Power Tube Bias Settings

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trendkill1168

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I know the majority of you out there are most likely seasoned tube amp users and are already aware of this but I thought I would post it anyway. I play metal and have always used solid state amps and am particularly fond of Randall in general. I have always wanted a really nice tube head so I got some cash together and bought the MTS because of it's versatility. So far I have the Recto and XTC modules. I have had the head for a couple of months but have not been totally happy with the sounds I've been getting and was wondering if I had made a bad choice. It has always had a good amount of gain and great bottom end but for my lead tones I was surprised that I was not getting good sustain and harmonics and overall my high notes just sounded flat. I am not the type of person who just gives up on things easily so this prompted me to try out a graphic EQ and then an overdrive pedal. I ran these pedals every which way and still the amp was not responding well. I then put a call into Eurotubes and condidered trying out a new set of power tubes and or preamp tubes. My head came equipped with JJ E34L's and I was told to make sure they were biased properly before I bought a new set and to run the them between 35 and 42 millivolts. So I wandered down to Radio Shack and purchased a digital multimeter for $19.00. Came home and tested the tubes and they were all burning at different settings and one was as low as 29 millivolts. I adjusted all of them to run exactly at 38 millivolts and plugged in. Holy ****!! This has made all the difference in the world. The amp is now everything I was looking for. Tons of sustain, high notes are ringing out clearly, there is great separation of all the notes when playing chords and it just has that killer tube amp vibe I was looking for. I can't wait to check out some of the other modules now. Only gear I am running at the moment is an MXR Micro Amp in the loop for clean boost on leads and a BBE Sonic Maximizer. I hope to get a G Major in the future for Midi controllable effects. So if your new to the MTS and you ain't getting the sounds you were hoping for check your bias levels. It only took 5 minutes to get it straightened out.
 
+100.

My RM50B combo's bias was outta whack straight from the factory, I think because it got a pair of crappy power tubes. They were horribly mismatched, I think because one was getting ready to go out - one had a red-colored "Ruby Tubes" logo and the other had a brown-colored logo, I think because the silkscreen was frying on the glass.

I also got a new pair of matched power tubes (the winged C Svet 6L6s) and the $19.00 Radio Shack multimeter, replaced and rebiased. Sound MUCH better and no problems since.
 
Jeff R said:
+100.

My RM50B combo's bias was outta whack straight from the factory, I think because it got a pair of crappy power tubes. They were horribly mismatched, I think because one was getting ready to go out - one had a red-colored "Ruby Tubes" logo and the other had a brown-colored logo, I think because the silkscreen was frying on the glass.

I also got a new pair of matched power tubes (the winged C Svet 6L6s) and the $19.00 Radio Shack multimeter, replaced and rebiased. Sound MUCH better and no problems since.

I'm telling you man, I was starting to get paranoid. It just puts a big grin on my face when I fire it up now. Mine was brand new too and I'm surprised that they were that far out. How do you like those 6L6's? I was contiplating running 2 E34L's and 2 6L6's to see what that sounds like but for right now it sounds wicked. Eurotubes told me they had a set of hot preamp tubes that I may want to try in my high gain modules so I may check them out. They are JJ High Gain ECC83S - 12AX7's. Only cost $10.00 a piece so it may be worth it to give them a whirl in my Recto module. Right now I think it runs Sovtek 12AX7's. The XTC module has Ruby preamp tubes.
 
My combo only uses a pair, not a quartet, and I'm running 6L6s. I've only used Boogies and Fenders over the past 10+ years so I'm a 6L6 fan by default. 34s to my ear sound better in a live performance environment playing rock but I don't gig anymore, I just play around the house and studio stuff every now and then, so I'm fine with the 6L6s in those applications. In the meantime I can manipulate my Recto module's gain and eq knobs to get a pretty convincing Marshall sound when I want to.

I haven't even started playing around with different tubes in modules/V1/etc. It sounds good so I'm cool for now.
 
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