Review and Measurements of Yamaha WXA-50 Streaming Amp

[amirm]

Where is the recommended list? I’ve only seen the review index.

I have not created such a list.

 

[Damian]

I have not created such a list.

Would be awesome, are you considering it as an idea?

 

[amirm]

Would be awesome, are you considering it as an idea?

Yes, and we have had arguments about it. People think it commercializes what I do. At the same time, I keep getting questions about what I recommend so I will probably create such a list at some point.

 

[peng]

This is a review and detailed measurements of the Yamaha WXA-50, multi-function DAC, pre-amp, power amp, streaming and multi-room unit. It is on kind loan from a member. Even though it came out a few years ago (2016?), it is widely available. Amazon shows it costs US $478.

Success of SONOS as a multi-room audio solution has been the envy of many traditional audio companies. Many have tried to chase them with Yamaha being one of the earlier ones.

The WXA-50 is a surprisingly heavy unit although looks somewhat unremarkable:

View attachment 28713​

The case is metal as best as I can tell which is good as the unit generates good bit of heat. Strangely the heat is concentrated on the left side yet the vents are on the right!
There is an IR hole on the left which confused me to no end, constantly wanting to push it to turn on the unit.

I am not a fan of a single light indicating input and overload condition of the amplifier. Worst part of the interface is the volume control which has no marking and no display. Unless you use the app, you have no idea what volume you have set this to. This made my testing maddeningly hard.

I downloaded the App and here, I was pleasantly surprised by the performance and reliability of it. With no configuration, the WXA-50 was recognized and manipulating its controls were instantaneous and reliable. I only used the App to reset the EQ, etc. so for its full functionality, you should seek out other reviews.

The back panel has extensive set of inputs and outputs although lacks USB:

View attachment 28714​

I was pleased to see both analog input and outputs.

Yamaha heavily courted the Custom Install (CI) industry to use this instead of SONOS and it shows from inclusion of trigger input and output for control. Inclusion of Toslink input goes along these lines to fetch audio from a TV being fed by HDMI.

DAC Audio Measurements
I briefly measured DAC performance. I read however that there are two DAC chips inside this unit (an ESS and Bur-brown/TI) and that the fixed output is driven by the latter. So this may not be representative of what happens when you stream music into this device:

View attachment 28716

This is decent performance although it degraded fair bit if I turned up the volume on the amplifier to max. That increased the higher order harmonics even though the output level of the DAC did not change. We have seen this before and likely is the power supply sagging causing DAC performance to suffer. SInce you don't listen at max volume level, I did not derate the WXA-50 performance when including it in the performance chart:

View attachment 28717

Amplifier Audio Measurements
Since we have analog inputs, I started my testing using that and got this for our usual dashboard at roughly 5 watts:
View attachment 28722

I played around with combination of input levels and volume control and performance was pretty consistent. SINAD (signal over noise and distortion) is actually quite respectable for an amplifier:

View attachment 28723

I tested the same, this time using Roon to stream the 1 kHz tone to it using Airplay:

View attachment 28724

We lose just a couple of dBs although distortion levels are a bit lower.

From here on, I tested the unit using its analog input unless specified.

Frequency response shows decent bandwidth and flat response in audible band:

View attachment 28725

No strange and limiting digitization of input is visible which is good.

Signal to noise ratio is good enough for 16 bit audio:

View attachment 28726


Let's get into all important measurement: power into 4 ohm versus distortion:
View attachment 28727

We are close to meeting the spec (I measure at much lower distortion than they do). We have cleaner power than either Sonos or Amazon amps although the SONOS has much more power.

Here is the performance at 8 ohm:
View attachment 28728

I don't have as much data for 8 ohm but what is there, shows competent performance but with just 55 watts on tap.

Intermodulation distortion versus power level tells a similar story:
View attachment 28729

THD+N versus frequency and power shows very predictable performance with no corner cases exposed:
View attachment 28730

Only 20 Hz tones gives it a bit of trouble with rising distortion above 10 watts but that is slight.

The unit also shut down at 20 kHz at max clipping level. I reduced the volume level a few notches and that went away even though I was still pushing the unit into hard clipping.

