Jump to content

Mesa Mark III and Simulclass switching... 60/100


Doittoday

Recommended Posts

  • Members

So if there's a half power/full power switch,

is half power just el34's? and full power is el34's and half 6l6's?

 

and that should affect the tone, not just the volume levels?

 

is that right? I can't find an answer in the operation manual

 

 

:confused:

Link to comment
Share on other sites

  • Members

There are 3 different types of Mark III power sections: SimulClass, 60/100 and 60 watt (and Coliseum, but that's a different beast alltogether).

 

With Simulclass, you switch between 15 (or 25 if green stripe) and 75 (85) watts. In Simulclass, the outer tubes are active, which can be either 34s or 6L6s and run in Class A.

 

In 60/100, you can switch between 60 and 100 watts (obviously), but IIRC, these power sections are designed to ONLY run 6L6 tubes. In a 60/100 or 60 watt-only setup, all tubes run in class A/B.

 

When you use the Simul or 60 watt switch, there isn't much of a volume difference. It's apparent, but it won't turn your 100 (or 75) watt monster into a good apartment amp. 15 watts is still pretty damn loud, 60 watts is REALLY f-ing loud. The primary difference is tone and feel. 15 watts compresses a LOT more at gig volumes and is much looser. 60 watts compresses a bit more than 100 at gig volumes.

 

Neither will compress at all in an apartment.

Link to comment
Share on other sites

  • Members

 

Oh cool, so I've got a Simul Class then, sweet.

 

 

On MIII's with simulclass:

 

whether its half or full power switched,

all the tubes are always active anyways? EL34/6L6's?

 

or the outer 6L6's only go active when full power is on?

 

and what's the point of this again? I'm still pretty confused

Link to comment
Share on other sites

  • Members

 

On MIII's with simulclass:


whether its half or full power switched,

all the tubes are always active anyways? EL34/6L6's?


or the outer 6L6's only go active when full power is on?


and what's the point of this again? I'm still pretty confused

 

 

On the 60/100 model, 60 watts = two inner tubes are on.

 

100watts = all tubes are on.

 

If you have EL34's on the outside and 6L6 in the inside, then 60watts will be only 6L6, and 100watts will be 6L6 + EL34.

 

-D

Link to comment
Share on other sites

  • Members

 

Wrong


My simulclass blue stripe has the half/full power switch. That is normal in the Mark III

 

 

Simulclass does not allow for half/full unless there is also an additional circuit which biases the outer power tubes back to A/B ... never seen that.

 

-D

Link to comment
Share on other sites

  • Members

 

my amp is a blue stripe...

says simulclass tagged in the back..

and has half/full power


maybe not a coincidence?

 

 

Hmm.. In this situation the class A circuit would shut off and you would be left with the 2 6L6's that are capable of 60Watts.... Makes sense to have the class A circuit only produce 40Watts. I'm thinking that you only have the 60/100 option for the simulclass then. This would need to remove the ground which would be shared by the two class A tubes.

 

-D

Link to comment
Share on other sites

  • Members

 

Your amp is labeled incorrectly.

 

 

Both these posts are correct. The explanation for the Simul-Class is correct and yes, there were quite a few amps that were incorrectly labeled. To be sure, get the schematics, open the amp and compare it to what you have, if you can't read schematics drop the chassis and give Mesa a call they might be able to give you some pointers to identify which version you have.

Link to comment
Share on other sites

  • Members

 

The long heads were labeled incorrectly.


This dude's amp is a Simulclass unless someone swiped a sticker from another amp(doubtful) and I am betting it is a long head.

 

 

This sounds right. I have a long head, simulclass red stripe and it has a half/full power switch on the front. The short heads had a simulclass switch on the back but for some reason, every long head, simulclass I've seen has a half/full switch on the front despite being simulclass.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...