Can DOS 2 Phantoms reproduce acoustic programme above 24kHz?

[struts]

Plenty of speculation and debate about this in lots of threads here but unfortunately having read all of them they are just that.  Speculation.  The situation, never totally clear, has been further confused by the contradictory information Devialet has provided in conjunction with the announcement of the ®evolution to Phantoms I and II.  

The simple fact is that even if 24/192 or 24/96 audio is being sent to the (master) speaker there is really no way of easily telling if the signal is being downsampled or samples are simply being discarded, in the master and/or slave in a stereo pair.  So whatever the upstream system says it is sending we simply don't know how much is making it through into the room.  As far as I can see the only way to actually prove whether the speaker is outputting any signal above 24kHz (i.e. 48kS/s) is to measure the (acoustic) audio output.  And since human beings can't hear 24kHz and above, what do you do?  Ask the dog??  I have two acoustic measurement tools at my disposal, a Center 325 sound level meter and a UMIK-1 mic (together with suitable measurement software such as REW) but unfortunately neither of these can measure signals above 24kHz.

So my aim with this thread is to find out if anybody actually has tools that can measure above 24kHz (or even better, above the 27kHz ceiling still mentioned by Devialet in their online specs) and if so whether Phantoms old or new, running DOS 1 or DOS 2, with or without Dialog, on their various inputs (Toslink, UPnP, RAAT), and with which specific Toslink receptacle, can actually output this programme.  Listening impressions are of limited interest in this context as there are way too many variables.  I am really interested to know if anyone can measure, or propose another method to prove or disprove this.

Please let's not use this thread to speculate, rant at Devialet, debate the importance or otherwise of hi res, or the value for money of Phantoms relative to other speakers.  Feel free to use the other threads for that.

Just the facts ma'am.  And civilised engineering discourse.  Please?

[ogs]

Plenty of speculation and debate about this in lots of threads here but unfortunately having read all of them they are just that.  Speculation. 

This image from Mitchco's Gold review at Audiophilestyle from 2017 indicates that 48kHz sampling was used then too. It may of course be that this is the treble response of the measurement mic used, but I doubt that.
   

[struts]

Good catch @ogs, had forgotten about that review. Unfortunately mitchco only says that his measurements are based on a sweep from 10Hz to 24kHz, implying (but not actually stating explicitly) that the limitation was in the test signal.

In other news I have ordered a UMIK-2 measurement mic which can sample up to 32/192. Stay tuned.


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[ICUDoc]

To me, struts, your question doesn't quite make sense.
There is no such thing as acoustic output above 24kHz (which is 24kS/s), inasmuch as humans can't hear that frequency, so it isn't really acoustic, let alone relevant anymore..
Do you perhaps mean "Can DOS2 Phantoms decode higher sample rates than 44.1 or 48kHz?"
At the end of the day, whether there is output at or above 24kHz is irrelevant- the question might be whether high-sample rate material results in better sound in the AUDIBLE spectrum (20-20 000Hz)?
And to that, I do not know the answer....

[ogs]

I have ordered a UMIK-2 measurement mic which can sample up to 32/192.  Stay tuned.

Does it come with a proper calibration file?

I didn't know mitchco only measured to 24k. Sorry about that!

[struts]

To me, struts, your question doesn't quite make sense.
There is no such thing as acoustic output above 24kHz (which is 24kS/s), inasmuch as humans can't hear that frequency, so it isn't really acoustic, let alone relevant anymore..
Do you perhaps mean "Can DOS2 Phantoms decode higher sample rates than 44.1 or 48kHz?"
At the end of the day, whether there is output at or above 24kHz is irrelevant- the question might be whether high-sample rate material results in better sound in the AUDIBLE spectrum (20-20 000Hz)?
And to that, I do not know the answer....

I’m going to nitpick a bit here, but not to be argumentative, so please bear with me:
1. There is such thing as acoustic output above 24kHz. You can measure it and it is there, just because it is ultrasonic and inaudible to us doesn’t mean it doesn’t exist. Dogs (and I believe bats) can hear it, but we can’t.
2. A 24kHz sine wave requires 48kS/s (thousand samples per second) to capture digitally. Nyquists theorem. Folks commonly use kHz to denote a sampling rate which is technically incorrect (or at least sloppy) as it becomes easy to confuse the acoustic frequency and the digital sampling rate needed to encode it, which is at least double.
3. All that said, I agree that it is what is audible (to us) that counts. But please let’s not start debating the validity of hi res audio and sampling rates above 44.1kS/s here. Do your research and your listening and choose what you want to believe. I for one am quite convinced that the presence of ultrasonic information changes our perception of the audible spectrum and I certainly think it sounds better. But to my original post, that isn’t really the point here.

So with all that said, while we disagree on some of the finer points we agree on the main one: it is what we can hear that matters!


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[struts]

I have ordered a UMIK-2 measurement mic which can sample up to 32/192.  Stay tuned.

Does it come with a proper calibration file?

I didn't know mitchco only measured to 24k. Sorry about that!

- Yes it does.

