Frequency measurements with different inputs

[thumb5]

I have done another test, using a very sophisticated spectrum analyzer: my ears.

I use the same. (Although my ears, not @Divasson's) However inaccurate they may be, they are after all the only thing that really matters.

Having said that, I would refer back to my earlier post and ask, does anyone know of a decent analyser software / microphone combination that they have actually used successfully with the Devialet / AIR?

I am thinking of playing with speaker positioning / room treatment to deal with some minor issues my own ears have detected, is there anything out there that might be useful? Or should I just stick with my trusty lug holes?

I have used both FuzzMeasure Pro and the Dirac Room Correction Suite on a Mac, both with the same MiniDSP U-MIK1 (calibrated). The results concur well, and - for what it's worth - don't show any sign of the comb filter behaviour Divasson is seeing (I was using exclusively Ethernet AIR in my tests).

I'd say having an analytical measurement method as an adjunct to your ears is very helpful. Just for example, you may be able to hear that something's not right without being able to say "there's a comb filter with a period of 2 kHz starting at 1 kHz". At least, I doubt I could say that just by listening!

[Antoine]

I also use REW and in my opinion it's very reliable. I use it with a Behringer ECM8000 measurement mic and an external M-Audio Fasttrack USB MKII USB soundcard which connects to an analog stereo input of my Devialet.

In this case it's maybe easiest to swap the Devialet with a loaner of the dealer, just swap the CF card and redo the measurements to determine if the Devialet is faulty. The USB input of the Devialet doesn't have a latency high enough to pose an issue I think. Like I said before the AIR ethernet/WiFi and USB are part of the DUET input card inside the Devialet. Toslink is part of the mainboard if I'm not mistaken. So the issue could be with this input card or something in the route to the DSP to which the other inputs are also connected.

Other option would be to lend a different type of measurement 'kit' from someone.

[Divasson]

Thank you all for your good suggestions.

Take a loaner from the dealer is complicated - I would need to bring back the Devialet to Spain where I bought it, and stay without it for a couple of weeks - I would not dare to take out of the country a loaner! So it is either back to Devialet or nothing.

I am using REW with the MiniDSP U-Mik1 with a calibration file. I am using pointing it to the loudspeakers (using the normal calibration file) and at an angle of 90º, pointing upwards, with a modified calibration file with a transfer function for 90º. I am using 44.1 sampling frequency. For measuring, i am using the settings below:

   

[thumb5]

If you asked them nicely, I wonder whether Devialet might lend you an input board to swap with the one you're currently using? (I should say I have no idea how easy or otherwise it might be to physically swap the boards.)

[Rufus McDufus]

the AIR ethernet/WiFi and USB are part of the DUET input card inside the Devialet.

Is this actually the case? Without opening mine up, but by looking at image on the internet it looks like ethernet is on the AIR board but USB & Toslink are on the board above (or below) it. Apologies as I may be misunderstanding what you meant by DUET card and my knowledge of Devialet interiors isn't good!

[Antoine]

No problem of course Rufus! I wasn't sure as well and doing the same as you (looking at some pictures) it looks like I wasn't completely right either. It looks like one of the two toslink inputs is on the mainboard (the 3,5mm jack one) and the other one is part of the DUET card (which is the replacement card for the former HDMI input card) or maybe the mainboard below. Also I was thinking, DUET perhaps stands for Devialet/Digital USB Ethernet Toslink proving my theory wrong again.

And I am even more confused now; I know AIR Wifi is on a separate card and if I remember correctly AIR ethernet couldn't/wouldn't work without that AIR WiFi card present so the "routing" of signals is very unclear to me. I hope the specialists at Devialet can and will do the 100% right "deducing" in troubleshooting this issue for Divasson!

[Confused]

You need to fine a picture of the innards of a slave, the AIR board will be the one that isn't there .....

[Rufus McDufus]

No problem of course Rufus! I wasn't sure as well and doing the same as you (looking at some pictures) it looks like I wasn't completely right either. It looks like one of the two toslink inputs is on the mainboard (the 3,5mm jack one) and the other one is part of the DUET card (which is the replacement card for the former HDMI input card) or maybe the mainboard below. Also I was thinking, DUET perhaps stands for Devialet/Digital USB Ethernet Toslink proving my theory wrong again.

And I am even more confused now; I know AIR Wifi is on a separate card and if I remember correctly AIR ethernet couldn't/wouldn't work without that AIR WiFi card present so the "routing" of signals is very unclear to me. I hope the specialists at Devialet can and will do the 100% right "deducing" in troubleshooting this issue for Divasson!

Ah, thanks for clarifying what the DUET card is!

[Antoine]

You need to fine a picture of the innards of a slave, the AIR board will be the one that isn't there .....

There's no doubt in my mind to what the AIR WiFi board is (I built it in myself in my former D-Premier ). What I don't understand is why the ethernet functionality depends on the AIR WiFi card. But this question isn't really important in this topic.

---

Thank you all for your good suggestions.

Take a loaner from the dealer is complicated - I would need to bring back the Devialet to Spain where I bought it, and stay without it for a couple of weeks - I would not dare to take out of the country a loaner! So it is either back to Devialet or nothing.

I am using REW with the MiniDSP U-Mik1 with a calibration file. I am using pointing it to the loudspeakers (using the normal calibration file) and at an angle of 90º, pointing upwards, with a modified calibration file with a transfer function for 90º. I am using 44.1 sampling frequency. For measuring, i am using the settings below:

Perhaps there's a local Oslo dealer willing to help you with a loaner. You'd only need it for about a few hours.

Regarding the REW settings. You could increase the length parameter to it's maximum (I believe it's 2M). This increases the accuracy of the measurements without any penalties/downsides.

[Jwg1749]

Could I suggest a quite different approach to this issue?

Instead of measuring the output of the speakers, why not analyse what’s going on in the Devialet itself (or upstream in the digital sources). You should be able to do this by recording the various inputs (Ethernet, wireless, optical) to a PC using the Devialet’s USB output, and then analysing their frequency spectra.

You could even null the files against one another using Audiodiffmaker.

This would enable you to narrow down where the problem is.

I've been thinking of doing this myself when I finally get around to comparing digital sources (some weeks away due to impending house move). It ought to be a reliable way of finding out what's going on upstream of the Devialet's DAC.

Matt