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Active filter board GB

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#144
Hi Jens,

I thought about the AD8066 (or two AD8065 with BrownDog adaptors)
for the HP filters and buffer (and "simple" OPA2134 for the LPF)-

Can it be stable in this application under any condition (unity gain and with this PCB)?

Thanks,

Avi.
 
#145
Looking at the schematics, I have never seen this sort of arrangement for the HP and LP sections. It seems different from typical LR circuits. Can anyone create an example of a speaker system using these boards? I would rather throw them into the simulation program and tweek it into something I'm happy with than start from stratch. Specifically I want to integrate a set of 10" woofers with my existing 2-way bookshelves, crossover at around 250Hz.
 
#146
cotdt said:
Looking at the schematics, I have never seen this sort of arrangement for the HP and LP sections. It seems different from typical LR circuits.
Click to expand...

First of all there is no such thing as a LR circuit. LR is a response of a circuit. Here the topology is an adaptation of the Sallen and Key filter.

It's not really very different from the original design topology, I added an output buffer to enable the builder to select freely between unity gain filters and filters with gain, but without having to think about what happens to signal levels and so on in the filter with gain.

A manual is underway to help the builders get started

To bob: I got your email, but have not had time to read it all yet

\Jens
 
#147
cotdt - if you are in a hurry, you can visit Jens' site and download the active filter two manual. Go into the tables of values used on page 8 and 9 and choose values to give you the desired response. For a fourth order Linkwitz Reilly response, set the Q of each stage at .71. This won't look like the topology you are used to seeing for L-R, but it will be the same response (try it in a circuit simulator)

You can use the MOX resistor calculations tab of the spreadsheet I posted for frequencies or capacitor values other than those listed.
 
#148
Hi Sorry to be off topic, but I can't find anb answer to my question.
I'm looking for software to help design an active filter.
Downloaded FilterPro already but that's too limited.
I want to keep the number of opamps as low as possible. This will imply a different topolgy.

Any suggestions?
Thanks,
SWDick.
 
#153
Scheduled ship date is 29 March. With UPS ground shipping, I expect the boards to arrive here 3-4 working days after that.

There are still a few unpaid orders, I'd appreciate prompt payment or let me know if you are no longer interested. I'll update the WIKI later today to include all who have ordered.

Pinkmouse, I reserved 6 boards for you based on your comments earlier.

If all who expressed an interest still want boards, there are 15 boards available. A few more will be available after everyone who prepaid receives their boards.

I'm still working on a manual. My goal is to have it ready for Jens' review this weekend. He's the real EE, I just stayed in a Holiday Inn Express last night (that is a spoof of a TV commercial for those outside the US)
 
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