- No worries! It was still a relevant datapoint as it is one of the few reviews where the reviewer has actually performed his own measurements rather than just regurgitating Devialet’s specs (unfortunately when Jim Austin wrote a piece on the Golds for Stereophile it was not a full review so no measurements from JA). Thanks!


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[streamy]

Good catch @ogs, had forgotten about that review.  Unfortunately mitchco only says that his measurements are based on a sweep from 10Hz to 24kHz, implying (but not actually stating explicitly) that the limitation was in the test signal.

In other news I have ordered a UMIK-2 measurement mic which can sample up to 32/192.  Stay tuned.


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Great you opened this thread! I’m fully with you when I asked if someone could make hires analog measurements a few days ago. I also saw the specs of the new UMIK-2 that will be able to answer the question. Unfortunately, it was sold out, so I did not consider to buy it as of yet. But great you did. According to the specifications the Gold Phantoms should play a 25kHz sine signal at higher than -6dB. This can then be recorded with the UMIK-2 when the sine signal is fed to the Phantoms with 24/96k or 24/192k. With 24/48k a 25k sine signal will be highly distorted due to aliasing. I’m looking forward to your results and would offer to make measurements on a DOS1 Phantom Gold system when you would lend me your UMIK-2 in case you have upgraded to DOS2.
Again thanks for your interest in investing here. For me it is surely important for taking decision to go for RAAT and DOS2 instead of the current system with RPi hats and Roon.

[streamy]

Today I had time to play a bit around with feeding hires signals to my Phantoms.
My system: two Gold Phantoms Model MX207 serial J50Nxxxxxx (made week 50, 2016);
One Silver Phantom serial H41Exxxxxx (made week 41, 2014)
All Phantoms are connected through PLC to a Dialog model VY104 serial K01Qxxxxxxx
Signal path: Roon NUC Ethernet =>Router=>WiFi=>RPi=>Digi+ => optical => Phantom (one to the left Gold set as stereo (living room) and to the Silver set as mix (dining room)
I generated with Audacity 30s stereo audio files with different sine signals -3dB, one set flac 24/192k and one set flac 24/96k. Both sets were identical containing sine signals, 1kHz, 20kHz, 22kHz, 25kHz, and one signal of a mixed 1kHz -20dB and 25kHz -3dB. Every signal scored a track.
Results: all tracks played in Roon and left the RPi to the Phantoms, no problem. I could well hear all signals containing the 1kHz sine (4 tracks, 2@192k and 2@96k). So the mixed signal of loud 25k sine and 1k sine was well audible (of course I heard the 1k sine and some low noise have the ear very close to the tweeter). This very similar on the Gold as on the Silver Phantoms. The noise on the Silver is louder (ADH1 vs. ADH2). Now comes the interesting part: I heard the noise when playing the 20k and the 22k sines on both systems. After the track is played the Phantoms mute the amplifier noise. On the Gold it produces a little click. On the Silvers it goes to mute. Then: when playing the 30s 25k sine signal after 3s both Phantoms go to mute. Roon continued to play the track, but the Phantoms mute. So this shows that a 25kHz signal is not played. However, I cannot say if in the mixed signal (1k and 25k) that plays and is not muted after 3seconds the 25k portion is audiable.

[struts]

Today I had time to play a bit around with feeding hires signals to my Phantoms.
My system: two Gold Phantoms Model MX207 serial J50Nxxxxxx (made week 50, 2016);
One Silver Phantom serial H41Exxxxxx (made week 41, 2014)
All Phantoms are connected through PLC to a Dialog model VY104 serial K01Qxxxxxxx
Signal path: Roon NUC Ethernet =>Router=>WiFi=>RPi=>Digi+ => optical => Phantom (one to the left Gold set as stereo (living room) and to the Silver set as mix (dining room)
I generated with Audacity 30s stereo audio files with different sine signals -3dB, one set flac 24/192k and one set flac 24/96k. Both sets were identical containing sine signals, 1kHz, 20kHz, 22kHz, 25kHz, and one signal of a mixed 1kHz -20dB and 25kHz -3dB. Every signal scored a track.
Results: all tracks played in Roon and left the RPi to the Phantoms, no problem. I could well hear all signals containing the 1kHz sine (4 tracks, 2@192k and 2@96k). So the mixed signal of loud 25k sine and 1k sine was well audible (of course I heard the 1k sine and some low noise have the ear very close to the tweeter). This very similar on the Gold as on the Silver Phantoms. The noise on the Silver is louder (ADH1 vs. ADH2). Now comes the interesting part: I heard the noise when playing the 20k and the 22k sines on both systems. After the track is played the Phantoms mute the amplifier noise. On the Gold it produces a little click. On the Silvers it goes to mute. Then: when playing the 30s 25k sine signal after 3s both Phantoms go to mute. Roon continued to play the track, but the Phantoms mute. So this shows that a 25kHz signal is not played. However, I cannot say if in the mixed signal (1k and 25k) that plays and is not muted after 3seconds the 25k portion is audiable.

Very interesting [mention]streamy [/mention]!! I have been starting to wonder whether Phantoms have ever actually played anything above 24kHz and your results seem to suggest that they don’t. I’ll do some tests of my own on DOS 2 when my UMIK-2 arrives.


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