JTM45 = 30 watts?

scottosan · Post by **scottosan** » Mon Jan 16, 2006 4:07 pm

The reason I'm asking is because I am getting one and want to use a Weber copper cap recto insted of tube recto. Aren't 5881's rated for 30 watts each? Are they biasing them really cold? I'm just curious about the wattage rating and blowing this thing up?

Flames1950 · Post by **Flames1950** » Mon Jan 16, 2006 5:18 pm

The tubes may be capable of putting out more watts than the circuit is asking them to.....look at some of the 2-6L6 Fenders such as the Bandmaster and Tremolux that don't push a full fifty watts, more like 30-35.......
Besides, that's thirty watts CLEAN. Who plays their JTM45 CLEAN??? It probably does the full 45-50 watts easily when distorted gloriously........

scottosan · Post by **scottosan** » Mon Jan 16, 2006 5:56 pm

Flames1950 wrote:The tubes may be capable of putting out more watts than the circuit is asking them to.....look at some of the 2-6L6 Fenders such as the Bandmaster and Tremolux that don't push a full fifty watts, more like 30-35.......
Besides, that's thirty watts CLEAN. Who plays their JTM45 CLEAN??? It probably does the full 45-50 watts easily when distorted gloriously........

Well the real reason I asked is because I just got one in from a friend to put one of my custom maste volume circuits and put in a Weber Copper Can rectifier WS1 that is just staright up silicone rectifier with no limiting like the other models. I put in my typical circuit and had reservations doing so because of not knowing how the 5881's would sound and the rectifier, etc. We were freaked out because it sounded freaking amazing, and dare I say better than the 50's and 100's that I've done for this particular store. I red that the reissue OT primary impedance was 6500 insted of 4k for (2) 5881. I'm wondering if the mismatch is what is giving it such a different sound. I just want to make sure I'm not going to blow this thing up.

rjgtr · Post by **rjgtr** » Mon Jan 16, 2006 6:01 pm

I've built a few amps using the JTM-45 output stage with both Tube and SS rectifiers. The 30 watts is largely a product of the lower plate voltages used in the JTM-45 design. I like it because it is a browner tone with a lot of body. The 5881s will be fine with the copper cap. For some fun also try a set of EL34s! The fat lower mids are great.