RX-V4600 Power Measurements and Analysis

Frequency Response
The frequency response out of the preamp was ruler flat in the audio band (20Hz to 20kHz +-0.1dB) with a -3dB point around 120kHz. I also observed no measurable difference between "Straight" and "Pure Direct".

FFT Distortion Analysis

When the analog preamp was driven at 1Vrms (typically ½ signal strength to achieve ½ of max power of most power amps with voltage gain of 29dB) distortion levels were (+0.497 + 88.955 = 89.452dBv) or 100*alog(-89.452/20) = .00337% This is certainly a commendably low distortion figure.

At 2Vrms, the preamp section of the RX-V4600 faltered. This is because Yamaha was likely using only a single rail 5V supply for the preamp section. I would prefer to see a preamp have the ability of driving 2Vrms undistorted to accommodate a wider assortment of power amplifiers. Though this didn't present any audible nasties when I used the RX-V4600 as a preamp to my Emotiva MPS-1 power amp, my advice here is to choose a power amp that can achieve maximum power output with about a 1.5Vrms input should you decide on buttressing your system with external amplification.

• The Inputs can handle 3Vrms unclipped!
• Outputs Deliver nearly 2Vrms output unclipped! But FFT distortion becomes very high once output exceeds 1.5Vrms.

Ch-A Signal to Noise Ratio (SNR)

With a 200mV Input Signal, I adjusted master volume for 1Vrms out, preamp gain (Av=5 or 14dB), I measured as follows:

• 18.5dBrA with signal
• -74.6dBrA without signal
• SNR: 93dBrA (commendable performance for a preamp at any price class)

Upon first inspection it would appear the RX-V4600 delivered similar power measurements to the RX-V2500 (see measurements and analysis ), until you take a closer look at the RX-V2500 power into 4-ohm loads. In the case where 2CH are driven into 4-ohms, the RX-V4600 delivered 184wpc @ 1% THD (onset of clipping) while the RX-V2500 delivered about 119wpc under the similar testing conditions. What's most impressive is the RX-V4600's apparent better handling of low impedance loads when compared to the lower priced RX-V2500 as can be seen in our output impedance and damping factor measurements.

With 200mV in and 2.82Vout into an 8-ohm load,

• < 10 Hz - 22k Hz bandwidth , no option filter and no weighting

Measured at 1 watt: 200mV input: Master Volume: -3.5dB

• At 1 watt: -21.69 dBrA
• At idle: -103.46 dBrA
• SNR: 81.7dB at 1 watt This is very good performance