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Hum, Ripple & Bias X

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Hi all - does anyone use these amp controls and can anyone give a simple guide on how to use them - I usually leave them at default as I only hear a difference in sound on higher hum settings, the ripple & bias X seem to do nothing to my ears 

 

all advice welcome - thanks 

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These parameters are so subtle (even in real tube amps) many players might not ever notice any difference.  

 

In a real tube amp with failing filter capacitors "ripple" is more noticeable as you play notes up the neck.  The notes mix sorta mix with the frequency of the ripple and creates a funny combined sound.  I'm not particularly fond of it but for authenticity I suppose it's a component of the soundscape?  

 

Bias mostly changes the "feel" of the output amp stage.  Cold bias will feel stiff and in extreme settings will become very bright and brittle sounding.  Hot bias will soften the feel and warm up the tone at the expense of tube life.  The other factor about bias is whether it's class A or class A/B?  In real amps the later needs to be adjusted correctly since the pairs of output tubes must equally share the positive/negative portions of the waveform.  

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If you want to see how the wave change when you tweak parameters and use Reaper (DAW), load the oscilloscope plug-in, in effect monitoring. Zooming in on the wave and start tweaking.

 

I can hear the sound change when tweaking the bias x when the preset uses higher gain or distortion effect but not hearing anything about the ripple effect.

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On a few amps, especially at higher gain, turn the hum and ripple up real high for some freaky (although to me, useless) sounds... there's some WACKY stuff it can do to your tone.

 

I pretty much always turn Hum and Ripple to 0 first ting when I dial up an amp.

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This has been posted many times here before

 

Sag

Controls power amp sag or compression 0% tight, 50% normal, 100% more touch for dynamic sustain.

 

Lower Sag values offer a "tighter" responsiveness for metal and djent playing; higher values provide more touch dynamics & sustain for blues and classic rock riffs. High Bias (closer to class A) reduces the effect of the Sag control. Sag doesn’t exist in class A amplifiers since the average plate current doesn’t change.

 

Sag is caused by the amplifiers power supply being unable to meet the demand when the map is pushed hard with high Master. When the power sags, the amp output drops and then recovers, creating a unique compression effect with some additional, but temporary distortion when you pick hard. Unlike compressors before the amp, sag compression occurs even when the amp is already very distorted.

 

Large sag gives more compression, better sustain, and can accentuate pick attack. But the amp will appear somewhat less responsive especially at the low end and can get muddy.

 

Hum

Controls how much heater hum interacts with your tone. Tube amplifiers generally used low voltage AC in the tube heaters, and sometimes this could add some hum into the signal.

 

At higher settings, things get freaky. Higher levels cause some intermodulation distortion as the heater hum mixes with the signal. Generally left at 0 unless you are looking for a specific effect.

Ripple

Controls how much AC ripple in the power supply interacts with your tone. The power supply of a tube amp is filtered with large capacitors. If the amp is driven hard, these capacitors can’t provide sufficient filtering and some AC ripple is introduced into the signal. This is similar to hum but is on the plate of the tube instead of the heater and has a different shape.

 

At higher settings, things get freaky. Also generally left at 0 unless you are looking for a specific effect.

 

Bias

Changes the Bias of the power tubes. Lower values achieve a "colder" Class AB biasing. At maximum, the amp is operating in Class A.

 

Higher or “hot" bias will increase the warmth, reduce headroom, distort earlier or at a lower Master setting, and (in a tube amp) decrease the tube life. Lower or “cold" bias will make the sound less sweet, but will tighten it up and make it more dynamic.

 

Bias X

Determines how the power amp tubes' voicing reacts when pushed hard, controlling how much the bias changes when the amp is driven hard. Bias X is a bit like Sag, except it controls change in a tube’s operating point due to change in the tube bias when the amp is driven hard.

 

Set low for a tighter feel. Set high for more tube compression. This parameter is highly reactive with the Drive and Master settings.

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Hi all - does anyone use these amp controls and can anyone give a simple guide on how to use them - I usually leave them at default as I only hear a difference in sound on higher hum settings, the ripple & bias X seem to do nothing to my ears 

 

all advice welcome - thanks 

 

I felt the same way initially as you about the Bias-X control but periodically I stumble upon amp models and presets where changing its settings makes a big difference. On others as you have observed changing it makes little to none. You can use a looper and find the models that are most impacted by it.

