@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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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.
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sorry for all the typos and missing grammar
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I picked up the RM-200 recently from a local seller for $1500. I'm not sure if the tubes were originally from Roger because none of them have the Ram Labs print on them. They came with Gold Lion KT88's, which I know that your Clio and Roger sell. The drivers are Sylvania 6BQ7A's, which I don't think are matched.
I also own the RM-10mk2. I'm not sure if I can afford to hang on to both, but it's too hard to decide between the two!!! They are both awesome, different, but also similar in things like rhythm, imaging, quietness, and drive. Where they differ might be to tube pre matching (they are both being driven by a Juicy Music Peach). The RM-10 seemingly more clear/air and has a little more punch. The 200 has better tone and more grounded low end with a deeper soundstage, although it is little more full creating what sounds like some midbass bump ( I could being not describing this correctly). The RM-10 can be a little fatiguing at times, but I think if I drove with a passive (LDR perhaps) it might mellow things out. The 200 is smoother with less fatiguing highs. I think with the 200 there might be a little impence issue with the 15k unbalanced input of the 200 and the Peach output imp. of 3.5k
The Freya seems the most likely choice given the differential balance and the friendly price tag :) |
Wonder how a Schiit Freya (balanced outputs) would pair with the RM-200? It seems to work well with several power amps I’ve tried it with so far. |
Me too, @pdreher. I bought my original for $2,000, and sold it for same when I found a Mk.2. Another balanced (via transformers) tube pre-amp that plays well with the amp is the EAR-Yoshino 868L (line only) or 868PL (take a wild guess ;-), or if you’re really flush the 912. I think ARC pre’s should be avoided, as they don’t like the amp’s low input impedance. The EAR’s will drive a 600 ohm load! |
There's also an RM9 MK2 listed by TMR with vintage Siemens EL34 tubes for $2,499 (can probably negotiate down to $2,250). I have the RM9 MK2 and have success with both RAM EL34's and GL KT88's. Great amp and a great value! I've owned many tube amps, some that retailed as high as $18K, but the RM9 MK2 is as good as any tube amp I've owned.
That $1500 price for the RM200 caught my eye. If I were in the market for a tube amp I'd snap it up in a heartbeat! |
I've used an Atma-Sphere MP-3 with the RM-200. Both units are fully differential from input to output which is an added benefit. I really don't know of another preamp that is fully balanced like the MP-3 but others might have recommendations there. However, there are plenty that offer balanced outputs which is not quite the same.
As for the tube swap I'm trying to save you that phone call because you'll be speaking to me. RAM 6BQ7A hand tested by Roger. You can play with other 6BQ7A or their "equivalents" at your own risk. Good luck trying to get those output tubes to balance. The driver and output are tied together so the offset of the driver tubes is critical.
The damping of the RM-200 is 10. That puts the output impedance at just under 1 ohm. The nice thing about Roger's amps is they respond well to light loading, which he recommends whenever possible. Meaning if you have an 8 ohm speaker use the 4 ohm tap, a 4 ohm speaker use the 2 ohm tap. Less distortion, more efficient operation, and you get more damping.
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Thanks for the help and clarification. I thought both versions were rated class A. This other person thinks that it's only the mk2 version and he thinks I'm intentionally misleading. I'm sure they sound different but that doesn't mean they both are not great amps. Some times designers change the model for a different audience who uses different kinds of speakers or that they just want to try something new and experiment. At first, I did not like the mk1 model but then I spent more time with it and realized how good it was with the tone and timbre of instruments, as well as the balance of other qualities throughout the frequency spectrum. I wish it did have a little more damped bass, but everything has tradeoffs. I will call Ram Labs about the tube swap because I know that they are used in these amps in unique ways.
Does anyone have suggestions for a good balanced tube preamp? |
The original can be sent in and brought up to Mk.2 status in every way except for the capacitor forming capability. No it can't. I was never aware of the upgrade, Roger never speaks of it these days, and if they were done in the past they aren't going to be done any longer. We will continue to service RM-200s. The 6BQ7A supplied by the Tube Audio Store are the correct driver tubes as they need to be aligned for offset which Roger does (and I will soon be doing) by hand. As for the output tubes, RAM KT-88 are stock, most folks like the Gold Lion KT-88, and my personal favorite is the GE 6550. Some people run KT-120, good luck with that. |
Yes, the first version of the Music Reference RM-200 was reviewed in Stereophile’s April 2002 issue and rated "A"(tubes). I owned the amp for several years and saved the magazine. It excelled even more with upgraded KT-88 tubes. A very solid performer, but I have since sold it and down sized to solid state integrate.
I'm not sure about subbing the 6BQ7. I would get in touch with tubeaudiostore.com and pose the question to them. |
Ah, okay. I'm pretty sure the original went into Class A after it's review by Fremer, as did the MK.2 of course. I owned one of the originals, and asked Roger Modjeski about the improvements made in the Mk.2 version. Beside the capacitor forming circuit (suggested to him by Richard Vandersteen), Roger told me he reduced the amp's distortion at high frequencies in about half (!), made the circuit more linear in general, and improved the amp's power supply and output transformers. The original can be sent in and brought up to Mk.2 status in every way except for the capacitor forming capability. You may be asking because of the new listing here on Audiogon of an original for $1500, a real good price. Even the original version puts to shame a number of higher-priced tube amps, those better known, better distributed, better advertised, and with more reviews. Brooks Berdan loved (RIP) Roger's stuff, but made a lot more money selling his customers Jadis and VTL. Brooks liked the RM-9 or RM-200 mated with Vandersteens, which made for a great moderately-priced system. |
Thanks for the reply, but I should have clarified, I meant "Stereophile Class A" rated. |
Actually, neither was Class-A, at least in stock form. Roger Modjeski offered the Mk.2 in Class-A as an option (there is currently one such listed on USAM), but I don't know if the same was true of the Mk.1. |
