Start up and shut down noise

K&K Audio / Lundahl Transformers

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Kevin,

Been a while since I have posted. I have been working on several PPP and CFSEP projects. I have been able to achieve some good results sonically but I have had some interesting oscillations (weird sounds) on start up and shut down.

My PPP amp employs cathode feedback through the primary of the OPT. I get a weird oscillation on start up when I use old stock EL84s in the output stage but only on certain speaker drivers. This does not happen using new stock EL84s. Interestingly, when the new stock EL84s are used, I get a loud sound that sounds like a slow cork pop on shut down. This does not happen with the old stock EL84s which have issues on startup.

On Cathode follower build, I get a motor boating sound on startup only when I use old stock 6L6 but not with old stock EL34s...

Short of serious trouble shooting with multiple valve complements and much hair pulling, I would like to short the outputs with an "On delay" on startup and short the outputs prior to shut down to cover all scenarios. I see you have delay kit. Could this be implemented to cover most of this?

Stuben

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Topic - Start up and shut down noise - Stuben 10:45:31 08/2/16 (2)

RE: Start up and shut down noise - KevinC 16:26:35 08/2/16 (1)

RE: Start up and shut down noise - Stuben 10:05:41 08/3/16 (0)

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