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TOPIC: NanoDIGI Magnepan 1.6 active XO+ 4 sub integration

NanoDIGI Magnepan 1.6 active XO+ 4 sub integration 10 months 2 weeks ago #41574

  • dumpingground
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I recently purchased the Minidsp NanoDIGI which is an all digital solution with one SPDIF/TOSLINK IN and 4 SPDIF outputs. With this solution one can use their own ADC and DAC to surround the NanoDIGI for a potentially more high end solution. Also with 4 SPDIF outputs, the nanoDIGI can support a 2 way active crossover plus 4 subwoofer integration all in the digital domain.

Reference Posts:

1. My Magnepan 1.6QR DIY Upgrade Story (OEM crossover upgraded parts)

2. My Magnepan 1.6QR DIY Upgrade II: Going Active!!

3. My Magnepan 1.6QR DIY Upgrade III: Going PLLXO!!

4. Bringing the HSU TN1220's into the modern era!

I feel like I am going backwards and forwards at the same time. With this upgrade I am in some sense returning to my Minidsp based solution. I was never completely happy with the Minidsp 2x4 solution since it relied on the built in ADC and DAC in the minidsp box. Now with the nanoDIGI I have a chance to go back to the DSP world for another try at an active crossover design.

Reference #1 above to see how to bypass the factory crossover to attach your power amps directly to the Magnepan 1.6 Tweeter and Woofer panels.

Reference #2 above to see how to setup the Minidsp DSP filters to emulate the factory Magnepan 1.6 crossover.

Reference #4 above to see how to emulate the HSU TN1220 Bass Optimizer box with Minidsp filters.

Here are some of the software and hardware choices in my solution:

MiniDSP nanoDIGI 2x8


Focusrite Scarlett 6i6 2nd Gen

Jriver Mediacenter Software

Plus Parasound HCA-1000A poweramps, Crown Drivecore XLS-1000 and XLS-1500 poweramps, HSU TN1220 subwoofers (2), SVS SB-1000 subwoofers (2). XMOS USB/SPDIF reclocker adapter.

Here are some of my Design Choices and Relevant Discussions:

1. MiniDSP nanoDIGI 2x8. I considered the MiniDSP SHD which combines many of the functions I am implementing here all in one box. However, since I already had the Focusrite, SMSL DAC's and audioprocessor PC with jriver, I decided to roll my own solution. The nanoDIGI can support IIR filters (it is not powerful enough for DIRAC or FIR filters). If I in the future goto FIR filters I can implement them in the audioPC with jriver and rephase. The nanoDIGI has an IR receiver and can switch between TOSLINK and SPDIF inputs via a IR remote signal. I am using this to switch between "Music" mode and "HT Bypass" mode. With the nanoDIGI I am able to implement the Magnepan crossover, HSU Bass Optimizer filters and the mains/subs integration/time align all in the digital domain. I was able to use the nanoDIGI delay function to adjust for the fact that my 4 subwoofers have different distances to my Main Listening Position (MLP). I was also able to implement a high pass filter on the woofer panel of the Magnepan's to offload the below 45 hz signal.

2. Jriver Media Center. Jriver supports DLNA and FIR filters via rephase. Jriver also has a 64bit math engine to support resampling of the bitstream to 24/96k which is the internal processing rate for the nanoDIGI. By converting all of the PCM audio to 24/96k before it gets to the nanoDIGI I can avoid the (potentially) lower quality ASRC function of the nanoDIGI. When operating my solution in "Music" mode, I am using the jriver software to implement volume control. The jriver WDM function allows me to pass all of the spotify music thru the jriver 64 bit engine prior to sending it on to the nanoDIGI.

3. Focusrite Scarlett USB ADC/DAC. The Focusrite supports 6 IN and 6 OUT. 4 Analog XLR plus 2 Digital SPDIF Inputs and Outputs. The Focusrite processes at 24/192k and has relatively high quality ADC and DAC inputs/outputs. The XLR pro level analog outputs are useful to me since my Crown power amps have XLR inputs for my subwoofers (and buttkicker) channels. With a XLR to RCA adapter I can take the preouts from my Yamaha AVR for the "HT Bypass" mode.

4. SMSL M8 DAC's. With the nanoDIGI solution, it is very easy to select (and later upgrade) the DAC's that are driving the tweeter and woofer power amplifiers. Also in my previous PLLXO (passive) solution, I had to include the input/output impedance of my preamp and poweramps in the PLLXO component value selections. Now with this active solution I can use whatever amps and DACS I wish. The SMSL M8 uses the ESS9018 DACs which measure and review well.

5. HT Bypass vs Music Mode. My system is for both 2 channel and 7.2 ATMOS hometheater listening/viewing. I need to be able to switch with a Harmony remote between the modes. Unfortunately the Focusrite USB interface does not support IR commands. Also, the Windows Control panel software for Focusrite does not support command line options. I did try using some Windows macro recording software (autohotkey) to trigger changing modes of sending IN/OUT routing thru the Focusrite to implement different audio routing modes. I could never get the macros to trigger reliably. So I added an existing XMOS USB/SPDIF to my setup.

HT Bypass Mode:

Yamaha AVR L/R Preout -> Focusrite XLR/RCA adapter input -> Focusrite SPDIF 24/96K output -> nanoDIGI SPDIF input -> nanoDIGI SPDIF out -> Focusrite (to subs) and SMSL DACS -> Parasound HCA-1000 power amps -> Magnepan Twt/Woofer panels.

The SVS, HSU and Buttkicker bass frequencies follow a similar initial path and then to the Focusrite analog outputs.

Music Mode:

Windows 10/Jriver PC -> XMOS USB to TOSLINK 24/96 output -> nanoDIGI TOSLINK input -> nanoDIGI SPDIF out -> Focusrite (to subs) and SMSL DACS -> Parasound HCA-1000 power amps -> Magnepan Twt/Woofer panels.

The SVS and HSU bass frequencies follow a similar initial path and then to the Focusrite analog outputs.

I recognize that I am using the TOSLINK input to the nanoDIGI for my "audiophile" music mode and the potentially higher quality SPDIF coax for the HT Bypass mode. However the Focusrite device only has SPDIF output.
Last Edit: 10 months 2 weeks ago by dumpingground.
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