View Full Version : Help Please: DIY Crossover for Altec 807-8A HF driver

04-03-2012, 06:54 PM
Can someone help me design or at least help me learn the basics how to design and build a DIY Crossover for an Altec 807-8A HF driver.

At the moment, I don't have much to go on other than
the horn driver is rated @ 30W, 8ohm.

Can I build a simple crossover and L-pad system that filters the low freq so as to protect the driver so I can hook it up parallel with any 8 ohm speaker jack up to
30W yet powered by any amp up to 100W?
I have several amps having different power ratings.

I will draw up what I am thinking of and post it to clarify.

04-04-2012, 04:46 PM
hmmm, 40 views and no replies....
Did I post this in the wrong place?

04-05-2012, 09:54 AM
At the moment, I don't have much to go on other than
the horn driver is rated @ 30W, 8ohm.

Its possible no one here has much more to go on than you do. What driver/speaker will be used with this?

I will draw up what I am thinking of and post it to clarify.

Have you done this yet?

A proper crossover is not a trivial project. Can you find a schematic of a crossover with this driver used in a system? That's where I would start. Post what you know or have found and we'll see if we can help.

All the best,

rudy sesztak
04-06-2012, 06:31 AM
Altec used a N801-8a crossover with that driver in some of there old systems. A 1209-8a 1200hz crossover can be used ( the 811b horn sounds better at 1200 hz).Check on line,and you will find schematics for both of those Altec crossovers.-RUDY

rudy sesztak
04-06-2012, 06:59 AM
A 800hz high pass filter for 807-8a- A 18 MFD capacitor in series,and a 2.2 mh coil across it.- RUDY

04-09-2012, 10:49 AM
I would start with a sweep of the driver to determine the resonant frequency of the drivers you have. Don't rely on published specifications, measure it. Then once you have Fs start at 3 times that frequency.

If it resonates at 250 Hz (example) then start at 750 Hz with a value of capacitor that provides the same amount of impedance as the driver at 750 hz. This is why you need to sweep the driver to create a curve for it.

Not sure how to do that? You can get a woofer tester from Parts express for about 100 dollars, a good investment for sure. It can help test the driver and even help design a network.

Once you have a basic network you can design more complicated circuits, all based on the driver impedance curve and ultimately the way it is used. Crossover design is an art and it takes a few trials to get the right combination. But the important thing to do is protect the driver from low frequency information outside it's operating range, and a basic capacitor that crosses over three times FS is a good starting point. The driver only handles 30 watts so you have to be careful.

04-17-2012, 01:04 PM
this forum might be a better place to ask -

www.diyaudio.com (http://www.diyaudio.com)

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