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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: Paul E. & Pooge posted by tomservo on June 10, 2003 at 09:58:23:
against floor and back wall.Wood is cut for a 22.5" x 25.25" mouth.
I agree that the EVM 15L is not ideal here. I think one of the problems is low Fs. I understand it's desirable to have Fs near the horn flare frequency. Wood is cut for a t=.665 and length of 32 or so inches.
One of the system issues is time alignment. Get the horn too long, and it gets more difficult to time align with the midrange, especially in the home setting.
You speak much of distortion. I fully agree that reducing it is ideal, and you are much more concerned about it in a pro setting. However, in a study of studio monitors by Newell and Holland, "Round the Horn", Studio Sound, March 1994, pp.59-70 (Reprinted in Speaker Builder, 8/94), they compared various styles of loudspeakers and tried to group them according to sound. Included in the study were the original Quads, horns, and cones. They found little correlation with regard to harmonic distortion or phase; mixed results on freqency response; and mixed, although generally good, correlation by horn length.
What they did find was a really good correlation when cepstral analysis was used as a comparison. The power cepstrum of a transfer function is the Fourier transform of the log of the transfer functions's amplitude. The plots are very effective in showing reflections existing as spikes aling the tine/distance axis. Thus, mouth or other reflections in a longer horn would be more delayed than that of a shorter horn, or one with fewer impedance discontinuities. Obviously, reduction of impedance discontinuities, especially at the mouth, appears critical to good sound. This is why I originally was interested in Keele's minimum reflection approach. I'm not knocking Leach. Leach is a better bandpass. What I'm trying to analyze, though, is what really matters, sound-wise, in the home environment. Is time alignment critical at 500Hz? I've heard it is. Long horns make this more difficult. It the natural rolloff of Keele at the high end good or bad for crossing over to the higher band? In other words, if Keele is down 3-db at 500Hz, is this a bad thing or a good thing for crossover? Keele would clearly have a different phase character at rolloff than Leach. Is it better to have bandwidth extended well above crossover and use a crossover, or allow the natural rolloff without one? This would need to be modeled also for a system integration standpoint.
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Follow Ups
- Re: Paul E. & Pooge - pooge 10:56:53 06/10/03 (0)
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