Hi to all: and especially to those who can help me on this one!
I have a push-pull tetrode amp (early 90s VTL, KT88 output valves). A hum has developed in the left-hand channel, and music in that channel is distorted. Bias voltage is within spec. on the unaffected channel (300mV across 10 Ohm); both output valves on the sick left channel measure around 120mV.
The problem manifested suddenly: the amp was fine when we stopped listening one night, but sick in the left channel the next time we switched on, about a week ago.
Could you suggest a few possible causes? Within the past twelve months or so Ive replaced all electrolytics except three original computer grade electrolytics per channel, two of which are filter caps. Im suspicious of these oldies, but I might be barking up the wrong tree.
I'd really appreciate it if somebody can point me in the right direction ...
Graham Woods
Melbourne, Australia
I have a push-pull tetrode amp (early 90s VTL, KT88 output valves). A hum has developed in the left-hand channel, and music in that channel is distorted. Bias voltage is within spec. on the unaffected channel (300mV across 10 Ohm); both output valves on the sick left channel measure around 120mV.
The problem manifested suddenly: the amp was fine when we stopped listening one night, but sick in the left channel the next time we switched on, about a week ago.
Could you suggest a few possible causes? Within the past twelve months or so Ive replaced all electrolytics except three original computer grade electrolytics per channel, two of which are filter caps. Im suspicious of these oldies, but I might be barking up the wrong tree.
I'd really appreciate it if somebody can point me in the right direction ...
Graham Woods
Melbourne, Australia