Denon POA-A1HDCI User Manual download pdf (Page 7)

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What I believe was happening here

wasthepowerdrawatlowfrequencies

didn’t allow enough time for the

capacitor bank to charge and at high

frequenciesthepowerdensityismuch

higher requiring a bigger transformer

to achieve these sustained power levels.

I couldn’t help to wonder just how

much more power the POA-A1HDCI

could have delivered if Denon chose

to employ one massive power supply

instead of multiple smaller ones for

better channel to channel isolation.

There are pros and cons to these

different methodologies but I believe

Denon struck a good balance here,

yielding the best of both worlds with

their hybrid mono block multi power

supply approach while also keeping the

box size reasonable for a high power

ten channel amplifier. Keep in mind

that this amp in bridged mode will yield

a HUGE +6dB of dynamic headroom

when driving a real speaker load with

music, even though sustained power

measurements aren’t all that much

higher into resistive loads driven by

continuous test tones.

Editorial Note on

Bridged Power Measurements

Keep in mind most review

publications don’t do continuous

power measurements and they usually

publish power measurements into

clippingat1%THD+Nat1kHz.Our

measurements are very conservative

and are continuous full bandwidth.

For more info on amplifier

measurements, see: The All Channels

Driven (ACD) Test.

Editorial Note

on Audioholics Power Ratings

It is clear that the POA-A1HDCI easily

hit the 150wpc power rating, delivering

MUCH more than specified into 8-ohm

loads in normal and bridged modes and

about dead on specified power delivery for

4-ohm loads for normal and bridged modes

of operation.

While the POA-A1HDCI was driving

4-ohm loads in bridged mode, I was able

to achieve the 1% power numbers at <.1%

THD + N in the above table at 1kHz

but distortion went up significantly at the

frequencyextremes(20Hzand20kHz).This

is why I scaled the measurements back to

ensure the amp delivered the measured

power at <0.1%THD + N full bandwidth

continuously.

Denon POA-A1HDCI FFT Analysis @ Full Rated Power

When testing 2 channels bridged mode

into a 4-ohm load, my APC S20 ran into an

overload condition but did manage to keep

thelineregulatedabove116Vrms.Thisgoes

to show you that continuous power testing

consumes far more power than real world

usage as I was never able to get my APC

S20 to state I was using greater than 30%

capacity even when I was blasting my system

at sustained 110dB listening levels in 7.1

surround modes at my listening area.

Upon peering at the spec sheet forthis

amp, it was obvious that the manufacturer

was specific about how they rated power.

They specified full bandwidth power at

<.05%THD+Nfor(150wpc,300wpcbridged)

for 8-ohmloads,butonly1kHz.7%THD+N

(300wpc, 500wpc bridged) when driving

4-ohm loads. Under these circumstances,

the POA-A1HDCI delivered as promised

and then some, but as an Audioholic, I would

de-rate the 4-ohm bridged continuous

power specification by 15% or so and

bolster the fact that you’ve got roughly

+6dBofdynamicheadroom.

Efficiency

With two-channels driven at full load, I

measured about 47-49% efficiency which

is good but not as great as I’ve seen in for

other linear Class A/B amplifier designs.

When the unit was idling with all amplifiers

turned on, it consumed about 275 watts. It’s

the idle power consumption of 10 channels

that kills the efficiency of this amplifier.

Too bad there isn’t a way to cut power on

unused channels.

SNR Measurement

When the POA-A1HDCI was driven to

full power into an 8-ohm load, I measured:

-117.15 dB below 31.77 dBV Reference

Level(at0.09%THD+N)<10Hz–22kHz

unfiltered and unweighted. This translates

down to 94.3dB SNR @ 1 watt which is

excellent and explains why this amp sounds

so crystal clean and quite at low power

levels.

FFT Distortion Analysis

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Denon POA-A1HDCI User Manual Page 7

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