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cathode resistance

edo

Power User
It's the only parameter that is not described anywhere, including axe wiki.. What is it and what does it do??
 

groovenut

Power User
I am going to make a few assumptions here because there isn't enough context in your post to know where in the axefx or axedit you are referring to.

The cathode resistance of a tube gain stage controls the quiescent bias point of the stage. This affects how the tube clips when overdriven and the harmonic content of the stage.

The cathode resistance of a cathode follower stage is the primary load of the stage. This affects a number of things from the responsiveness of the stage due to loading, signal compression, and harmonic content based on current through the device.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Sets the cathode resistance of the power tubes. Should only be used with "Class A" amps, i.e. AC-20 DLX, etc. Lower values increase the bias current. Note that some amps have separate bias resistors while others have a shared bias resistor. The choice of split/shared is not exposed to the user.
 

Wolfenstein98k

Power User
What sort of sound effects can a user who doesn't know these terms expect? What reason would someone have to turn to this parameter?

(Just asking so there's something to add to the Wiki, and I personally have no idea what to expect from it :p )
 

Perdikament

Power User
I am going to make a few assumptions here because there isn't enough context in your post to know where in the axefx or axedit you are referring to.

The cathode resistance of a tube gain stage controls the quiescent bias point of the stage. This affects how the tube clips when overdriven and the harmonic content of the stage.

The cathode resistance of a cathode follower stage is the primary load of the stage. This affects a number of things from the responsiveness of the stage due to loading, signal compression, and harmonic content based on current through the device.
Well, while we're here and harmonic content has been brought up....
Is there a specific parameter or set of parameters that tweak the harmonic content? If I wanted to bring out more harmonic content, what should I be tweaking.. and would more prevalent Harmonics lend to earlier or more easily controlled feedback?
 

StickMan

Experienced
I am going to make a few assumptions here because there isn't enough context in your post to know where in the axefx or axedit you are referring to.

The cathode resistance of a tube gain stage controls the quiescent bias point of the stage. This affects how the tube clips when overdriven and the harmonic content of the stage.

The cathode resistance of a cathode follower stage is the primary load of the stage. This affects a number of things from the responsiveness of the stage due to loading, signal compression, and harmonic content based on current through the device.
"Darmok and Jalad at Tanagra"
 

Hubertus

Power User
Yeah, I was referring to bringing out odd/even order harmonic content, and which control(s) will allow the shaping/tweaking of these.
I don't know definitively but I think it'd be the preamp bias
''Getting the right balance of even and odd harmonics is one of the keys to achieving "edge of breakup" tones. Experiment with the bias point to find your optimum tone.''
http://forum.fractalaudio.com/threads/preamp-bias.110726/
 

Perdikament

Power User
''Getting the right balance of even and odd harmonics is one of the keys to achieving "edge of breakup" tones. Experiment with the bias point to find your optimum tone.''
http://forum.fractalaudio.com/threads/preamp-bias.110726/
Thanks! I vaguely remember reading that at some point awhile back.. exactly what I was curious about.. plus the cathode resistance in Class A as well.
I owned a few Class A Mesa Mavericks years ago & they had a sweet sound of their own.
This is all good stuff to know especially cause the Axe does such a great job on the edge of breakup stuff, these parameters should help in really fine tuning the feel & sound.
 

Perdikament

Power User
The second order is one octave up the fourth is two up & so on.
I think the 3rd order is up an octave + a perfect fifth..
...I think. :cool:
 

Rex

Legend!
The second order is one octave up the fourth is two up & so on.
I think the 3rd order is up an octave + a perfect fifth..
...I think. :cool:
Harmonics are whole multiples of the fundamental frequency. For example, a 1 KHz tone has harmonics at 2 KHz, 3 KHz, 4 KHz, 5 KHz, 6 KHz, etc. Even harmonics are 2 KHz, 4 KHz, 6 KHz, 8 KHz, 10 KHz, etc. But only some of the even harmonics are octaves (2,4,8,16...).
 
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