A Question About the N-800 Crossover?

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A pair of N-800-D crossovers appear on eBay at the link below. They're marked 12 ohm, which I am curious about because I've only seen Altec drivers designated 8, 16 and 20 ohms - I don't remember seeing any called 12 ohm. Does anybody know if there were 12 ohm systems sometime in the distant past?

http://cgi.ebay.com/ws/eBayISAPI.dll...category=14977

[marcuswilson]

My guess is that they were for systems with double 24 ohm woofers and horns.

[dennis gilliam]

I have an old tech sheet on them, and it was an approximation, easily used on either 8- or 16-Ohm systems. Seems the impedance of the total load didn't make enough of a difference to the breakovcer point.

DG

[Fitts]

I would suggest that while these crossovers would probably work with 8 or 16 ohm speakers that they would work best at their rated impedance. Fortunately, you can add 4 ohm resistors to 8 ohm speakers to get the proper impedance of 12 ohms so they should be adaptable to most applications.

[marcuswilson]

Dave,

The addition of 4 ohm resistors in series with an 8 ohm driver will cause a significant degredation in performance.

The resistor will absorb a third of the power.
It will change the Qes of the woofer significantly, altering the bass response.
It will change the frequency response in both drivers due to the driver impedance varying with frequency.

I am surprised Altec would make 8, 12 , and 16 ohm crossovers and advise the 12s could be used on 8 or 16 ohm systems. I'm certain this is insufficient reason to make them.

I stick to my previous post's reasoning.

[AL-TEC]

The N-800 cross-overs that you found on auction are very early 12 ohm 800 hz units. If the caps in them are up to par, and these are still working, I would use them on the 16 ohm tap of a vintage tube amp. On a "direct coupled" solid-state amplifier it won't really matter that they are 12 ohm rated.
It would be a slight problem matching this early cross-over to newer "nominally" rated 8 ohm drivers.(cross-over point would be shifted to "who knows what")
If I were you, and you wanted an "N-800" cross-over, I would look for the green 16 ohm "N-800-D" of which there are most of the time quite a few availible. These would be best and suitable for the early 16 ohm rated (usually green) Altec drivers such as 803/515B woofers, and 802 HF music drivers.

AL-TEC...........