Simul-Class question

[DaveP]

I have a dumb question. If you have a Simul-Class and run 4 6L6 what mode should you run it Class A or Simul mode?

 

[DaveP]

Thanks, that's what I thought and through reading the manuals it never really comes out and says it, just states info on using the EL34's in the outer sockets.

 

[tony777]

FYI: Simul class mode is both class a/b and class a.
Class a mode is (you guessed it) only the two outer tubes on, what it does is that it turns the middle tubes which runs in class a/b off.

 

[emperor_black]

FYI: Simul class mode is both class a/b and class a.
Class a mode is (you guessed it) only the two outer tubes on, what it does is that it turns the middle tubes which runs in class a/b off.

I've always wondered what happens to the middle tubes in Class A. So, is it correct to say, I can lengthen the life of the middle two tubes by running the amp always in Class A?

 

[stephen sawall]

I use both all the time .... they have a different sound and feel. I use Class A less.

 

[tony777]

FYI: Simul class mode is both class a/b and class a.
Class a mode is (you guessed it) only the two outer tubes on, what it does is that it turns the middle tubes which runs in class a/b off.

I've always wondered what happens to the middle tubes in Class A. So, is it correct to say, I can lengthen the life of the middle two tubes by running the amp always in Class A?

Absolutely, they are switched off, it's only the heater that glows.

 

[straitouttahell]

FYI: Simul class mode is both class a/b and class a.

For what I know about the SC circuit, the two outer tubes are polarized nowhere near Class A. They just have a different polarization to make them sound like something that resembles Class A.

Apart from that, both choices sound good. I tend not to use Class A because it gives me the feeling as if the tone "stays in the amp" rather than being projected out of the speaker. Sorry, can't find better words to explain it

 

[dwsabianguy]

Well, true Class A or not, it sounds good to me. But I know what you're talking about with the Class A mode not really projecting, it's very quiet when compared to full Simul-Class. But you can get some really cool power amp distortion without blowing your eardrums.

I tend to use SC and switch between Triode and Pentode on my Mark IV, but it's fine to use any of them.

 

[sultan_of_sound]

Well, true Class A or not, it sounds good to me. But I know what you're talking about with the Class A mode not really projecting, it's very quiet when compared to full Simul-Class. But you can get some really cool power amp distortion without blowing your eardrums.

I tend to use SC and switch between Triode and Pentode on my Mark IV, but it's fine to use any of them.

I have an '85 SOB w/SC.... works like this:

Class-A mode: 15watt class-A biased output only.... Fender Tweed kind of tone and breakup....great for small venues.

SC mode: 15watt Class-A output "transformer-blended" with 60watt (modern, efficient) Class-AB output. Still get the great tweed tone, but add a big power boost for larger venues.

You can also pull out the two Class-A tubes and run it in pure Class-AB (60 watts) for a third tone option (SC switch ON). Won't hurt the amp.

Class-A tubes will die much faster.... their always on (unless you pull them), and they run more current through them (that's what Class-A is....always conducting). Can spread the wear out across all four tubes if you rotate them periodically (inner and outer pairs.... but only if all 6L6's).

 

[Fronzil]

I have an '85 SOB w/SC....

You can also pull out the two Class-A tubes and run it in pure Class-AB (60 watts) for a third tone option (SC switch ON). Won't hurt the amp.

Maybe you can do this in with SOB but do not do this with a Simul-Class Mark series amp!!

With a Mark you could pull the two inner tubes and run it in "Class A" mode (uses the two outer tubes only).
You need all 4 power tubes in their sockets to run a Mark in Simul-Class.

qft

 

[sultan_of_sound]

I have an '85 SOB w/SC....

You can also pull out the two Class-A tubes and run it in pure Class-AB (60 watts) for a third tone option (SC switch ON). Won't hurt the amp.

Maybe you can do this in with SOB but do not do this with a Simul-Class Mark series amp!!

With a Mark you could pull the two inner tubes and run it in "Class A" mode (uses the two outer tubes only).
You need all 4 power tubes in their sockets to run a Mark in Simul-Class.

So I'm curious.... How is SimulClass implemented (obviously differently) in the Mark series as compared to the SOB?