High gain cathode bias bros?

  • Thread starter Thread starter Nigel
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Nigel

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Anyone here into it? I've got the bug and love it. My dad is the same way. He'd been playing a Guytron but heard my Orange Rocker 30 and bought one immediately. Needed a loop so he got a sick deal on a Rockerverb MK III and converted it. Happiest he's ever been.

I fought my Zinky Mofo for years, but now with asymmetrical clipping and cathode bias, there's no hint of harshness (mismatched power tubes by 10 ma) and still have plenty of cut. I burn through KT77's like the Guytron does EL-84's but man, oh man, the tone is finally God-tier.

Anyone else like big bottles and cathode bias for high gain glory?
 
I’ve always wanted to try it. I think it would be glorious.
 
CB is squishy but has a nice rawness factor and character with the lack of Negative Feedback..
 
Fixed or cathode bias has nothing to do with whether the circuit uses negative feedback. Negative feedback comes off the OPT and connects to the phase inverter.

My experience has been that cathode bias only affects the feel, making the amp more saggy / squishy vs fixed bias. I haven't detected any effect on tone. The squish can be overcome somewhat by using a massive bypass cap on the bias resistor. Something in the 1000uf range works well to stiffen things up a bit if you want.

I own a Rocker 30, and think its a cool amp for sure. Very unique tone and feel. It's the only cathode biased / high gain design I've come across .
If anyone is aware of any other amps like this, please post them up.
 
fusedbrain said:
Fixed or cathode bias has nothing to do with whether the circuit uses negative feedback. Negative feedback comes off the OPT and connects to the phase inverter.

My experience has been that cathode bias only affects the feel, making the amp more saggy / squishy vs fixed bias. I haven't detected any effect on tone. The squish can be overcome somewhat by using a massive bypass cap on the bias resistor. Something in the 1000uf range works well to stiffen things up a bit if you want.

I own a Rocker 30, and think its a cool amp for sure. Very unique tone and feel. It's the only cathode biased / high gain design I've come across .
If anyone is aware of any other amps like this, please post them up.
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The Rocker runs at 325v of B+ and tubes at 22-23 watts idle.

My Zinky has a 100w power transformer for 2 output tubes and runs about 480v of B+ which gets loud and is a bit stiffer. I also run the tubes at 30 watts idle each. This coupled with the Trainwreck special OT @ about 3K is neat neat neat. Super low current draw KT77’s add the beef and live a good while, as the higher draw specimens are weaker and don’t hold up. I get them matched but have different value cathode resistors on each one to provide mismatch for asymmetrical clipping and heightened even order harmonics. Quite a picky palette!
 
I had a Budda amp 20yrs ago, when people were buying them, and I believe that was CB... it sounded fine
 
I used a single ended cathode biased power section for a 2203 combo amp that I built, it works and sounds good and it makes swapping tubes a bit more convenient but an amp with adjustable bias can be tweaked more to what your ears like. I also have found that I prefer amps with NFB that the cathode biased amps don't have.

A colder bias introduces more crossover distortion to the sinewave of the output signal and tends to add a more toothy crunchiness that I tend to prefer in Marshall type amps. It has been said that slight crossover distortion is inherent to the Marshall sound and i tend to agree.

As you increase the bias hotter to tone gets warmer, fatter, smoother less crunchy. It's all about personal taste really.

I used to subscribe to the hot bias crowd like 70% of dissipation but as the years went by I realized I was was just pushing the tubes harder for not much of a benefit tonewise. These days I bias in the 50-60% plate dissipation have better tube longevity and equally great tone.
 
Those Zinky Mofo's where really great tonemachines. Weren't those descendants of the Fender Zinky Prosonic amp?
 
It’s the chassis and transformers from a Sovtek MiG60 paired with an AC-15 clean and Tonemaster (59 Bassman mod) drive.
 
Does changing the bias effect the tone ???

I haven't noticed on my amps. But does seem to effect the feel.

What benefits or disadvantages come from using 50% compared with 70% dissipation ???

I'm talking about where there isn't crossover distortion on the low side and loss of definition on the high.

I typically ran in the 65 -70% range....now I'm using 50% dissipation.
 
stephen sawall said:
Does changing the bias effect the tone ???

I haven't noticed on my amps. But does seem to effect the feel.

What benefits or disadvantages come from using 50% compared with 70% dissipation ???

I'm talking about where there isn't crossover distortion on the low side and loss of definition on the high.

I typically ran in the 65 -70% range....now I'm using 50% dissipation.
Click to expand...
In my experience it depends on the circuit and the tubes. My Zinky never sounded right unless the bias was high, which led me to cathode bias so it wouldn’t die!

My Rivera sounds great at 70%.

Guitarist in my old band had a 5150 and it sounded killer with the super low bias they’re known for.
 
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