# Future Mac/iPad Build?



## organic.freq (Sep 12, 2015)

I'm planning a system a year or two from now when I return to the States, so I cannot attempt any of this hands on. Please correct me if there are any weak links or something that does not work in theory.

My only experience is car builds was from 20+ years ago, so very rusty...

Goals:

1. Maintain stock head unit and speakers. Only AUX IN utilized for Videos playing via the stock speakers. Mids/Tweeters located in pillars... Midbass kickpanel.

2. iPad to complement stock system, not integrate. iPad used to only remotely control Audirvana+ via A+ Remote, not used in audio loop. Also thinking of using a PS4 controller to control Audirvana+ when iPad is not around.

3. Balanced, accurate sound. Not too much boominess.

Will something like this work?:

Audirvana+ -> OS X -> Local In-Car Wifi Access Point <- iPad iOS <- A+ Remote (Software)

Intel NUC Hackintosh running OS X -> (Audirvana+ Integer mode compat) USB2SPDIF [e.g. M2Tech EVO] -> Transportable NOS R2R DAC -> Helix Pro -> Mosconi Amps -> Scanspeak R2904 -> Scanspeak 12MU -> TBD Midbass -> Illusion Audio C10/C12 XL (Hardware)

Intel NUC Audio Out -> Stock Head Unit

Intel NUC DisplayPort -> Computer Monitor

Computer Monitor(s) in back for Youtube Videos/KODI connected to AUX input to stock system. Play through stock speakers...

Questions:

DAC not needed? Prefer to run own DAC. Do DSP's have their own internal DAC?

Helix Pro allows 96kHz from DAC/Source. Just feed it a 96kHz signal and it should be fine?

I plan to run SACD isos DSD64 Stereo from Audirvana+ -> 88.2 kHz -> Helix Pro...

Sorry if the questions are pretty RAW. I just started getting back into this stuff...

Note: Considered MPD Rasberry PI2 Linux route with Android mpd client, but Audirvana+/A+ route cleaner UI. Both BitPerfect.


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## subterFUSE (Sep 21, 2009)

Cool idea. I've always wished I could have a Mac Mini in my car, but always hesitated because of not knowing a convenient way to interface with it.


I can't answer all of your questions, but here are a few:


If you are using an outboard DSP like the Helix Pro, then you don't need a DAC. You will be better off with a digital output going directly into the DSP.

All DSP processors are Digital, hence the name DSP. They only work in the Digital Domain, so if you feed them an analog signal then the first thing that happens is the processor converts analog to digital. This is a step you ideally want to avoid because each conversion that happens potentially degrades audio quality a little bit.

Most DSP units will also have a DAC inside them which converts the processed digital signal to analog so it can feed the amps.

Therefore, if you had your own outboard DAC that would mean you are converting from Digital to Analog once before hitting the DSP. Then the DSP would convert A/D, and then it would convert D/A again. That's 3 conversions. If you feed a digital output into the DSP directly, then it will only convert from D/A 1 time.



The Helix Pro has the highest resolution of any car-audio specific DSP on the market today. It can accept up to 96kHz sample rates, in 2 channel stereo only. It cannot accept multichannel audio. As long as you feed it a 2-channel source with 96kHz or lower sample rate, it should theoretically be fine.

I'm not sure about DSD, however. The Helix Pro definitely does not decode DSD streams. You need special hardware to do that, so you might need to convert your DSD music to a format like FLAC? There is free software available that can do it. XLD on Mac is an example. Or you might need an outboard DAC that can decode DSD streams? Or does Audirvana decode the DSD?? DSD is something I just don't know much about.

Just as an example.... Sony is releasing a DSD capable head unit soon. It has an optical output but you can't play DSD over optical because the stream must be decoded. So DSD audio has to go through the head unit DAC and come out analog for DSD to work on it. But standard PCM can go through the optical output and bypass the internal DAC just fine.


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## organic.freq (Sep 12, 2015)

Thanks for your reply.

First, I love your horn setup. Will follow that thread. Second, I think it was your reply in the Helix Pro thread that got be considering 96kHz as a possibility. I was not aware it was even available until that post.

The Audirvana software is really nice for audio playback and organization. It’s simple, stable and has DSD playback.

from audirvana site:
All major file formats
WAVE, AIFF, Apple Lossless, FLAC, WavPack, APE, Cue Sheets, M4A, MP3
And DSD formats: DSF, DSDIFF (including DST compressed), SACD ISO

The DSP explanation is very clear. Thank you. I guess I can remove having a custom home DAC out of the equation.

