Active crossovers vs. DSP

speedygg1

Member
2013-03-26 3:15 am
I'm currently using two Marchand Electronics active crossovers in parallel as a tri amped set up. They are the XM6 models which allow variable crossover points and adjustable gain on all three amps.

Although I like the Xovers and have never had a problem with them, I'm looking at various manufacturers digital loudspeaker controllers.

They provide crossover work in the digital realm and time delay.
From what I've read so far, the DSP's are designed to work with P.A. systems and "shave off" both the high and low frequencies.
They also provide impedance miss matches to regular audiophile amps.
And, don't have enough gain.

Is it really worth the extra money to go with the digital crossover?
 

tuyen

Member
2008-10-12 2:34 pm
This topic is of interest to myself too.

I have tried a DBX Driverack 480 in the past, but it's start-up/shutdown *POPS* were scary. I read that some of the MiniDSP units which seem very popular, suffer similar issues?

Does something higher-end in terms of DSP crossovers like the DEQX units face these issues?

The Pioneer D-23 electronic crossover unit I have does not exhibit any startup-shutdown pops..
 

speedygg1

Member
2013-03-26 3:15 am
active vs digital crossover

The Driverack unit would be my first choice as a digital processor.
The reviews I've read show them to be rugged and reliable. As well as easy to use. However, the reviews were all posted by P.A. technicians for use in P.A. systems.

In the few reviews posted by audiophiles, their complaints were that the digital units "recessed" the stereo image. The high frequencies used by our ears to locate specific sounds were subdued. For me, I don't think I want to make the tradeoff.

The best units are the DEQX. Specificly built for stereophiles or audiophiles. The prices at 4 to 5 thousand dollars are for me, unjustified.
Once understanding the manual and it's programing, it does everything possibe.

I'm leaning towards keeping my two Marchand active crossovers or switching to two 4 way mono xovers to work in stereo. I'd like to be able to have a fourth crossover point in stereo for stereo 15" subwoofers.

Thanks for your reponse and listebing to my "two cents".
 
Have you seen

http://www.diyaudio.com/forums/digital-line-level/215379-dsp-xover-project-part-2-a.html

WAF - Wroclaw Audio Force

I have fleetingly tried Behringer 2496 and then the above.

I'm very happy with the sound quality and implementation. No start or turn off pops either.
For my rig (5 way horns) DSP gives a lot of flexibility for improving in room measured responses and time aligning the tapped horns that is impossible physically.

Bear in mind that it is a DIY unit but the support from Nick is superb.
 

speedygg1

Member
2013-03-26 3:15 am
digital crossovers

Hello and thank you for your reply.
I'm using an older Adcom GCD-750 cd player. Have considered using it as a transport with an outboard dac.

Yes, I believe the Marchand Xovers are op amp based.

The cd player feeds an Adcom GFP-750 pre amp. I use it's passive attentuator for volume control and bypass the active stage. It then sends the signal to the first xover and out to the other xover to allow me a 3 way to tri amp.

Would really like to step up to a dsp and replace the Marchands.
I've read that many of the available dsp's are built for p.a. use and shave off the high frequencies. I also like the idea of being able to accurately time align the drivers.

Any opinions or info would be appreciated.

Thanks again.
 
I checked out some online internal pics of the Adcom player, its a very nice looking piece of work. The DAC chips look to be PCM1702s - is it built as a transport and DAC inside the same box? I ask because it looks to have an S/PDIF receiver chip in there, it also has the best digital filter chip known to man (PMD100) so it would be a bit of a pity not to use its D/A functions. I haven't seen any DSP based XOs using such high-end DAC chips, so chances are if you use an external digital XO as your DAC you'll be taking a step backwards in SQ.
 
Sure its entirely possible to screw up a decent chip with poor PSU and/or layout. Conversely though you can't get a silk purse from a sow's ear - start with an S-D chip from Cirrus and there's very little point in attention to the finer details, the ceiling's already firmly in place. At least that was my experience in trying to improve a CS4398.
 

speedygg1

Member
2013-03-26 3:15 am
digital crossovers

The Adcom GCD-750 is an "all in one" cd player. Transport and A/D in one box. I had received some replies about it's construction and that it is, and was, well made for it's time.

Now that I've gotten it back from the repair shop (technician said it had a broken drawer belt and cleaned the laser mirror) I intend to keep it.
I can not see any benefit in replacing it with a 24 Bit player or an outboard D/A converter.

