Dominique, could you tell me the dimensions of your bass port? I suppose it all depends on what drivers you are using and I still haven't wrapped my fingers around all of the Altec parts numbers. My A7-500 bought new in 1976 doesn't show up in any old literature. It is a plywood (3/4" plywood) enclosure with the small removable bass driver rear panel, the horn was installed in the front port, and it looks like your A7, except it has a routered out round cornered cloth covered port panel. It came with the 416-8A woofer, N501-8A crossover, I think 511B horn but since it is now enclosed in a sealed horn box and I can't see the horn driver, I will guess has the 802D compression driver. Make sence?