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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: Puzzled by your two examples vs desired output range posted by Bill Fitzmaurice on December 31, 2023 at 14:06:55:
Hi Bill
I am in a similar boat, i started with the old Akabak when PSpice was the only way to model crossovers and never got around to trying Hornresp. Akabak can be as detailed as you care to make the model AND it's usefulness is only as great as it's ability to predict what you have built and not how cool it looks on screen.
In that area, there are some fudge factors one needs to add in Akabak to get a high degree of accuracy and those values you can deduce from the measured results (if it's that important).
This is exactly the same when simulating electronic circuits and that often means a "C" is 2 or 3 or more components in the model depending on what your looking for and how closely.
I would assume Hornresp in the model here and figures i derived are for the region where the driver / radiator has available mobility, this would be the region seen as the big impedance peak when in a sealed box.
THAT (the region under that peak) is the region where horn loading can greatly increase the efficiency by loading that area with an acoustic radiation load. IF one has a horn that is around 50% efficiency, one see's instead of a big wide impedance peak like a sealed box, most of the time the impedance under that peak is now around 2X Rdc. Thank heaven for high directivity as a typical hf compression drivers here actual broad band efficiency is rather low even with a high compression ratio..
Another way to describe that active area is the upper part of the impedance slope is controlled by the moving mass and the lower slope by the system compliance (box and suspension stiffness). At the high end, one can add some extension in exchange for 1 order steeper roll off with the right size front volume when applicable.
In between those slopes one can load the driver significantly AND importantly, adding a horn, the air mass in the throat is part of the new impedance curve AND that added mass (looks like a capacitor) increases as the frequency falls as one approaches the knee in the response.
Reactance annulling is when the change in air mass as the frequency falls (a property with some adjustment in the hyperbolic expansion rate) is offset by by the system compliance, in effect making it "at resonance" not at one frequency but over some added range extending the availability of the driver to be loaded to a lower frequency. As if in a parallel R,L, C circuit, the C was automatically variable over some small range to maintain the peak in the impedance.
I don't know about Hornresp but in Akabak, the assumption is a simple piston and i am not sure how it deals with horn loaded piston radiators that are larger than K=1. It does show directivity for any size radiator and horn. For sure, with a good compression ratio, one does not get as good measured results vs predicted above that.
Happy New Year
Tom
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Follow Ups
- RE: Puzzled by your two examples vs desired output range - tomservo 07:54:24 01/01/24 (0)
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