Fillmore 50 Half power switch

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golfnut

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I'm just wondering how this half power switch works? I thought maybe it turns off one of the 6L6 tubes. When I look in the back of the amp they are both lit up.
 
Likely pentode and triode modes, although the owner's manual does not mention it. The 25 watt setting really works well for bedroom use. It actually behaves like a 25w amp.
 
In my FM 100 manual it states that for the 25W or low setting the wiring is switched from pentode to triode. The half setting puts 2 power tubes into standby reducing the power by half.
 
Boogie Chillen said:
In my FM 100 manual it states that for the 25W or low setting the wiring is switched from pentode to triode. The half setting puts 2 power tubes into standby reducing the power by half.

So if I am to assume that one of my 6L6 power tubes is put in to standby for the half power switch then my question is, am I wearing out one of the tubes more than the other? I've been running on half power alot and I'm thinking that 80% of my use is going to be on half power.
 
golfnut said:
Boogie Chillen said:
In my FM 100 manual it states that for the 25W or low setting the wiring is switched from pentode to triode. The half setting puts 2 power tubes into standby reducing the power by half.

So if I am to assume that one of my 6L6 power tubes is put in to standby for the half power switch then my question is, am I wearing out one of the tubes more than the other? I've been running on half power alot and I'm thinking that 80% of my use is going to be on half power.

This is from the Mesa website on the amplifier features tab for the Fillmore 50, under Power Amp Details,
"MESA's proprietary Dyna-Watt™, Class A/B Power Amp with a single, global Full/Half Power Switch - Each setting features a different wiring configurations, Pentode or Triode respectively. Choose from 2 power tubes operating in Class A/B Triode for lush harmonics and a sweet, liquid feel at lower volumes, producing 20 (Clean)/28 (Max) Watts or; 2 tubes operating in Class A/B Pentode for maximum power, punch and clarity, producing 40 (Clean)/60 (Max) Watts."
I don't think that the FM 50 has a standby mode for half the power tubes like the FM 100 has. All your power tubes are running in each power setting, just different wiring.
Have a look at pg 24 of your manual, the tube replacement diagram, it shows what is going on for each power setting.
 
Boogie Chillen said:
golfnut said:
Boogie Chillen said:
In my FM 100 manual it states that for the 25W or low setting the wiring is switched from pentode to triode. The half setting puts 2 power tubes into standby reducing the power by half.

So if I am to assume that one of my 6L6 power tubes is put in to standby for the half power switch then my question is, am I wearing out one of the tubes more than the other? I've been running on half power alot and I'm thinking that 80% of my use is going to be on half power.

This is from the Mesa website on the amplifier features tab for the Fillmore 50, under Power Amp Details,
"MESA's proprietary Dyna-Watt™, Class A/B Power Amp with a single, global Full/Half Power Switch - Each setting features a different wiring configurations, Pentode or Triode respectively. Choose from 2 power tubes operating in Class A/B Triode for lush harmonics and a sweet, liquid feel at lower volumes, producing 20 (Clean)/28 (Max) Watts or; 2 tubes operating in Class A/B Pentode for maximum power, punch and clarity, producing 40 (Clean)/60 (Max) Watts."
I don't think that the FM 50 has a standby mode for half the power tubes like the FM 100 has. All your power tubes are running in each power setting, just different wiring.
Have a look at pg 24 of your manual, the tube replacement diagram, it shows what is going on for each power setting.


Thank you.
 
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