Power Rating of RM200T

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joeling39

Power Rating of RM200T
« on: 29 Jan 2014, 03:01 am »
Dear Roger,

May I know the rated power of the RM200T ? These are class A devices with balanced input ?

Where in Malaysia / Singapore can I audition them ?

Thank you.

Regards,
Joe Ling

Roger A. Modjeski

Re: Power Rating of RM200T
« Reply #1 on: 30 Jan 2014, 05:00 pm »
The power into a matched load is 100 watts/ch. Into unmatched loads lower than the tap the power is greater. There is plenty of power and extra current as the amp can go from class A to AB1 to AB2 as volume increases.  The amplifier is fully balanced input and output (rarely done) and has the same performance driven unbalanced (single ended). However, using it balanced has the advantage of rejecting cable and ground loop noise. Many balanced input amps do not perform well driven unbalanced.  The common mode rejection of the RM-200 exceeds 100 dB. The amplifier is also very low noise and suitable for the most sensitive speakers.

There is an excellent review in Stereophile December 2011.  http://www.stereophile.com/content/music-reference-rm-200-mkii-power-amplifier

I will post dealer details soon.

tubegroove

  • Jr. Member
  • Posts: 64
Re: Power Rating of RM200T
« Reply #2 on: 5 Feb 2014, 12:54 pm »
How many watts Class A ?

Roger A. Modjeski

Re: Power Rating of RM200T
« Reply #3 on: 6 Feb 2014, 04:22 pm »
How many watts Class A ?

When you make and AB amp there is not much in the class A power range. This is something I plan to cover in the class. The simple answer is once the signal current exceeds the bias you leave class A and go into AB. Nothing wrong with that but a true class A amp needs a lot of dissipation which means a lot of tubes and power consumption. The Jadis JA-200 is a good example that achieves 140 watts with ten KT-88 output tubes and draws about 500 watts per channel. Each tube in that amp is at max dissipation of 40 watts.

I make a Class A version of the RM-200 that is 40 watts. Although the standard RM-200 is very low distortion, the class a version is lower as it should be. Also remember that with any of my amps going down on the taps lowers the distortion because it expands the class A region as it reduces the signal current by providing a higher impedance load to the tubes.  Going from the 8 ohm tap to the 1 ohm tap triples the class a region.