Carr Roamer pentode to triode?

V

violindave

Inspired
The actual amp has two modes pentode and can switch to triode. I don't see that on the Fractal amp. Am I missing where to find it?
 
It’s a power reducing feature that if I remember correctly (I used to own one and talked to Steve Carr about this, but it’s been some years) just shuts off part of each power tube instead of turning one off completely. Apparently that sounds better. So essentially it just lowers the output power and the headroom a bit. The real amp doesn’t have a master volume, so I’m sure you could replicate the effect with the available master in the ideal settings.
 
Spanky437 said:
It’s a power reducing feature that if I remember correctly (I used to own one and talked to Steve Carr about this, but it’s been some years) just shuts off part of each power tube instead of turning one off completely. Apparently that sounds better. So essentially it just lowers the output power and the headroom a bit. The real amp doesn’t have a master volume, so I’m sure you could replicate the effect with the available master in the ideal settings.
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I'd probably try the Master Volume Trim in the Advanced page of the Amp block.

I've never actually tried it before, but might be the right choice here.

See page 18 of the Blocks Guide.
 
I’ve had an FM9 for like 2 weeks, so I’m sure you’d know better than me 🤣 I’m just pretty familiar with how Carr does things and know that it’s his way of avoiding a master volume.
 
Spanky437 said:
I’ve had an FM9 for like 2 weeks, so I’m sure you’d know better than me 🤣 I’m just pretty familiar with how Carr does things and know that it’s his way of avoiding a master volume.
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First we need to know which setting was used when modeling.

Lowering MV would be opposite (I think) of going from pentode to triode. It will have more headroom because you're reducing the input.

Increasing MV Trim would reduce the headroom.
 
unix-guy said:
First we need to know which setting was used when modeling.

Lowering MV would be opposite (I think) of going from pentode to triode. It will have more headroom because you're reducing the input.

Increasing MV Trim would reduce the headroom.
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Yeah that’s something the OP is going to have to play with, I was just trying to help. But if it was modeled in full pentode mode (most likely) then reducing the MV (which the amp doesn’t have) by half (like down to 4-6) would reduce the headroom considerably and would cause that thinner, earlier breakup that triode mode would cause. I haven’t had enough time to play with any of those real advanced settings yet, but old school amp settings I know. Hopefully the OP finds the settings they’re looking for.
 
Spanky437 said:
Yeah that’s something the OP is going to have to play with, I was just trying to help. But if it was modeled in full pentode mode (most likely) then reducing the MV (which the amp doesn’t have) by half (like down to 4-6) would reduce the headroom considerably and would cause that thinner, earlier breakup that triode mode would cause. I haven’t had enough time to play with any of those real advanced settings yet, but old school amp settings I know. Hopefully the OP finds the settings they’re looking for.
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Reducing MV doesn't reduce headroom, it increases it.

The higher MV is set, the more signal is going to the input of the power section and the more it's going to distort.

Watch the Headroom meter as you play and turn MV down. You will see that the bar gets farther from 0, where 0 is no headroom.
 
On the actual amp, which I have the shift to triode at least on violin gives a smoother, fatter [or just less highs it seems], tone with less impact, less overdriven I guess or less tube might put it better. But I'll play with the suggestions see what happens. I suspect it is modelled on pentode
 
Yeah, the switch to triode gives a mid focus to the overall amp character, and lower headroom and volume in general.

I’ve never felt that I’ve achieved a 1:1 comparison between my actual Rambler run in pentode mode and the model, even when running the axe through a 6l6 power amp into the same cab. The model breaks up much earlier, has less usable range on the bass (gets muddy, whereas I can crank the real amp’s bass), and doesn’t have the same sparkle as the real amp. But conversely, the triode setting on the amp never did much for me, as I like the bigger, cleaner tone of the pentodes.

All that said, models like the Supro and smaller tweeds remind me more of the triode setting, but in some ways better than the real amp.
 
Switching to Triode makes the tube a bit muddier, as it becomes less efficient when you get rid of the screens. You might try VARIAC settings to approximate the loss of headroom.
 
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