Rogue Audio M-120 vs M-150

HI KILLERPIGLET
THANKS ,I WILL LOOK INTO IT.
I WAS ALSO TOLD TO GO WITH VANDERSTEENS 3C OR MAGNEPANS 1.6 OR MEADOWLARK NIGHTHAWKS OR JOSEPH AUDIO RM25 OR PROAC'S 2,5
THE NIGHTHAWKS ARE KILLERS BUT THE PRICE IS STIFF ,LOVE VANDERSTEENS TOO. MOST LIKELY I WILL GO WITH USED.
BEST REGARDS
GEORGE

I just bought a pair of 150. These amps with stock tubes really makes my Manepan 20 top end sound very real without any harhness. I can now play Beatles,Abba,Beach Boys, and sit back enjoy until the end of time. Non harsh, Non glare, Non bright.
Very sweet like pure sex. Price tag is small.

Terryakhan
good choice,i didn't pay much for mines either(for high-end they are a bargain)and i love Beatles Abba Beach boys too as well as heavier classic rock .happy listening
george

Well, I guess it’s about time I write my impressions of the amps. Unfortunately it was nearly two months between sending the amps in for the upgrade until I could really do any serious listening. UPS took ten days to get the amps to Rogue and then a week to get them back to me. Rogue took just over two weeks to do the upgrade which was faster than they said so I can’t complain there. And just my luck, just when I got them back I had an infection that constricted my left ear canal and greatly attenuated my hearing in that ear, especially the high end. So, it’s pretty hard for me to tell a lot of difference in the sound of the two amps, the M-120’s sounded great, as do the M-150’s.

Rogue was supposed to use KT88’s with the upgrade but installed 6550’s by mistake, so after making sure the amps worked OK I took the new 6550’s out and installed the ones out of the M-120’s. I talked to Mark and he said he would either swap the tubes free of charge or sell me the KT88’s at his cost. I should have the KT88’s on Monday. I’m using RCA clear tops for the 12au7’s and 50’s vintage Matsushita 12ax7’s. As I said, I’m hard pressed to tell any major differences in the sound but for sure the sound stage is marginally wider and has a little more depth. In terms of sound quality too much time went by to tell any difference, both version sound great. I have not tried them with the stock small signal tubes from the M-120’s yet.

These amps run MUCH cooler than the M-120’s did. I’m really amazed at the difference there. The M-120’s even got the top cover over the transformers to hot to comfortably hold my hand on for more than a few seconds. The cover on the M-150’s only get luke warm, even after playing them loud for a long period of time. The output tubes also run MUCH cooler, putting out very little heat compared to the M-120;s. In a darkened room the plates on the output tubes in the M-120’s always glowed a dull red near the “wings” but in the M-150’s there is no hint of any glow from the plates. My speakers are relatively efficient at 92db/watt so both amps in triode mode will effortlessly play louder than I care to play them with no sign of any strain.

The M-120’s didn’t take kindly to the very high impedance that the powered subs presented to them and the output tubes would start to oscillate at about 2hz when I turned them up very loud and would continue to oscillate after turning them down so I would have to shut them off to stop it once it had started. The cure was a 20 ohm resistor across the output terminals. With the resistor they worked flawlessly and still had more power than I could use. The M-150’s do not do this, no matter what volume I play them at so no more need for the resistors.

I ordered a set of JJ E34L’s to try in them and received them today. Obviously they have not burned in yet but I’ll give my initial impressions. I don’t know how much less power the amps produce with these tubes compared to the 6550’s but it’s still more than I will use. The high end is very noticeably rolled off. A lot of details on the very high end that were very prominent with the 6550’s are barely noticeable with the E34L’s. At first I just plain didn’t like it, sounded almost like my tweeters had quit working but after a couple of hours I got more used to it. The bass is still very strong and dives right down to the deepest notes without ever sounding muddy, just good and clean without overpowering the rest of the music. The midrange is very nice, making vocals sound very good with no hint of harshness even on higher pitched female vocals such as Dolly Parton. In the few hours I’ve listened to them I’ve played some of the tracks I’m most familiar with from some older Dolly Parton, Dave and Sugar, Dire Straits, Pink Floyd, The Kinks, C. W. McCall, Emmylou Harris, and The Who, all on LP’s. I also played a couple of tracks from a Mary Kathryn CD and a Annie Herring CD. The two CD’s have some extremely deep bass which sounded very clean and didn’t skew up the mids. In all cases the vocals sound a little more natural than with the 6550’s. However if the high end doesn’t come around I don’t think the trade off is worth it. I look forward to getting the KT88’s so I can try them out The hard part will be leaving the E34L’s in long enough to get them thoroughly burned in before trying the KT88’s. Then, once the KT88’s are burned in I can compare all three sets to see which I really prefer. Once I get that figured out I may try an alternate brand of whichever type turns out to be my favorite. Then it will be time to experiment with different 6SN7’s in my preamp...

Well, I guess I’ve rambled on long enough. Hopefully some of it made some sense...

Have a good day
Brad

Brad,
thank you for the excellent follow-up.

I'm expecting (hey, do I look radiant or what?) the amps back soon. They've been gone for three weeks.

It'd be interesting to see how the KT88's match against the JAN GE 6550A's.

I'd also like to try some el34's in there eventually.

I tried running the amps in triode, but I found them too mushy and lacking impact so I've been running them in ultralinear. I will try he new and improved 150's in triode and see how that works out. Can youth change the mode while the amps are on?

Funny thing with the 120's, I first got them they would run hot has h-e-double-hockey-sticks, then I switched from the EH to Svetlana tubes, and the heat dropped by at least 75%. It was so bad at first, I had to keep the AC on and the door open! Heck, standing with bare feet on the floor close to the amps would feel hot, and you would not want to put your hand anywhere too close to the tubes.

I have since tried the EH tubes, and they ran fine without too much heat. Not sure what changed to cause that difference. Maybe they had to "break in" first dot dot dot question mark.

KP