Help with sim on this new Altec mid bass horn

Hi audio friends

I'm wondering if you'd kindly look over the attached drawing.

I've designed this for a couple of reasons.

1. The measurements of the outside cabinet exactly meet my room restrictions.
2. I already have the Altec/GPA 416-8G woofers (8 ohm versions, brand new)
3. The design incorporates both bass reflex loading and front loading for efficiency
4. The design picks up some other proven horns, eg the Altec 816 plus JBL similar versions (but these have quite weak bass below 80Hz)
New Page 2

I'm wondering what ideas people could add to make this work?

In particular -

1. desired flare rate. I'm using a standard 30 inch constant radius, as per flare on the Altec VOTT A5/7. The top and bottom sections are curved, the two side pieces are straight.
2. porting. I think I'll just suck it and see, using 3-4 smaller 3-inch ports, where I can close off and tune accordingly.
3. dampening. I'll start with fibre/wool filling for first attempt.

My target is for a good bass response from 70hz to 800Hz with approx 98-100dB, where these will be crossed over to an Altec 511 horn using Altec GPA 902 one-inch compression driver. Xover to be decided, but likely to be MiniDSP active to best tune the bass and give some EQ where needed down low. I will complement the horn with dual tapped bass horns from 30Hz to 100Hz later on.

Kind regards



  • Altec fron loaded horn drawing v1.pdf
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