Mig-50

[jobedissectional]

I ama bass player, but I have this as a play amp for guitar. The thing desperately needs new tubes. I have always had solid stat bass amps (I amnot counting the tube pre-amps) so I really do not know jack squat about tubes.

Does anyone know what tubes I need? I would also like input on varieties of brand and type that might change the sound (keep in mind that this is not my primary rig and I do not want to blow a lot o cash on it). Lastly, someone mentioned I should have it "benched" when the tubes are replaced... what does this mean? Is it neede?


Thanks

[gtrdr]

This amp takes 2 x 5881/6L6 power tubes and 3 x 12AX7 preamp tubes.
I personally like Groove Tubes, but other good alternatives are ElectroHarmonix and JJ. The 5881 and 6L6 are essentially interchangeable.

The whole "benchwork" is basically to set the grid bias of the power tubes, which needs to be done whenever you change them. It should be done by a technician, and should cost around $25. If you buy Groove Tubes and end up liking them, you can use the same type and grade (they are graded from 1-10) and never have to worry about the bias again. If you're really adventurous, you can try setting it for KT-66 tubes (another 6L6 substitute, though has some different bias requirements than the 6L6, but almost always can be set appropriately). The KT-66 is an awesome sounding tube, and since the Sovtek is essentially a Marshall clone they would probably sound good - the Groove Tubes KT-66HP would be my recommendation. If you're happy with the amp, though, stick with what you have.

[Whoopysnorp]

You can sort of get away with not biasing with every tube change, but you run the risk of either running your tubes very hot and thus getting very warm tone but shortening the tube life drastically (Van Halen ran his tubes very hot) or running them very cold and getting harsher, more unpleasant tone (the bias of the Peavey 5150/6505 amps is fixed very cold from the factory). You want to find the happy medium that gives you reasonable tube life and warm tone.

[Ol'boy rivers]

More on tube types, Depending on -how- you play your bass mabye you should look into different tubes. I'm assuming the amp came with 12AX7's, Try a set of 12AT7's and see the difference. ( Tonally, There will be one. I wouldn't stoop all the way to 12AU7's, They start to lower volume drasticly. ) There is another 12A*7 type, That is just between a 12AX7 and a 12AT7, Try them all in different positions ( Driver tubes, Preamp tubes. ) and see what happens. ( If you don't know -alot- about your amp and the tube positions, Just by a set of a single type of preamp tube and go crazy. ) And, I don't know if the amp is Class A or AB. ( It wasen't stated, I'm just trying to help you out here ) If it is class A and you are SURE IT IS CLASS A then you just need to purchase a new set of Power tubes, Class A requires no Bias settings.