Spectrum of 1 kHz tone with no AES filter shows the usual noise in high frequencies we get from class-D amps:
View attachment 28731

While this looks ugly, the spikes near audio band are way down at -75 dB which is very good. I have tested amps where these levels are much, much higher.

The two channels have different switching frequencies. Not sure if this is on purpose or variation in the clock source of their modulators. The two beat against each other likely creating the intermodulation spikes that we see throughout the range.

Conclusions
Unlike the bag of parts performance I often see in these modern streaming products, the Yamaha WXA-50 seems to have benefited from some attention to raw performance of each subsystem. There are no funny results, strange pipelines that go in and out of digital domain, etc. The performance graphs are all smooth with no sudden jaggies or other anomalies. This makes it easier to use the unit, not having to work around its weakness (I am talking to you SONOS).

We also have decent amount of power, approaching 100 watts into 4 ohm which should be plenty. If you add the subwoofer to it, you will be golden even at high SPLs.

The app likewise, gives a feeling of polish that I often find lacking in competing products.

In summary, I did not raise an eyebrow when measuring the Yamaha WXA-50. It won't provide competition to state-of-the-art separate products but it also doesn't embarrass. As such, I am going to put the WXA-50 on my recommended list.

------
Questions, comments, critique, etc. are welcome.

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The SNR graphs does not specify if the results were unweighted or weighted, I just wonder how it should be compared to say the AV8805's DNR that does specify AES17, so are those two graphs comparable, that is the AV8805 is about 15 dB better? Thanks

 

[Midwest Blade]

I bought the WXC-50 and a Yamaha A-S301 for the condo system as I was concerned with the possible limitations of the WXA-50. The WXC performs flawlessly for streaming of Tidal and Pandora, I get some drop out from Tidal but it is them not me. We have a strong wifi and I think some of the poor reviews stem from connectivity. I believe the A-S301 gives me some broader options than the WXA-50 but I sure would have liked the smaller footprint. Oh well, not the end of the audio world as we know it.

 

[SimpleTheater]

I bought the WXC-50 and a Yamaha A-S301 for the condo system as I was concerned with the possible limitations of the WXA-50. The WXC performs flawlessly for streaming of Tidal and Pandora, I get some drop out from Tidal but it is them not me. We have a strong wifi and I think some of the poor reviews stem from connectivity. I believe the A-S301 gives me some broader options than the WXA-50 but I sure would have liked the smaller footprint. Oh well, not the end of the audio world as we know it.

It might not be Tidal. I had this issue with Spotify and then saw a post about Time Warners slow dns servers. The recommendation was to use Googles [8.8.8.8] and [8.8.4.4]

After making those changes in the modem, no problems since.

 

[Jimster480]

This is pretty decent I suppose.... although $500 is a decently steep price considering.
There is a Heos amp which does something quite similar. I have a few Heos products (although not the amp) and I'd be interested in seeing where it stands.

 

[Matias]

Does anyone sell buffers to use with the ICEpower modules? Their performance seems to be linked to the impedance and design of the input stage but I haven't seen anyone offer inputs for sale for the DIY crowd.

ICEpower 125ASX2 already has built in buffer and power supply, so not much possible to tinker as much as with nCore NC500 variants.

Of course one can add an additional buffer before a buffer just to color the sound to one's likings, as PS Audio does with their Analog Cell before the modules in their Stellar power amps. Stellar S300 below uses ICEpower 300AS1, which also has buffer on the board.

 

[amirm]

The SNR graphs does not specify if the results were unweighted or weighted, I just wonder how it should be compared to say the AV8805's DNR that does specify AES17, so are those two graphs comparable, that is the AV8805 is about 15 dB better? Thanks

There is no weighting in either measurement from me. AES17 scheme is used for digital inputs, SNR for analog. The former is because some DACs mute their output if you send them zeros. So the AES17 sends them a -60 dB signal. With analog inputs, we don't have to worry about that.

But yes, if you see 15 dB difference, that is big difference.

