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....
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....
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
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
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
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
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?
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?
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.
sam9 said:
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
phase_accurate said:
That depends. You can eliminate pre-ringing on the listening axis if you use FIR on highpass, for example, and generate the lowpass by subtracting the highpass from a suitably delayed input signal: the summed transfer function will add up to exactly 1.0.
You still get some pre-ringing off-axis, what with differential time delay and non-uniform dispersion between drivers, but you can minimize that by using a sane transfer function, such as a one octave transition region between passband and stopband. The drivers have to be well behaved for about a third of an octave on the far side of the crossover frequency, no big deal when a 4th order analog xover wants at least one octave out.
In other words, FIR filters are best used with a bit of moderation in the specification - that way you get the maximum benefit with the least side effects.
Cheers,
Francois.
AndrewT said:
Hence my user-ID.
Seriously, if you want to pursue the subject this site contains references to some good books for starters:
http://dspguru.com/info/books/favor.htm
Cheers,
Francois.
Hi
While the flexibility of DSPs attract me. I went and got the Silicon
Chip three way crossover which is based on an ESP design.
All data available on the net including the circuit board. To upgrade the TL071s might be wise with say the ASE-AUDIOTUNING boards or some other better ICs. The Design was in the SC journal Jan 2003! When I get it finished I post how it sounds together with the Dipole array panes 16 3"mid range and 12 tweeters per side ! Ideal is to tweak with a DSP system and then finish with a IC analogue system IHMO.
http://www.siliconchip.com.au/cms/A_30278/article.html
While the flexibility of DSPs attract me. I went and got the Silicon
Chip three way crossover which is based on an ESP design.
All data available on the net including the circuit board. To upgrade the TL071s might be wise with say the ASE-AUDIOTUNING boards or some other better ICs. The Design was in the SC journal Jan 2003! When I get it finished I post how it sounds together with the Dipole array panes 16 3"mid range and 12 tweeters per side ! Ideal is to tweak with a DSP system and then finish with a IC analogue system IHMO.
http://www.siliconchip.com.au/cms/A_30278/article.html
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Zodiac said:
How you hear a performance is purely a function of the original and transfer function between it and you - concert hall to recording, recording to room, room to ear drum, ear drum to brain, and what happens within your brain. It doesn't matter how you achieve that transfer function.
Audiophile acceptance comes mostly from pseudo-science (if it has fewer components it must be better) and psychological influences which are very powerful (when you expect an expensive cable to sound better it does to you regardless of whether differences exist).
When you avoid changing your perception and have competant circuit designs appropriate for the application (flat frequency response within the pass-band, noise floor below the threshold of audibility, etc) you can't hear the difference between straight wire and a dozen op-amps, analog and digital.
The Orion cross-over is a competant analog design.
As long as you avoid ground loops it doesn't raise the noise floor over what you have with the amplifier inputs shorted. The noise floor of well-regarded tube gear (I've used a Marantz 7C with my Orions) is way above that.
Component tolerances are 1% on the resistors and 2% on the capacitors. The corresponding changes in cross-over frequency are well below what you have with affordable passive components, don't change with output level, and are inaudible. The resistor tolerances give you +/-.09dB level differences which are well below what you have with affordable passive components, don't change with output level, and are inaudible.
Just build it and you'll be _very_ happy.
People have had problems with off-the-shelf DSP solutions. Keeping an acceptable noise floor/dynamic range often requires running the source at the full output voltage and controlling volume with a 6-channel volume control between cross-over and preamp.
http://home.comcast.net/~dreite/preamp/volume_control.htm
Digital makes it a lot easier to tweak a new design but it has all the shortcomings mentioned before -- it works best with a digital input and multichannel volume controls after the DSP box, significantly reducing ease of use. If you don't do all that, SQ suffers. Even if you do all that, the best you can hope for is to equal a well done analog XO, not surpass it, unless you pony up the big bucks for something like a DEQX with its linear-phase filters. I'd probably go digital if designing something new but for an established design like the Orion, where the analog XO has been painstakingly done by a real pro like SL, I don't see the point. Less convenience, worse SQ, equal cost (or more), what's the upside?
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