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Phono stage hiss - Measurements
#11
Here are Devialet's instructions for recording from the Expert Pro via USB: 
.pdf   bi-dir-tutorial.pdf (Size: 1.35 MB / Downloads: 12) .

If you're using a Mac, the main difference from the procedure @Confused posted above is to use the Audio MIDI Setup program to select the Devialet as the input device before starting Audacity (page 6 of the document).

Hope this helps...
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK
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#12
I Would be Wery interessant What they Can do in devialet factory , to fix the Hiss ploblem With Lov output cartridge , software update? We vill see.
AVM  8.3  Rosso volterra 2 ,speaker cable and other cable audio note , turntable tt2 de luxe , caridge clearaudio carisma mm, primare bd mrk 2 shyunata power generator,
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#13
(23-Sep-2019, 11:18)Confused Wrote: I am a long way from being an expert in making a recordings from the Devialet's USB, but I have successfully made a recording and sent it to Mathieu Pernot, so in response to the posts above I will try to do an easy "step by step" guide.  I am sure that there are others on this forum that know far more about using Audacity than I do, so this is a kind of idiots guide, written by an idiot.  However, it worked for me, and it should help other beginners to at least get going.  If there are more competent users of Audacity than myself out there, please feel free to chime in with tips and advice.  I can only cover the very basic stuff with my level of knowledge.

I used Audacity software to make the recording, this is widely recognised as being one of the best "free" software packages.  So the first step would be to load Audacity onto your PC or laptop, it is available in Mac or Windows versions, so this should suit most people.

https://www.audacityteam.org/download/

As the idea of this test is to make a recording of the noise from your Devialet's phono stage only, not the noise that your very sensitive turntable, tonearm and cabling might be picking up, you should temporarily remove the turntable's RCA connectors from the phono input of the Devialet.

You then need to connect you Laptop to the USB connection of the Devialet, and select the phono input on the Devialet.

Assuming you are using a Windows Laptop of PC, you need to check that the Devialet "Expert Pro USB" is shown as the input in "Sound Settings", see below:



If you then open Audacity, in the pull down menu on the top tool bar you need to set the "microphone" input to "Expert Pro USB Audio", see below.  (or Expert USB Audio if you don't have a Pro)  



In the bottom left hand corner of Audacity there is a pull down menu that lets you select sample rate, I used 96000Hz.

Now you are ready to make the recording.  Simply hit the red circular record button on the top toolbar and you will see the recording commence, let it run for maybe 15 or 20 seconds, that is all you need.

Then select "File", "Export Audio" and you can save the recording as a .WAV file.  That's it, you have made a recording of whatever hiss or noise your phono stage may have.

You can play the recording back in Audacity, you may need to turn the volume up a bit, but if you do you should hear a lovely recording of phono stage hiss.

You can analyse the recording yourself in Audacity, or maybe cheat like I did and email your recording to someone who can use Oceanaudio, see the various posts at the start of this thread.

The recordings can be sent to Mathieu Pernot at Devialet:

mp@devialet.com

Note that if you have just made a 15 or 20 second recording, you should be able to send the recording file as a simple attachment.  The file size will be relatively small, so no need to use DropBox or similar.

When you sent your recordings to Mathieu, make sure you mention your phono stage settings used when making the recording, for example RIAA 1976, 0.39mV, 30 ohms, or whatever loading and gain you might be using.

So that is my idiots guide written by an idiot.  Unfortunately this only covers use of Audacity on a Windows PC.  I am sure that the procedure will be similar on a Mac, but I do not have a Mac available to try this at the moment.  Maybe Mac users could advise any subtle differences to the procedure.

I hope this helps, and good luck if you decide to give this a try. 
Thanks for this advice - I have sent my sample to Mathieu
Devialet Expert Pro 220, ATC SCM40 speakers, Pro-Ject Xtension 9 turntable, Chord Signature XL speaker cable
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#14
Thanks All! I also just sent a sample to Mathieu.
Devialet 220 pro expert; Focal 1028 Be; Rega RP6; Ortofon Quintet Black
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#15
Got a reply from Mathieu that he will analyze the sample in the coming weeks. I will keep you posted.
Devialet 220 pro expert; Focal 1028 Be; Rega RP6; Ortofon Quintet Black
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#16
What do you Think they Can do With the ploblem about hiss , Any idea?
AVM  8.3  Rosso volterra 2 ,speaker cable and other cable audio note , turntable tt2 de luxe , caridge clearaudio carisma mm, primare bd mrk 2 shyunata power generator,
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#17
I heard back from Mathieu, here's a copy of his email (which he asked me to share), plus a spectrum picture of my audio sample. Note his 'next steps' comments, anyone any views on this?

