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Old 15th October 2013, 08:16 AM   #11
Eldam is offline Eldam  France
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Thanks for the input,

the Xonar card had a hard tweak...i have to read it all but i like the work of Abraxalito, more easy for me cause surface mount is not my cup of tea...
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Old 1st November 2013, 07:27 AM   #12
danhilu is offline danhilu  Switzerland
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Hi all, Eldam,
very interested by this post,
one solution for combining cheap processing (your "Synchrone" solution) and high quality DAC would be to output from the PC in digital -> HDMI.
I found the "Richard's stuff" way is promising ( Digital Crossover/EQ with Open-Source Software: HOWTO | Richard's Stuff).
With HDMI 7.1 audio you can (or I should write "should be able to", I've not yet tried) plug into a 5.1 or 7.1 receiver as a DAC. You can choose a high end one if you wish (used ones to be found pretty cheap on internet - ebay and the such).
Another benefit of this solution is that you get volume control on all channels for free (which enables you to keep worling at line level on the DAC and therefore remove quantification noise or distorsion wich is an essential problem on the DCX2496).
Please keep us posted of your thoughts !
Merci,
Danhilu
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Old 3rd November 2013, 05:03 PM   #13
Eldam is offline Eldam  France
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Thank you for your boost,

The problem is I'm not sure to know what I exactly need... just learned than the Crossover + phase have to be FIR and the corrections of peaks or/and room in IIR !

I can go with "asynchrone solution" because have already data storage + volume streaming solution (with SqueezeBox Duet + smartphone + duett remote control). As say Soundcheck, I'm not against an another system i full pc: Linux or others as I'm not against a minimalist solution : a miniDigi between the streamer Duett and a multi DAC.

I read than the MiniShark works better than the MiniDiGI but don't know if it's true. And maybe not too expensive to buy one IIS DAC module ESSxxxx23 by pair of drivers for multi amp and may be one Wolfson for the bass driver. Tweaking a pc soundcard at 500 dollars... to have not a super DAC...maybe good but not super !)

HDMI... is there choice ? Oppo ? I don't know asynchrone plug like the amareno/USB with HDMI if using normal DACS (SPIDF) or HDMI to IIS ?

With IIS.... is there ussues with clocks and digital ground loop because multiple IC ?

in my mind to be serious, The dac is the masterchoice if active crossover because all the processors for Crossovers and DRC seem strong enough ?
have problems too with measurement ! .... ouf I have classics speakers for the moment to listen to music !


What do you think ?
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Old 3rd November 2013, 07:02 PM   #14
danhilu is offline danhilu  Switzerland
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Salut Eldam,
I think you have quite a lot of questions ;-)
My view is
1. I want to try active crossover - analog filter are expensive and sonicaly poor and demanding for the power amp. And a nightmare to design for a 3 way speaker.
2. "Richard's stuff" way is architecturaly elegant because you split the active crossover - on a computer - and the DAC - which you can export anywhere you want thanks to HDMI or S/PDIF. On classical active crossover solution; like the famous DCX2496, you're stuck with the DAC, with no freedom to play arround.
Plus it is cheap, because you can use any mass market PC for the digital part, and any (decent) HDMI capable Power amp for the DAC & power amp. Of course you also can decide to go with a high end DAC (with hard to prove benefit in my opinion - but this is another story).

I'm still wondering whether I want to re-install Linux on an old spare PC, so that I can try the concept in the real life withour spending a , or I buy a new low power device (like a Celeron 1007U with max power 17W, with build in HDMI & SPDIF output).

Please keep us posted with your progress.
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Old 3rd November 2013, 08:37 PM   #15
Eldam is offline Eldam  France
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Yes I have always a lot of questions because that's my project management method...The only "filter" where W questions/answers is good ... go no-go, then buy only... because after DIY cost too much for the quality of (my) results !

Thanks for the input.

1) agree, even just set up a tweeter (that I experiment for few weeks)
2) many people talk about the Richard stuff way, there are anothers too, but for me the feeling of the control remote for control library and digital volume has to be here for me and i'm happy for that with SqueezeBox. That's why my OP question... Don't see really linux plateform that manage smartphones for remote : Android or Iphone (I'm Android...)

Don't know any DAC with HDMI... I have to re read Richard stuf review..
like too the answer to me by an another french Zaireeka in another thread about Processor + tweasted pair Audio Sabre plateform... RME ADAT out -> Dantimax Optorec (a kit converting ADAT to I2S)
OptoRec/Gen

We have to avoid the factory of jitter ! another problem with I2S is the shorter wires possible and where the masterclock is...

Last edited by Eldam; 3rd November 2013 at 09:03 PM.
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Old 3rd November 2013, 10:54 PM   #16
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danhilu, I've done the Richard's stuff route, and while it wasn't exactly simple to get working, I'm very satisfied with the results. System hasn't crashed one time, sound is excellent, and it's easy to tweak.

