Harman Kardon could really be the best amp (he he he)! Why?
You see, one time, I came across with an internet site which publish review of AVRs, and I quote “the Harman Kardon has a penchant for Class A amplifier”.
So that’s why, I said. So this explains a lot about their specs figure. So if you care, let me explain further.
Class A vs. Class B amplifiers.
Class B amplifiers are the most popular tech of amplifiers. This is manufactured by the majority of brands. Todate, I only encountered HK doing otherwise (class A) and Panasonic about a thing called class H.
Sonically, Class A is very clean (short of saying distortion free). If there is at all distortion figure in HK, it may probably came from its preamp stages (tone controls, processor circuits, etc). Class B (in its raw form) has distortion issue, but the addition of extra preamp stages somehow resolve this figure to the minimum.
However, class A amp are the most inefficient of amplifiers. When you say classB will deliver 50 watts of music power, the power consumed to deliver such music power is almost the same – 50 watts. For class A amplifiers, delivering 50 watts of music power is to consume around 150 watts (actually 200 watts theoretically).
This explains the HK specs. With HK 2550 you have,
Power Consumption 72W idle,580W maximum (2 channels driven)
In idle stereo mode, as in no music being made, HK 2550 will consume 72 watts (preamp plus amp stage).
Let’s say 20% of this is attributed to preamp stages, this makes 58 watts idle power (for both channels).
HK2550 was measured to deliver clean power up to about 73.4 watts (maximum). So if you attain a listening power of say 75 watts – then the consumption will be about 75watts (per channel) x2 (stereo) x 3 (factor of class A) or about 450 watts consumption (using 4 as factor can end you in 600 watts or near the 580 watts in the specs sheet!).
This also explain that upon powering up, HK will get hot even without driving any music (idle) – this is equivalent to the 72watts idle mode.
So, if you have 5 channels in idle mode, then you will have at least 58 watts (per channel idle) x 5 (channels) or roughly 300 watts + 14 watts (attributed to preamp stages) or a total of 314 watts (idle power pa lang to ha). And when you start driving your amp (listen to music) to the amp limit (at 75 watts), you can easily approach the 600watts (with the additional 300 watts or 5channels of 60watts HT mode) .
This also explain why its power supply should be able to handle big currents (note the HCC blitz).
I have a Yamaha vintage (AVR-1000) with switchable class B or Class A amp. Too hot when in class A – but so good a music.
HK & Rotel? HK has the edge in sonics due to its amplifier design but at the expense of more wasted power (300%). So with the Meralco PPA, at least you know how your HK will be affecting your hidden bill. If music is more important than the bill, HK is simply the best – but will cost you more operating it.
Me? Dreaming of owning an HK 3550 - will be used mostly for stereo listening. - ENJOY!!!
