Altec 825

I stumbled across an Altec 825 on 3D warehouse, and started to wonder how would modern driver perform in such enclosure. Since I had data for Celestion TRUVOX TF 1530, I started Sketchup and Hornresp, and this is what I got.

 This is 3D model from 3D Warehouse

 Enclosure from ebay. In my simulations I modeled box as Altec 828, with closed front pole.

Reverse engineering using advanced centerline method

So, after analyzing enclosure, I made compound horn in hornresp, which looked like this:

 This is power response, rolloff begins at about 55-60Hz, as predicted.

 Impedance curve.

Compound horn model.

I was wondering if I can make things simpler. Therefore, I modeled Compound horn as Exponential horn + BR box. It looked like this:

 Not exactly the same, but very close.

 Impedance curve also very similar to previous model.

Simplified Compound horn enclosure.

I decided to use simplified model. After litle tweaking of BR port, with final area of port of 500 cm^2:

 -3db point is below 40Hz.

Impedance curve looks more like BR now.

So much for now, stay tuned...