Yes, I used an old PC to install Linux on. Single core AMD 64-bit, with 2 gig ram. It uses at most 5% of the processor and less than one gig of ram. It's not hit swap yet.
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Old 4th November 2013, 08:10 PM   #17
danhilu is offline danhilu  Switzerland
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jplesset, thank you for these details, I still need to choose my 5.1 audio output - with SPDIF - so that I can try. Then I'll try - I may come back with a lot of question since the "Richard's stuff" page is a bit dry.
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Old 4th November 2013, 08:19 PM   #18
danhilu is offline danhilu  Switzerland
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Eldam, I've read your original post again so that I understand you.
There is one point I invite you to reconsider. Doing volume control on the signal before doing the crossover leads to quantification noise. You risk to end up having a 6 bit usefull signal althoug you use expensive 24bits DACs.
Note that this is the main reason why many complain that the DCX2496 is "noisy".

Let me try to explain, and please be forgiving with my explanation, doing my best. My values are surely wrong, but you'll get the idea if you stick to it.
Let's take a track, coded on 24 bits, which has been optimised so that its peak signal is at the max value. Your peak signal has all bits sets to 1, i.e. (I think) something like 0x07FFFFF (max positive value on digned 24bit), ie decimal 8388607.
The quantification noise (means the error caused by a digital approximation of an analog signal) is (theoretically) one bit, so the noise is 1/8388607.
Which is 0,000012%. This is .. excellent. Of course not hearable, but nice.

Now let's assume you do not listen to the signal at max volume, which would blow your tweeter away. You listen at, say, 1/10th of the volume, which is a typical volume for in house. 1/10the of the volume means, on my preamp, -75dB. I never remember, dB are tricky, but I think the signal gets divided by two each time you remove 6 dB, here 12 times. 8388607 divided by 2, 12 times, You are actually removing 12 bits out of 12, is 2048 (actually instead of having 24 bits you have 12 bits). Quanrtification noise is 1/2048 is 0.05%. Which is less nice (although probably still hard to hear). And, considering the peak is never at max level, and the DAC is not perfect, you'll have even worse situation. And if now you even turn the volume down, then you're in a bad situation.

It is far better to do all computation and crossover with max "line level" signal (most of the 24 bit info), and do the DAC with line level, and do the volume control as late as possible, idealy in analog (where you do not have any quantification noise).

But then you have a problem because you want to have a volume control on 6 channels, which is not common. There are solutions (look for DCX2496 DIY volume in google) but they are expensive and DIY. My solution is to use a multi chanel amplifier (or "receiver"). And, for the cost of one fancy sound card, you get on ebay used 5+1 receiver with digital input (S/PDIF or HDMI) and volume control and power amplifier.
Note there are also digital preamps like the Sony EP9ES.

Hope my lenghty explanation is not more confusing than helping..
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Old 5th November 2013, 01:07 PM   #19
Eldam is offline Eldam  France
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Thanks, yes it helps. No more confusing because more data helps to understand better. With no knowledge it's impossible to drive the puzzle at its end.

For the moment : the numeric volume control of the squeezebox is used in the last 10 % of maximum volume just for confort before to go to the separated DAC (= before it so wrong) and the general volume is managed after the DAC by the analog preamp ! I hope using remote control for volume between 9O and 100 (max position) don't cause to many problems.

Yes I saw six channel volume analog interface exist...some of them can be expensive but some in France make good inexpensive ones with multiple Vishay 2 channels stacked together.

I saw than Nuforce (thanks for sony ref too) make numeric preamp.

So the better if no numeric preamp is analogic volume control after the DACS. I assume too than the db level between drivers is managed in the numeric domain by the crossover interface (numeric if PC and not in analogic domain la Linkwitz with IC and electronics parts).

Ok I understand why HDMI with soundcard if AV multiamp receiver with embeded multiDAC is used (how is managed the split of signals in it between DAC and amps and volume interface ?).

In my mind and in relation to my OP, the dacs and the amps are important to improve the classical passive solutions:

- Better if DACs can be choosen after crossover and DRC processing
- Better if amps can be choosen after the DACs (hypex or others)

What I can't understand now is that the volume of drivers for crossover is set by the soft in numeric domain. Is it equal to quantification noise ? Or do we have to manage an analogic attenuation after the DACS.

I can say better a 12 channel analogic control because i like to set up with precision left and right volume without Balance plot (i can hear it and sometimes do another set up for another disc... i am a fanatic of stereo room perception ! )

It could be simplier to go with powerDAC, i've got one from hifymeDIY with volume remote control (but think the attenuation is maid in the DAC chip...) but still thinking it's too poor solution at the moment. By the way multipowerdac amp are AV receiver for the moment !

Have we go back with opa like active crossover IC boards la Linkwitz...himself seem pleased by processors but doesn't believe in DRC with multipoint correction in FIR domain.

Am i right ? JPlesset seems to say : don't matter, just do it, even a basic souncard with reliable set up will sound better than passive.

At the end i have to say it's very important to manage the volume and the library with remote control because if not i prefer go back to my rega planar 3 and vynils .
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Old 19th November 2013, 10:27 AM   #20
Eldam is offline Eldam  France
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Hi
Have please a question: if external souncard without SHARC: Where is maid Software DSP processing ? With the computer processor ? A dedicated 32 bits Sharc chip is better ?
Mini personal computer then usb to async I2S then Dacs are ok for REW or RePhase?
Hesitate between minisharc grom minidsp and computer...
Both i would use external Dac like curyman or tweastedpetaudio...or both in three ways.
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