Interesting thread. It's a bit apples/oranges to compare analog/DSP because each have their advantages/disadvantages. The Orion is a bit of special case because of the largish EQ requirements and possible clipping concerns with some of the DSP-based crossovers like the DCX. (DSP boxes make the addition of room correction simpler though.)
Steve Dodds uses the DCX2496 with his "Bob" system and has good results. http://www.doddsy.net/steve6_009.htm
However, the EQ requirements for the woofers are not as great as the Orion so it's a better situation.
"however it is distinctly unaudiophile to have 10 opamp stages between signal source" What a ridiculous statement. 🙂 More than likely the signal has already passed through dozens of op-amps before ever being mastered onto a CD. A few more...if they accomplish a beneficial goal and are well designed...are certainly not anything to worry about.
Cheers,
Davey.
Steve Dodds uses the DCX2496 with his "Bob" system and has good results. http://www.doddsy.net/steve6_009.htm
However, the EQ requirements for the woofers are not as great as the Orion so it's a better situation.
"however it is distinctly unaudiophile to have 10 opamp stages between signal source" What a ridiculous statement. 🙂 More than likely the signal has already passed through dozens of op-amps before ever being mastered onto a CD. A few more...if they accomplish a beneficial goal and are well designed...are certainly not anything to worry about.
Cheers,
Davey.
Thanks for all your replies. Some interesting points
There are a significant number of op-amp stages in the Orion XO which must contribute something to the sound - a simple experiment with a opamp follower circuit will show you that. So the question arises how to minimise the effect of these additional stages. DSP would be one route but the gain problem arises with the Orion, which introduces a raft of additional complexity, due to the need for downstream volume control and/or addtional offboard opamp stages. Furthermore, I am not convinced that the D/A converters and analog output stages in the cheaper off the shelf DSP boxes are as good as they could be due to cost constraints plus the issue of additional A/D conversion or the effect of a non-optimal SPDIF / AES reciever circuit. The cost of optimising these issues is sizeable (optimised D/A and output stages, remote 6 channel volume control), suggesting that a computer based XO (e.g. Brutefir, LYNX AES16 soundcard) could provide a solution.
The benefits of DSP appear to be the ability to introduce room correction and phase linear XOs. Something like the DEQX. I remember Mac (a diyaudio contributor) said the DEQX was a definite improvement over previous analogue efforts. Any1 else have any experience?
So other solutions could be appropriate - biasing op-amps into class A, optimising grounding, rolling discrete op-amps....
There are a significant number of op-amp stages in the Orion XO which must contribute something to the sound - a simple experiment with a opamp follower circuit will show you that. So the question arises how to minimise the effect of these additional stages. DSP would be one route but the gain problem arises with the Orion, which introduces a raft of additional complexity, due to the need for downstream volume control and/or addtional offboard opamp stages. Furthermore, I am not convinced that the D/A converters and analog output stages in the cheaper off the shelf DSP boxes are as good as they could be due to cost constraints plus the issue of additional A/D conversion or the effect of a non-optimal SPDIF / AES reciever circuit. The cost of optimising these issues is sizeable (optimised D/A and output stages, remote 6 channel volume control), suggesting that a computer based XO (e.g. Brutefir, LYNX AES16 soundcard) could provide a solution.
The benefits of DSP appear to be the ability to introduce room correction and phase linear XOs. Something like the DEQX. I remember Mac (a diyaudio contributor) said the DEQX was a definite improvement over previous analogue efforts. Any1 else have any experience?
So other solutions could be appropriate - biasing op-amps into class A, optimising grounding, rolling discrete op-amps....
Zodiac said:
From what i undersatnd there is a lot of room for improvement in this unit as well... The fellow from OverKill Audio says he has significantly improved the ones he uses with a better case, and an analog power supply.
dave
I've performed such experiments and I can't hear any difference with good-quality modern opamps, e.g. 2134 or 627. Most of their bad reputation (IMHO) is 30-year-old news from back when they were trying to use opamps that weren't suited to audio. Of course, maybe I'm just deaf. 😉
Re: Re: Active crossovers - opamps vs DSP
Not often... CDs don't cut it compared to a good phono rig... a good CD player usually has any op-amps ripped out and replaced with discrete or a tube stage.
Chips are good at the digital parts.
dave
Dave Jones said:
Not often... CDs don't cut it compared to a good phono rig... a good CD player usually has any op-amps ripped out and replaced with discrete or a tube stage.
