WiiM Pro - Review & Measurements (Streamer)

[nanook]

Depends on the DAC and what inputs it uses, here's the SMSL D6s on all 3 inputs

View attachment 408219

Sure, this is a well designed piece of gear. It does not add measurable jitter to the instrument-grade input signal for coax and optical and the rest of the circuit does not disturb the clock from the XMOS when using USB.
The point I'm trying to make is that we don't know how good the spectrum would look like for the D-6s (or any other well behaved DAC) with a lousy input signal.

I'm aware that this discussion is "academic" unless you're using the gear for measurements, but it's the ASR.

 

[pjug]

@magreen See here.

Jitter over digital outputs for different WiiMs

Let's talk about the jitter over digital outputs. I will use the Holo Audio Spring 3 DAC which is a true NOS DAC and has an unique ability to turn off its PLL. This way I can compare a raw performance of the outputs in j-test. Ultra, toslink: Ultra, coaxial: Pro, toslink: Pro...

forum.wiimhome.com

The 48Khz, 96Khz, and 192Khz J-tests all look clean when I run optical out from the Pro to my DAC. But anyway is the 192KHz optical result shown in that link (graph copied below) even an issue? What do the higher frequency J-tests tell us?

 

[dguillor]

Maybe they don't. I get strange eq correction, quite different from the one REW with umik suggest me

I also get very different results from the Wiim Pro room eq than from REW. Don’t have a clue why.

 

[staticV3]

I also get very different results from the Wiim Pro room eq than from REW. Don’t have a clue why.

Different targets, different target fitting algorithm, different raw response measurement.

 

[Romario]

I also get very different results from the Wiim Pro room eq than from REW. Don’t have a clue why.

Between measurements you have to reset the eq to flat. Every time.

 

[Bdee1]

Do you think wiim will fix the PEQ issue with the digital out?

 

[Joffy1780]

Do you think wiim will fix the PEQ issue with the digital out?

What is the issue?

 

[GarrardZero100]

I plan to solder out the microphone and extend it with a 3 meter cable and make it pluggable. Has anyone done this? I expect that this will not have any significant effect on the measurement, agree?

 

[staticV3]

I plan to solder out the microphone and extend it with a 3 meter cable and make it pluggable. Has anyone done this? I expect that this will not have any significant effect on the measurement, agree?

What measurement?

The WiiM's built-in microphone is just for settng lip sync. It cannot be used for frequency response measurements.

 

[GarrardZero100]

What measurement?

The WiiM's built-in microphone is just for settng lip sync. It cannot be used for frequency response measurements.

The app tells you to hold the Wiim Pro in the listening position for a room correction measurement. The built-in microphone does that.

 

[staticV3]

The app tells you to hold the Wiim Pro in the listening position for a room correction measurement. The built-in microphone does that.

Ah my bad. They must've added that option since I last looked into it.

Have you considered just using your phone or phone+external mic? Seems a lot more straightforward.

 

[GarrardZero100]

Ah my bad. They must've added that option since I last looked into it.

Have you considered just using your phone or phone+external mic? Seems a lot more straightforward.

 

[GarrardZero100]

I also have a calibrated microphone but then you have to load the file in the Wiim Pro somehow and that is just too complicated. With a phone this doesn't seem easy to me either. Or did Wiim make an App for this? Removing the built-in microphone and extending it seemed easier to me.

 

[nanook]

Aside from frequency response issues with the mobile- phone mics, I suspect, there might be some automatic gain control (AGC) involved. Also most phones have at least 2 mics in order to suppress ambient sounds. I have no idea if Android allows the WiiM App to switch to a single microphone - ideally the one located at the top of the phone.

I think WiiM pretty much knew that with such a large zoo of Android phones RC might be "difficult" - carefully speaking. Maybe, they added the feature to use the mic inside the WiiM device, since this will be a lot more consistent.
Unfortunately it's not possible to use the Mic in the Remote-Control; this would need the mic being located at the tip of the RC, an ADC and some memory in the Remote-Control. The data could easily be transferred to the WiiM via Bluetooth.
This wold be my proposal for a future Remote-Control

My results using my phone (Google Pixel 5) were really discouraging - it just did not at sound right after RC - so I ordered a UMIK-1

@GarrardZero100: There will be some change in the frequency response when you take the microphone out of the WiiM and operate it externally. The baffle the WiiM provides leads to a shelf-filter like characteristic for the mic inside the WiiM Pro. WiiM may have corrected for this "baffle-step" in software. In case they did, you would end up with a wrong frequency response with the mic operated outside the WiiM housing. This baffle-step should however be located in the kHz region for the dimensions of the WiiM Pro.
Literature on this: https://www.jobst-audio.de/en/articles/measurement-development/bafflestep-bassstack

 

[GarrardZero100]

Aside from frequency response issues with the mobile- phone mics, I suspect, there might be some automatic gain control (AGC) involved. Also most phones have at least 2 mics in order to suppress ambient sounds. I have no idea if Android allows the WiiM App to switch to a single microphone - ideally the one located at the top of the phone.

