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Old 27th January 2014, 02:10 PM   #1
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Red face Full active home cinema needs DSP

Hello,

I am not sure if this is the right place to post my query...

Some time ago I build myself some speakers for my home cinema (5.1) with 41hz amps (5 amp4s and 1 amp1). The loudspeakers are setup full active (no passive crossovers) fed by two soundcard with the kx drivers.

Now I would like to get away from the old soundcard solution and use an external DSP. I would like to feed the dsp with a digital signal from the pc or some other source and get 11 analog signals from it (with crossover, equalizing and some delay).

What device could I use to do this? Would I need to get two devices (I think most donīt have so much output channels)? I think it will need DSP/DD/otherFormat decoding in it, since the signal is not decoded in the blueray player / pc when fed by spdif?

I was thinking to buy a ADAU development board, but I am not sure if I can handle the programming (the sigma studio is looking pretty forward so) or if the use of a development board is suitable at all .

I am not experienced with programming DSP (other then setting up DSP via the kx drivers or user interfaces in car audio systems. Thus I am not really familiar with programming filters directly (I am a software developer in C#, Java).

Is this possible at all?
If yes, than maybe someone can give me a push in the right direction?

Thanks and best regards
Christian
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Old 27th January 2014, 08:19 PM   #2
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Yes, it's possible. Most discussion about such is in the Open Source DSP XOs thread in this forum. Another way of answering your question as to the number of devices required is to look at the IO counts in Analog's SigmaDSP parametric table. If you're unsure of your ability to copy the hex dump SigmaStudio generates into a SigmaDSP device plan on a large learning curve for this project.
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Old 28th January 2014, 07:00 AM   #3
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Hey,
thanks for your answer.

I will read through the thread you posted and dig through the pages ;-)

The question about the number of possible needed devices was rather targeted at "ready made" devices, rather than at the development board. As far as I looked I didnīt find a device with 11 or more channels.

I have been looking at the ADAU1442 development board, and that board has 16channel analog output. But would it be possible to use it for multichannel decoding (DTS, DD,...)? I read somewhere that would require plugins for SigmaStudio not available to ordinary people?

As I have not used SigmaStudio before, the question about handling the programming was more about how much has to be programmed manualy (with a deeper understanding of DSP coding) or if pretty much everything is drag and drop ;-) I really think I can handle the upload of a file to an external device

Greetings
Christian
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Old 28th January 2014, 12:42 PM   #4
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ADAU1442 evaluation board is expensive:

EVAL-ADAU1442EBZ

Minidsp.com has some boards which might do, they use the Analog Devices SigmaDSP's as well, see Welcome to the world of miniDSP | MiniDSP

You can't get full quality 5.1 signal using SPDIF anyway, you might as well try finding BD player with analog outputs (not cheaper though, OPPO has got some: OPPO Digital - Universal Network 3D Blu-ray Players - Buy Direct from the Manufacturer ). Then you could use the miniDSP's, you would need 3 of them if you use the 2x4 miniDSP's (MiniDSP kit | MiniDSP) and if youre speakers are two-way.

Instead of expensive OPPO you might use regular BD player with HDMI output and an external audio decoders like these (for some reason links don't work):
Code:
http://www.ebay.com/bhp/hdmi-audio-decoder
http://www.ebay.com/itm/HDMI-Digital-Multi-Channel-To-Analog-Surround-Sound-Audio-Decoder-/230667796058

Last edited by mhelin; 28th January 2014 at 12:53 PM.
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Old 28th January 2014, 03:46 PM   #5
notio is offline notio  United States
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Quote:
I read somewhere that would require plugins for SigmaStudio not available to ordinary people?
Yes, I believe that's true. If you try to download the Dolby 5.1 decoder plugin for SigmaStudio from this page... DTS 5.1 Decoder for SHARC | Analog Devices

...you will be led to an agreement which says, "Please note: You need to be a Dolby or DTS "qualified recipient" to receive a Dolby or DTS module. This implies that you have already signed a license agreement with Dolby or DTS. Evaluation code for most Dolby modules is available for immediate download direct from the ADI website."

