Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Frequency measurements with different inputs
#1
My username is Divasson but today I would steal Confused's. Bear with me.

My sole source is a Mac Mini + Audirvana 2.0 -> Devialet 200 -> Mapleshade double helix -> Gallo Strada 2 on Mapleshade stands. Power cables are Mapleshade clearview. There is a Russ Andrews ultra purifier power filter in parallel.

I had try to make Ethernet Air work seamlessly with Audirvana without success (very cumbersome to change sampling frequency and most of my latest purchases are high rez), so I set on USB. It was clear, but too uncomfortable to listen in the medium term. So I downloaded the REW wizard software and connected a calibrated U-Mik microphone.

Here are the readings: (if you can't see them, I have uploaded also as pictures in the attached files)

   

No wonder it does not sound good! This comb-like profile screams "interference". And look at the -30 dB through peak-to-peak at 1160 Hz!!
Lets try then Ethernet (keeping everything else connected all the time).

   

A little better, but not too much. What is happening here?

Let's see Wifi Air:

   

Better, but still a lot of comb-like effect in the highs.

Just for the sake of completeness, lets try Toslink. I bought sometime ago a 256-fiberglass toslink cable (as opposed to typical plastic fiber ones)

   

The best of them all by far. What is happening here? Can anyone of you enlighten me? (that's what I meant by "Confused")

Let's compare all of them together. See that wifi air gets the "combs" in line with USB, NOT Ethernet Air:

   

Again: can someone help me?

More findings: the picture is basically the same if I keep only one connection active (i.e., if I disconnect the Ethernet when using USB and viceversa, and disconnecting both when using Wifi or Toslink)

As for sound, Toslink is the most comfortable to listen to of all - while it may lack some clarity and bite compared with the others.

The others may be unlistenable from time to time, depending on the recording.
Oslo: sources: Mac Mini/Itunes/Audirvana,  glassfiber toslink/Mapleshade clearview USB to D200;
Double helix to Gallo Strada 2 with mapleshade stands, TR3 subwoofer.

Spain: Oppo 95 vacuumstate modded, Kimber select 1021, Linn Classik Movie Di to Gallo Solos through Goertz Python cable


Reply
#2
I'm confused too.....
Reply
#3
Wow...this looks really bad..

edit: wrote the text below but see now WiFi is as bad as the "connected" USB and ethernet so it can't be the electrical interference if WiFi is just as bad when there is NO direct electrical connection made between the Mac and Devialet. If there isn't a direct connection I'd suspect a faulty Duet input board.


---
Toslink creates a galvanically isolated connection so "electrically separates" your Mac from the Devialet. If the Mac generates a lot of interference this could be the cause, but I'd say it's really bad so I myself would think something's wrong with the Duet input card. The toslink interface is, if I'm not mistaken, part of the mainboard.

You could try a complete different computer and see if this helps. Also check your earthing, are the Mac and Devialet both on the same AC circuit?

If it doens't help I'd contact your dealer or Devialet directly with these findings.

Good luck!
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
Reply
#4
Actually, although both are on the same circuit, the Devialet is grounded (3-prong schuko connector) while the Mac mini is a figure-8 power cable. That may account for something.

Now that I'm thinking - I need to check the sampling rates on both sides - may there be a sample rate conversion going on?
Oslo: sources: Mac Mini/Itunes/Audirvana,  glassfiber toslink/Mapleshade clearview USB to D200;
Double helix to Gallo Strada 2 with mapleshade stands, TR3 subwoofer.

Spain: Oppo 95 vacuumstate modded, Kimber select 1021, Linn Classik Movie Di to Gallo Solos through Goertz Python cable


Reply
#5
Ah ok, no if the Mac is supplied with that unearthed figure-8 cable it's alright and it doesn't need earthing. Also, as I already wrote, if this problem persists with AIR WiFi and there are no electrical connections between Mac and Devialet it really can't be interference.

To make sure it's not the Mac (software wise) I'd try to connect a different PC, set it up as basic as possible (i.e. install AIR and some music player) but to me this looks like a bigger problem. No way a thing like a re-/upsampler or SRC could cause these kind of differences.
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
Reply
#6
interesting, below 800hz they seem aligned, above 800 there's a frequency shift between troughs. Note how the offset looks about the same for each trough, and because it's a log scale that means the same ratio (and not the same delta). Its about 25% for each trough (925 to 1200) (2800 to 3300) (etc).

If it was aliasing then I believe the offsets would be constant (function of (f1+f2) or (f1-f2)), so on a log scale the gaps would appear to get smaller as frequency increased.

