MDAC First Listen (part 00100110)

[alloja]

/ again, MDAC offtopic below, I promise to stop with these /

Heh, sorry I didn't reply earlier, I had a post in the making with specs overview for all of those, but you were faster.

No problem jirij, thanks a lot for taking the trouble of drawing up the list! Maybe not really completely offtopic though, as we could potentially help fellow PFM'ers on the way to some lightweight, MDAC2-compatible, integrated, free software solution, don't you think ?

I'd like to emphasize that my "least suitable platform" remark was based on the technical design of RPi, not its price/performance ratio or community support. That said, if all you need is simple 16/44.1 streaming to a USB/SPDIF DAC box from an existing NAS box, the RPi will do that just fine (excl. the cases where it doesn't - dropouts, ...).

Yes, I understood this completely. Obviously, you're much more of a hardware expert than I am, so may I ask you please what you think of the quadcore Cubox-i4pro, which doesn't feature in your shortlist? I thought it would have enough HP to achieve exactly what I described in my previous post, but maybe I am completely wrong. Or would the i2ex be enough? Wouldn't either still beat the RPi2 by today's standards?

As a matter of fact, 16/44.1 isn't enough for me, I'd like to go as high as 24/96, or even replay the odd native DSD or DOP file, as the MDAC2 will be compatible. And yes, I did read about the dropouts issue on the 1st gen RPis...

A wired ethernet connection will be available to whichever platform I'll try, so we even needn't worry about wireless links. And as for SATA connections to the HDD, I'd rather continue using my existing (external, 2.5", USB-powered) WD with the server/streamer to be, provided the board can provide enough juice to power it up correctly. My current Dockstar-based setup, relying on a device which was originally intended to be paired with 2.5" HDDs, obviously doesn't have any limitation from this point of view...

Thanks in advance for your insights and
/ YES, we'll try to stop the OT now /

 

[JohnW]

Nope, still the same.

Another strange thing is that when I turn off the pc, the MDAC goes into inactive state, but after 2-3 seconds gets back at 96KHz and stays that way.

If I put the pc to sleep, the MDAC stays in inactive mode during sleep. When I wake up the pc, MDAC's USB output is working.

nirolf,

I know many owners who use Windows7 + MDAC so this behaviour is somewhat odd - do you have another system (different brand of PC) to help understand the culprit.

A10 had an odd issue with USB upon Power-up with some systems, but A08 was always well behaved.

 

[JohnW]

I bought another AppleTV to replace my 720p one - the latest 1080p model's optical out now works fine with my M-DAC, unlike the first iteration of the higher res version (the USB output from my Mac Mini sounds better but the ATV still has its uses).
Note to John - will pay the 4th instalment at the end of March.
As an aside, the ATV is due a refresh - Apple is missing a trick not putting in a full web browser - maybe they will this time around.

Thats good to know, looks like Apple got there act together - thank you

 

[jirij]

No problem jirij, thanks a lot for taking the trouble of drawing up the list! Maybe not really completely offtopic though, as we could potentially help fellow PFM'ers on the way to some lightweight, MDAC2-compatible, integrated, free software solution, don't you think ?

I try to provide support on the generic kernel level from which every such device (hopefully) benefits. If you want to prepare a volumio-like distro, knock yourself out. If you aim to produce a <5MB image, you can explore the wonders of buildroot - pretty much the smallest userspace you can get.

Yes, I understood this completely. Obviously, you're much more of a hardware expert than I am, so may I ask you please what you think of the quadcore Cubox-i4pro, which doesn't feature in your shortlist?

Since I don't own any of the boards, I wouldn't call myself a hardware expert in that area. Specifically for the streaming - some boards might handle USB isochronous transfers better than others, but there's no easy way to predict that without actually trying. None of them use the "standard" EHCI/XHCI like desktops/laptops do.
As I was asked to provide a list of competition for the RPi, I listed only the cheapest (though still usable, spec wise) boards I know of - Cubox i4pro is $140, quite a big jump from a $35 RPi 2, so it didn't make the list. There's literally over a hundred boards between the price points of RPi and i4pro.