You can probably hack-simulate it using L+R for the center and L-R for the surround, but it isn't perfect.
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Old 29th January 2014, 07:21 AM   #6
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Quote:
Originally Posted by mhelin View Post
ADAU1442 evaluation board is expensive:
Yeah, but if it would have been able to do what I wanted I would have been willing to pay the price.

Quote:
Originally Posted by mhelin View Post
Minidsp.com has some boards which might do, they use the Analog Devices SigmaDSP's ... an external audio decoders
That could be a way to go. Right now this would probably be the easiest way to do it. I would probably get this converter HDMI Dolby DTS PCM 5 1 7 1 to Optical Digital Audio Converter Decoder | eBay (it seems that the converter from the second link can not convert HD audio to analog).

Quote:
Originally Posted by notio
Yes, I believe that's true.
You can probably hack-simulate it
That is sad ;-) Thus the development board has died for me, because the price for it is too high to get an suboptimal solution... But thanks for the confirmation.

I somehow believe that there is no optimal solution for this.

As an alternative I was thinking about buying an av receiver to do the multichannel stuf and use the included amps for the bass-midrange speakers. Are there av receivers with build in frequency filters, so that I could define a lowpass for the speakers? Then I could use the pre out to a dsp / crossover and feed the tweeters...

Or are there any new soundcard capable of doing what the kx drivers do?

I am even thinking of building passiv crossovers for my speakers :-(

Thanks for your answers!
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Old 29th January 2014, 01:16 PM   #7
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Even best external DSP will mess up video synch.

Best solution is likely JRiver media player which has accommodations for this. Otherwise an outboard video delay line becomes necessary.
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Old 30th January 2014, 01:52 AM   #8
dangus is offline dangus  Canada
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Emotiva makes some HDMI pre/processors (like an AVR without the amps). UMC-200 7.1 Home Theater Preamp/Surround Processor | Emotiva Audio | High-end audio components for audiophiles and videophiles, spanning 2-channel music systems, as well as 5.1 and 7.1 home theaters. Products include multichannel amplifiers, stereo a Too bad it costs more than many AVRs.

There's something to be said for joining the dark side and getting an AVR. Most will have DSP that does some room correction (Audyssey, MCACC), and there's often adjustments for the subwoofer crossover frequency. Some AVRs have multichannel preamp outputs, but that's a rare feature. I've been unimpressed with the reliability of the Pioneer AVR that I bought new 7 years ago, but a thrift-store Onkyo of the same vintage works great.
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Old 30th January 2014, 10:15 PM   #9
chrisb is offline chrisb  Canada
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dangus - I'd definitely agree with the value packed into most mid price range mainstream AVRs - within the last year I've helped a couple of family members set up 5.1 systems with Marantz units, and found them to be not just a bit easier to navigate through the setup routine, but vastly superior in performance to both my own Denon (AVR1610) and a several year old Onkyo bundled system that one of them replaced (can't remember the model number) .

While doing some research on the Marantzes, I found that even the entry level of the SR series (currently that'd be the 5008) have full 7.2 pre-amp outputs, so with enough outboard boxes, I should think one could easily accommodate active biamping of any combination of channels, while retaining the Audyssey calibration and EQ functionality - which makes set up a breeze.

One of these rigs was an SR7005, which was the first unit I've personally used that allowed for assignment of one of the pairs of amp channels to bi-amping of the front mains - albeit assuming passive XO in the enclosures themselves. Since this system included a vintage pair of B&W floorstanders with bi-amp ready crossovers, we thought - WTF, why not. Not only was it as easy peasy to set up as a normal 5.1 system , but it felt good not to let those amp channels sit idle.

And as Barleywater intimated, it's nice to retain as much of the switching and DSP of audio and video signals in the same box as possible - if for no other reason that the cost savings on interconnects .
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Old 31st January 2014, 08:37 AM   #10
DorinD is offline DorinD  Romania
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Maybe simething like this will do the trick:
nanoAVR 8x8 | MiniDSP
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