Make the Amp BIAS "hotter" ...... which control(s) do I adjust ?

[ben ifin]

Hi all !

Background

Probably a simple question but many moons ago - before going over to Vox/DC30 Land - I ran a real Mesa Boogie MK 3 Purple Stripe Rev / Graphic non-Simul-class Combo.

Whenever my tech set it up for me he always told me he set the Amps Bias to run a good amount "hotter" than spec ... it seemed to chew up Tubes a bit quicker ..... but I always liked this as it gave it a bit of a nicer / smoother-gain-breakup sound.

My question is:-

=> in the FM3 if I want to duplicate running an Amps BIAS "hotter" which controls do I adjust (?)

Many thanks in advance,
Ben

 

[mr_fender]

Grid Bias in the Power Amp section

 

[ben ifin]

Grid Bias in the Power Amp section

Many thanks

All the best,
Ben

 

[TSJMajesty]

https://forum.fractalaudio.com/thre...gner-ecstasy-class-a-mode.145294/post-1718463

 

[ben ifin]

Grid Bias in the Power Amp section

Many thanks

All the best,
Ben

Interestingly, on the Tweed Deluxe and the DC30 EF86 it is already set to the max. of 1.0 ......wonder why (?)

Ben

 

[mr_fender]

Those two amps are cathode biased. Same goes for the Fender Champs, Vox AC-15 and AC-30, as well as their variants like the Morgan AC-20.

 

[ben ifin]

Those two amps are cathode biased. Same goes for the Fender Champs, Vox AC-15 and AC-30, as well as their variants like the Morgan AC-20.

Thanks I'm out of my technical depth here .......

....... so given there's no setting to adjust the BIAS in these Amps ....... is there a setting to achieve the equivalent of running them "hotter" (?) -or- is that non-doable for these style amps (?)

Ben

 

[skolacki]

Thanks I'm out of my technical depth here .......

....... so given there's no setting to adjust the BIAS in these Amps ....... is there a setting to achieve the equivalent of running them "hotter" (?) -or- is that non-doable for these style amps (?)

Ben

Maybe try playing with the variac settings on the power supply page. You can run the whole amp with lower or higher voltage. You don’t even need to worry about blowing your amp up.

 

[JoKeR III]

Thanks I'm out of my technical depth here .......

....... so given there's no setting to adjust the BIAS in these Amps ....... is there a setting to achieve the equivalent of running them "hotter" (?) -or- is that non-doable for these style amps (?)

Ben

Cathode Resistance will act as the "bias" control in these amps. It acts in reverse though; lower values will result in a hotter bias and vice-versa. You can find more info in the Fractal Wiki, look in the Amp block parameters.

 

[ben ifin]

Cathode Resistance will act as the "bias" control in these amps. It acts in reverse though; lower values will result in a hotter bias and vice-versa. You can find more info in the Fractal Wiki, look in the Amp block parameters.

Many thanks for all the suggestions ^^ this ^^ did the trick for my Tweed Deluxe and DC 30 EF 86 Amp tones.

All the best to all
Ben