As a matter of fact, 16/44.1 isn't enough for me, I'd like to go as high as 24/96, or even replay the odd native DSD or DOP file, as the MDAC2 will be compatible. And yes, I did read about the dropouts issue on the 1st gen RPis...

I'd say anything >1GHz quadcore ARMv7 can play 32/384, DSD256 or even repack DFF/DSF as DoP on the fly (since it's just repacking, no encoding), however others disagree a bit ("Only works reliably on some very fast Android devices, please try before you buy specifically for this format.").

Generally speaking, using the USB for data transfer puts bigger load on the CPU than any other transfer method, so it's IMHO best to use a dedicated ethernet PHY and/or a SATA interface (even with emulated ahci). This is what slowed the original RPi down when used as a NAS for USB HDD - it had to pass the data twice over USB on the single weak 700MHz core and since USB doesn't do DMA, the CPU had to do all the work.
If you have to use the USB for HDD, at least make sure USB is not being used to stream the data out or hope that the device is powerful enough to handle it. In my opnion, for audio streaming, most devices are powerful enough. Also, fancy 3D UI will slow down the system considerably, something headless would be better.

 

[alloja]

Thanks again, jirij, that's really helpful; I'll certainly bear all this in mind whilst looking for a replacement for my current setup (or, in the end, deciding to keep everything as is...). No, I won't go as far as creating my own volumio-like, but will certainly keep it all headless, storing the files on a (hopefully silent) ethernet-attached NAS if need be.
Time to ssh into that squeezeplug and check that CPU load according to top ...

 

[Vinz]

nirolf,

I know many owners who use Windows7 + MDAC so this behaviour is somewhat odd - do you have another system (different brand of PC) to help understand the culprit.

A10 had an odd issue with USB upon Power-up with some systems, but A08 was always well behaved.

I have the same issue with both firmwares. I never noticed it because I usually turn the MDAC and the computer at the same time.

There is also another issue. If the MDAC is turned on before the computer It won't work because the MDAC is expecting 16bit/44.1hz. Cycling inputs solves that too but it's a bit annoying to do that every single day.

 

[iansr]

Can somebody else try this see if you hear any difference. Instead of connecting my RPi to my MDAC with a USB cable I used a USB A to B adaptor and plugged it directly into the Pi and the MDAC. So my Pi is now as close as you can get to being plugged directly into my MDAC. And unless I'm losing my marbles the SQ is significantly better.

 

[rmgalley]

Hi John,

I’ve just been catching up on the thread after a gap of 2+ weeks. I’ve just become aware you are accepting the next L2 Development instalment. In anticipation of the email notification I have just sent my payment. It is really exciting things are coming along apace and evaluations by listening tests are not far off. Thanks for all the work you’ve been putting in, but I guessed you weren’t for having a haircut until the weather became warmer .

Normally only a maximum of two or three days would have elapsed between reading this forum thread. Exercising my mind of late has been catching up on the ‘BBC Audio Factory’ blog and implementing changes detailed in the ‘Logitech Squeezebox' (Slim Devices) forum. Thankfully, for the time being, I have all my BBC internet radio services back again – until such time as the BBC next decides to break them.

Some background, and somewhat off-topic:

Many will know 5 weeks ago the BBC withdrew the AAC encoded radio streams in favour of HTTP chunked delivery (AAC encapsulated in both Apple HLS and Adobe HDS containers). Unfortunately most internet radios and streamers, other than three Pure devices, cannot natively handle the new streams.

Fortunately Squeezebox family devices, with LMS, now have a way of restoring normal functionality due to new ‘BBC iPlayer’ and 'BBC iPlayer Extras’ plugins developed by ‘bpa’ and ‘Triode’. Many here will be using Triode’s ‘Enhanced Digital Output’ plugin allowing asynchronous USB operation with their MDAC.

