[Robin]

This is first post.
Please give me some comment.

I got Music Reference RM5 Mk II this month. "REV. G" and "860728" are marked on a circuit board of the RM5.

I wanted new preamp with a RIAA equalizer, because my old LUXMAN transistor preamp got out of order. I searched a good tube preamp with a RIAA equalizer. I found RM5 at music reference WEB site and read design principles of Roger Modjeski. So I decided to get RM5.

My RM5 is running with no problem now. Perhaps it includes original electrolytic capacitors and switches. I think it was produced in later 1980s. About 20 years have past from its production.

I heard that electrolytic capacitors have limited lifetime. Should I replace the electrolytic capacitors? And what should I do for maintenance?

[Ericus Rex]

Roger does talk about old caps deep within another topic on this board.  I scanned the the topics on the first page but couldn't find it.  Do some reading of the past two pages of posts and you'll find his comments.  Basically he said 'don't worry about them'...I think.

Good luck searching and welcome to AC!

[Robin]

Thank you for your comment.

Searching electrolytic capacitors replacing, I found it is talked on "RM-5 faceplates" topic.

Speaking of updating the RM-5, the Mk III and prior versions would be at least 15 years old now.

         Question 2: Is it advised to send in an older RM-5 to have the capacitors (and for that matter resistors) checked at this point in time?

The issue with caps and resistors aging (and going out of spec) is not specific to Music Reference, but any type of electronic gear.

On most discussion boards, people advise that after 15 years, there is a very good chance that they will have drifted, dried up, etc... You may not necessarily hear or notice this changing over time, but it happens. You've still got people using gear from the '70s untouched, but I highly doubt the kit sounds anymore like intended or to potential.

This reply is applicable only to electrolytic capacitors. Mylar and other film caps do not deteriorate with age as long as no moisture gets in.

Replacing electrolytic capacitors is better, is't it? Because electrolytic capacitors deteriorate with age.

[K.C.]

Roger went through my original RM-9 when it was 17 years old and found no problems with the caps.

Having someone check your RM-5 is not a bad idea, but I wouldn't replace the caps based on assumption.

[Roger A. Modjeski]

Don't fret about the capacitors. In my designs they last a very long time because all my equipment runs cool. Electrolytic capacitor life is directly affected by temperature doubling for every 10 degrees C. Film caps don't much care about temperature but they do care about moisture.

There were indeed some capacitors made in the 50's and 60's that developed problems. The bumblebees come to mind. Their problem was a failed experiment in molding a case that later cracked and let moisture in.

Case in point: I just finished going over a Marantz 8B power amp. All the power supply lytics were fine and very high quality. Some small cathode bypass caps were fine too. The only thing I replaced was a 2 section lytic in the bias circuit. It had lost it's end seal but was still working. I replaced it because the negative bias is something we don't want to loose.

I hope this puts some to rest.

[Robin]

Thank you, Roger.

I'll use my RM5 under cool condition as possible as I can. So my RM5 must run without trouble.