Article: The Value Proposition in Computer Audio: Entering Multichannel at the Ground Floor

[bluesman]

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[bluesman]

49 minutes ago, The Computer Audiophile said:

Thanks so much for the thorough article @bluesman! I'm such a newbie when it comes to multichannel, but since Pearl Jam released its new album Gigaton in Dolby ATMOS, I'm close to finally jumping onboard. 

So I suppose now we have to stop dissing Muzak and thank it for the concept of ceiling speakers...... 😝 

[bluesman]

21 minutes ago, Bill Brown said:

What I would like is plugins in a computer to process, then USB (or HDMI) to a multichannel DAC (or all of it in something like a Metric Halo interface).  There seem to be some plugins, but mostly for production/post-production.  I'll keep an eye out.

I don’t know exactly how the processing of 2 channel source material to MC output is done. But it’s done well by both proprietary programs like JRMC and Roon and by many open source players.  So you don’t have to look far or spend money to add this function to your computer.  You might want to review my article on front end audio software to find one for your computer -  here’s the summary table, which you can search for “MC” to find those that do it.  
 

I’m particularly pleased with HDMI for audio.  Driving good electronics, I believe it’s the equal of USB and coax for SQ.  Sadly, I don’t have a DAC that has HDMI plus USB - so I can only A/B the former against coax and optical into my Elite receiver. But from comparing it to USB into DACs and analog endpoints of the same spec and vintage, I think my belief is well founded.

 

Thanks a lot for your kind words!

 

David

[bluesman]

23 hours ago, Skip Pack said:

Superbly crafted article! It provides what I need to get going on MC music. I've been using RPi's for five years, and figured that pointers to successful configurations were what I needed, rather than plunging down successive rabbit holes. I have a room set up with 4.1 right now, with wiring for 5.1 centered on an old Yamaha RVX-375, which seems so sound nice.  It only has one spdif coax for digital input aside from HDMI. My RPi3+ with a spdif hat should drive that nicely. The octo sounds like a very reasonable alternative, so I suppose the issues will be the ease and accuracy timing out and balancing the channels, and the DAC quality. Thanks very much.

Thanks!!  You don't need an Octo or an spdif HAT to play MC through your Yamaha receiver - HDMI from the Pi is fine.  As I recall, your Yamaha has the same (or similar) 24/192 DAC chips as my Pioneer and should sound fine through decent speakers.  The Octo is a nice device, but it sounds no better than my Elite receiver. Assuming you have MC source files at or below 24/192 and/or your player will reformat your 2 channel files to MC, you don't need to add any additional hardware or software.

 

Timing and balance problems do not exist when cabling the Octo to analog endpoints.  The only such problems I encountered were with BT wireless MC.

[bluesman]

10 hours ago, thotdoc said:

Ok. I reread it.  Got it. I'd gotten to thinking about using a v g DAC I had here and lost the thread.

 

Just to clarify:  you need an analog output channel for each channel in your chosen audio output format.  A complete channel includes hardware conversion of the digital signal to analog, plus amplification and a speaker.  Conversion can occur in a DAC at the beginning of the chain or integrated into an amplification stage further downstream.
 

With traditional analog amplification, digital conversion to analog happens at line level (in the DAC) before input into the first analog stage.  If you use digital amplification, the conversion from digital to analog happens at or near the last stage in the hardware (the power output stage that drives the speaker).

 

So no matter how you shuffle the hardware deck, each audio output channel needs its own D-to-A conversion, amplification, and transduction.  A 2 channel DAC will only convert and deliver 2 channels of analog audio to the amplification stages.  The Octo card has 8 discrete DAC channels.  Digital audio interfaces have enough for their max output formats, so a 5.1 DAI has 6 channels and outputs.  Basic HT receivers are usually 7.1 .  If you input 4 channel source material, you’ll get 4 audio channels from 4 of the 8 outputs and nothing from the other 4.

[bluesman]

11 minutes ago, Bill Brown said:

I was interested in getting started with a center channel then going on from there.  SW player with plugins to MC DAC.

As I recall, the AuroMatic 2D plugin lists for $600 per the B&H website.  I was hoping to find a less costly way to try this, but I’ve not found one yet.  If you succeed, please post about what you found.  Thx!

[bluesman]

1 hour ago, Bill Brown said:

I just can't stand all the bells and whistles, love simplicity, buying maximal quality for the price on the features I need.

