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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: RE: Constant Directivity Horn Recommendations posted by Cask05 on June 18, 2025 at 05:34:12:
Hi
So the reason i went with the mid cone drivers on the first version (Unity horn) was because your ears are the most sensitive to harmonic distortion were your ears are most sensitive. If you consider the general equal loudness curves for ones ears, that curve inverted is like the ear's frequency response.
In that day 2 inch exit drivers were the norm and so was the "ice pick in the forehead" sound, so why was it sound systems sounded bright with increasing loudness??.
So my thought was ok I have to start over in life after the shuttle disaster ended Intersonics. A friend asked me to design a speaker for commercial sound. I had gotten back from Egypt, was hired to measure the acoustics in the GP for a movie and at a Christmas party, my friend said "make me a speaker out of a pyramid" I said yeah it will sharpen the sound haha, and i would grant your if i had a magic wand, funny guy (he was).
The next day the reality set in what speaker to make?
And i thought about the upside of CD horns and Don Davis's words about the down side (poor lf loading on the driver).
And what fundamentals have harmonics that fall in the 2-4 KHz ice pick range?
The early TEF systems could plot the harmonics vs frequency and it was easy to measure those drivers being grossly distorted down low at what seemed like modest power.
So the hunch was if i coupled mid drivers into the horn where the expansion rate (the impedance transformation high pass) was suitable for mids (in at 300Hz) that the low compression ratio and large area would be lower in distortion.
It was in fact vastly lower because of the low pass acoustic filter (the port mass and front volume) AND the notch's low pass in the response above the operating band.
The HP3562 had showed about .12% thd at 100dB 1m, about 1/200 of the 2 inch at the same spl. I thought ok this is cool.
An electrical or dsp low pass filter doesn't reduce distortion produced by the driver below crossover but an acoustic low pass does as it is after the distortion was produced but before it enters the horn. If the drivers radiation interact where the distance is less than 1/4 wl, then the radiations combine coherently into one source (like closely spaced subwoofers also have mutual coupling except now inside the horn).
I glanced at the link, they got the patent part wrong, the Unity patent expired but the reason for the improvement patent (Synergy horn) was i was not able to make all the crossover phase shift go away in the 3 way Unity horns. The time order of the drivers was ideally the inverse of the crossover's group delay but it was hard to find the path, can't do it the named slope shapes..
I had read a paper of Dick Heyser's when Doug ran the Heyser library where he describes an imaginary full range loudspeaker that radiated as a single point in space over a broad bandwidth. So far as a single source, it did that but i was really keen on making it work as a single driver the rest of the way to preserve time so it would produce a square wave broad band and over a wide angle too.
What i was missing was a better understanding of the mid ports and that investigation made it easier top make a 3rd and 4th order passive crossover without N order phase shift.
Now all three ranges combined into the radiation of a single full range driver..
The first successful passive filter was the SH-50's.
This is the one I made about 21 years ago now, a living room measurement of that one.
That speaker and the ones that followed launched the company.
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Follow Ups
- RE: Constant Directivity Horn Recommendations - tomservo 12:25:32 06/19/25 (0)
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