This is a review and detailed measurements of the Onkyo TX-RZ50 9.2 8K THX Certified AV Receiver. It was purchased new by a member and drop shipped to me for testing. It costs US $1,399.
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Looks like all AVR companies are trying to break the mold of just dual rotary controls to something different. While I appreciate the additional buttons and knobs here, they are impossible to see in the dark as far as labels. Here is the back panel:
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I appreciated the quick start-up and the high resolution of the on-screen display. It was also nice of it to tell me at the end of setup that there was a new firmware. What I didn't appreciate was it not recognizing my hardwired Ethernet cable requiring a second try even though I had it plugged it a while back. Update was slow which I could tolerate but not finishing with "Update Complete" (or something like it) and then sitting there non-functional! You had to power cycle it to get it to work.
The distinguishing aspect of this AVR is adoption of Dirac by a mass market company like Onkyo in their AVR. Dirac room EQ should perform far better than simpler scheme in the AVR (although I have not tested either in this instance). There is a nice app to control it all as well so you don't need a computer if you don't want to have one (and can use AVR's own mic).
Note: the follow set of measurements are expanded from my normal set which is already quite extensive for AVRs. If you are new to these reviews, don't be taken back. Most of them are for the diehard measurement folks in the forum.
I will summarize everything in the conclusion section.
Onkyo TX-RZ50 DAC Measurements
As usual I start with the important bit which is how well the AVR converts digital audio samples to analog.
Pure mode was selected for all the measurements (see later in the review on effect of this setting). Let's start with S/PDIF:
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As usual I set the volume control such that we get 2 volt output which required setting it to 84.5. Unit displays "Reference" at 82 by the way but at that level, you won't be able to drive all amplifiers to their full power rating. Let's now switch to HDMI:
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General performance is the same but now we have symmetrical spikes around our main tone which indicates low frequency jitter component. This is unfortunate. Putting SINAD which is the relative sum of noise and distortion in context we get slightly above average rating:
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Since the unit can output more than 2 volts, let's see the full range of output vs performance:
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Good to see you have headroom up to 3.5 volt if you need it to drive a low gain amplifier.
Measuring dynamic range we get:
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Multitone test shows jitter components we saw in the dashboard which I ignored for my distortion-free range computation:
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Oddly when I ran my specific jitter test, it was S/PDIF which fell behind HDMI:
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Objectively neither performance is proper but from audibility point of view, spikes are low enough as to not matter.
Linearity was "good enough" for the class:
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I was pleasantly surprised to see a choice of filters although you only have a choice of two (and "auto" which seems to set to Sharp):
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Notice the typical roll off in the audible band with slow filter so my choice would be the sharp one. The filter choice naturally makes a difference in our THD+N versus frequency:
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As you see the slow filter does better but I think that is because it is attenuating the in-band response, reducing the noise and power of harmonics. Either way though, this is not anything to write home about.
While we are here, let's see the effect of Pure mode:
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Odd to see that low frequency rise in distortion.
Base Management and Pure Mode Investigation
These AVRs are opaque when it comes to what they do when they activate their digital processing and accompanying resampling. So I decided to investigate with frequency response measurement using 192 kHz sampling. This rate is usually outside of unit's internal processing rate so if there is some, we will see its effect. Let's see what happens when we turn Pure mode on and off:
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It is clear that turning ON the Pure mode disables all internal resampling giving us almost full bandwidth of 96 kHz which we would expect. Turn Pure mode off and response gets truncated sharply. My guess is that internal sample rate is 44.1 or likely 48 kHz.
I then configured an 80 Hz high-pass filter for the fronts and measured its effect:
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As soon as you enable bass management, resampling is forced on you (blue curve). This is a shame as bass processing should be doable at higher sample rate. I guess the pipeline is all or nothing when it comes to processing. Fortunately you have the option of using Pure mode but that defeats bass management so no bookshelf speaker may apply. You have to use full range speakers.
Notice that this run in Pure mode (red and green) has a spike. This would come and go depending on settings of the frequency response sweep (green spike). It may be a bug or ringing of the resampling filter. Onkyo should investigate and fix this. Fortunately it is at 60 kHz so not an audible concern but maybe it pushes some external amp into oscillation.
Onkyo TX-RZ50 Amplifier Measurements
My goal here is to figure out how good the internal amplifier is relative to an external one. This is hard to do as we have to tease out the transparency level of various ways of feeding the amplifier. Let's start with analog input by adjusting our gain to be 29 dB:
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If you don't use the Pure mode -- which is probably how most of you use it -- you will lose performance:
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Sadly that is in the form of rising noise floor. Going with the better of the two, the ranking is not great and well below competition:
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Some of you have been looking at using external DACs as a way to improve performance of these AV Products. There, you would be feeding the amplifier up to 2 volts in unbalanced mode so I decided to test that condition. To get to the same 5 watt output, I cranked the volume down until I achieved that output:
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Noise floor goes down enough to buy us 3 dB more SINAD. Let's do the same with HDMI input, i.e. using internal DAC:
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So you could do better with external DAC but it is likely not worth the hassle as the amp itself doesn't have much more to give.
Crosstalk was below average:
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In Pure mode, frequency response is extended and nice:
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And here is our multitone test:
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Disappointing.
Onkyo TX-RZ50 Power Amplifier Testing
This testing cost me anther hour of sleep (went to bed near 4:00 am!). I started with measuring 4 ohm power as I usually do and got ridiculously low level of output before clipping. I checked all the settings, set the amp to 6 vs 4 ohm and back, power save mode off, etc. but nothing would fix it. On a hunch, I disconnected the power cable, waited a bit and powered the unit back on. I got full power twice but then it limited:
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Clearly there is some monitoring going on internally causing the amplifier to go into ECO/power limiting mode. With 8 ohm load, I didn't see this problem:
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Given that vast majority of speakers today are 4 ohm or even lower, this is a serious problem. I could understand it if the amp was cooking but it was quite cool running with the upper fan off. Traditionally this mode would be triggered if you set the amplifier to 4 ohm mode but per above, this did not have an effect here.
Given this problem I could not run my max and peak power. But did run my frequency sweeps post a power cable removal:
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Notice how it pulled power back half way through the test. I am hoping this is microprocessor controlled so can be fixed with a firmware upgrade.
This is a showstopper bug as far as I am concerned.
Conclusions
The inclusion of proper Room EQ in mid-priced AVRs is major news indeed. Alas, my job here is to characterize the performance of the platform itself and the news there is not good. The amplifier has serious power limiting "feature" and even without it, it is not competitive with other products out there. Company can and should do better than this. I am confident a clean up pass with measurements can produce a better product. For too long review sites have done such a cursory job here as to allow these practices to continue. Hopefully that era is behind us. I know a number of companies are taking this domain seriously like the companies did in 1970s. So if Onkyo doesn't get with the program, it will fall behind.
The morass of pipeline processing also needs documentation and this is a message for the entire industry. Don't leave the customer in the dark and lead to dissatisfaction when they read an analysis like mine. Up the processing capability and make it a feature to perform all the functions at the native sample rate of the content. I think people will pay a few hundred dollars more to get this.
Anyway, I can't recommend the Onkyo TX-RZ50. If they fix the power handling issue, they may then get a marginal recommendation from me.
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