Musical fidelity p270

ingemar · 11th June 2006, 11:34 AM

Hi there guys.Sombody who knows how heavy my p270 is biased in class A operation?I have it in a workshop right now and the guy that is modefying the amp is telling me that the maximum output in class A is 1 watt,otherwise im going to destroy my electrolyts.To me it sounds strange that it is just 1 watt in class A operation!!With best regards Ingemar

AndrewT · 12th June 2006, 09:06 PM

Hi,
no real data, but I believe this is a high bias amp that puts out 130W into 8ohms in Class AB.

I suspect from the heatsink size (about 15inch by 8inch on each channel) that the bias is set to allow about 25% of maximum power in ClassA. i.e. about 30W being equivalent to 2.75Apk and Ibias of about 1.4A.

Leolabs · 13th June 2006, 03:28 PM

Hi,ingemar.You can check for yourself with a multimeter.

jacco vermeulen · 13th June 2006, 05:12 PM

Quote:

1 watt in class A

The P270 was good for 10 watts in class A, bias per side is around 0.8 amps.
Heatsinks of the P270 were SK56 types, which are good for a little under 0.45 C/W at 4" high, 0.36 C/W for 6". Compared to other MF products the P-series had relatively cool heatsinks, the P270 did not run that hot.
Turn the bias up to 30 watts and you can fry eggs on it. The MT200 Mosfet type output stage of the P270(same devices as in the B&W cube amps) makes it a very inefficient class A amplifier.

11th June 2006, 11:34 AM	#1
ingemar diyAudio Member Join Date: Apr 2006 Location: gothenburg	Musical fidelity p270 Hi there guys.Sombody who knows how heavy my p270 is biased in class A operation?I have it in a workshop right now and the guy that is modefying the amp is telling me that the maximum output in class A is 1 watt,otherwise im going to destroy my electrolyts.To me it sounds strange that it is just 1 watt in class A operation!!With best regards Ingemar

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12th June 2006, 09:06 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, no real data, but I believe this is a high bias amp that puts out 130W into 8ohms in Class AB. I suspect from the heatsink size (about 15inch by 8inch on each channel) that the bias is set to allow about 25% of maximum power in ClassA. i.e. about 30W being equivalent to 2.75Apk and Ibias of about 1.4A.

13th June 2006, 03:28 PM	#3
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Hi,ingemar.You can check for yourself with a multimeter.