22 June 2010|
|Pioneer GM-D9500F Amplifier|
When it came time to sit down and listen to the new Pioneer amp, I connected it so the front channels drove my reference speakers and the rear channels were bridged to a 4 ohm subwoofer system. The front channel crossover was set to 40Hz high pass, and the sub was crossed over at 80Hz. I adjusted the gains and settled in for some listening, and a few hours later, I came away rather impressed by the diminutive little four channel amp. It proved it could drive a system with authority, and the quality of the sound was quite good as well. Without signal applied the amplifier was very quiet and had a zero audible noise floor. Stereo separation was also excellent and the GM-D9500F did a very good job of creating a solid stereo image with a strong “phantom center”, but occasionally seemed to lack a bit of the sense of “space” and movement that I have observed in some recordings. I noticed this most when listening to large complex orchestral performances or when playing pure acoustic recordings done in a large open space. To be fair however, I do my evaluation listening in a very quiet, acoustically treated room and I sit in the sweet spot between a pair of very good sounding loudspeakers. So what I’m talking about “missing” is the kind of detail that’s seldom even possible to hear in a typical car audio system. When I cranked up the gain on the woofer and pushed the amp really hard for about 15 minutes, I noticed that the heatsink did get fairly warm to the touch, but the amp showed no audible sign of stress.
Moving the GM-D9500F to the test bench, I ran the usual battery of tests and did my best to break things but everything turned out very good. The amplifier actually produces quite a bit more than its rated power, and it will even produce the rated power at a battery voltage of 12.6 volts. I haven’t seen an amplifier with this much “headroom” in the power spec for a long time, and it was very refreshing. Well done Pioneer! Signal-to-noise measured well and so did crosstalk which verified my listening impressions. Output impedance of 0.036 Ohms was about average for a full range Class D design but interchannel phase coherency was excellent. The crossovers worked exactly
as intended and the amplifier was exceptionally efficient at any power level. I did perform a fairly brutal full power thermal test and the results were okay but not as good as I had hoped. Remember, this is a very small amp and it makes a lot of power! Based on this evidence, if you are often going to run the GM-D9500F really hard, make sure it’s mounted in a spot with plenty of airflow, which is simply a good installation practice anyway.
Priced around the $269 mark in the U.S., you’d have to look long and hard to find another four channel amp with this much power, in this small of a package. And when it sounds great to boot, I’d say Pioneer just made life a little tougher for their competition.