TOPIC:

Based on my measurements with REW and a UMIK-1, the SHD Studio or Volumio is altering the integrity of all files rendered via Volumio. This was validated by measuring and viewing the impulse and step response of my speakers. I will post images of both below.

First some information on the issue as it's not happening on all inputs:

My SDH Studio is connected to my Naim NAC 272 DAC / Preamp via coaxial SPDIF.

I have a Wi-DG in repeater mode connected to the SHD Studio via LAN cable. I have enabled Roon via Volumio and now can use the SHD Studio as a Roon Endpoint.

I also have a chromecast built into my Sony TV which also acts as a Roon endpoint. The TV is connected to the SHD Studio via Toslink.

I have used the exact same REW sweep (48 kHz) in all tests. All measurements were made with Dirac On.

Signals fed through Roon>Chromecast>SHD Studio>Naim NAC 272 are hitting my DAC with full integrity of the file as you can see in the attached images. Signals fed through Roon>Volumio SHD Studio > Naim NAC 272 are not. I have disabled all Volumio processing as well as in Roon. Interestingly, a USB stick with the same exact REW Sweep, managed by Volumio, also exhibits the same exact behavior as Roon via Volumio which leads me to believe this is an issue with Volumio or its implementation on SHD Studio.

I have an SHD Studio and have downloaded all recent updates including the version of Dirac released 11/13.

Obviously this is disappointing! These issues have an audible impact on critical listening.

I'm hoping MiniDSP can help support this issue - thanks!

Interesting!

If you really want to lodge a support request the proper way is: support.minidsp.com/support/tickets/new

You'll get much better engagement there

joelkarp wrote:

Interestingly, a USB stick with the same exact REW Sweep, managed by Volumio, also exhibits the same exact behavior

Hi, did you generate and use a timing reference? I'm assuming you are using REW offline measurement as described here - www.roomeqwizard.com/betahelp/help_en-GB...inemeasurements.html

Thank you for the link - I will fill out a support ticket!

Yes, I'm using the timing reference.

What does your SPL measurement look like - is it as expected?

How would you describe the audible impact?

The steps image appears to suggest the Volumio path has a delay of around 8ms, is inverted and low pass filtered. The delay and inversion will likely be inconsequential audibly but the filtering should make it sound very dark.

As for the impulse image, the Volumio path appears to show a rising sine sweep which I find puzzling. Otherwise it appears to still have the around 8ms delay and inversion.

<How would you describe the audible impact?>

All the magic in vocals is gone.

entripy wrote:

As for the impulse image, the Volumio path appears to show a rising sine sweep which I find puzzling.

I suspect a measurement anomaly of some kind. If I put an actual impulse (at 96k) through Volumio via DLNA and record the digital output of the SHD, the impulse survives (relatively) unscathed. Top is the impulse, bottom is the recorded output (ignore any apparent time difference between the two channels, the recorded one is trimmed):



The recorded output above has clearly been band-limited. Applying a sinc filter at 20kHz to the impulse before transmitting it results in:

With that said, I'm unable to get an impulse response via swept sine much different to @joelkarp.

To me that suggests the apparent problem is an analysis problem rather than an actual one. REW bug perhaps? The impulse trace looks too much like a swept sine chirp. As if the wrong buffer is returned from the rather complicated process involved, something related to the stimulus for the DUT rather than the response.

Did you guys see my post about the volume normalization bug??
I suspect the effects of that are what you're seeing here with the impulse measurements.

Dave.

dreite wrote:

Did you guys see my post about the volume normalization bug??
I suspect the effects of that are what you're seeing here with the impulse measurements.

Dave.

Could you provide a link?

@dreite - is your bug only via the volumio player or input wide on the SHD? A link would be helpful.

Also, I hope it is clear from my initial post that Roon to Chromecast to the SHD via Toslink measures beautifully via the REW Sweep. But, USB to Volumio and / or Roon to Volumio via LAN do not. I do not see how validated results on one input can be a measuring anomaly nor some other device-wide bug.

Joel

Your initial post was clear. Was mine with the actual time domain plots not?

joelkarp wrote:

@dreite - is your bug only via the volumio player or input wide on the SHD? A link would be helpful.

Also, I hope it is clear from my initial post that Roon to Chromecast to the SHD via Toslink measures beautifully via the REW Sweep. But, USB to Volumio and / or Roon to Volumio via LAN do not. I do not see how validated results on one input can be a measuring anomaly nor some other device-wide bug.

Joel

Yes, the issue only exists with sources via the Volumio part of the architecture. Any input other than the "LAN" input should be fine.
Read this thread:
www.minidsp.com/forum/shd-series/16389-v...-louder-after-update

Dave.