I think WiiM pretty much knew that with such a large zoo of Android phones RC might be "difficult" - carefully speaking. Maybe, they added the feature to use the mic inside the WiiM device, since this will be a lot more consistent.
Unfortunately it's not possible to use the Mic in the Remote-Control; this would need the mic being located at the tip of the RC, an ADC and some memory in the Remote-Control. The data could easily be transferred to the WiiM via Bluetooth.
This wold be my proposal for a future Remote-Control

My results using my phone (Google Pixel 5) were really discouraging - it just did not at sound right after RC - so I ordered a UMIK-1

@GarrardZero100: There will be some change in the frequency response when you take the microphone out of the WiiM and operate it externally. The baffle the WiiM provides leads to a shelf-filter like characteristic for the mic inside the WiiM Pro. WiiM may have corrected for this "baffle-step" in software. In case they did, you would end up with a wrong frequency response with the mic operated outside the WiiM housing. This baffle-step should however be located in the kHz region for the dimensions of the WiiM Pro.
Literature on this: https://www.jobst-audio.de/en/articles/measurement-development/bafflestep-bassstack

Baffle step effect will be there but I estimate that this is small since I think the microphone is not attached to the housing but soldered to the PCB. But this is a guess that I will only know after I have opened the housing. I will also compare the measurement with the microphone in and out of the housing. However, I am curious if anyone has done this yet?

 

[nanook]

I think the microphone is not attached to the housing but soldered to the PCB.

On a PCB photo it looks like there's some "guide" for the sound and the black stuff is usually supposed to couple the guide "airtight" to the hole. If there's nothing alike, the small hole with the huge volume inside the WiiM would create a very effective acoustic HP-filter.

 

[GarrardZero100]

On a PCB photo it looks like there's some "guide" for the sound and the black stuff is usually supposed to couple the guide "airtight" to the hole. If there's nothing alike, the small hole with the huge volume inside the WiiM would create a very effective acoustic HP-filter.

View attachment 412156

Great, thanks for the picture. I'll think about it. It's always possible to compare the measurements in and out of the housing. I might have some time at Christmas. And in the meantime, there might be more posts with ideas or comments.

 

[nanook]

Well, @Ralph_Cramden showed photos without this "acoustic guide / seal": https://audiosciencereview.com/forum/index.php?threads/wiim-pro-streamer.39576/post-1529667

No idea, whether he has removed this cap to reveal the microphone chip, or whether units were built without it. Just for the purpose of evaluating an acoustical delay it might work without.
Anyways, you will find out. And of course, comparing mic inside vs. outside would at last give you a clue.

Be warned: Looking at Ralph-Cramden's pics, the miccrophone chip is a tiny SMD component. You may be able to carefully desolder it with a SMD hot air station, but you will likely never get it in place again!
I'm really experienced in SMD soldering, but I wouldn't dare to remove it.

 

[GarrardZero100]

This is where it ends. I have had bad experiences with soldering SMT parts. I don't want to ruin a perfectly good Wiim Pro. After all, I think the measuring system and equalizer are a fantastic option. It has, especially in the low frequencies, given a beautiful effect by flattening a few peaks.

 

[nanook]

This is where it ends. I have had bad experiences with soldering SMT parts. I don't want to ruin a perfectly good Wiim Pro.

Fully understood ! It's not worth to take this much risk to damage the WiiM Pro.

And in case WiiM has done a good job with the acoustic hood of the microphone chip and eventually even corrected for the baffle- step (I'm aware that this is the terminus for loudspeakers, the correct terminus for microphones may be different) the result might be fairly good. The MEMS microphones usually are fairly flat in most of the audio band.

I have not yet received my UMIK-1. Eventually someone who owns a WiiM Pro (Plus) and a USB-mic can compare calibrations performed with
1) built in microphone of the WiiM Pro
2) external USB- microphone