Power Cycling Mystery

It could be a simple relay that is making a bad connection. When you cycle it off, it will clean itself and make a new connection, at turn on.

Another possibility is, somewhere in the circuit, there can be a bad connection. The inrush current (at turn on) can cause a little arc, and temporarily weld/solder the contact back together. This also can happen inside a semiconductor itself.

Hi Bryon,

I don't see anything implausible about that, and probably the explanation is along the lines of the things the others have suggested. The circuit reset that occurs at power on undoubtedly clears out and affects a great many things, which may in turn affect subtle interactions between seemingly unrelated circuits, caused by effects such as noise coupling.

It's probably not possible to hypothesize anything more specific without knowing the details of the particular design, and perhaps even if those details are known.

The one additional point I would make is that I recall that some time ago you found that removing some unneeded modules and the top cover from the G68 resolved a heat problem it had. Are you still running with the top cover removed? If so, perhaps that is contributing to rfi that may be radiated from the digital circuits in the G68 into other components in the system, which could conceivably result in the haze and high frequency distortion you described via intermodulation with signal. The rfi conceivably being sensitive to circuit conditions that would be affected by a periodic reset.

In any event, you've discovered a simple tweak that is beneficial in your particular system, so I'd just go with it!

Best,
-- Al

Thanks everyone.

Vhiner - That's an interesting theory about the clock. If power cycling results in better clock performance, then it might also result in less jitter. That's consistent with the type of improvement I experience from power cycling -- less high frequency harmonic distortion and imaging haze, both of which I associate with jitter.

Hi Al - That's an interesting theory about RFI. I never thought of that. I will put the top back on and see what happens. Thanks!

bc

Byron,

Since you're already opening your unit and you notice power changes, you might want to consider upgrading the unit's fuse/fuses if you haven't already. The improvement surprises many people.

Vhiner - I had the unit extensively modified by Reference Audio Mods -- new PSU, new clock, etc.. I believe he also replaced the fuse. I will take a look. Thanks for the suggestion.

Al - I put the top cover back on and I didn't hear any difference. Still puzzled about why power cycling would improve things, but of course I'm no EE! :-)

Let me ask another stupid question...

Could there be any connection between the beneficial effects of power cycling and the fact that, when the unit is powered down, it often emits a broadband pop/thump? Could there be some kind of "buildup," the elimination of which results in better sound?

bc