I'm with you on that philosophy.  For my "off duty" listening, my music server is Roon ROCK on a NUC and my main players are Pi 4s with Bridge.  The living room Pi drives an SMSL SU-8 into a Prima Luna power amp and Focal 726 towers.  The den Pi drives an iFi DSD Nano into a pair of JBL 305LSRs or my AKG 701QJs.  Every other room has a Chromecast Audio driving inexpensive powered speakers via optical, except for the water-resistant JBL in my bathroom that only has an analog input. 

 

I also run JRiver Media Center on each Pi, on my Linux DAW/media box, and on my workhorse Win10 PC.  JRMC lets me listen to my music anywhere around the world over the internet, and it's the best player I've found for MC on the Octo.

 

The OctoPi is running 5.1 JRiver into 3 JBL 305s and a Stewart PA100B driving my Rogers LS3/5as.  I'm enjoying MC more and more, and this system is very listenable, great value, and simple as Pi (sorry, but I couldn't resist...).  I do plan to acquire an ESI Gigaport EX as soon as I can find one.  They were introduced at the 2020 NAMM show, but getting them into the hands of the public has obviously been problematic during the pandemic. Once I get that (and assuming SQ is significantly better than the Octo), I'll add another pair of JBLs and use my Yamaha sub for a matched 5.1 system that will also be for "off duty" use.

 

For me, most opinions without experience are worthless.  So I've always tried everything I could - hardware, software, methods, program sources, etc.  But quality, simplicity and value are the metrics I hold most dear and try to balance in daily life.

[bluesman]

1 hour ago, Kal Rubinson said:

It came "free" with my Marantz AV8805.

It’s all in your point of view, Kal.  You also got great electronics “free” in that Marantz - but the case and controls cost about $4500.

 

The AuroMatic 2D plugin is $669 right now at Dale Audio and €595 direct from Auro.  The 3D plugin is €1195 (~1400 USD) from Auro.  This is a bit rich for people with Raspberry Pi streamers 😗

[bluesman]

15 hours ago, jrobbins50 said:

I’ve never used any of the Marantz options.

I'm not sure why you use the analog inputs when your Bel Canto has optical and coax outputs (assuming it's like other BCs I've seen).  If you're doing it because you prefer the SQ of the BC's integral DAC to that of the Marantz DACs, you'll negate that by adding Marantz A-D and D-A processing on top of a signal that's already been converted to analog by the Bel Canto. 

 

Auro may not be accessible by digital input.  But I've not seen a MC receiver that wouldn't apply Dolby & other more common internal MC processing to digital input, since most MC receivers are bought for HT and most HT users connect their TVs, cable boxes, and other sources to their receivers digitally.  All you have to do is push a button to turn these effects on.  If I were you, I'd connect your Bel Canto digitally to your Marantz and start listening to the various ambience syntheses available to you.  Once you see what they can do, you'll have a better idea of if and how much you like the concept.

 

I'm also confused about your Okto DAC8 Pro.  Why do you need it if you have a MC receiver?  I know of no advantage to driving the unbalanced analog inputs of the Marantz with an 8 channel balanced DAC.  What source material are you using, if your Bel Canto is connected directly to the Marantz's analog inputs?  How are you listening to it with only a 2.2 speaker setup?

 

2.2 is generally used to mean 2 full range speakers and 2 subs.  If that's what you have, I assume you also have some kind of MC HT speaker setup, since you bought a pretty serious MC receiver.  If so, you can experience the various effects available in your Marantz through your HT speakers - they may not be high end audio quality, but they're good enough to demo the effects.  If you don't have a HT setup, some of the synthesized ambience programs are usable with 2 channels.  They do make a difference you should try, if only to be able to understand what they do - you don't have to like it or use it forever.

 

 

[bluesman]

1 hour ago, Kal Rubinson said:

superior to the d/a in the Marantz.

As I said above, “If you're doing it because you prefer the SQ of the BC's integral DAC to that of the Marantz DACs, you'll negate that by adding Marantz A-D and D-A processing on top of a signal that's already been converted to analog by the Bel Canto”.  That’s obviously also true for the Okto.

 

Almost all HT receivers convert analog input to digital before it reaches the DSP chips. They then run the processed digital signals through a DAC for analog output to the speakers.
 

So if the OP prefers the SQ of his Okto or his Bel Canto to the internal DACs in the Marantz, he’s almost certainly negating that advantage when adding DSP.  He’s reprocessing the analog output signal with the same DACs after adding a preparatory pass through the Marantz’s ADC. This can only degrade SQ and makes no sense to me. 
 

