Half power 101

[Spewnz]

why bother? but yes prolly

 

[RectoStudioGuy]

Doing essentially the same just by flipping the switch

 

[Spewnz]

+10

Doing essentially the same just by flipping the switch

 

[RectoStudioGuy]

It'll just be more clean

 

[MrMarkIII]

Flipping the switch to half power turns off two of the tubes, correct?
(Actually, they are still "on", just switched out of the circuit for the time being.)
Removing one of the remaining pair will not lower the power to 25 watts.
Power tubes work in pairs. One pushes while the other pulls, each amplifying half the signal. Removing one of the remaining pair will make the amp sound like uber-distorted crap. If it doesn't break.

 

[94Tremoverb]

If - like all the other Mesa amps with this feature as far as I know - the half power switch works by switching off two power tubes (just the signal current, not the filaments - they will still glow orange), pulling one pair of tubes will either make no difference at all (if you pull the pair that's off) or give complete silence (if you pull the pair that's on).

But, if you are *always* going to use the amp in half-power mode, it is better to physically remove the two 'off' tubes - running tubes for very extended time with the filaments on but no current flowing is not good for them.

Some other amps (eg Marshall Jubilees and JCM900s) with half-power switches do it by running all the tubes, but in Triode mode instead of Pentode. In this case, removing two of the tubes will halve the power again.

In either case, if you're running only half the tubes, you should connect the speaker to the jack for half its impedance - ie 4 ohms for an 8-ohm cabinet. This isn't strictly essential and it won't do much harm if you don't, but it will wear out the tubes slightly faster if you don't, and won't quite sound the same.

 

[t0aj15]

prolly

Just curious, what language is that? I can't find it in my dictionary. :roll:

 

[Spewnz]

prolly

Just curious, what language is that? I can't find it in my dictionary. :roll:

wow just wow man....

 

[MesallicA]

prolly

Just curious, what language is that? I can't find it in my dictionary. :roll:

http://www.urbandictionary.com/define.php?term=prolly

 

[Spewnz]

good man

 

[t0aj15]

It really is a shame if that's the dictionary this generation relies on. Just because it's in print doesn't make it a fact. They called the last generation-gen x, what's this generation-gen lazy.

 

[ryjan]

Absolutely destroying the king's english! :lol:

 

[Spewnz]

for the record there is a vast difference between falling into the 'net vernacular once in a while and these kids with their constant use of mindless acronyms and misspellings so cool it once and while. This isn't an English Studies master class, its a board for musicians lets keep it that way. 8)

 

[Turumbar82]

It really is a shame if that's the dictionary this generation relies on. Just because it's in print doesn't make it a fact. They called the last generation-gen x, what's this generation-gen lazy.

If you need to start getting picky on words then what dictionary did you get "generation gen-X" from when it's just "generation x"

Please don't tell me that you have never used slang in your life.

 

[Old BF Shred]

Some other amps (eg Marshall Jubilees and JCM900s) with half-power switches do it by running all the tubes, but in Triode mode instead of Pentode. In this case, removing two of the tubes will halve the power again.

My old Carvin X100B was like this too. It essentially removed the voltage from the screen grid and ran in triode mode for approx. half power. Then I added a switch to lift the cathodes from ground for 2 of the tubes (on either side of the OT, that is) which stopped any current from flowing through them. That resulted in roughly "quarter power" (it was still very loud, though!). It sounded good that way....wish I'd have kept that amp..... :roll:

 

[RectoStudioGuy]

Won't hurt...just no point is all