Originally Posted by chrisexv6
Thats one of the huge advantage of class D: very little "sag" as more channels are loaded. Only losing 28W/channel between 2 channels driven and 7. In comparison I havent seen exact tests of an Onkyo 809 at all channels driven, but the estimate is probably about the same as what the SC61 tested at.
No my friend, the estimate is not about the same, it is not even close to the SC-61/SC-1222K. Actually if you go for the numbers of a $2000 Onkyo receiver, the TX-NR3010:
Onkyo TX-NR3010 A/V Receiver HT Labs Measures
Two channels driven continuously into 8-ohm loads:
0.1% distortion at 167.8 watts
1% distortion at 189.5 watts
Five channels driven continuously into 8-ohm loads:
0.1% distortion at 122.1 watts
1% distortion at 142.2 watts
Seven channels driven continuously into 8-ohm loads:
0.1% distortion at 114.1 watts
1% distortion at 127.2 watts
You can find that this high level Onkyo drops the power per channel a 27% when going from 2 to 5 ch, twice the amount of the SC-1222K that drops only 14%. With 7 channels the drop is around 50W per channel against the 28W of the SC-1222K. Take into account that we are comparing a $2000 Onkyo Receiver against a $550 SC-1222K.
One more thing, the SC-1222K is 4ohm certified and it delivers 190 W/ch with 4 ohms speakers while still running cold.
Talking to everyone, what we have now in the market is a changing scenario with very good traditional A/B stages against the natural replacement, the PWM switched amplification, more commonly known as digital amplification or class D or ICE or D3... whatever. Pioneer was improving the previous ICE stages with the new D3, nonetheless the big improvement is not only the efficiency, but also the lower distortion and higher SNR. This is why I changed from Marantz to THIS Pioneer. The problem with the switched amps was always the EMI, it seems that Pioneer have solved this issue. We will see other brands using switched amps in forthcoming years. Same hapenned in the TV arena 10 years ago when moving from CRTs to PDPs first and LCDs later.
Regarding the reliability, the transistors of the A/B stage are always biased, thus their life is counting even when there is no source, just because there is a biasing current flowing through the transistor channel. In switched amps, there is no current unless there is a signal, this is why it is cold and the theoretical life of the active components is much higher.
Sorry for the length of this post.
RegardsEdited by okibcn - 2/25/13 at 7:26pm