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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: RE: You may be overloading the transformer. posted by lektrik on January 15, 2008 at 17:31:20:
The difference is slight, 1.6 amps versus 1.5 amps, but if the power transformer supplies the tube filaments, this might be the source of your issue.
The self-bias circuit might also be causing the KT88s to draw more plate current. This would be worth checking. Perhaps the circuit is out of adjustment.
Most transformers have a small amount of mechanical hum under no- or light-load operation. The hum can get loud if the transformer gets close to maximum design load, or if there is enough harmonic distortion in the AC (the so-called 'DC on the AC' problem). Your comment that the transformer gets almost too hot to touch after a while suggests the transformer is running close to its maximum load. Adding more filter capacitance is not a good thing to do, as it increases the resistive losses in the transformer windings.
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Follow Ups
- KT88s draw more filament current than EL34s. - Al Sekela 10:57:30 01/17/08 (5)
- More info...... - lektrik 20:44:24 01/17/08 (4)
- Confirms that it is the tube bias... - Al Sekela 12:41:11 01/18/08 (3)
- More info, again............ - lektrik 10:22:01 01/19/08 (2)
- Checked the bias......... - lektrik 16:19:21 01/19/08 (1)
- OK for the tubes, perhaps too much for the power transformer. - Al Sekela 12:01:05 01/20/08 (0)
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