 

[invaderzim]

ICEpower 125ASX2 already has built in buffer and power supply, so not much possible to tinker as much as with nCore NC500 variants.

Of course one can add an additional buffer before a buffer just to color the sound to one's likings, as PS Audio does with their Analog Cell before the modules in their Stellar power amps. Stellar S300 below uses ICEpower 300AS1, which also has buffer on the board.

That is good to know. So the 125ASX2 isn't affected by having a volume control placed before it like the 50ASX2?

 

[Matias]

That is good to know. So the 125ASX2 isn't affected by having a volume control placed before it like the 50ASX2?

Don't know...

 

[maty]

PS Audio,

I am still waiting for the promised technical response regarding the dominant H3 profile with its IcePower 700AS implementation. The PS Audio buffer is the guilty.

https://www.stereophile.com/content/ps-audio-stellar-m700-monoblock-power-amplifier-measurements

and...

PS Audio's Stellar M700 packs a lot of power into a small, cool-running case, and offers respectable measured performance.—John Atkinson

 

[Matias]

@maty it is like adding tubes to the signal path: it is not in a lower distortion sense, but rather as a (supposedly) pleasant euphonic sound.

 

[maty]

You have a good/very good amp module like IcePower 700AS. If you want to add coloration, let H2 be predominant like SET, never H3.

That if H2 or H3 or without harmonics is a debatable subject, to the liking of the listener. Nevertheless, the HF intermodulation 19+20 kHz is unacceptable.

Fig.10 PS Audio Stellar M700, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 200W peak into 4 ohms (linear frequency scale).

 

[peng]

There is no weighting in either measurement from me. AES17 scheme is used for digital inputs, SNR for analog. The former is because some DACs mute their output if you send them zeros. So the AES17 sends them a -60 dB signal. With analog inputs, we don't have to worry about that.

But yes, if you see 15 dB difference, that is big difference.

The 15 dB (110 vs 95) difference is observed by comparing the DR graph (with the AES17 filter) in your measurements on the AV8805 to your SNR (you are saying there is no weighting/filters) measurements on the WX-A50.

So, is that a fair comparison, i.e. AV8805 DR vs WX-A50 SNR? I am not 100% sure because one is Dynamic range, the other is Signal to noise, I thought they would be the same if no filters are used, but in this case filter was used in the AV8805's DR measurement.

 

[JJB70]

This appears to be a competent product from a recognised manufacturer which is available via regular retail channels and will be entirely satisfactory for most people selling at a reasonable price. Seems like a pretty good deal to me.

 

[HammerSandwich]

So the 125ASX2 isn't affected by having a volume control placed before it like the 50ASX2?

This is the relevant page from the 50ASX2's datasheet. The 125's sheet has the exact same info, except the cap values have been removed.

 

[invaderzim]

This is the relevant page from the 50ASX2's datasheet. The 125's sheet has the exact same info, except the cap values have been removed.

View attachment 29038

The bits I've read says that the Ice amps react poorly to having a physical volume control before them and they have to have a really low input impedance.

 

[sajunky]

This is the relevant page from the 50ASX2's datasheet. The 125's sheet has the exact same info, except the cap values have been removed.

View attachment 29038

It cannot be 100nF, it is why cap values were removed in the 125AX2 datasheet. But the second value (1nF) is correct, it gives impedance of 8kOhms with resistor 100Ohm in series @20kHz, exactly what they say.

Just want to add a note that physically it could be a cap of a smaller value, the picture may give just a combined figure with impedance of the opamp which is frequency dependent due to the negative feedback (not shown).

For us there is only one important information. ASX-series input impedance is frequency dependant, 8kOhm is a minimum in the acoustic band, so don't mess up with a passive pot DIY solutions. Direct cable connection to the preamp or a DAC will work 100%, there is no need for a separate buffer.

 

[kniff]

Yes, and we have had arguments about it. People think it commercializes what I do. At the same time, I keep getting questions about what I recommend so I will probably create such a list at some point.

Such a list would be highly appreciated. Maybe if you avoid direct rankings on the list you retain a level of objecitivty while still steering people towards products that deserve praise and have measured well.