Notes sound pinched off ... almost like a gating effect.
Moderators: pompeiisneaks, Colossal
Notes sound pinched off ... almost like a gating effect.
I get tons of gain and volume from my wreck build but it sounds like the notes get sort of pinched off. Kind of like a noise gate effect. Anyone else experience this? If so, do you know how to eliminate it? My Marshall simply gushes in comparison!
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Tube_S_Cream
- Posts: 14
- Joined: Tue Jun 06, 2006 9:05 am
Re: Notes sound pinched off ... almost like a gating effect.
What about bias of the power stage...
Check the grid voltages of the EL34s. If they're too negative, the tubes are cutting off. A good starting point for Bias is a voltage of approx. -35V.
40 Volts ore more can cause exactly that effect you describe.
If it's so, turn down that bias voltage until you hear everything clean and undistorted with a very small input signal. If ou turn it too low, the bias current will get too high and you may see your anode plates glow. Lower than 30V is not necessary.
For better measuring you can switch 1 ohm resistors from cathode EL34 to gnd instead of a direct cathode-gnd-connection. You may leave them there because they don't harm the sound of the amp, but now you can easily measure the voltage drop across the resistor with a DVM and "translate" it to Bias-current (e.g. 10mV = 10mA).
Greetz
Tube_S_Cream
Check the grid voltages of the EL34s. If they're too negative, the tubes are cutting off. A good starting point for Bias is a voltage of approx. -35V.
40 Volts ore more can cause exactly that effect you describe.
If it's so, turn down that bias voltage until you hear everything clean and undistorted with a very small input signal. If ou turn it too low, the bias current will get too high and you may see your anode plates glow. Lower than 30V is not necessary.
For better measuring you can switch 1 ohm resistors from cathode EL34 to gnd instead of a direct cathode-gnd-connection. You may leave them there because they don't harm the sound of the amp, but now you can easily measure the voltage drop across the resistor with a DVM and "translate" it to Bias-current (e.g. 10mV = 10mA).
Greetz
Tube_S_Cream
Re: Notes sound pinched off ... almost like a gating effect.
sounds like blocking distortion. You might have missed a value somewhere on a gain stage. Too much gain ? ?