Matching tubes in a Simul-Class

[MesieBooga]

Do I need to buy matching tubes (EL34's/6L6's) for a SimulClass IIC+? Or just matching in pairs?

 

[Joey707]

The inside pair need to match and the outside pair need to match. So, if you're using Mesa tubes, in a IIC+ simul the inside pair should be a matched pair of 6L6's color code gray. The outside pair can be a matched pair of 6L6's or EL34's. Color code red or yellow for 6L6's I'm not sure of the color code for EL 34's.

 

[mtnb1kr]

The inside pair need to match and the outside pair need to match. So, if you're using Mesa tubes, in a IIC+ simul the inside pair should be a matched pair of 6L6's color code gray. The outside pair can be a matched pair of 6L6's or EL34's. Color code red or yellow for 6L6's I'm not sure of the color code for EL 34's.

Do the insides need to be gray? Also what do the color codes means. I guess I'm under the impression that certain colors give earlier breakup or headroom?

 

[Joey707]

Yes, the inside pair need to be gray. The outside pair should be red. The color code relates to current draw. Using the correct color tubes allows the set bias to work properly.

 

[mtnb1kr]

Yes, the inside pair need to be gray. The outside pair should be red. The color code relates to current draw. Using the correct color tubes allows the set bias to work properly.

Where do I find this info. My Mark IV has 6l6's Gray inside, Red out. I'd like to try el34's and have found a guy with gray set will these work? My manual doesn't say which colors to buy only that I should buy Mesa cause of the bias match. On the Boogie web site there is no information on the coding and if you go to order tubes they don't specify which code.

 

[Joey707]

I called Mike B. at Mesa. The color codes I mentioned are what he recommeded for a IIC+ simul-class amp. I would imagine a MK IV will require different color code tubes. I would call Mesa and ask. I have never owned a MK IV so I can't tell you what's correct.

 

[MesieBooga]

Great Info 707! Thanks!