The BBC iPlayer update details are at: http://forums.slimdevices.com/showthread.php?103312-BBCiPlayer-plugin-a-guick-fix-guide. Unfortunately the fix only applies to Squeezebox devices. Owners of such as Linn, Naim, Cambridge Audio, Sonos, Marantz, Grace and many more have been left high and dry.

For those minded to protest against this situation I would urge signing the petition, directed at the BBC Trust and BBC Director General, ‘Restore AAC audio and Listen Again indefinitely for internet radio devices’, information on which can be found at: http://www.pinkfishmedia.net/forum/showthread.php?t=170403

Roger.

 

[Bob L]

Can somebody else try this see if you hear any difference. Instead of connecting my RPi to my MDAC with a USB cable I used a USB A to B adaptor and plugged it directly into the Pi and the MDAC. So my Pi is now as close as you can get to being plugged directly into my MDAC. And unless I'm losing my marbles the SQ is significantly better.

Well, I can't do the experiment, but if some people find it's worthwhile to spend £300 or more on a USB cable because the sound is better than with an £5 one, getting rid of the cable altogether (or nearly so) could be better still.

 

[davidjt]

Listening to some of my favorite music over the weekend, and thinking about that 'Are we ever happy with what we have got?' thread had me wondering once again.
Without my No.1 amp, and consequently unable to use XLRs, the sound from the existing system is still pretty much all I could wish for. This time last year the sheer 'presence' of the performers I'm enjoying now would have persuaded me that my search was over.

In which case, why on earth am I investing in a new DAC and yet another amp?

So, no pressure then John!

 

[JohnW]

I have a sample of the Touch Screen Colour LCD display for the MDAC2 HQ chassis - I'm not very happy with it as it has limited viewing angle - I'll see if I can find a better panel, ideally a Colour OLED, but that will have to wait until my trip to China.

 

[Hubert481]

for me the current display is perfect, as i am using the remote control. (no need for touch screen)

 

[davidjt]

for me the current display is perfect, as i am using the remote control. (no need for touch screen)

+1

If a new screen (+HQ psu +remote) allows us to restore the original MDAC: Great!
But something as close as possible to the original screen would be ideal.

 

[sq225917]

+1i use tablet to control apple mac so touch screen doesn't matter to me. Nice feature though.

 

[ti33er]

Personally, I would prefer a screen that will last and not decay over time but Captain Westlake must build something that he can gaze upon and be proud of, after all this time and effort?

 

[Stuart Frazer]

I have a Squeezebox Touch but never use the touch screen feature. I control it via the remote or tablet/phone.

 

[ti33er]

Messiuers is the MDAC2 board still on course for Friday? I'm sure most of us are going to be eying this thread every 5 seconds!! :-D

 

[JohnW]

Messiuers is the MDAC2 board still on course for Friday? I'm sure most of us are going to be eying this thread every 5 seconds!! :-D

The PCB vendor over etched the inner layers so they are having to re-run the PCB's... while Its disappointing it does give me extra time to work on the VFET amps...

 

[JohnW]

WRT the Touch screen, as I start to design the Digital PCB I need to think about the future firmware / software feature we will add to the MDAC2 over the next couple of years.

The prime advantage of the touch screen is that we can add buttons and user controls as required - not to mention a larger HiRes colour display, think Room Correction curves, EQ Curves, ADC input level display etc.

The MDAC2 is a very powerful platform so I'd personally like to add a Jitter analysers mode and Audio measurement features for my own personal use - a larger HiRes Touch screen will come in handy for these.

Sorry for being rather cryptic & brief, I'm working on the VFET amp and time is running out before the MDAC2 PCB returns....

 

[JemHayward]

for me the current display is perfect, as i am using the remote control. (no need for touch screen)

I never interact with the front panel - I look at it to check volume on occasion, as my speakers never sound "loud", but my streamer is headless, and so everything is controlled from my phone or tablet. I only use the MDAC remote for volume. I'd be happy with a completely headless MDAC2 with a control app, but I can see that as a bit too far for some, but I think people are getting used to remote interfaces now, its impossible to control my TV via buttons on the object itself, and I think the hifi industry will have to follow suit.