Hiraga's crossover for Altec A5x

[Pano]

I don't know where the cabs were originally built. Likely in Europe. The horns were USA built, I assume.

The mods were done in Paris at #1 Boulevard Ney, the old offices of the Nouvelle Revue du Son. Circa 1986. There was a funky concrete storage room beside the loading dock near the giant rolls of newsprint were I did the work. Just me, some Nantex plywood, a few tools and some tar.

[sanpablo]

Dear Pano,

First, thank you for your help.

At present, i'm building a 828B cabinet... with autocad.

I had many problems with the vintage drivers, so, i want to use :
- 515-8G
- 902-8A
- 511B (i don't found altec's horns drawings)

In the article, page 12 : "the other horn is an old 806 C" I found nothing on @, non-existent...
Page 6 : "a JBL ring type tweeter" On the crossover, we haven't the components.

Thanks & A+

[Pano]

Hey sanpablo. I think he means an 805 multicell horn. I've never seen an 806, which would be 8 cells/600Hz. I started with the big 803 horns (8 cells/300Hz) but moved to the 1005 which I like better. One of the JBL 2402-2405 can be used as a tweeter.

About the crossover. I don't remember! It was a long time ago and I did not know much about crossovers then. It was passive, it was 2 way + super tweeter, but that is all I remember. I certainly do not remember the part values. As many times as I connected those things, I ought to remember, but I don't, alas. however the values are all there in the article. You'll still need to tune it to your room.

The 511A is OK, but does not have the magic of the multocell horns. It will get you started, tho.

The cabinet is super important. I doubled the inside of it with Nantex plywood. The most insane, heavy, dense, hard wood I've ever seen. Like iron. (The French Onken cabinets were also built of it.) Also I put a heavy layer of tar behind the horn flares. This is important. I did the same this year with my A5s. And added bracing to the curves. And braces inside the cabinet. With all that, it is super heavy but has NO box sound. Really amazing.

I get at least 1 email a week about the crossover and the box tuning. The crossover was published, but the box tuning remains a mystery. The port was made smaller, for sure. We might be able to figure it out from the photos on the Melaudia website.

Edit. Looking at recent photo it looks like the port has an area of ~330 cm^2. That should put the tuning at about 52Hz, if the port has no more depth than the box wall, which is what I remember.