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Conrad Johnson Classic noisy channel.

I have owned this from new and upgraded it to se.Before and after the mod,the left channel tube rush becomes noisy after 3 months use.I am a moderate user,approx 3-4 hours use per day and do not leave the pre on when not in use.I have used 3 sets of mullard m8080/cv4058 tubes with the same result.Swapping tubes from left to right,noise swaps to right channel.Have had pre checked and all tube voltages are within spec.Are there any other classic users with this problem.Dave.
dre

Showing 3 responses by erik_squires

erik_squires
5,268 posts
 
The PV10 has a single power supply though, not sure about the classic. The odd part is that it's only happening on one channel.

Later PV models had split power supplies per channel.
erik_squires
5,268 posts
 
Wait, swapping tubes works? Why don't you just swap across sets?? :)

Keep the good one and swap out the noisy one. Am I missing something?
erik_squires
5,268 posts
 
So as the PV series progressed they added regulator sections, for reliability and channel isolation.

The 10, having a single regulation pathway, would get noisy on both channels at the same time, but I believe by the 12 it was staggered, with one shared regulator, followed by two individual sections.

In either event, I strongly recommend heat sink fins on those little regulators to improve the lifespan. About $0.20 or something, super cheap. Use a tiny bit of grease and pop them on. 

Best,

E
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