My A7-500s. A journey

**Panomaniac** · November 26th, 2009, 09:19 PM

Well the 288 and 291 (I think) were spec'd for 500Hz. I thought that might just be because of being spec'd on a 500Hz horn. But even on the 300 horn they drop like a stone under 250Hz, so crossing them an octave above that is a good idea. Keeps it out of distortion, phase problems, excursion, etc.

I may try to get them down to about 425 acoustic, but if they don't sound good down there, no point in it. Will be interesting to find the sweet spot.

**Altec Best** · November 26th, 2009, 10:04 PM

But that is the fun part isn't getting to play with all the different horns,drivers,etc..

let me pose this question which driver did Altec recommend for the 803 multicell all of their large format drivers are 500 hz the 803 is 300 hz horn so they have no driver that goes to 300 hz does that make sense

**Panomaniac** · November 26th, 2009, 10:32 PM

A good question! The 290 driver, AKA "Giant Voice" seems to be what was meant for the 300Hz horns. I'm sure someone here can verify. They can play low and had a phenolic diaphragm. Could handle a lot of power.

Almost bought a pair, but I'm sure the 288 is much better for my app.

**Old Guy** · November 27th, 2009, 12:33 AM

Originally Posted by Panomaniac

The 290 driver, AKA "Giant Voice" seems to be what was meant for the 300Hz horns.

The 300 Hz horns were originally for voice paging.
And Altec did recommend a 300 Hz driver.

This sheet states the 288 to handle 10 watts from 300 hz up. Just a little hard to read.
http://www.lansingheritage.org/image...1947/page3.jpg

The field coil 287 was rated to 300, and the permanent mag 387 also, at 20 watt "peaks" when less than 12 dB/octave, ie just a protection capacitor...

http://www.lansingheritage.org/image...943/page07.jpg

I suspect somebody had an attack of honesty and changed the 20 watt "peaks" to 10 watts for the 288 spec.

Of course at 98 db from 1/10 watt, you don't get a lot of volume at full power, but note the dual driver adapters as GM mentioned...and things weren't as loud in those days.

As the need for volume went up so did the need for power handling, therefore the 290. But the Aluminum frams were used regularly from 300 for voice paging early on.

**Altec Best** · November 27th, 2009, 02:06 AM

Originally Posted by Old Guy

The 300 Hz horns were originally for voice paging.
And Altec did recommend a 300 Hz driver.

This sheet states the 288 to handle 10 watts from 300 hz up. Just a little hard to read.

.

See I knew OG would find it.