Re: Criteria for short horn loaded midrange woofer.
When dealing with simple conical mid horns, the likes of which were used on the EV SH1502ER, does the mid woofer need special properties? Or do these mid horns act more like waveguides wherein they are simply restricting the radiation pattern of a front mounted woofer and any type of driver can be used?
I know that with subs a high EBP means the driver will work better in a horn, but I don't know if that holds true for the short, straight horns like you find on a mid cab.
Does anyone have any guidelines, or reading that can point me in the right direction?
Thanks,
-=Tim=-
Robert Burns pointed you in the right direction.
To answer your specific question, simple conical mid horns like these
serve primarily to help match the mid driver dispersion to the HF driver. Reducing the dispersion tends to raise the on axis sensitivity, assuming the speaker dispersion is wider than the sidewall angle at the crossover point.
Below that, the horn's output, being too small to impart directivity, will diffract, but will provide some impedance match to the air down to about 1/4 wavelength, so it still is louder than a direct radiator.
The driver will still give it's usual front loaded/ported efficiency below the horn cutoff, so units like the SH1502ER, the old Yamaha 4115H, and the Altec A7 which used a stubby horn in a ''full range'' cabinet all have a stepped response, the upper response being 3 dB or more ''hotter'' than the below horn cutoff response.
Horn mids like the Mackie HD 1531 are usually crossed over fairly high (250-400 Hz) and then EQ applied to account for whatever sensitivity difference there may be between top and bottom of the range used.
Most ''standard'' PA type speakers will work OK in mid horn/waveguide cabinets.
