The baffle has an 8 X 13 inch opening in it. But on the front side of the baffle the horn opens up to approximately 8 X 17 inches. There's no transition.

Is there an inherent problem with this? Would it be better if the top and bottom surfaces were angled so that the horn section began with an 8 X 13 inch section?

Thanks

• http://www.lansingheritage.org/images/altec/catalogs/1978-pro/page11.jpg

http://www.jblpro.com/pub/technote/tn_v1n21.pdf

They specifically lead you to believe that the constriction plate is a problem instead of a tuning help. It makes some sense, and I have paused while considering driver and lens to think this through. My original design was thinking an Altec like constrictor, but I am now leaning toward less throat with no restriction.

Any ideas to help me clear my head?

In bass horns you can design a throat size without a plate and hope for the best, or design the horn, build it, and then use a constrictor plate as a fine tuning apparatus. I'm not positive about the Altec situation, but in the case of Klipsch that's exactly what happened. Paul Klipsch wasn't satisfied that the KHorn worked as well as it could, so he tossed in a restrictor plate to see if it made the horn work better. It did. It's a far easier process to play around with various restrictor plates than to rebuild the horn in a dozen different configurations. It's a very safe bet the Altec plate size was arrived at the same way.

There are advantages to smaller throats, primarily in that they can give better HF loading, but they can also take the Fs(h)[driver/horn system resonance] too low. A constrictor plate is a simple but effective way to adjust the Fh(s)without major surgery.