Altec 811 Horn

[Lunes]

Hi,
I'm quite new in this business.I'm right at the beginning to build up my Altec home hifi
speaker.What I would like to know now is if I can run this sectoral horn with a pair of 288-16ohm driver or do I have to go for different one like the 802 or 804?Is there any rule ? It would be very kind if somebody could give me advice.

[dennis gilliam]

The 811 horn will not mate up to a 288 driver. The horn is for the small-series, the 288 is of the large series. You will need to use an 800-series driver on the 811 horn. You might find the rare (sort of) 511 horn that will mate to a 288 driver. Altec made a few of these.

The simple way to keep track is the number of bolts involved in the driver mounting: 2 bolts=800's (802, 806, 807, 808, 809, 902). 3 bolts=288 (291, 299, 290)

[Lunes]

Thanks,
is that only a problem because the hole pattern is not matching each other?
Or is that also due to the acustical configuration?
Regards

[GM]

Acoustic loading is part of it, but the biggie is that the 800-900 series small format drivers have a 1" dia. exit, while the large format drivers have a 1.4"dia. exit. Since it's essential to have as closely matching junctions to the lens (horn) as practical to keep nasty standing waves from reflecting back into driver and others out the mouth, each has their own 'family' of lens to choose from depending on the XO point and coverage angles desired.

GM

[Steve Burger]

I have actually seen an 811 shortened and modified with the larger exit. I did not get a chance to hear it however. The 511b can be modified fairly easily to a 511e.