Denon AVR-5805 Measurements Cont.

Frequency Response at 1 watt was ruler flat within the audio band with a -3db point of about 125kHz.

Whether driving at 1watt or full rated power, frequency response uniformity of the AVR-5805 amp section was exceptional.

When driving the AVR-5805 at around 157wpc into 8 ohms, I ran a frequency response sweep against a 4 ohm load under the same test conditions where it happily delivered exactly twice the power (315wpc).

This indicated two things:

• The Denon amp had a low enough output impedance and enough power supply reserves to act like an ideal voltage source to double down its power delivery as the load impedance halved.
• While doing so, it maintained excellent frequency response uniformity (falling well within our preferred +-.25dB deviation window) indicating excellent gain product bandwidth and lack of slew induced distortion when driven hard.

Since the AVR-5805 sported a cool "Bi-Amp" mode, I wanted to see if it could deliver the goods in this scenario. I configured the AVR-5805 front channels for biamping and tested for maximum unclipped power.

Editorial Note on Power Measurements
We do NOT hold the line voltage constant like some publications do, as we believe in testing for real world conditions. Consumers typically don't have the luxury of stabilizing their power and/or providing enough wall current to source max power with all channels driven (a very unrealistic test condition and a very idealistic test load we might add). In any event, I was able to achieve a 170wpc at 0.1% THD with four channels driven but noted that my dedicated 20A line sagged from 124V to 119V under this test. In reality, the AVR-5805 probably could have delivered an extra 10wpc or so in a more sterile lab environment. This test certainly proved the AVR-5805 was a true powerhouse. For the fun of it I reran this test for five channels driven and was able to achieve about 145wpc at 0.1% distortion but again watched the line voltage sag down to 110V during this test. Thus again, this amp is certainly able to deliver the full capabilities of a 15A outlet and then some! Based on the amount of power reserves available in this receiver I would venture to say if you had a stabilized dedicated line to run this receiver, it could probably drive up to 7 channels simultaneously at full bandwidth unclipped at its rated 170wpc into 8 ohms assuming an internal fuse doesn't blown first. Before you actually declare your set-up can achieve this power, consider this: The efficiency of a typical class A/B amp, such as the ones found in this receiver, is around 35-40%. Let's assume 40% in this instance. In order to deliver 170wpc x 7, it would require: 170*7/.4 = 2975 watts! For a 120VAC system your line would be required to deliver 25 amps! Unless you are running 3 phase power, or convince the power company to run 6AWG romex and up the circuit breaker from a standard 15A to a hulking 25A, this simply isn't gonna happen (no, not even with name brand separates). Not to mention the fact that UL certified products such as this one are limited to 15A power consumption at the interface connector for safety reasons. Remember this next time your friend boasts about his dedicated 7CH 200wpc Class A/B amp which sports a single line cord connection.

For more information on this, check out The All Channels Driven (ACD) Test Fallacy

In reality, the power supply and amp section of the AVR-5805 are not the limiting factors for maximum power delivery for all channels driven, the outlet and power receptacle are.

Food for thought for power freaks that think they will actually use this much power in all channels at the same time.

Distortion at 1 watt was practically nonexistent. A quick glance at the AVR-5805's distortion profile at 1 watt revealed excellent results (+9.369+90.188)dBv = 99.557dBv (about 5dB better than the Integra Research RDA-7.1 ) or 100*log(-99.557/20) = .001%.