The Yamaha RX-A1040 measurements are done using an Audio Precision APx582 analyzer loaned to me by Audio Precision. Testing is done over RCA and HDMI and measured using the RCA preouts and speaker level outputs.
Signal-to-Noise ratio for HDMI measures all the way at 114.3 dB from 20Hz-20kHz with an A-weighing. Without the weighing it drops to 107.8 dB and without the 20Hz-20kHz filter it falls down to 95.0 dB due to high frequency line noise. These numbers are very good and well past what I found when I measured any of the $600 receivers out there and even 6-8dB better than the Anthem MRX 510 receiver.
Crosstalk between the channels in HDMI is -80 dB for both and -75 dB for RCA inputs.
Frequency Response is +/- 0.16 dB from 20Hz to 20kHz with a gradual roll-off after that. Some receivers and processors are flatter than this but the difference is likely inaudible.
Looking at a -60 dBFS, 1 kHz sine wave we see the spurious noise tones are around -130 dB or below. There is a 60 Hz power tone at -110 dB but nothing else of any concern.
The DAC shows linear response down to almost -100dB. There are some noise ripples below there and then everything is drowned by noise at -108dB. The final noise floor is low but from -95dBFS to -116dBFS the signal has been distorted This is not seen in any DAC but the most cheapest. It shows that the analog section of the DAC has low noise but the digital section that drives the analog is not working correctly. These distortion deviations may hide larger problems that can only be heard by the ear. Tones that slide around so they are hard for a spectrum analyzer to detect. Although the SNR shows 108dBFS this is a phony number. It is with minimal digital bits being toggled after the region of distortion. It is just the noise floor of the DAC after it has created significant distortion.
A -108dBFS noise floor would imply a 17.6bit equivalent performance but the actual performance problems start at -95dBFS. This is a 15.7bit performance.
The noise ripples can be better seen with the line linearity graph below between -85dBFS to -105dBFS . From -95dBFS to -140dBFS the curve above is more revealing.
The effect of the non-linearity can be seen in the time domain with the -90dBFS sine wave shown in the time domain. Note it looks more like a tringle wave with the tops cut off.
The linearity of the -90dBFS sine wave results in significant distortion in the frequency domain. Note the many spurs are just 20dB down. They extend well out in frequency reflecting the flat top of the sine wave. Normally all that would be seen would be noise. If closed back headphones were used and the level adjusted so the -90dBFS / 24bit sine wave could be heard it would have some tonal background not just noise.
THD+N Level is constant from -140 dB to -20 dB before a rise of around 20 dB after that.
Looking at a 1 kHz sine wave from 0Hz – 1000Hz shows the power noise spikes at 60Hz increments are -110dB below the fundamental. There are distinct sidebands next to the 1 kHz test tone that appear to resemble some jitter. This comes in at -93 dB or below.
Looking at the same test tone out to 10 kHz we see the 3rd harmonic is the largest at -84 dB and the odd-order harmonics fall off quickly after that while the even order ones dominate. More interesting are the small spurs just below 3 kHz and 5 kHz and then vanish afterwards. I am not sure what they are at all but they are -130dB below the fundamental and on most receivers would be buried below the noise floor.
Moving onto RCA performance, we see a very flat noise floor with a 1 kHz test tone. The 60Hz and 180Hz power spurs are barely visible above the floor and the spurious side tones we saw from the HDMI test data is gone. This is very good performance with RCA inputs.
THD+N Ratio falls down to a minimum of <0.002% with a 300mV input and rises up to 0.015% with a 1.5V input.
Frequency response is ruler flat on the RCA inputs. There is a variation of 0.005 dB from 20Hz-20kHz.
With a 1kHz test tone, the Yamaha RX-A1040 is past 130 watts into two channels with 8 ohm loads before 0.1% THD+N.
With a 20Hz test tone, the Yamaha still manages to put out almost 140 watts per channel into 8 ohms before 0.1% THD+N. The amplifier section of the RX-A1040 is very well designed and can handle even full-range speakers that might dip down into the 4 ohm range, like the Revel f208.
Driving five channels full range into 8 ohm loads produces 57 watts of power before hitting 0.1% THD+N. While this does show the amplifier section will eventually run out of power when driving more than two channels, it doesn’t represent a real-world simulation at all.
With RCA sources, the Yamaha RX-A1040 is very quiet and neutral and will let them shine through. With HDMI sources the performance is very good, but products using the ESS 9016 DAC like the Yamaha CX-A5000 perform even better. For $1,100 it is unlikely there is another receiver that can outperform the Yamaha RX-A1040 in these areas.
|Bench Test Summary|
|SNR, A-weighted:||114.4 dB|
|Stereo Watts, 8 ohm load:||132.2 Watts|
|Stereo Watts, 4 ohm load:||187.8 Watts|
|All Channels Driven Watts, 8 ohm load:||57.2 Watts|
|Frequency Response (1kHz Relative):||+/- 0.160 dB|
|IMD, 19kHz+20kHz:||-95.8 dB|
|Summary:||The RCA test data Yamaha RX-A1040 is very good but the DAC shows issues with low-level signals and an effect bit-depth of just around 15.7 bits. The power amplifier is very good with plenty of power for 8 ohm and 4 ohm loads. While some of the numbers are very good, there are issues we can see in the DAC in certain tests.|