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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
sojs OP
13 posts
 
Raul:
I have thought about using V-Cap oil caps. The Teflon caps are too expensive in my application since the RM-4 uses 5.0uf value. A very reputable person in audio modification told me that V-cap teflon is 9 if Dynamicap is 10. So, I am holding off that mod for now.

Thanks,
Steve
Ag insider logo xs@2x
rauliruegas
13,050 posts
 
Dear Steve: Before I use the V-caps I try: Wima, Sonicaps, Aeon, Solen, MIT, Audicaps, Dynamicaps, Hovland, etcc.. on my speakers crossover.

For me, the V.caps hands down any of the others ones. I think that you have to try, not with the Teflon ones but the metallized prolypropylene ones. High recomended !!!!!

Regards and enjoy the music.
Raul.
s23chang
619 posts
 
The V-cap oil caps were not as preferred as the dynamicap by some reviewer on AA. He gave V-cap TFTFs 2 thumbs up. However, Teflon version doesn't come in 5 uf size from Chris's website. It will probably be surper expensive to make a teflon version that size.
Steve,
I wonder if you loose the warmness after replaced the original caps with Dynamicaps.
sojs OP
13 posts
 
S23chang:
I could not tell the sonic changes of replacing the original caps with Dynamicaps, because I have changed lots of other parts together at the same time. I know I should have modded one part at a time. The original caps are yellow colored Rel-Caps. I have also tried Auricaps at this position, and found it sounded too forward and loose. Dynamicaps are more neutral.

I had 2 different versions of Counterpoint SA-5 preamps. One was older model with yellow Rel-Caps, and the other used white Wondercaps. The one with Rel-Caps sound significantly better. It sounded very delicate, warm, detailed, and very musical. I was disapointed with the Wondercap version (dry and transistor like sound).
s23chang
619 posts
 
Hi Steve, thx for your reply.
Yes. Both the RM-4 and the Counterpoint SA-2 I have are the yellow Rel-Caps. Exactly like what you described.
Rm-4 had additional by-pass cap to enhance or clean up high frequency response.
I guess the SS power supply is quicker and more dynamic than the tube version in SA-2.
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