Straight 8 speaker plans
- Thread starter Bas Horneman
- Start date
The Wayback machine is your friend: http://web.archive.org/web/20110114033031/http://www.bottlehead.com/straight 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:
For any future dishonest types trawling the forums looking for ideas to steal and profit by, please note caveat posted by Doc.B:
I did notice the plans said "treated" drivers. I wonder if these are the MCM 55-1870's?
A real good 5.25in driver that has no nasty peak is the AC130-F1. It's substantially more expensive though but I have crossed it with first order with good success. 8 of tbem per side would break the bank though.
A real good 5.25in driver that has no nasty peak is the AC130-F1. It's substantially more expensive though but I have crossed it with first order with good success. 8 of tbem per side would break the bank though.
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.
-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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