Tube Amplifiers
Trinty asked:

Furthermore, no ebay (which has turned into the land of attending too many deception) where can I convince an oscilloscope used to influence the guitar amps for a reasonable price? Links appreciated.


2 Comments so far

  1. The Legend of Lopez Aragon on September 23, 2009 7:38 pm

    Why not ask Jeeves?

  2. tkquestion on September 25, 2009 8:05 am

    You really don’t need a O’scope to do what you are wanting to do.

    Bias adjustment involves applying a correct voltage to the grid (input) side of the tube, so that when the signal appears, the tube is correctly set for class-A, AB, AB1, AB2, B, or C operations. So if you know what this voltage is, (should be on the schematic), then you’ll only need to have a volt meter with very high input impedance.

    If you want a O’scope, since you are using it in the audio range, the maximum bandwidth should be ok at around 300khz. (you’d usually want 10 times the max frequency) and DUAL TRACE so that you can see input and output at the same time. Even with this, you won’t see much. More than likely, you need to put it in x-y mode and see the slope to see what is happening at the cross over point (where it passes zero). To do this right, you’ll also need a function generator….

    It’d be probably cheaper to get this done by a professional. There are many place on the net where you can buy a used scope. Don’t forget, you’ll also need a probe, too. That’ll cost you about 50 dollars (minimum) each.

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