Power tube distortion? Steve D

[Spirit of 76]

At what setting on the master volume of a 2466 are the power tubes being driven hard enough to be giving up that warm distortion? I understand that the VM has a post phase inverter master volume, Is the phase inverter valve the only power tube that produces distortion or saturation or do the other tubes play into it as well? There are claims that the PI valve is where the Holy Grail tone is generated and the other tubes just power the speakers. Is this why the ppimv exists? What's better a ppimv or an attenuator for giving the most true power distortion? If I consider getting a non master volume amp like the 1959 or 1987X is it better to use an attenuator or a ppimv?

[kissfanps]

I find the power tubes start to breakup around 4 and start to cook around 6-8 on the master.

When you have a master, you are adjusting the signal going into the power amp section of the circuit after it has already passed through preamp. Thus, you can really juice the preamp without the deafening volume.

[SteveD]

It heavily depends on how you set the preamp controls. Everyone's idea of where the sweet spot is for power amp drive varies as well.

[Spirit of 76]

I am running the detail and body at 4 and the master at 5.

[kissfanps]

With this amp, the settings are totally dependent on the guitar you are using and the type of player you are. The amp seriously puts out what you put into it. Any minor alteration in front of the amp like cable, guitar wood, pickup type and height, pot values, and how you actually touch the strings will come through. So, I always take suggested settings with a grain of salt because I might need different settings to achieve the same "tone" especially in a different room with different ears.

[TubeStack]

It heavily depends on how you set the preamp controls.

Hi Steve, thanks again for making such an amazing amp. I love my 2466 dearly. :)

Does increasing the level of the preamp controls lower the spot on the master volume at which the power tubes will distort/start to sweat?

For example, I like the preamp controls in the 3 to 3.5 range and I'm finding the power tubes don't breakup until 7-8 on the MV. If I raise the preamp controls to the 4 to 6 range, will the power tubes start to breakup up earlier, at say, 6 on the MV?

[Mats A]

As I find it with my 2266 (And I usually play HDR detail 9, body 7, bass middle and treble around 5) the biggest difference when you turn the amp up is that you get less of that high end sizzle that you hear at lower volumes (Guess that sizzle is part of the Marshall sound since it´s audible on most Marshall amps especially on lower volumes) You don´t get that much more distortion. And that happens on my amp with the master around 7 or 8 playing a Les Paul with PAF´s. The output valves may distort but I think for the most part it´s the preamp and phase inverter valves.
Many amp techs claim that transformers and speakers affect the tone more than the type of output valves.

[SteveD]

Does increasing the level of the preamp controls lower the spot on the master volume at which the power tubes will distort/start to sweat?

To an extent but you are also generating more distortion in the preamp.

Whatever the settings of your preamp controls you can tell by sound and feel when the power amp muscle starts taking a noticable effect by turning up the Master Volume. How much of an affect is optimum is down to personal preference.

[TubeStack]

Thanks Steve! It's such a cool thing that you're on this forum and so ready to help. Cheers.