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TOPIC: Re: Stereo>NanoDIGI>2xOpenDRC-DI2xDAC>2 x 2 system

Stereo>NanoDIGI>2xOpenDR​C-DI2xDAC>2 x 2 system 7 years 2 weeks ago #6584

Audio mastering room, two mains (high pass) + two subs. Stereo SPDIF, sample rates vary from 44.1 to 96k. Room is very well tuned.

I must use digital-only devices to derive a miniDSP solution (no AD or DA conversion).

I'm wanting OpenDRC-DI to assist with final room and speaker tweaks.

Path = stereo SPDIF to NanoDIGI for crossover, which then passes stereo main to 1 x OpenDRC-DI and stereo sub to 1 x OpenDRC-DI, which then pass stereo main and stereo sub channels to a 4 channel DAC.

Problem = I want all miniDSP ASRC to run at 96k, not 48k.

The above path would require 4 x OpenDRC-DI (one for each speaker) to run at 96k.

In other words:
Solution A(1 x NanoDIGI, 4 x OpenDRC-DI = $1375 + $400 software = $1775)
Path = stereo SPDIF to NanoDIGI for crossover, which then passes mains to 2 x OpenDRC-DI and subs to 2 x OpenDRC-DI, which then pass mono main and sub channels to a 4 channel DAC.

"Hmmm" I thought, "Maybe I can use the mono from each original stereo channel to feed 2 x OpenDRC-DI, which would then feed NanoDIGI for crossover....."

(I couldnt figure out how to exclude NanoDIGI because the stereo outputs of 2 x OpenDRC-DI when used in mono mode would not be useful to my 4 channel DAC)

I'd need another NanoDIGI on front to split the SPDIF, or I could use a simple splitter box to save $$.

So, this would derive:
Solution B(2 x NanoDIGI, 2 x OpenDRC-DI = $960 + $400 software = $1360)
Path = stereo SPDIF to NanoDIGI/splitter for dupe SPDIF, which then passes Left (mono) to 1 x OpenDRC-DI and Right (mono) to 1 x OpenDRC-DI, which then pass mono main and sub channels to NanoDIGI for crossover to 4 channel DAC.

Solution A has each OpenDRC-DI correcting on a per-speaker box basis (which could be useful in some ways but counter-productive in other ways)

Solution B has each OpenDRC-DI correcting one side of a full range stereo system (which seems more sensible)

Or I could simply buy a single DEQX box and not be fussed with the complexities of figuring out a 96k miniDSP solution....and that would mean I wouldnt also have to build enclosures, power supplies for NanoDIGI...

Any thoughts or suggestions would be greatly appreciated!

Thanks
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Re: Stereo>NanoDIGI>2xOpenDR​C-DI2xDAC>2 x 2 system 7 years 1 week ago #6639

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Right now, for the configuration you're looking for (FIR @ 96kHz for Room correction), the OpenDRC wouldn't work since the current plug-in (2x2) only runs at 48kHz.

So for that reason, if you only want 96kHz, the above wouldn't work.

With this said, if 48kHz wasn't to be a problem, the configuration you thought about would indeed be best achieved with 1 x OpenDRC DI(doing the stereo room correction using FIR filters) + 1 x nanoDIGI (doing filtering).

Like any of our products, we always develop new plug-ins to fit on the hardware platforms(concept of the product). The limitation at 96khz is that it will take 2xTimes the DSP power and therefore the FIR/Room correction resolution wouldn't be as good as 48kHz. Take it that way, at 96Khz on an OpenDRC (unless we change massively the way FIR is done), it would not do as good of a job as a 48kHz Room correction (better resolution on the FIR taps).

Hoping this info helps.

DevTeam
MiniDSP, building a DIY DSP community one board at a time.
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Re: Stereo>NanoDIGI>2xOpenDR​C-DI2xDAC>2 x 2 system 7 years 1 week ago #6648

Thanks. Can you please confirm if 12228 FIR taps is actually possible at 48k when using 2 x openDRC?

Uli seems to think it isnt possible....the online info seems contradictory.

Here's some of what Uli had to say with regard to 12228 FIR taps:

"The OpenDRC-DI datasheet is talking about stereo with 6144 taps filters @ 48 kHz samplerate. And mono with a 12288 taps filter @ 48 kHz.

Now the manual of the program delivered by miniDSP says
4.1.4 Input channel mode
This plug-in is versatile enough to operate in 3 configurations for stereo or 2 way crossover configurations:
- Stereo mode: Left & Right channels having a dedicated path
- Mono mode: Channel 1 (Left) channel is being duplicated to both processing chains (e.g. 2way crossover left side)
- Mono mode: Channel 2 (Right) channel is being duplicated to both processing chains (e.g. 2way crossover right side)

This means that there is no mono mode with 12288 taps. A mono signal is split to 2-ways with each way carried out by a 6144 taps filter.

Please ask miniDSP. It is no problem for me to create the required filters (filter software) but the hardware has to support it."


Thanks
Last Edit: 7 years 1 week ago by NoDelusions.
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Re: Stereo>NanoDIGI>2xOpenDR​C-DI2xDAC>2 x 2 system 7 years 1 week ago #6661

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Ok, the first thing to realize and learn about our product, is that it's not the hardware platform (i.e. OpenDRC-AN/DI or miniDSP 2x8/8x8/10x10/ etc) that is defining the processing power of a product, but it's the plug-in. You can read the basics of the product for more details here: www.minidsp.com/products/the-product-concept

In other words, for you to know what an OpenDRC or a miniDSP is able to do in terms of processing power once you've established the I/O configuration, you need to look at the plug-in section. Makes sense?

The plug-in for the OpenDRC is the 2x2 at this point of time: www.minidsp.com/products/opendrc-series/opendrc-plug-ins
As you can see it only supports 6144taps @ 48kHz even in mono mode (see the DSP flow diagram). Like any of our platforms, we'll keep developping new plug-ins to complement with different variants but for now on 6144taps is the limits.

The summary table (though saying "Template FIR configuration depending on the plug-in" ) is indeed a bit confusing by mentioning the total amount of taps here. It should really say "look at the plug-in". We've updated it about it. FIR taps processing power are defined by the amount of memory and CPU power. The reason why we put it here in the hardware is really only to give an idea of the overall amount of taps.i.e. could be 1528taps per ch in a 8ch configuration. makes sense?

Hoping this info helps and clarifies,

DevTeam
MiniDSP, building a DIY DSP community one board at a time.
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