RX-V659 Measurements & Analysis
Amplifier Efficiency Measurements for linear a/b amps such as the ones employed in this receiver typically range from 40-50% depending on the load the power supply of the amplifier sees. The closer you get to full load, the higher the efficiency usually becomes (assuming you aren't over taxing the power supply and power devices of the amp causing excessive thermal losses). The RX-V659 achieved around 50% efficiency which was quite impressive for a receiver employing a conventional linear amp design.
|
# Ch
|
Power Consumption |
Power Delivered |
Load |
Efficiency |
|---|---|---|---|---|
|
1 |
269 watts |
132 watts |
8 ohms |
49 % |
|
2 |
449 watts |
120 watts |
8 ohms |
53 % |
|
2 |
396 watts |
200 watts |
4 ohms |
51 % |
|
1 |
676 watts |
170 watts |
4 ohms |
50 % |
Power Bandwidth
Yamaha RX-V659 Frequency Response at 1 watt
The Yamaha RX-V659 possesses a wide bandwidth amplifier topology with a -3dB point in excess of 100kHz.
Yamaha RX-V659 Frequency Response at Full Power
At full continuous unclipped power (132wpc x 1; 8 ohms, 120wpc x 2; 8 ohms; full bandwidth with less than 0.1% THD+N), the RX-V659 still maintained excellent bandwidth linearity with a -3dB point of 65kHz despite we were driving the receiver way beyond its rated 100wpc power specification. Into 4 ohms, the RX-V659 was able to deliver continuous power levels at a whopping 200wpc x 1 and 170wpc x 2 with less than 0.1% THD + N. The amplifier section of this receiver is truly underrated. I never encountered a budget A/V surround receiver that could deliver this kind of power before. Truly amazing.
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 this receiver is a true workhorse for its asking price.
For more info on amplifier measurements, see: The All Channels Driven (ACD) Test
FFT Distortion Analysis
FFT Analysis @ 1 watt
At 1 watt into 8 ohms, the RX-V659 exhibited impressively low distortion (9.031+74.521)dBv = 83.56dBV or 100*alog^-1(-83.56/20) = .007% THD + N which is very clean as expected.
FFT Analysis @ 100 watts
(29.067 + 51.791)dBv = 80.86dBv or 100*alog^-1(-80.86/20) = .009% THD + N which indicates as per my power measurements, the amp section in this receiver is too conservatively rated. Most impressive for a $1000 receiver let alone one that costs roughly half of that!
Amplifier Output Impedance & Damping Factor
Amplifier Output Impedance
The amplifier output impedance fell right within our desired 100 mohm or less mark for the entire audible bandwidth up to 10kHz with just a slight increase above at the upper 20kHz frequency range. This is the type of performance I like to see in an A/V receiver and not expected for a product of this price class.
Amplifier Damping Factor
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 and falls slightly under the 90 mark above 1kHz we like to see on uncompromising designs. All in all, this is quite an impressive result and rivals some of the earlier and more costly Yamaha receivers we have reviewed in the past while also exceeding our minimum 50 value we like to see in amplifiers for 8 ohm loads and even does so with 4 ohm loads as well. We've never seen such stellar results in a receiver of this price class.
