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-   -   Digital Crossover Vs Existing DACs (http://www.diyaudio.com/forums/digital-line-level/206996-digital-crossover-vs-existing-dacs.html)

Silent Screamer 18th February 2012 10:31 AM

Digital Crossover Vs Existing DACs
 
Firstly I would like to apologise in advance for my ignorance in this matter, but I have recently been enlightened to the benefits of active crossovers, and I would really like to use the best DACs available.
The problem is from what I have read so far it must pass through a ADC to DAC process, adding yet another to the string I already have.
I was running a Rotel RDV-1093 in front of my Rotel RSP-1570 and it made little difference which DACs I used as I believe they both have similar Burr-Brown DACs. I was given the opportunity to trial an Oppo BDP-83 SE to try out, and needless to say one was purchased and the RDV-1093 returned to the box.
Now the difference between the Oppo and the RSP-1570 on the analogue side is chalk and cheese, and most of the time I use the DACs in the Oppo and bypass the DACs in the Rotel via the bypass option when I want to listen to music.
If I was to use a digital crossover with its own DACs I fear I am going to wind up with an inferior sound.
From what I can work out the following devices use these DACs
Oppo
Oppo Chip Set: ES 9018 4dacs/channel (ESS) - ESS Sabre chip
Oppo Op Amps: TI NI 5332A
Rotel RSP-1570
Can’t find it published but believe they are Burr-Brown
a dual 32 bit DSP processor and 24 bit/192kHz digital-to-analog convertors.
Ground Sound - DCN23BOX
We have used high performance Burr-Brown (Texas Instrument) converters to achieve a low noise floor and outstanding sound quality. The filter runs at 96 kHz with a bit depth of 24bits
Behringer Ultradrive Pro DCX2496
- High-end AKM 24-bit/96 kHz A/D and D/A converters for ultimate signal integrity and wide dynamic range (113 dB)
MiniDSP
miniDSP 8x8 kit is an enhanced and innovative platform from the miniDSP Team. Combining high quality audio algorithms, 24bit digital audio, high specs ADC/DAC converters

Can anyone please point me in the direction of the best performing digital crossover please...

Draki 18th February 2012 06:10 PM

With digital crossovers you can't really use Oppo's DAC:
- some have only analogue L/R input so the (analogue) signal output from Oppo, or any other source for that matter, will have to go thru the ADC first, then the DSP chips and then the DC own DACs;
- some (e.g. Behringer DCX) have a digital input - in which case you will be omitting Oppo's DAC entirely - so that it goes directly to DSP chips and thence to output DACs.
I have the Behringer and while in stock form it is OK-ish, some mods are really needed to make it a much better sounding unit.
For instance Pilhgam Audio or Selectronic digital input boards.
On the output side there are also several options. Pilgham has a nice Jann Didden' designed output board with on-board volume ciontrol; another option is a capacitor passive output version, see Selectronic or Scott Endler's site (user name "Sendler" on this forum); last but not least a transformer coupled passive output. I have this last one. With those mods the DCX is very good sounding crossover/DAC.

Ground Sound looks OK but have no experience. Their top model though looks excellent (at a cost!).
You are in Australia: look into DEQX....

Pano 18th February 2012 07:42 PM

You know the DCN23BOX is on sale for a great price, right? Have a look here:
http://www.diyaudio.com/forums/vendo...ml#post2912346

Silent Screamer 18th February 2012 11:44 PM

5 Attachment(s)
Pano the offer is for the 115v version which would let out the magic blue smoke if I plug it into an Australian 240v electrical grid ;)

Ok I think I probably got ahead of myself with that question, so let me go back one step before I evaluate each of the solutions mentioned.

For me to determine the best digital crossover, I really need to understand what takes place inside the various pieces of equipment I already have.

I know there are ADC and DACs in various bits and pieces but I really don’t know what happens on a schematic level.

So if anyone can unravel what takes place that would be fantastic...

Probably if we look at this from two angles the digital path taken and the analogue path taken.

In the photos I have included shots of the inputs and outputs of each of the devices in question.

