290-8k bolt up to which horns?

[scootertrs]

I have a 290-8k driver that I would like to use as a mid-hi driver for a guitar amp cabinet. I am looking for a horn that is approximately the same size as my 511b's, but use the 3 bolt flange. I have a nice horn that accomodates a 4 bolt flange, but the 290-8k does not have the holes drilled out for that mounting... anyway, my intentions were to use that other horn with a 906-8a I already have.

I understand that the 290-8L has the option of 3 or 4 bolt mounting, but the 8k does not... how easy is it to remove the front segment off that 290-8k driver to achieve the 4 hole pattern?

[Todd W. White]

The Altec 25544 Adaptor adapts the 3-bolt pattern drivers to 4-bolt pattern horns. It was a flate square plate with four studs welded to it, and three holes for the 3-bolt driver. You installed the thick rubber gasket on the driver, then use short bolts to attach the plate to the driver. Then, you install the thin rubber gasket, then insert the 4-bolts onto the 4-bolt horn and tighten the lockwashers and nuts.

These are hard to find, but you could, conceivably, make one.

[dhook17322]

Might be as easy to modify the back plate on the horn to match the Altec pattern. If you didn't want to try it, a local machine shop would do that for a small amount.

[scootertrs]

I thought if dissassembly was not such a problem, I could modify the front of the 290-8k to have the 4 bolt mount... like the 290-8L

thanks

[cclark65]

I have one of those adapter plates laying here.

[cclark65]

Scootertrs, email me if you want it.

[cclark65]

Originally posted by Dave H.:
Might be as easy to modify the back plate on the horn to match the Altec pattern. If you didn't want to try it, a local machine shop would do that for a small amount.

<font size="2" face="Verdana, Helvetica, sans-serif">Dave, I think the horn he has is an MRII594B, and it doesn't have a plate that can be modified easily, the throat is the same size as the mounting plate (outside anyway) and has slots for accessing the bolts.

[dhook17322]

That modification wouldn't work in that instance of course - ddn't know what horn he had. I have 4 different throat adapters and it would be pretty easy to add another bolt hole pattern if the mating bolt circle was similar. I would be uncomfortable drilling and tapping new stud holes in a driver, especially an Alnico model.
That's another reason why I love this board - access to helpful knowledgeable folks.

[Datubie]

He could just get a 311-60 or 90.

[dhook17322]

Or a 511-E would work. Don't see them on ebay much unfortunately.