Straight 8 speaker plans

The Wayback machine is your friend: 8/Straight8.pdf

For any future dishonest types trawling the forums looking for ideas to steal and profit by, please note caveat posted by Doc.B:

Thanks to Glynn W for sending me scans of the old plans for the Bottlehead Straight 8. This design is owned by Bottlehead Corp., and we are granting you permission to build one copy for your own use. Anyone caught trying to sell speakers built from these plans for commercial gain should first be measured by a tailor to see what size lawsuit they wear.
To a point. Since you're interested:

-The Straight 8 crossover went through a few variations & ended up with an asymmetric 3rd order (3rd order electrical + Zobel on the midbass array, 2nd order electrical + a parallel & a series notch on the tweeter). Don't ask me what the acoustic slopes were -I didn't back-engineer it, nor would I think it fair to do so. That would be tricky in any case because of the next point.

-The Straight 8 was the last in a series of designs that they'd played with for the best part of a decade. The 1870 was used, with some damar coating + a couple of other tweaks IIRC, presumably to mechanically damp out a bell mode. However: as I understand it, at some point, the OEM making the 1870 changed the driver design without bothering to tell anyone. Going by fallible memory, the curvilinear profile went west, along with a couple of other things. Basically, it wasn't the same driver, and it was no longer usable. So the Straight 8 was retired, and I think they informally point people toward Clark Blumenstein's speakers now as he's nearby and also offers nice bamboo ply etc. plinths for Bottlehead kits.
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Bas Horneman

diyAudio Moderator Emeritus
2002-04-03 12:03 am
The Netherlands
as those look like aluminum cone mid bass drivers that may have a peak up high that will leak through a first order.


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