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Music Reference RM-200

Was the original RM-200 rated class A or just the MK.2? I remember both of them being, but I want some validation, someone has questioned me rudely about it. Also, can you sub a ECC180 for the 6BQ7 driver tube in the amp? 

Thanks
enobenetto
enobenetto OP
67 posts
 
sorry for all the typos and missing grammar

clio09
3,354 posts
 
We don't brand the Gold Lion KT-88s so those could have possibly come from us. We brand the Chinese KT-88s. I'm pretty sure our 6BQ7s are Sylvania but we brand them as well.

One way to determine how well balanced the output tubes are is to take a volt meter, set it to volts DC, and preferably set to measure for mV. In the back of the amp at the binding posts, for the left channel put the red probe in one pot and the black probe in the other and you can measure the difference, which should be quite a small number. less than a couple of mV. Then repeat for the right channel. You should also check the bias as well after the amp has been on a while. A good reading would be around 36 mV.

The RM-10 is my favorite MR amp. I've owned one for over 10 years now. Great match with my Lightspeed Attenuator. You really need an active or buffered output preamp with the RM-200 as the input impedance in both unbalanced and balanced is fairly low. I've spent a lot of time with the RM-200 as well. It's a nice amp and if you have speakers with difficult loads it's an amp that can get the job done as it increases power as the speakers impedance drops.
mbo's avatar
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mbo
9 posts
 

@clio09 -

Thanks very much for your detailed info on the RM-200 in this thread.  I've had a much-loved one (s/n #2019) since 2005 or so.  Even brought it down to Santa Barbara for repair one time.  Didn't get to meet Roger, though he replaced a transformer for me.

I think i understood you to say that the RM-200 is fully balanced *differential* from input to output.  I've just ordered a new REL subwoofer which i plan to connect using their high-level input (connects to the speaker terminals on the amp).  The connection is different for differential amps (the ground wire doesn't connect to the negative terminal) so i want to make sure i get it right.

I've used it for years with an Audio Research LS-25 mkII preamp which i believe is also fully balanced (but that's not really relevant to my current question ;-^).

Thanks again,

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