View Single Post
Old 20th May 2016, 12:16 pm   #162
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
Default Re: Solid state preamp for EL84

At the moment that looks a possibility, connect the volume control to the grid again etc so it's as it was before with your preamp connected.

Measure the grid voltage and the cathode voltage both with respect to chassis.

If the valve is drawing grid current it could be a defective valve or something external.

If the grid draws grid current the grids input impedance plummets, that low impedance in conjunction with the relatively high source impedance will cause the positive peaks of the input waveform to clip.

Lawrence
ms660 is offline