Note also that the troughs appear to realign at about 10k. However I think this is misleading, and that above 10k the same troughs are still offset from each other by 25% but appear superimposed on the adjacent trough......

What's also interesting is that the offsets only affect troughs. The peaks seem to remain aligned throughout.
Why is everything aligned below 10k ?

Troughs = room node cancellations, but these mostly appear at low frequencies. What's going on above 10k I cannot guess. Could it be Nyquist related ? what source are you using ? Is it redbook 44.1k ? A 20k source can only resolve above half he source frequency, ie 10k.......

I can't help much more, but my guess is that there is something wrong with the test setup, but can't really guess what........., so I just leave my observations here in case somebody more knowledgeable about the protocols can see a pattern....
 _________________________________________________________________________
Aurender X100, Audiophilleo, Devialet 200, Verity Audio Parsifal Ovation Monitors
Leiden, the Netherlands
Reply
#7
Krass's post makes me remember that is is important to set REW to output the same sample rate as is default for AIR/Devialet USB. Differences could lead to unpredictable results. I'd fix them both to 44.1kHz just to be sure.

edit: I had a mismatch once and this resulted in a lot of distortion while playing the REW testtone (pink noise). I'm not sure how that would have measured as I heard and corrected this before starting the measurement process.
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
Reply
#8
Tested Ethernet Air making sure that both REW, Air and Audio Midi Setup are aligned on 16/44.1 - the graph still exhibits the hair comb figure.

(23-Sep-2014, 23:29)Divasson Wrote: Tested Ethernet Air making sure that both REW, Air and Audio Midi Setup are aligned on 16/44.1 - the graph still exhibits the hair comb figure.

PS: I am NOT using Audirvana for the tests - REW direct to USB, Air or Toslink
Oslo: sources: Mac Mini/Itunes/Audirvana,  glassfiber toslink/Mapleshade clearview USB to D200;
Double helix to Gallo Strada 2 with mapleshade stands, TR3 subwoofer.

Spain: Oppo 95 vacuumstate modded, Kimber select 1021, Linn Classik Movie Di to Gallo Solos through Goertz Python cable


Reply
#9
Is there any chance the microphone was in a slightly different location or an adjacent piece of furniture was moved between measurements?

I can see no reason why differences between the various digital connections would cause what you are showing, but moving the measuring microphone, or a reflecting surface near it, a few cm would do exactly what your measurements show (except the optical result ???).

All your plots look like the errors are down to room reflections, as if the room is a very sparsely furnished modern style room (which are hopeless for good sound quality, unfortunately) or reflections from a hard surface near the measuring microphone.
Devialet Original d'Atelier 44 Core, Job Pre/225, Goldmund PH2, Goldmund Reference/T3f /Ortofon A90, Goldmund Mimesis 36+ & Chord Blu, iMac/Air, Lynx Theta, Tune Audio Anima, Goldmund Epilog 1&2, REL Studio. Dialog, Silver Phantoms, Branch stands, copper cables (mainly).
Oxfordshire

Reply
#10
(24-Sep-2014, 13:50)f1eng Wrote: Is there any chance the microphone was in a slightly different location or an adjacent piece of furniture was moved between measurements?

I can see no reason why differences between the various digital connections would cause what you are showing, but moving the measuring microphone, or a reflecting surface near it, a few cm would do exactly what your measurements show (except the optical result ???).

All your plots look like the errors are down to room reflections, as if the room is a very sparsely furnished modern style room (which are hopeless for good sound quality, unfortunately) or reflections from a hard surface near the measuring microphone.

Good questions!

All the measurements above were taken within a 5 minutes period, with absolutely no changes in microphone position (or anything else for that matter), and even I myself was standing in the same position, well outside of the "magic triangle" of both loudspeakers and the microphone.

I did not have to move since I was controlling the computer with a wireless mouse-like device.

No appliance was switched on or off, and only the refrigerator was on during the whole period. The only lights on were "old style" lightbulbs - the noisier led or fluorescent lighting was switched off for the test. No air conditioning (we're doing the test in Oslo!)

Immediately after performing the Toslink test I repeated the wifi and Ethernet again (due to my surprise) and the results were equivalent to the initial ones.
Oslo: sources: Mac Mini/Itunes/Audirvana,  glassfiber toslink/Mapleshade clearview USB to D200;
Double helix to Gallo Strada 2 with mapleshade stands, TR3 subwoofer.

Spain: Oppo 95 vacuumstate modded, Kimber select 1021, Linn Classik Movie Di to Gallo Solos through Goertz Python cable


Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)