2 pairs of Heybrook HB3's that sound very different !!?

[Shane]

Very interesting! The black ones definitely have MDF baffles, and the teak ones are chipboard. I'd forgotten that early ones had chipboard baffles. Do they have removeable crossovers?

[Shane]

I'd agree with Richard that any water-based sealant would be OK, or even blu-tak at a push, but don't use anything solvent-based. As for the grease round the inside of the midranges, no idea. Certainly not original.

[JwEs]

Finally ordered the mastic I'll be using a polimer based neutral one and take off the drivers while it dries...

@Shane
Yes but the serial nr. on the black ones is lower, maybe they were made at the time of switch over...

Yes both crossovers are detachable, on the back they're both the same as every other series 2 photo I've seen on the net.
I'll be taking off the the crossovers later on and I'll post pics...Maybe there are also some surprises there.
The only difference is that the tweeter on the black ones only has three screws.

[Shane]

Interesting! I don't remember any HB3s having four-bolt tweeters, and I also don't remember any changes to the cab construction such as changing baffles from chipboard to MDF. I left Heybrook in June '84, and I suspect these changes were made shortly afterwards. The fact that the black cabs seem to be the earlier type despite being later numbers is probably because they're black. Cabs were ordered in batches of (I think) 50 pairs, and a reasonable guess was made as to how many of each finish would be needed. I suspect that the black cabs are from an earlier batch than the teak ones, but stayed in stock for a while waiting for an order to come in for black. That would date both pairs to some time after my departure, but before the adoption of the plastic-covered baffles in 1986 (Like these http://www.rehifi.se/pub_images/orig...5395_17196.jpg ).