What is the best way?

[KevinDean]

Among all the amplifiers I've possessed throughout my 63 years of life, the Fender Vibro-King stands out as my absolute favorite. Undoubtedly, it's incredibly loud! However, the sound it produces is incredibly rich, three-dimensional, and responsive. I'm interested in hearing your suggestions on how to retain the magical qualities of this amplifier while reducing its output volume. Should I consider a power scaling modification (preferably non-destructive if possible)? Or perhaps power soaking at the output? Maybe a PPIMV (Post-Phase Inverter Master Volume)? I'd greatly appreciate any suggestions you might have.

[Stevem]

Unfortunately a lot of great sounds only take place once a given SPL level is in the room with you.

This is why endless players have been gong thru amp after amp after amp, and a ton of them with only a single 10" speaker and your just not getting into the promised land with set up like that .

Tell your drummer that he has to play with brushes for the rest of his life and no more rim shots, it the same kinda thing!

[WhopperPlate]

Unfortunately a lot of great sounds only take place once a given SPL level is in the room with you.

This is why endless players have been gong thru amp after amp after amp, and a ton of them with only a single 10" speaker and your just not getting into the promised land with set up like that .

Tell your drummer that he has to play with brushes for the rest of his life and no more rim shots, it the same kinda thing!

While this is certainly true to an extent , the vibro king has some unique circuitry that definitely would set it apart from typical fender and Marshall derived circuits . a quasi fender standalone reverb style circuit (cathode follower on dry tone) cascaded into the two plate fed gain stages after the effects loop, with the tonestack last. That’s not even getting into the poweramp

If you hear something different and unique then that would stand to reason …

[WhopperPlate]

Should I consider a power scaling modification (preferably non-destructive if possible)? Or perhaps power soaking at the output? Maybe a PPIMV (Post-Phase Inverter Master Volume)? I'd greatly appreciate any suggestions you might have.

This amp doesn’t have negative feedback , so maybe a post phase inverter master might be the ticket to reduce volume most transparently.

[rangdipkin]

Another vote for PPIMV here... apart from no global feedback, the PI tail resistor is pretty big for a pair of 6L6, 39k! That likely means the PI doesn't have a huge amount of swing, power tube distortion (if any) will be coming later in the game. In addition to this, the PI power supply node is on the low side as well, 285 if Im reading the schematic correctly.

[cdemike]

If it's within your means, I'm a big believer in attenuators, which are not all created equal. I've been reasonably happy with my Weber MASS, but a project I have planned probably for next year is to try making the JohnH attenuator that came out of the Marshall forum (reasonably affordable, especially compared to the big-dollar attenuators like the Iron Man which get a lot of attention from guys on the internet). You can get the power tubes and output transformer working hard, which impacts the feel in my experience, though I haven't played through a Lar/Mar type master volume yet.

[WhopperPlate]

If it's within your means, I'm a big believer in attenuators, which are not all created equal. I've been reasonably happy with my Weber MASS, but a project I have planned probably for next year is to try making the JohnH attenuator that came out of the Marshall forum (reasonably affordable, especially compared to the big-dollar attenuators like the Iron Man which get a lot of attention from guys on the internet). You can get the power tubes and output transformer working hard, which impacts the feel in my experience, though I haven't played through a Lar/Mar type master volume yet.

While I like a Weber mass , it’s not transparent , and the parts for a post phase master are cheaper. I have never gotten the attenuator setup to not feel like everything is delayed and compressed . I get better dynamics straight into a cab . My 2 cents fwiw