Stereomour II Question

[Cary]

I know this question is somewhat subjective. I own a SEX 2.1 with upgraded caps and C4S, what would be a difference in sound quality between it and a stock Stereomour II?

[Paul Birkeland]

The stock S2 will have about double the output power and more hum (without the DC filament supply upgrade).  The output half of the 6DN7/6FJ7 is definitely not as linear as a 2A3, but PJ has it loaded pretty conservatively for low distortion and noise in the SEX amp.  The Stereomour II definitely has room for upgrades that take it way beyond what a maxed out SEX amp can do. 

I would say on a subjective side I am always surprised by how good a SEX amp sounds on speakers, but the added headroom and linearity from the Stereomour is immediately apparent when switching between the two.

[Cary]

Thank you Paul! I have a possible deal going for a pair of Mcintosh MC50 amps, for the price of a stock Stereomour. I personally think the Stereomour maybe is the way to go, since I can upgrade it. The Mcintosh amps would need restoring.

[IndyNate]

FWIW before I became a 45 convert, I had a 300b and 2A3 amp I would switch back and forth, and I was always astonished how much I preferred the 2A3 over the 300B. Thick and gushing midrange that really inspired me. I've not heard any of the S.E.X. amps, but the 2A3 also always beat out any single ended indirect heated triode/pentode amp heard/owned. So, if you have my ears/prefs, I think you'll be blown away by the 2A3.

[Paul Birkeland]

I had a 300b and 2A3 amp I would switch back and forth, and I was always astonished how much I preferred the 2A3 over the 300B.

This may have a lot more to do with the circuit design rather than the tubes themselves.  An amp like this is rarely designed for a 300B, but rather often the switch will simply apply 5V to the tube filaments instead of 2.5V so you can plug a 300B in.  The 300B really wants a lot more B+ voltage than a 2A3, higher output transformer primary impedance, a bit more of an air gap in the output transformer, and some extra drive voltage to really work properly. 

[Thermioniclife]

You might consider getting a hold of those MC 50's for a future project, just sayin.

[Tubegopher]

OK guys, I am going to give my opinion here. You may like it or you may not, but, I would think twice before I bought the McIntosh MC50's. Over the years, I have owned MC240's and MC275's. This was some years ago.
They are very nice looking, but I never fell in love with how they sounded. I am currently listening to a couple of single ended, mono block 300B amps that Paul Birkeland provided design assistance on and I have never been happier. The McIntosh amps don't hold a candle to well designed single ended 300B amplifiers with quality output transformers. Yes, you have to use efficient speakers as they don't put out the 50 or 75 watts per channel, but ... they just don't sound as good. Get speakers that are 92 db 1 watt one meter or higher and you will be pleased!
Again... just my opinion from a 72 year old that has been involved with audio since the 1970's.

I used to manage the original Magnolia Hi Fi store in Magnolia village back in 74-75 era. I remember having a McIntosh Service Event where Dave O'Brien serviced several McIntosh MC240 and MC275 amplifiers. He would put his metal sticker on the amps with DOB as his signature!

[Paul Birkeland]

The MC-50 is a solid state monoblock with autoformers at the outputs. 

If you're shopping for MC-50s, I would take a meter and check to be sure there isn't continuity between the legs themselves nor each leg and the case of each output device (with the amp off of course).  Finding replacement output devices for some of these amps can be a huge challenge!