Active crossover integrateable?

flacoman · 7th May 2010, 11:22 PM

Hello all!
Which of the power op-amps out there would be the best bet for use as it's own active crossover? I'd seen this done in the days of the LM12 and built a few of them for full range use , but have no real knowledge of the newer generation of devices.
I had in mind a smallish active setup with an actively controlled 2-way + sub layout, but wonder if the devices would behave themselves. Having baffle compensation and good control of the cone in one fell swoop would probably help my speaker designs sound a wee bit better!
TIA
Jorge

planet10 · 8th May 2010, 01:27 AM

It is an opAmp so, within the limits of its gain requirements, you can wrap a 2nd order Sallen-Key around it, and if necessary add another RC in front to get 3rd order.

dave

pacificblue · 8th May 2010, 06:31 AM

The Overture series ICs as an example all need a minimum gain of 10 for stablility. With a Sallen-Key filter you will have lower gains outside of the passband. The additional effort to compensate for that could be higher than using the filters before the power amp.

Or you would have to find a unity gain stable power opamp. The OPA549 could be such a candidate.

7th May 2010, 11:22 PM	#1
flacoman diyAudio Member Join Date: Feb 2006 Location: Ft Laud. Fla	Active crossover integrateable? Hello all! Which of the power op-amps out there would be the best bet for use as it's own active crossover? I'd seen this done in the days of the LM12 and built a few of them for full range use , but have no real knowledge of the newer generation of devices. I had in mind a smallish active setup with an actively controlled 2-way + sub layout, but wonder if the devices would behave themselves. Having baffle compensation and good control of the cone in one fell swoop would probably help my speaker designs sound a wee bit better! TIA Jorge

8th May 2010, 01:27 AM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	It is an opAmp so, within the limits of its gain requirements, you can wrap a 2nd order Sallen-Key around it, and if necessary add another RC in front to get 3rd order. dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

8th May 2010, 06:31 AM	#3
pacificblue diyAudio Member Join Date: May 2008	The Overture series ICs as an example all need a minimum gain of 10 for stablility. With a Sallen-Key filter you will have lower gains outside of the passband. The additional effort to compensate for that could be higher than using the filters before the power amp. Or you would have to find a unity gain stable power opamp. The OPA549 could be such a candidate. __________________ If you've always done it like that, then it's probably wrong. (Henry Ford)

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