"Wally" wrote in message

As some of you may be aware, I have an on-going speaker rebuild
fantasy bubbling away in the background. The plan is to bi-amp, and
part of this involves a second line output on the pre-amp, to send a
signal to the bass amp. The bass/midrange driver will have no
high-pass components in the crossover - I intend to let the bass roll
off naturally, and try to match the low-pass filter feeding the subs
to this roll-off. I'm edging towards trying to make a prototype
filter and would welcome comments...

The pre-amp is a Cambridge A75. The chips it uses are NE5534N op-amps,
evidently low-noise and suitable for high quality audio. My intention
was to use the same chips for my active filter / output stage, on the
assumption that the pre-amp's PSU will be delivering the right
voltage(s). However, it looks like these chips are no longer made -
what would be a suitable alternative?

The 5532 is basically a dual 5534, and readily available.

I know next to nothing about solid state electronics, but my efforts
so far would suggest that I want to use an integrator and a phase
inverter. The integrator provides the actual filtering effect (I
think), but is 180 degrees out at the crossover, decreasing to 90
degrees lower down.

You really need to find "Op Amp CookBook" and/Active Filter Cookbook" and
read it, or both of them.

http://www.amazon.com/exec/obidos/tg...841988-2752050

http://www.amazon.com/exec/obidos/tg...841988-2752050

Arny Krueger wrote:

The 5532 is basically a dual 5534, and readily available.

Noted.


You really need to find "Op Amp CookBook" and/Active Filter
Cookbook" and read it, or both of them.

Cheers. I'll see what I can come up with.


--
Wally
www.artbywally.com
www.wally.myby.co.uk