[copperlynx]

Dear all,

I have just bought a RM-9 MkII (my second stay with this great amp). The unit does not have Low/Medium/High gain switch. Serial # is in mid-600s.
Any other known RM-9 MkII units with no gain/feedback switch? What was the default setting for such units? I hope it is wired with "High" Gain - I remember that my previous RM-9 MkII sounded its best in "High" Gain setting. How can I find out (any R/C values to check?)
Any word of knowledge will be appreciated.

Felix

[GMuffley]

The R/C values may be listed on the schematic for the gain settings, but I have never seen an RM-9 MK I or MK II without a gain switch.

[copperlynx]

My first encounter as well. It was never installed - the top plate does not even have a hole for the switch! Here it is:

http://www.canuckaudiomart.com/view_images.php?cat=Amplifiers&catnick=amplifiers&cfid=183011&image_id=1670310

[nurxhunter]

My stock RM-9 Mk2 has no gain switch. 

[rbwalt]

i had a mk2 for 11 yrs and mine had a gain switch. the ones without are setup to sound like ones on the medium setting which was equal to a damping factor of about 10. to be sure ask roger he knows best.

rob w.

[copperlynx]

the ones without are setup to sound like ones on the medium setting which was equal to a damping factor of about 10.

Judging by the sound, this is probably correct. I would opt for the high gain setting with slightly more open sound - also a bit more suitable for my passive volume control. I will try to contact Roger. BTW, the unit is top-notch, very quiet and clean. Lots of storage time I guess.

[rbwalt]

glad you like it copper. if you get a chance listen to a rm9se. it is smoother,quieter,more dynamic, better sound staging and more open sounding.only about 18 or 19 were built.

rob w.

[copperlynx]

I noticed RM9 SE on audiogon. Outside of my current price range though...

[rbwalt]

on the rm9se. i know the owner. he bought his after he heard mine.if anyone is interested in the amp it will be in top notch shape.

rob w.

[jig50]

I also have an M9mk2 without the gain switch. When I queried Roger about this several years ago he said something along the lines of--the switch was omitted due to the fact that most users were using x-feedback position so the switch was removed for the sake of sonic purity. In comparison to a rm9mk1 I had, the mk2 had noticeably better midrange, so I guess he was onto something. I never have missed the switch. 

[copperlynx]

From my memories of the switch-installed RM9 Mk II, non-switch version sounds like medium feedback setting. With most speakers, I liked low fedback/high gain slightly more.

[rbwalt]

 when i had my mk2 i always had my gain switch set to medium.my rm9se has none and it is set at about 8 or 10 which works great on my merlins.

rob.

[Ralph]

A note of dissention: I find that the ability to control gain and therefore feedback and damping is an absolute blessing. Admittedly, my RM-9 is driving a pair of hybrid ESL's, but I found that by using the LO gain setting, I could safely light load the speakers on the 2-ohm taps and avoid the numerous fuse blowings that occured on the HI gain setting. Plus, and maybe even more importantly, the LO gain further increased the transparency of the amp and eliminated the tonal imbalance between the cone woofers and the stat panels.
Ralph