Those line level connections are also prone to noise of many kinds - electrical, RFI etc. And the Okto is fully balanced.  Running balanced XLR to unbalanced RCA removes another potential SQ improvement by eliminating common mode rejection. So that logic also seems flawed to me.

[bluesman]

29 minutes ago, Kal Rubinson said:

This Marantz does not do this nor does mine.  There is no a/d nor, of course, an additional d/a with the 7.1 analog multichannel inputs, only with the stereo analog inputs.

So the internal MC DSP simulations and ambience synthesis functions like Dolby are also non-functional on the analog MC inputs?  
 

The only reason I can see for this would be the assumption that any and all DSP is being applied ahead of a DAC in a front end that has no analog power output stage.  If so, why would anyone buy (or, for that matter, try to sell) a $4k+ receiver to use as an analog amplifier in lieu of better amplifiers for the same money? 
 

You seem to be contradicting yourself with the statement that “[t]his Marantz does not do this nor does mine.  There is no a/d nor, of course, an additional d/a with the 7.1 analog multichannel inputs, only with the stereo analog inputs”.  These Marantzes do exactly this - but (as you tell us) it’s only on input through the stereo RCAs and not on the 7.1 analog inputs.  It’s being done to the Bel Canto’s signal in the OP’s 8802 - just not to the Okto’s output.

[bluesman]

I misinterpreted a critical piece of information because of one of your posts, Kal -

 

On 9/21/2020 at 4:34 PM, Kal Rubinson said:

Yes, to use Auro-2D, you supply the Marantz with a stereo source input and it will output an Auro-2D 5.1 or 7.1 signal to your 5.1 or 7.1 speaker setup.

 

You say clearly in this quote that the Marantz will output an Auro-2D 5.1 or 7.1 signal "to your...speaker setup".  It can't do that without an amplifier, which led me (and perhaps others) to believe that the Marantz units in question are receivers.  I just looked at their specs, and they're clearly not receivers - they're (as you described them) "pre-pros".  Forgive me for not knowing this, but my series is focused on the value oriented audiophile.  A $4k+ HT preamp is not commonly thought of as being a value oriented audio device.  Until today, I was entirely unfamiliar with this genre except for the Emotiva 700.

 

As the OP makes no mention at all of amplifiers or speakers in any of his multiple posts, it was logical to assume from his posts and yours that his Marantz is a receiver.  But with or without an output stage, he'll be running his 2 channel analog signal from his DACs through another AD-DA chain if he uses any DSP that's embedded in the Marantz or added by subscription from a 3rd party (i.e. Auro).  So any sonic advantage of his DACs over those in the Marantz will be diluted or washed away by additional ADA conversions and the use of unbalanced 2 conductor analog interconnects.

 

Whether the OP would prefer the SQ of the Marantz DAC with optical connections to his Bel Canto and Okto with analog connections is an interesting question, to which I'd love to know the answer.  But if the Marantz AD & DA convertors are suboptimal, are there higher quality pre-pros that might obviate the desire for a separate DAC up front?

[bluesman]

1 hour ago, sfhollis said:

So now I have an 8ch minidsp 88D, an 8ch DAC, and a 7-ch amp. All with 6ch free. I was thinking this is just begging for some multich experimentation.

 

The trick is. I need to get 8ch of AES out of my tower PC somehow. Right now it sends stereo audio to a Matrix USB transport that has one AES out for the 88d.

You may be making it harder to get MC than it needs to be for you by insisting on use of your current devices.  I assume you have your reasons for having bought that setup, but you don’t need all that stuff to do what you want to do.
 

If your PC has HDMI out, the easiest and cheapest alternative is probably to spend $300 on something like an Essence Evolve II HDMI DAC - you’ll have 8 analog RCA line outs to drive your amplifier directly.  An ESI Gigaport will turn USB input into the same 8 analog outs, if you prefer USB to HDMI.  And a UDIO8 will give you 8 AES channels out from USB.

 

If you use the MinuDSP for Dirac, you’ll need an AES MC sound card in your PC to drive it.
 

AES is not the easiest or most common modality for consumer audio.  There are AES MC sound cards for your PC, if you really want to go that route.  Most, like the Digigram PCX881e and VX822e, are sold to broadcast and recording industry businesses.  If it were me, I’d simplify rather than add yet more equipment.