Mi-horn - anybody tried them?

Nuuk said:
I came across these (I am referring to the driver extensions). Has anbody tried these and if so do they 'do what it says on the tin'? :cool:

I haven't tried those, but I did take a normal dome tweeter (Seas 27TDFC) and added a very short horn as a wave guide. Interesting results. The speaker has to be EQ'ed for smooth response, but has lower distortion after EQ.

http://www.zaphaudio.com/hornconversion.html

I doubt that the mi-horn driver extensions do anything other than make the driver response ragged. There are a few likely issues. Mainly, the size of the horn is too small in relation to the radiating suface, and the outer edge of the horn is free-air rather than flush with a baffle. What will result is edge reflection and diffraction, some frequencies increased from the horn shape, but dips in response at other nearby frequencies. The response curve will likely be uncontrollable.

Of course, I say all this without actually testing one.
 
Greets!

I didn't wait for all the info to load (super slow dial-up), but assuming they only claim to improve DI (directivity, i.e. reduce off axis reflections) above ~2 kHz, then they should work as advertised, though they probably create more problems than they solve WRT the 'sweet spot' response unless their effects are accounted for in the speaker's design from the get-go.

Yes, horn edge diffraction has periodically been a 'hot topic' since the beginning of telephone design. Many horn designs don't need it though since their dispersion narrows with increasing frequency, so at the WLs where it would be an issue, the lens is 'out of the way', ergo there's nothing to cause any reflections till the frequency is low enough for standing waves to develop across them. This requires they either need to be terminated to an acoustically large baffle or rolled over or damped with foam/fiberglass insulation/whatever for best performance, which of course solves any potential edge diffraction problems also.

GM
 
i actually have a pair of mi-horns!

they were doing a promo thing and giving them away for free! i got a pair for my tweeters because i was curious. my $200 speakers easily bested a $20k pair! just kidding...

they basically sounded more "focused" and more line a line source. but it of course sounded closed in and a bit muffled. but if you have bright tweeters (which i did), it actually softened them a bit. but overall, it was a gimmick. it sounded better in very very few ways, and mostly worse in a few ways. it wasnt a giant leap forward. it could come down to a matter of taste though. people who like the klipsch sound (the closed in loud "shouting" horn sound) would like these things. they made your speakers sound like they were shouting.

edit:

if anyone wants them just to play with for grins, let me know, ill send em to you for just the shipping costs.
 
GM said:
Greets!

Yes, horn edge diffraction has periodically been a 'hot topic' since the beginning of telephone design. Many horn designs don't need it though since their dispersion narrows with increasing frequency, so at the WLs where it would be an issue, the lens is 'out of the way', ergo there's nothing to cause any reflections till the frequency is low enough for standing waves to develop across them. [...etc...]

GM

Truth. I designed a horn about 25 years ago (oh Lord, that far back?) which got around edge diffraction by using a three inch radius on the sidewalls, after a 15 inch long conical section. It worked surprisingly well; as soon as you couldn't see the throat you didn't hear the horn, and within the intended dispersion pattern the response was quite even until the driver limit (JBL 2482, about 5 kHz on a good day).

It turns out that a conical section after the throat match geometry (on which more anon if anyone's interested), along with a largish radius at the mouth, is not a bad approximation to a slightly higher frequency exponential curve if you take into account the expansion of phase plug and driver throat. The straight edge of a single conical section lets the wavefront expand evenly across the frequency domain, as opposed to the multiple sidewall breaks of standard "constant-directivity" horns, and the end curve provides a smooth transition from fractional-space expansion to 2pi space at the mouth.

[1] round is OK, although rectangular gives better results in real rooms.


Francois.
 
Re: Re: Mi-horn - anybody tried them?

Zaph said:


I haven't tried those, but I did take a normal dome tweeter (Seas 27TDFC) and added a very short horn as a wave guide. Interesting results. The speaker has to be EQ'ed for smooth response, but has lower distortion after EQ.

http://www.zaphaudio.com/hornconversion.html


That's pretty cool. Just wondering, could you please show the cumulative spectral decay curve of the horned tweeter after the capacitor? The CSD you have includes the 6 dB lump in the upper mids, which somewhat skews the decay results.


Thanks in advance,
Francois.