(first photo the BDP-95 which is the likely replacement for the BDP-83SE once I go 3D, which is some time off and would probably need to go to the RSP-1572 as well)

From the Oppo to the Rotel I am using IXOS 1000 Gamma Studio Connect for each of the analogue channels to the Rotel, and an IXOS XHT658-100 for the digital HDMI connection.

From the Rotel RSP-1570 to the Rotel D Class digital amps I am using IXOS 1051 75 ohm Silver Conductor Digital Interconnect.

bbggg 19th February 2012 03:27 AM

Have you looked into Metric Halo? The 2882 and ULN2 do 24/96 whereas the ULN8 does 8x 192/24 and includes all necessary software. A LIO8 +DSP will do the same for le$$. SQ is claimed to be SotA.

Silent Screamer 22nd February 2012 11:31 AM

Thanks bbggg, price is a bit steep and it looks like you need to be a sound engineer to use otherwise looks like a top piece of gear.

Just thinking about something Draki said... “With digital crossovers you can't really use Oppo's DAC:
- some have only analogue L/R input so the (analogue) signal output from Oppo, or any other source for that matter, will have to go thru the ADC first, then the DSP chips and then the DC own DACs;

So if I can’t take advantage of the better DACs in the Oppo would I be better off with staying passive?
If using inferior DACs is still preferable to passive, then digital inputs would be a good item to have to avoid Oppo digital out to ACD to DAC?

Draki 22nd February 2012 12:02 PM

Silent Screamer
Do you want to build new set of active speakers or want to activate a passive one?
The solution will depend ultimately on you speaker system. Going active has benefits but a well-designed passive has it's strengths also. Note that active is not easy since you still need to know what filters/slopes to use and some measuring equipment will help - the same is true for the passives.
If going active with a digital crossover, then yes, it is better to have a digital input.
On the other hand you could activate with an analog crossover in which case you will use the Oppo's Dac and it's analog output.
Again: need to know the speakers you intend to work with. Are they 2-way or 3-way? For a 2-way maybe better to go passive with a well-designed crossover (all analog from the Oppo thru the speakers).
If 3-way then another option is a plate amp/crossover for the bass and a passive for the M+T (again all analog thru).
Many choices and possibilities , there is not one general rule.

Silent Screamer 22nd February 2012 12:33 PM

Thanks for that Draki... Definitely looking to go active on a new set of speaker will probably sell the Cremona’s as is or keep them passive and use elsewhere.
Looking for 3 way possibly even 4 way.
Not sure what you mean by this “On the other hand you could activate with an analog crossover in which case you will use the Oppo's Dac and it's analog output.
Sounds like your saying put an analogue crossover in front of the amp???
Also this “If 3-way then another option is a plate amp/crossover for the bass and a passive for the M+T (again all analog thru).” Never heard of it can you please explain the options you presented thanks...

HYPERTUNE 22nd February 2012 12:40 PM

I've looked at every dsp based active crossover system I can find and I keep coming back to the Groundsound DCN28. To me, it has the best combination of features as it is not just an 8 channel crossover, but also does a very good job as a preamp, with source selection and volume control, etc. Nice features like staged amp power switching make it obvious that it is intended to be more like a control system for an active speaker setup than just a crossover.

The DCN28 uses quite good dac chips (4 x pcm1798 I think) and although they might not spec as well as a es9018, it's arguable that the analogue stage after the dac is more important and in that area it seems Groundsound have paid a lot of attention.

Put it this way, even if the oppo dac/output stage were better than the DCN28, it would most likely be impossible to pick it and certainly negligible compared to the gains possible with active speakers and eq/room correction.

Another good point is that attenuation is done after the dacs allowing them to run at max resolution. Even individual channel adjustment can be done post dac.

If your budget allows, I think it would be your best bet. Certainly well worth considering.

Draki 22nd February 2012 12:44 PM

Hi

Yes you can activate also with analog ACTIVE crossover (e.g. marchand electronics). It is used between the preamp and the power amps driving the speaker drivers directly:
Oppo analog out -> preamp -> analogue active c/o -> power amps -> speaker drivers

With a plate amp (e.g. Hypex, PartsExpress..... many more) you are still all analog:
The plate amp (a.k.a. sub-woofer amp) is needed for each stereo bass and will drive it directly , The main 2 ch power amp will be driving the Mid+Tweeter "ways" which are presumably passively crossed.


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