[ROAD KING II] Is this power sag, or something else?

[kiyiko]

https://soundcloud.com/user606171745/sag

Turn my amp up to max volume, hit a big chord, and when it releases my noise floor and everything drops.

This does NOT happen when my loop/solo/output controls are set to BYPASS.

This does not happen in any case when diode rectification is ENABLED.

Only happens at high amp volume.

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Is this power sag, or some other issue? Perhaps some kind of mismatch in my FX loop or weak rectifier tubes?

If it is power sag, is it a "problem", or characteristic of tube amps?

If this is not characteristic of tube amps, what's a possible solution?

 

[bandit2013]

If it does not happen with the FX loop in hard bypass and with tube rectification in use, you could probably rule out the Rectifier tubes.
However, if it does occur with FX in hard bypass and tube rectification tracking is used, I assume the answer is yes, the tube rectifiers can't keep up and the supply voltage is dropping below threshold to maintain power tube or preamp tube operation. How much use are on the Rectifier tubes and power tubes. In general, I have not been pleased with the current production 5U4GB's. This is the tube that has given me grief more so than the power tubes in my Mark V when using 90W mode (since it is bypassed by diodes). RK and Roadster as well as the DR and TR have a different power supply design so that being said, hard to predict the life span of the 5U4GB. I have only had my Roadster since June of this year and it performs well with diode or tube rectification and most volume levels (just never ran it full tilt yet). I believe it uses the same main preamp board, only difference would be in the power board and addition of the progressive linkage. (I may be way off though).

If in all cases, when tube rectifier tracking is used, but only happens when the FX is not in hard bypass:
My assumption would relate to the cathode follower in V5 used as an attenuator for the FX send (even if the FX loop is not used with anything connected to it, it still attenuates then the other half of V5 is used to amplify the signal to be controlled by the master volume.) You can check this by changing V5 to a new tube. That would leave one question, was this something that recently happened? Cathode follower circuits are hard on preamp tubes. (note that this is just an assumption). Since it take more power or current to sustain the low frequencies than it does to maintain the higher frequencies the power supply voltage will drop due to the response of the rectifier tube is slow compared to silicon diodes. The supply voltage may be dropping low enough to cause the attenuation circuit of V5 to drop out. This is only an assumption based on your comments.