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RM-4 vs. MCP-33

I have recently purchased the Audio Research MCP-33 phono pre-pre amp, and compared it to my heavily modified Music Reference RM-4 pre-pre(Dynamicaps, Vashay nudes, Blackgate caps, fred diodes, premium power cord, etc) RM-4.
Here is the listening impression so far. My regular phono preamp Counterpoint SA-9 is out to Mike Elliott for upgrads, so I have borrowed my friend's Wright Sound WPP-200C for the audition.

My modified RM-4:
very transparant, lots of details without sounding bright, a little polite sounding, instruments a little thinner than the ARC unit, very smooth and silky, better micro dynamics

MCP-33:
I had to change the tubes to Amprerex Buggle Boy 6DJ8s since the stock Telefunkens sounds too thin and bright to me.
This unit has definitely more macro dynamics than the RM-4, so it is more suited for jazz and pop with rhythm. The RM-4 is more polite and silky smooth sounding, so classical music is good with the RM-4.
So, the MCP-33 has somewhat more apparant (macro) dynamics, a little more foward in the midrange, a little thicker sounding than the RM-4, while the RM-4 is more transparant, smoother and has better resolution and more detail. Occasionally, I felt a little hardness in the high frequency from MCP-33, but I need more listening before I can be sure. Guess the premium parts installed on the RM-4 has paid off (parts alone cost over $1000). The MCP-33 indeed sounds very good, and I am sure stock MCP-33 would outperform unmodified RM-4.

If I had to pick one of them, I would pick the RM-4 because the transparancy of RM-4 is quite addictive. Maybe I would change some parts on the MCP-33 and find out if it gets better.

Any thoughts on the comprasion?

My system is VPI TNT 5/JMW 12.5/Shelter 501 II/Modified Acoustat Servo OTL power amps/Acoustat model 8
Steve
sojs
76doublebass's avatar
76doublebass
254 posts
 
Thats interesting of the work done on the RM-4.
I use to own a RM-4 for about 5 years when it first came out.
I used it with the ARC SP-8 for moving coil head amp
reproduction.As I recall you could solder in your own resistor to load it too the proper value you needed.
Even stocked the unit has a wonderful bloom in the midband
and a very musical unit at that.Roger Modjeski used very high quality tubes with this unit.
The RM-4 is a great find if u can locate one on the open market used.
I have done many experimental mods using Vishays myself
and I'm very familiar what this resistor is capable of.I.E.
A huge reduction of the noise room floor,A very,very transparent resistor,which opens up this vast 3D Soundstage
that is locked tight with perfect imaging around the instruments playing in this soundfield.
I have not audiotioned the ARC Head Amp your refering too
But I'm sure if this was moded out it would sound much better then the RM-4.
Happy Listening
Don
s23chang
619 posts
 
Totally agreed with Steve.

RM-4 is the best head amp I've came across and it is still in my current setup. I only bought it because I had Roger modified one of the tube amp for me and recognized his good work. I then bought the RM-5 preamp and the phono section realized the phono section was really good ( much better than the line stage to match my system.)

I've used both the Counterpoint and Audio Reseach and neither came close to what Music Reference RM-4 offered.
I've tested the stock RM-4 with Arc SP-8, SP-11 MK II, Counterpoint 5000 and H.K. Citation I MM sections to mate with RM-4. They all worked out well with my VDH Black Beauty Cartridge.

Not only it is quieter and smoother sounding, it also has much better dynamic than both ARC and Counterpoint.
The ARC and Counterpoint has too much hiss when compared to RM-4. I've compared to many good step up transformers and I still prefer the RM-4.

You'll be surprised vintage stock HK Citation I phono section for MM is better than ARC SP-8, SP-10, SP-11, counterpoint SA5000, Lehman Black cube and etc.. Compared them in many setups and this preamp really sound better than the most. The line stage needs upgrade to better resistors (Carbon was a little bit soft and lack of focus than metal film type) and power supply caps then it will be as good or better than the most of the modern line stage. I wish Stewart Hegeman had design more of these timeless tube gears other than two amps ( Lafayette KT-550 and HK Citation II ) and this preamp.
sojs OP
13 posts
 
Don is right about Vishays. I have noticed the RM-4 to be extremely quite after installing Vishays (along with Caps).
My cartridge has about .4mv output, so tube hiss is not audible at normal listening level. So, my analog setup is deal quite at the listening position. It's pretty amazing with all tube head amp and phono preamp. With about .2mv output cartridge I would get slight tube hiss with regular NOS tubes. Low noise tubes will be dead quite, but it's hard to find NOS with low noise. Registers can be soldered to change input impedence. The RM-4 has about 30db of gain, which is a little too high for me. I am using SA-9 phono preamp volume control (providing only 0db to -15db range), and I have to use the lowest volume setting and it's not low enough for me.

I have compared the RM-4 to Counterpoint SA-2 about 15 years ago. Counterpoint sounded too thick and colored. It also emitted DC voltage when the AC line voltage changes slightly, which the factory could not fix and recommended usage of power conditioner. Even with the power conditioner my Apogee Duettas bass panal was moving badly.

I heard good things about the HK Citation One. Will try it if I have a chance.

I have ordered Bent audio TX-103 transformers and will post how it compares if you are interested.

Steve
Ag insider logo xs@2x
rauliruegas
13,005 posts
 
Dear Steve: Something that can do an improvement on your RM-4 is to change the Dynamicaps for V-caps. This ones can do a great difference ( for the better ) in the quality sound reproduction.

Regards and enjoy the music.
Raul.
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