Sure, you can load it down to around 25 Hz if the horn's big enough, so will work fine in one adequately sized for just about any XO point.

GM

Ron

I have run some compression drivers at much below their rated frequency, but at a fraction of their power rating.

Let me put it this way, a 288 is approx 15 watt rated, at 250 hz I would guess your max might be between 3 and 5 watts before ending the life of the diaphram.

If you need to use a horn lower than the compression drivers you have available, why not use a cone driver in a horn!!!!

Just my 2 cents worth, how lucky do you feel?

I pay good money for my Great Plains 399 drivers(288-8K clones), I can't afford to replace diaphrams just for a experiment.

Sorry to be a spoil-sport!

Ron

OK then, why did Altec recommend the 288, etc., drivers with a 300 Hz 2nd order XO on their 300 Hz multicell and sectoral horn series, not to mention the 31 and 329 series they carried over from W.E. (the '3' denoting 300 Hz), without derating them?

GM

I'm not trying to rain on anyones parade, just saying that using a Altec 288 below 500hz was not what they were designed for.

Also the many lower frequency horns (1003B/8003B/etc) were actually used at 500hz crossover unless a different driver than the 288 were used.

Ron

Understood, and what you say is true as far as it goes, but you've come to an erroneous conclusion based on insufficient information. If you do the research on the models I listed you'll find that Altec listed the 288/300 Hz combo on these horns and if you study compression driver design and do some PWT measurements you'll see why they will perform at rated power at XO points much lower than 300 Hz IF the horn lens is designed to support it. Consider that the 'grandaddy' of these drivers is the 1" W.E. 555, which when loaded with the 15A lens has a full power BW of 100-5 kHz, and if someone wanted to make an even bigger lens it could be lowered considerably.

GM