HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

After a fair bit of head scratching and mind changing, I have decided to settle on building a pair of concrete cubes. I will be fitting the doc mod 12 inch drivers and the 5.5 inch drivers and tweeters making them a copy of the BBCubes but made from concrete.

I’m thinking about the best way to cast the cabs as a single unit but I’m also thinking about casting each panel separately and bonding them together. The second option would certainly be easier but I assume casting the cabs as a single unit is ultimately better. Can anyone shed any light on this? Also would the cabs have enough mass as to not require steel plates? I can always just try them with plates and see if it makes a difference but I don’t want to unnecessarily buy steel if there is no need.

Blimey, you have booked yourself a lot of headaches - good luck.

Yeah I’m expecting this project to cause me to lose my sanity but I want to at least give it a try. If all else fails I will just make steel lined ply cabs but I think trying concrete will be fun if nothing else! Pics will follow as the project goes on but this will be a slow one. I still need to buy the 5.5 inch drivers yet.

If anyone has any casting suggestions which could help then please get involved - I need all the help and advice I can get with this!!!

Get a tea chest, pour concrete on each side at a time, when dry hammer and chisel and the wood should come off. How you them make the holes for the drivers is beyond me, that is going to be your big problem, casting around those holes.

I was thinking that I could just place a correct hole sized object in the mould and the concrete would just set around it. I think this will be a case of trial and error. Luckily concrete is pretty cheap so I can afford some failures!

Can you afford a fork lift truck to move the things?

There is one going cheap in that Super-fi auction.

I will cross that bridge when I come to it!!

The only realistic way will be to make formers for each panel you want to cast. 2 sets of formers as these will likely end up damaged when you take them off, so you won't be able to use the formers again for the second speaker. driver holes either need to be formed when pouring or cut out with diamond tools. (the diamond hole saws contractors use to cut holes in brick walls for boiler flues ect) The big driver will have to be formed not cut, you wont get a bricksaw that big.
Cast some threaded rods into the panels and corresponding holes in the other panels and bolt them together, then gobbo over the bolts
They will not be man portable

Do you think each panel could be cast with mitred edges and then put together as you would with a wooden cabinet using some kind of industrial bonding agent???