I finally took some time this afternoon for an analysis.
Attached is the spectrum of your audio sample:
- The S-shape is due to the RIAA curved applied to the incoming stream. Without this curve it would be flat.
- The reference level is to be measured at 1kHz : approx -99dBc
- The bass level at 20 Hz is 20dB higher, as expected
- The treble level at 20 kHz is 20dB lower, as expected
- The response of both channels is identical, no mismatch
- The response is deprived of any unwanted tone or resonance (which would immediately appear over the spectrum)

Feel free to share this picture and/or my comments on the forum. The obtained performance in no load mode is to my opinion excellent.
Next steps would be to redo the same measurements while playing a record with a sinewave in order to achieve and measure the SNR figure.
The perception of noise has always to be compared with the intensity of the reproduced signal (or the music)

I do use this one (can be found in many online shops)

https://store.acousticsounds.com/d/35532...t_Up_Tools

Have a good week-end
Mathieu


Attached Files Thumbnail(s)
   
Devialet Expert Pro 220, ATC SCM40 speakers, Pro-Ject Xtension 9 turntable, Chord Signature XL speaker cable
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#18
I got exactly the same reply from Mathieu as well. Spectrum picture also looks similar.

I have replied the following:
Thank you for your time and effort. So if i understand correctly if there would be a tone like a hiss it would show up in the graph as it would interupt the fluid line of the graph , but it isn’t. However, to me there is a hiss audible. Do you also hear this? Does this mean that the hiss falls within specs? Wouldn’t it be possible with the dsp capabilities of the devialet to make the output of the phonostage more quiet?

To be continued.
Devialet 220 pro expert; Focal 1028 Be; Rega RP6; Ortofon Quintet Black
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#19
I got the following reply from Mathieu:

Hi Maarten,

I recommend you give the audio sample you sent me a try on any digital input of your amplifier, using your computer as a source. USB is a good choice.
That will give you a rendition of the noise floor spectrum. Of course you will have to apply a lot of gain on your amp to hear something (probably in the positive region)

Note that this analysis is only the first of a series : now please also send me the same recording but with your turntable connected and motor off
Then the same with motor on
Then the same playing a silent track from a test record.
etc...

We are in the beginning of a incremental process. We have now the proof that the internal A/D convertor is within our specs.

BR,
Mathieu

I will keep you posted
Devialet 220 pro expert; Focal 1028 Be; Rega RP6; Ortofon Quintet Black
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#20
I too received a response from Mathieu.  My graph looks very similar to those already posted, although I have a curious upward kink at 14 kHz.  This is particularly curious, as not only is this aspect different to the graphs referring to other phono stages, but it was not picked up in the analysis performed on my recording by @thumb5 and myself, see the first page of this thread.  I think I will need to quiz Mathieu further on this point.  Anyway, I have no idea why this aspect should be different in my case, but this is what Mathieu had to say:

I finally took some time this afternoon for an analysis.
Attached is the spectrum of your audio sample:
- The S-shape is due to the RIAA curved applied to the incoming stream. Without this curve it would be flat.
- The reference level is to be measured at 1kHz : approx -102dBc
- The bass level at 20 Hz is 20dB higher, as expected
- The treble level at 20 kHz should be 20dB lower, but it appears the noise floor increases after 14kHz
- The response of both channels is identical, no mismatch
- The response is deprived of any unwanted tone or resonance (which would immediately appear over the spectrum)

Feel free to share this picture and/or my comments on the forum. The obtained performance in no load mode is to my opinion excellent.
Next steps would be to redo the same measurements while playing a record with a sinewave in order to achieve and measure the SNR figure.
The perception of noise has always to be compared with the intensity of the reproduced signal (or the music)

I do use this one (can be found in many online shops)

https://store.acousticsounds.com/d/35532...t_Up_Tools

   

So what to make of all this?  Clearly Mathieu thinks that the level of noise / hiss is acceptable in my case, which is also true of the others already analysed.  In fact, in my case Mathieu is happy to state that the performance is "excellent".

My view has always been that the fact that the hiss is there is a little annoying, but as I am unaware of it when actually playing and listening to records, I am happy to consider the performance as acceptable.  That said, as an audiophile, I consider that the very fact that there is some noise is itself is undesirable, and I would prefer if it was reduced or eliminated.

So this begs a question.  Are all the phono stages performing in a similar way, or are those used by @Greg @Finn and others who find the level of hiss unacceptable actually under performing?  Or to put in another way, are those of us more or less happy with the phono stage simply more tolerant of the hiss than others, or is there a hardware difference?  We will know the answer to this if and when others send in there recordings.  It should be noted that I have run the same cartridge as Finn (Candenza Black), which is at the lower end of cartridge outputs.

This also makes me think of some posts a while ago which suggested that the phono stage in the D-Premier was superior to that ultimately used in the Expert series and onwards.  I have no idea if there is actually a technical difference with the D-Premier phono stage, but one thing that would be fascinating to do would be compare a "hiss" recording of a D-Premier phono stage with one from an Expert.

If there is anyone out there with a D-Premier who could make such a recording, I would be more than happy to make an equivalent recording with my Pro, using exactly the same phono stage settings.

It is a long shot, but is there anyone out there with a D-Premier willing to give this a try?
1000 Pro - KEF Blade - iFi Zen Stream - Mutec REF10 - MC3+USB - Pro-Ject Signature 12
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