I prefer running a Intel NUC over a Mac Mini for upgradability purposes. It is half the cost and has a lower footprint. In a few years, can possibly put a 3TB SSD in the NUC. Plus 16GB RAM is optimal for Audirvana. Much easier to manage for upgradability as well as reasonable costs. OS X runs stable on the NUC. The only negative is not having a optical output, but USB2SPDIF is available and may perform better.

Audirvana handles the decoding of DSD. In theory, it should feed straight into the DSP with no special hardware. I cannot test hands on, but anybody with a Macbook with Audirvana, a SACD iso, optical cable to feed into a Helix Pro should be able to test without the need of a Mac Mini.

Would love to hear the SQ with this setup, especially with horns, since source material / mastering is important.

I’m in the no after market head unit camp …

oh, can you feed the DSP different sources? Say 1. Audi Stock -> MoBridge DA1. 2. Portable device 3. Mac Mini. if yes, is there a remote or something to select the source for the helix pro?

thanks again. much appreciated.


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## subterFUSE (Sep 21, 2009)

The Helix DSP Pro comes with 1 set of digital inputs (toslink and coax). There is an add-on HEC module that can add a second set of digital inputs.

I am running 2 optical sources in my car.

1 = mobridge

2 = Audison Bit Play


Sent from my iPhone using Tapatalk


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## organic.freq (Sep 12, 2015)

sweet. the coax supports up to 192kHz. can possibly play 176kHz with sacd. also, noticed there is a helix pro remote on the crutchfield page.

found out audirvana converts dsd to pcm on-the-fly, unless you have a dsd dac :-( :

from audirvana site:

Native DSD Streaming

With a DSD over PCM compatible DAC, DSD64, DSD128, and beyond can be streamed natively for direct playback of the DSD signal by the DAC.

With non DSD DACs, DSD audio files are automatically downsampled in memory to PCM before playback using a high-quality 64-bit multistage algorithm.

but... after digging... but unsure if this is for the 8-channel helix or the helix pro, found dac is possibly cirrus logic cs4385 or something similar:

www.cirrus.com/jp/pubs/proDatasheet/CS4385_F2.pdf

it looks like it supports sacd/dsd if you feed it a dsd digital signal.

found this link after as well to confirm possibility this is the correct dac:

www.diymobileaudio.com/forum/car-audio-classifieds/205890-fs-256gb-ipod-5-5-gen-wolfson-dac-3.html

so something like audirvana+ (integer mode) -> USB -> PurePower -> audiophilileo 1 or 2 -> optical/coax -> helix pro might have possiblities. chances look good it can stream dsd natively.

audiophilileo 1&2 support dsd stream "DSD64 supported via DoP"

http://audiophilleo.com/audiophilleo1.aspx

much appreciated subterfuse. have much better clarity now...

just need to dig some more to confirm hellix pro is indeed using the 4385.


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## organic.freq (Sep 12, 2015)

final notes:

* although this seems technically possible to run native DSD via the Helix Pro, there is no way to really know until this is tested.

found this comment @ http://parttimeaudiophile.com/2013/09/06/audiophileo-1-with-pure-power-the-little-combo-that-could/:

<I>Good question. Technically, it does. The AP1 supports DSD64 playback via the DoP method, and there’s even a Special Edition for $150 more than does DSD128 and up to 384KHz PCM too. 
The problem is most DACs won’t accept that over SPDIF. The DoP spec allows for it (the signal appears to like 24/176.4 PCM) but I’ve yet to find a DAC that actually does it. So far I tried the Resonessence Invicta, the Yulong DA8, and the Matrix X-Sabre, all DSD capable DACs. They all try to play it (again, as 24/176.4) but the sound is all static or hiss. I’ve read the Mytek or the new Benchmark DAC 2 may handle DoP over SPDIF, but I have my doubts until someone actually confirms it. 
That said, these manufacturers are still figuring out what people want. I have no doubt some future DACs will support it.</I>

* in place of a local wifi setup with an additional iPad app (A+), one can run a wired setup from OS X -> iPad to display as a monitor using Duet display. so should be able to run the audirvana interface directly from OS X with touchscreen capabilities.

Duet Display - Ex-Apple Engineers Turn Your iPad into a Second Display for your Mac

will place the duet display in another thread since it maybe helpful for another applications.


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