Active crossovers - opamps vs DSP

[Zodiac]

For a while I have been pondering over this dilemma. Both have their supposed pros and cons. Application is for a active three way system (Linkwitz Orion). BTW I have read many comments about the amount of gain needed in the shelving filter for the dipole woofers, but this thread is not about that, rather it is about sound quality...

Opamps can be designed with a specific application in mind, and measureable THD and noise figures are very good, however it is distinctly unaudiophile to have 10 opamp stages between signal source and power amp

DSP based speaker management systems such as the DEQX or BSS Minidrive have the advantage that everything is done in the digital domain, hence reducing signal degradation of opamps and associated passive componentry.

There have been a couple of threads that have skirted around this subject but none that have addressed it from a sound quality perspective. I would be interested in perspectives from those who have trodden this path before me....

[JensRasmussen]

DSP is better IMHO - but you need alot of expensive converters and also understanding of the singnal flow and how to make sure that no clippling occour in the digital filter.

I use analoge filters at the moment, they are easier to implement, and requeres less hardware.

If you buy a ready made solution, you will have a hard time getting any information regarding these things, but if you are luckey you might be able to change the converter if the original ones are cheap.

Don't belive everything is better just cause it's digital, DSP has problems of it's own, they are just a bit () different form the analoge filters.

\Jens

[sam9]

At least add to your DSP least Behringer's DCX2496. It's "Pro" equipment and the cosmetics might put you off but the price is good. I use a different product from them for room EQ plus subwoofer integration, DSP8024, and found the results very good. It too does not have a high-end look and violates all kind od of purist idea, but for me the bottom line is that everything sounds better when it is swithched in rather than bypassed.

The "string of opamps" notion worries me too. I'm about 1/2 way trough my "master amp" project, but I'm already starting to think about a preamp. This leads into thinking about opamps. I have been looking (only looking so far) at the Linear Technology publication AN67-63 about creating a "super opamp". I think you could construct these on a small PCB with a 90deg 8-pin header that would let you use it like a SIP-8 opamp on the main PCB -- Just rambling for now

[darkfenriz]

the never-to-underestimate adventage of DSP is no phase distorion of FIR filters and so little amplitude distortion at crossover frequencies.

[phase_accurate]

the never-to-underestimate adventage of DSP is no phase distorion of FIR filters and so little amplitude distortion at crossover frequencies.

Don't forget to mention that this comes at the cost of pre-ringing.
One can do phase-linear active crossovers in the analog domain as well, though they won't be as steep as a FIR admittedly.

Regards

Charles

[MBK]

In the Orion you have allpass delay filters as well, don't forget that, though I think the Behringer can do that.

If you buy the Orion I'd stick with Linkwitz's designe though. He has ironed out the many, many fine tunig issues in his analog XO. I don't think you will gain much with DSP unless you invest a lot of time and you know what you're doing.

String of opamps - well, yes, but the Behringer contains them too. Not to speak of the ADC and DAC string if you use analog sources.

Sam9 - have you looked at the MOX thread and discrete opamp for it?

[sam9]

I missed the MOX when it appeared -- thanks for the reference.

[darkfenriz]

phase_accurate

what is pre-ringing??

regards

[sam9]

Marchand (www.marchandelec.com) sells kits for active XO's. I haven't tried any, but I did build one of his amps long, long ago and recall that the quality was good.

[planet10]

Originally posted by sam9
Marchand (www.marchandelec.com) sells kits for active XO's. I haven't tried any, but I did build one of his amps long, long ago and recall that the quality was good.

I had a full-blown XM-9 ... once my system reached a certain resolution it was clear it was adding a veil to the sound ... with the drawbacks outweighing the benefits i passed it along...

The Marchand passive LC XO i find very intriguing thou (i'd guess it may well be their best XO product).

I've also seen their tube XO (with many of their 48-step level controls -- that one was big bucks) -- it looks an interesting product, but too many miss-piggy stages in series with the signal for my taste.

dave