Senior Member
Location: Sheffield
Posts: 225
I'm John.
Croft preamp whistling.
Hi All,
I have a croft micro, upgraded by Glenn a couple of years ago to 25r spec. Over the weekend it's started to make a loud whistling sound through the speakers. It's present on both line and Phono inputs, and is insensitive to volume control position even when set to "zero". It does, however go away when the "mute" switch is engaged. Initially suspected a microphonic line stage valve, but replacing this didn't help. Anyone have any ideas?
Cheers
John
Senior Member
Location: Alicante. Spain.
Posts: 1,885
I'm Adrian.
Is it on one channel or both? Have you swapped out all valves?
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Senior Member
Location: Sheffield
Posts: 225
I'm John.
On both channels. As it's present when the line input is selected I'd assumed (perhaps incorrectly?) that the phono stage valves couldn't be the problem.Originally Posted by farflungstar
Senior Member
Location: Sheffield
Posts: 225
I'm John.
Any good amp fixers in Sheffield? (Or maybe I should send it to Mr Croft).
Pishanto Specialist & Super-Daftee
Location: Dagenham Essex
Posts: 11,215
I'm Allen.
This
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Senior Member
Location: Sheffield
Posts: 225
I'm John.
Cricket season, though.This
Banned
Location: NE England
Posts: 4,173
I'm Jez.
I can also fix it of course... as I'm sure Audio Al intended to mention if it hadn't slipped his mind....
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Pishanto Specialist & Super-Daftee
Location: Dagenham Essex
Posts: 11,215
I'm Allen.
Are you a valve amp specialist Jez ? wasnt aware of that if you are .
[
Senior Member
Location: Sheffield
Posts: 225
I'm John.
Well, it looks like it was indeed a dodgy phono stage valve. I replaced these and the whistling seems to have gone (hesitate to say for sure, as the noise tended to come and go.....).
Thanks to all for the helpful suggestions.
Senior Member
Location: East Riding of Yorkshire these days
Posts: 4,779
I'm Shaun.
Brilliant John, so glad you got it fixed so easily.
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