[celo]

I have never owned a tube amp. I have owned, tube DACs, CD Players, preamps but they are easy to maintain. I always read people need to change their amp tubes after certain hours and things get expensive, you need to change tubes to get it going Then there is biasing, etc.

Can someone tell me the pros and cons of owning a tube amp?

There is a Music Reference RM-9 for sale locally and I was wondering if this one is a good start for me. They are pretty powerful for a tube amp, 100wpc, but it is pretty old (unit looks clean) What should I look for if I decide to go with this amp?

The video/image of the amp.

https://www.dropbox.com/scl/fi/qxxagvev71pt3kox8ln55/ScreenRecording_09-02-2024-21-34-37_1.mov?rlkey=aorm0fab83ystt2zhw7igcwbr&st=1ztwzey4&dl=0

[FullRangeMan]

Can someone tell me the pros and cons of owning a tube amp?[/color]
Just dont buy amps that use silly tubes as 300B or rare tubes.
As a first amp also stay away from big Triodes as 845,211,805.
How old are the amp?
Good capacitors may last 10/15 years, good transformers 20.

What should I look for if I decide to go with this amp?
Why the owner are selling?
There is any inside photo?
Any amp audition ?
http://www.glowinthedarkaudio.com/music-reference-otl1.html

[musicdre]

pros:  liquid sound.  ability to tweak sound via tube rolling.  heat (in winter). 
cons:  need to match with appropriate speakers. getting too caught up in tube rolling.  heat (in summer)

unlless you have very inefficient speakers, imho, you dont need/want a 100wpc tube amp.  with tube amps, the lower the power, often the better sound
if you do have inefficient speakers, borrow some more efficient speakers to try out tube amp

listen to some tube amps.  if no availability locally, travel to an audio show.

have fun in your investigation.  and report back.

[FullRangeMan]

you dont need/want a 100wpc tube amp.  with tube amps, the lower the power, often the better sound
+ 1. Mainly SET amps under 10W.

[celo]

Thanks for the replies. My speakers are relatively insensitive, 83db, nominal 8ohm, min 6 ohm. So, not too sensitive but easy load.

[FullRangeMan]

This really bad news, you will need a huge amp with a muscular power supply.

[/mp]

Roger A. Modjeski, the man behind Music Reference died about 5 years ago. He built & sold electronics under the Music Reference banner. Try the wayback machine to access its website. He also tested & sold tubes under the RAM Labs banner which his former apprentice still runs AFAIK. I suggest contacting him for more information about RM9s, servicing them, parts availability & possibly info specific to this particular unit.

Music Reference had a manufacturers circle at this website. Consider reading it for more info. Several of his models were reviewed over the years. One can google for them FWIW. Trust your own ears.

RM was generous with his time & knowledge. He is missed.

[Leadfeathers]

Hi all -
  Don't know that I have much to offer here, beyond my experience with an RM-9, especially of a technical nature.  And, also, I came here looking to post an RM-9 question, so I'll piggyback on this thread.
   First of all, I've owned my RM-9 for 15+ years, though inconsistent use over the last few because I moved to a place with a poor listening room, so didn't feel that I was getting as much from it.  But, that amp has provided me the most delicious listening I've ever had.  It had EL-34's as the power tubes when I bought it, and the previous owner included 6550's with the purchase, which I think I switched to pretty quickly. 
   Several years ago, I switched to KT-120's, using 4 of those vs. 8 of the other.  (This change was endorsed by Roger Modjeski, the designer/builder of the amp, in a thread here on Audio Circle.) Truly loved the sound, clarity, bass. First experience of 3 dimensional soundstage. 

[Leadfeathers]

Continued reply, didn't intend to post yet.
  About 2 years ago, I lost the right channel.  Took it to a nearby electronics repair service, paid about $400 to get it going again.  Never felt like it returned to its previous quality of sound or depth. 
  So, when the left channel went out about 4 months ago, I looked for another place to take it.  Found George Meyer Audio in Los Angeles, who basically went through the whole unit, replaced multiple caps, and other items.  Which leads me to the questions I came here for:
  1.  The guy I dealt with said my 4 KT-120's had to be replaced because they had "no gain".  He said not to use them in the newly repaired unit or I'd be bringing back to them for repair again.  I know from my efforts to isolate the problem with the left side, swapping everthing around, that all 4 tubes functioned and amplified, so I didn't really get what he was saying.  But he wasn't inclined to explain much. 
  So, any thoughts about that?  I've ordered replacements anyway.
  2.  Besides the 8 power tubes, there are 4 others in this amp, all 6922/6DJ8.  I think they are identified as input tubes, and driver tubes.
      One of the driver tubes was bad.  I have multiple pair of that size and pin configuration.  My question to the experienced among you is, from a tube-rolling perspective, which of the pair, input or driver, will have the most effect on the sound? 

Thanks for any help.  I'll start a new thread to more appropriately place this question. 

Jeff

[mick wolfe]

I've found power tubes to be the most influential, provided both the pre-amp and driver tubes are up to spec of course. I also feel it would be a wise move to go back to the originally designed 8 power tube configuration as well. There are many possibilities in the EL34/KT77 family, not to mention KT88's as well.