell section (the big part) which has no diffraction effects and is uniformly directional at the mouth. However, in order to feed it we need a feed line which is very much diffracting. That is why you see a slot at the back of the bell. Again, the slot has to be so narrow that it does not become directional. The bell section will do that job.

Ech, very complicated.

Gil

[BerndH]

I have a source for a EV-ST 350. Would it be a good replacement for the K-77?

Bernd

[ZAKO]

I understand the Ev st350 uses the same diaphram as the EV t35 . But a larger magnet giving 1 or 2db better effiency. The 350 came in two types of horns....diffraction... & baby cheeks.

[BerndH]

Maron,

Did you heard the ST-350 baby cheek in comparison with the K-77 / T-35? Is there a big difference in sound, not only efficiency?

Bernd

[TBrennan]

THe ST-350 has much wider dispersion than the T-35 or T-350, it's gonna sound different. EV recommended it's use with an EQ circuit due to it's constant directivity, a pal of mine has the info sheet with a diagram of the circuit recommended.

I heard the ST-350 on many occasions years ago in EV Sentry IIIs and IVs, it certainly sounded good. It's been a long time since I've heard it now.

[D-MAN]

I had the EV T350 on my old 70's Klones back then. I upgraded to them from the smaller t35's which were rather weak IMO.

I liked the biggun's though, wish I still had them...

DM