I gather from your reply, that using a digital crossover would be a step backwards in sound quality as it's D/A converter would reduce the quality from the D/A converter in my CD player?

The two Marchand Crossovers are the XM-6 models connected in parallel for a 3 way out. I can change the crossover points with a dial and see it on an LED. I can also set the gain for all three amps with dials. I hesitate to replace them.

Any suggestions to improve the sound quality would be appreciated.
Also, thanks for your help.
Mike
 
I gather from your reply, that using a digital crossover would be a step backwards in sound quality as it's D/A converter would reduce the quality from the D/A converter in my CD player?

That's true for all the digital crossovers I've seen to date which have their own DACs. But I doubt I've seen all of them and presumably there are some with digital outputs where you can select your own outboard DAC? Such a choice would allow you to use the D/A portion of your CD player - use that for the mid-range in a 3-way as I reckon that's the most critical band for SQ.
 
Dac and dsp

Thanks for your response.
I think what you are saying is, the output stage and the DAC of the Adcom cd player are pretty darn good as is? Especially the DAC.

Output it's signal to the analog input of a dsp. Which then converts again to digital for it's processing. Then it would be converted back again to analog as outputs to the amps.

Should I be concerned with the DSP's input and output resistances?
Or, it's output gains?
Would there be any mismatch?

I ask this because except for a few, like the DEQX and the mini dsp, all the digital loudspeaker controllers in the marketplace are designed for P.A. usage. My concern is they might not work together with my audiophile cd player and amps.

Your opinions would be appreciated.
Thanks.
 
Output it's signal to the analog input of a dsp. Which then converts again to digital for it's processing. Then it would be converted back again to analog as outputs to the amps..

What you are saying wont work.
I think what Richard was suggesting is to use a DSP which has a SPDIF output and then output SPDIF to your CD player and then use the CD players DAC to decode the midrange signals.

presumably there are some with digital outputs where you can select your own outboard DAC?
Yes. here it is: mini DSP nano digi.

Should I be concerned with the DSP's input and output resistances?
Or, it's output gains?
Would there be any mismatch?

If you go with the nano digi, you can use domestic unbalanced DACs to connect to your domestic amplifiers - in this case you wont have any issues with levels.

I ask this because except for a few, like the DEQX and the mini dsp, all the digital loudspeaker controllers in the marketplace are designed for P.A. usage. My concern is they might not work together with my audiophile cd player and amps.
Your opinions would be appreciated.
Thanks.

My question back to you, is why are you looking at anything other than mini DSP for home use? Its really cheap, and it works. And if you want to avoid nasty sounding DAC chips, they have the aforementioned nano digi board so you can use your own high quality DAC. Problem solved.
 
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DSP

Thanks for the replies.

I had looked into the P.A. digital lodspeaker controllers because I thought they were all that was available for audiophile use. The DEQX and Lake units are in the 4 to 5K range and outside my budget.

I like the Mini DSP units and the Nano one in the box with power supply and remote. As long as the Mini DSP's are supplied with easy to understand programing instructions and there's no chance of blowing out all 3 of my amplifiers and my 3 way speakers, I might give them a try.
 
Personally, I dont think the $5K pro DSP units offer significantly better sound quality than a mini DSP. What they offer is a good reputation for sound quality amongst pro users, a robust enclosure for touring use, and good limiters and compressors. But these features are not necessarily required in a home environment. Most DSP based processors they are either using SHARC, or Sigma DSP chips. From hearing both I'm not sure I could say one necessarily sounds better than the other. Even the Behringer DCX2496 using the SHARC sounds roughly the same as more expensive processors. personally I wouldn't use any off the shelf processor because I dont like their DAC chips, but the nano digi to me seems like it has some potential.
 
DSP

Hi and thanks again for your reply and helpful experience.

I have looked at the Mini Dsp units and they appear to do a great job.
One programs everything first via a link up to their home computer.
It does include time delay for the drivers and e.q..
I cannot tell, if one is stuck with what one programs into it.
And must through trial and error, adjust by ear.
Or, like the DEQX unit, one runs a test with a calibrated mic and the unit adjusts everything in real time.

Also, and bear with me as I'm not as knowlagable as many here about digital, does it accept the digital out from the cd player or the analog output from the cd players DAC?

Thanks again for your help.