RX-Z11 Measurements & Analysis

Preamp Section

Yamaha RX-Z11 Preamp Frequency Response

I measured a ruler flat frequency response with a -3dB point around 173kHz in “Pure Direct” mode. Once the DSP was engaged, I noticed a +1.8dB bump centered around 80Hz in DSP mode which puzzled me for a moment until I realized I was the one that caused that bump when I manual edited the PEQ on the main channels. It’s reassuring that I confirmed Yamaha’s manual PEQ adjustments work exactly as expected.

Yamaha RX-Z11 Preamp FFT Distortion Analysis

With 200mVin, I set the master volume until I reached 1Vrms out of the preamp. The output was so pristine that I couldn’t measure any appreciable harmonics. I had to run the preamp up to 2Vrms out and 400Mv in to start measuring something appreciable but beyond the limits of audibility. Low distortion hardly qualifies for what I measured (7.161+103.303)dBv = 110.5dBV or 100*alog^-1(-110.5/20) = .0003% THD + N which is among the lowest distortion I’ve ever measured in a preamp regardless of price.

SNR
With 200mVin and 1Vout, SNR = 87.6dB (unweighted) in pure direct mode. This is an excellent measurement, and with its ample drive capability proves the RX-Z11 can hold its own with the very finest home theater preamps on the market.

The RX-Z11 can accept a signal up to 3.6Vrms and output 4.7Vrms under .01% THD +N. This is more than enough gain to drive virtually any power amplifier to maximum gain (THX amps require about 2Vrms). In the past I measured lower end Yamaha receivers that couldn’t output more than 1.5Vrms without the onset of hard clipping. This is NOT one of those receivers.

Power Amp Section

Power Bandwidth & Distortion

Yamaha RX-Z11 Frequency Response at 1 watt & Full Power

The RX-Z11 displayed excellent frequency response uniformity with a ruler flat response in the audio passband and an unwavering -3dB point of 136kHz at every power level. This is a design tribute that Yamaha boasts and lives up to!

Yamaha RX-Z11 Power vs Distortion

I measured continuous power vs distortion by setting up a regulated sweep in my Audio Precision to automatically adjust input level until the maximum power output is achieved at < 0.1% THD + N. The RX-Z11 was plugged directly into an APC S-15 Power Conditioner with regulation to ensure the line never dropped below 118Vrms.

Power output: <0.1% THD + N
1CH, 8 ohms: 190wpc
2CH, 8 ohms: 172wpc
1CH, 4 ohms: 300wpc
2CH, 4 ohms: 256wpc

Keep in mind most review publications don’t do continuous power measurements and they usually publish power measurements into clipping at 1% THD + N. Our measurements are very conservative and it is clear that the 140wpc power rating of this receiver is greatly understated as Yamaha is delivering MUCH more than specified.

For more info on amplifier measurements, see: The All Channels Driven (ACD) Test

With two channels driven at full load, I measured about 55% efficiency which is quite good for a linear Class A/B amplifier. When the unit was idling with all amplifiers turned on, it consumed about 126 watts. When I engaged “preamp mode” which shuts off the amps in the main zone, the idle power dropped to about 90 watts.

FFT Distortion Analysis

Yamaha RX-Z11 FFT Analysis @ Full Rated Power

At 1 watt into 8 ohms, the RX-Z11 displayed excellent results (+9.056 + 82.271)dBv = 91.3dBv or 100*alog^-1(-91.3/20) = .003% THD + N. At full rated power (140wpc, 8 ohms) the RX-Z11 again exhibited excellent distortion measurements (30.39 + 53.14)dBv =83.5dBv or 100*alog^-1(-83.5 /20) = .007 THD + N. These results weren’t quite as low as I measured on the RX-V2700 but I suspect Yamaha is employing a higher amount of negative feedback in this amplifier design as you will see in the amplifier output impedance measurements to follow.

Amplifier Output Impedance & Damping Factor

Yamaha RX-Z11 Amplifier Output Impedance under various loading conditions

The RX-Z11 exhibited one of the lowest output impedance profiles I’ve ever measured in an amplifier which indicates to me they are employing a lot of negative feedback but also using quality output devices and a large enough power supply to be stable at full power into 4 ohm loads. It fell well below our desired 100 mohm or less mark for the entire audible bandwidth up to 20kHz and maintained itself even when driving at max sustained power levels into 8 ohm and 4 ohm loads. This proves that the RX-Z11 will sound consistently good no matter what loudspeaker load it is driving.

Yamaha RX-Z11 Amplifier Damping Factor under various loading conditions

The amplifier damping factor is about what I expected based on the measured output impedance. It is uniformly good across the entire audio frequency range at around the 100 mark (50 is a minimum we like to see in all amplifiers of uncompromising design) when driving an 8 ohm loads. Into 4 ohm loads the Damping factor is exactly as expected, ½ the 8 ohm value and demonstrates that the Z11 is happy to drive low impedance loads at full power.

Channel to Channel Crosstalk

Yamaha RX-Z11 Crosstalk at Full Rated Power vs Frequency

Running a full range frequency sweep from the preamp all the way through the power amp at full rated power (140wpc @ 8 ohms), I measured channel to channel crosstalk on two adjacent channels where one channel was the disturber and the other was the DUT. The Audio Precision plotted crosstalk of both channels over frequency by varying the Distruber/DUT channels. You can see the RX-Z11 produced great crosstalk measurements (90dB at 1kHz) with only a slight increase up at the frequency extremes (low frequency because of magnetic coupling and high frequency because of capacitive coupling). This test really exemplifies the careful board and magnetics layout of this 11 channel receiver.

SNR Measurement

With 200mV in, 8 ohms I measured an SNR of 75.5dB (un-weighted) at 1 watt power level in pure direct and stereo modes which again is a very good measurement. I did note however that once the DSP is engaged or stereo mode set to non-direct to allow sub out, noise jumps up about 10dB. This is audible only if your head is in close proximity to any particular loudspeaker with the volume turned up and no program material is playing.