Chips are good at the digital parts.
dave
Big Dada said:
Hey Big Dada
The more I think about this and read others opinions and commercial efforts in this area (Emotive Excellence, Overkill Audio, NHT, Omen Ra), makes me think that the ONLY real way to go if DSP is to be pursued is to use a computer to store music, do phase linear XOs and room correction and feed out multiple digital signals to dacs with volume control after the dacs. I just need someone to build me a PC with ability to use phase linear XOs and room correction....(and yes, I have been following others progress in this area, it seems like a significant amount of work and cost to get this set up working!)
Hey Nanu
I agree with your assessment of PC based storage, player & DSP, time and cost.
And it is right there on my to-do list.
My guess is it will all be oldhat in 5years time. So you could just play some music and chill out till then.
I agree with your assessment of PC based storage, player & DSP, time and cost.
And it is right there on my to-do list.
My guess is it will all be oldhat in 5years time. So you could just play some music and chill out till then.
Big Dada said:Hey Nanu
I agree with your assessment of PC based storage, player & DSP, time and cost.
And it is right there on my to-do list.
My guess is it will all be oldhat in 5years time. So you could just play some music and chill out till then.
If it is oldhat in 5 years time it may just be coming to the top of your to do list
Zodiac said:If it is oldhat in 5 years time it may just be coming to the top of your to do list
If its my todo list 5 years might be too soon 🙂
dave
Hi Dave
Slightly off-topic, but close enough: How does your subtractive x-over perform ?
Regards
Charles
Slightly off-topic, but close enough: How does your subtractive x-over perform ?
Regards
Charles
phase_accurate said:
At the moment not well... half the parts are still in theri baggie next to the breadboard 🙂
Soon... its on the coffee table and the wife will be on me to finish it and get it off...
dave
phase_accurate said:
I've been reading some articles and threads about subtractive crossovers recently, with all the good things told about them, I really wonder why so few people are using them
There are actually two disadvantages: shallower slopes and wider overlap than filters like LR-4 for instance.
The first one can be dealt with by the use of suitable drivers the second one will lead to increased amp power needed (in the crossover area).
Regards
Charles
Huh? A subtractive crossover can easily be built with exactly the same slopes and overlap as an LR-4....or just about any other crossover configuration.
I think the reason you don't see subtractive crossovers used more is they're not any less complex than a typical Sallen-Key or State-Variable topology since they need a differential amplifier and all-pass filter circuit to create the complement to the actual filter section. It's about the same number of active stages any way you proceed.
Also, subtractive crossovers are similar to the State-variable in that asymetrical slopes and independent xover frequencies are not supported.
Cheers,
Davey.
I think the reason you don't see subtractive crossovers used more is they're not any less complex than a typical Sallen-Key or State-Variable topology since they need a differential amplifier and all-pass filter circuit to create the complement to the actual filter section. It's about the same number of active stages any way you proceed.
Also, subtractive crossovers are similar to the State-variable in that asymetrical slopes and independent xover frequencies are not supported.
Cheers,
Davey.
phase_accurate said:
There seems to be a misunderstanding. I never talk about those subtractive crossovers that mimic an LR for instance since I see no reason for using them at all.
When I say subtractive crossover then I mean the constant-voltage and transient-perfect type of subtractive crossover.
And those have asymmetric slopes (at least in their simplest form) and they also have large overlap and humps.
Regards
Charles
When I say subtractive crossover then I mean the constant-voltage and transient-perfect type of subtractive crossover.
And those have asymmetric slopes (at least in their simplest form) and they also have large overlap and humps.
Regards
Charles
Hi,
I don't listen to the subtractive filter I bought.
When first wired in it sounded pretty poor, no worse than that.
I then learned how to measure it's outputs and discovered that the xover slopes and F3db points were all over the place and not even coincident.
Later found a mistake in the circuit board that mixed up one of the subtractive phases on both channels. Threw it in the cupboard & went back to passive xover.
Getting ready to go active again after a gap of 15 or so years.
I don't listen to the subtractive filter I bought.
When first wired in it sounded pretty poor, no worse than that.
I then learned how to measure it's outputs and discovered that the xover slopes and F3db points were all over the place and not even coincident.
Later found a mistake in the circuit board that mixed up one of the subtractive phases on both channels. Threw it in the cupboard & went back to passive xover.
Getting ready to go active again after a gap of 15 or so years.
Big Dada said:
The drummer was lurking in the shape of a Benchmark DAC1 that I picked up as a reference for my 2nd all out non-os implementation. It is more transparent and dynamic than my old dac, showing that the Orions are very sensitive to changes upstream....but does not have as much musicality or tonal colour as the non-os.
After I've finished the Class Ds (one is nearly ready) I will start on the all out non-os implementation, I will be interested to see how close I can get it to the Benchmark....
- Status
- Not open for further replies.