 

I tend to run ripple down low or not at all. The "Ripple" I enjoy comes on a wave, in a bottle, or was written by Robert Hunter.

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not sure exactly how to use them, but I find on some amps, raising the bias will clean up the amp, while lowering it on others will clean it up.

 

grab the bias, slide it up, slide it down, see what you like.

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not sure exactly how to use them, but I find on some amps, raising the bias will clean up the amp, while lowering it on others will clean it up.

 

grab the bias, slide it up, slide it down, see what you like.

yes it seems like a headroom type control

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Hi all

I think that the sag, bias and ripple controls all work together in a useful way....

I use the Helix into a power amp and guitar cab (no cab modelling), mostly with clean-ish and fairly moderate drive sounds. I had always felt that, while still excellent, the Helix felt a little 'stiff', lacking the bounce I like and it had a slight sort of 'honk' in the sound which I could not easily remove with eq. I had put this down to using a SS power amp. Adjusting the bias and sag helped to a degree. I had thought that the ripple control was probably redundant and had it turned it to 0. Then by chance I found this article about ripple in the power supplies of Fender amps:

Class AB Power Supply Ripple - Amp Books

It's rather technical but a very interesting read. The conclusion is that after removing all the ripple from the amp it became lifeless, flat and lacking dynamics and chime.

As a result I experimented with the control by making identical patches with varying amounts of ripple. You have to be scrupulous about level matching between patches as setting the control around 0 is slightly hotter than when the control is some way up. It interacts with the bias and sag so there can be a lot of tweakage! Its a subtle effect but once you home in on it it's quite noticeable. I did a blind test with a guitarist friend who is very critical and he agreed with my findings without me giving him any hints.

For the sound I like, I much prefer the ripple control turned up to around 4.5. There seems to be more life in it and the elusive 'honk' has virtually gone.

Of course this could all be in my head (!), but I did spend a considerable length of time comparing tones. It might not make as much difference if you are using shed loads of gain perhaps, or if you are using modelled cabs, I don't really know- it may even be undesirable for you. However, it has made a subtle but still big difference for me in the tone and feel that I like. I'm fairly sure that Line6 would have set the models default values to match the real life amps.

Give it a try and see what you think...

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I use the Helix into a power amp and guitar cab (no cab modelling), mostly with clean-ish and fairly moderate drive sounds.

 

Very interesting and now that I read your experience and the article I'd be interested in what power amp you are using

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Sag, Bias and Bias X won’t do much unless the power amp is distorting. If the master is turned down and the gain turned up, the preamps will be contributing the distortion and Sag, Bias and Bias X won’t do much of anything. If the master is turned all the way up, the the initial distortion will be in the poweramp and then these controls will have some impact.

 

Rather than talk about cold/hot bias, I’ll use the parameter values. Bias at 0 will make the power amp a bit cleaner, brighter (it will take more drive to make it distort) and possibly harsher. Bias at 50 will be how the amp was generally intended to run and is a good starting point. Bias at 10 will make the amp distort earlier and make it harder to clean up as you turn the drive or guitar volume down. Some amps might distort all the time if the bias is set really high.

 

BiasX is like sag - it controls how much the bias changes as the amp is driven harder. If the power amp isn’t clipping, BiasX will have no effect. If the power amp is clipping a lot, the BiasX will have more effect. BiasX at 0 will not change the amp tone much as the power amp is driven harder. BiasX at 10 will cause the Bias to change more as the amp is driven harder.

 

Now how that matters and effects the sound is a bit less clear to me. Here’s a guess. As the power amp is driven harder, the power supply sags under the load - plate voltages go down while the bias voltage goes up (since the bias voltage is negative). Having the bias voltage go up makes the bias hotter as the amp is driven harder. So the amp will distort a bit more. But it will also get warmer, there will be less highs and fizz as you drive the amp harder. So BiasX might act somewhat like a dynamic hi cut - as the amp is driven harder and distorts more, there’s a bit more high cut to tame the fizz. This can be very useful.

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Very interesting and now that I read your experience and the article I'd be interested in what power amp you are using

 

I'm mostly using a Matrix GT800FX, but I also have 2 guitar cabs with built in amp modules that are originally intended to be used to make passive PA cabs active. The amps are JB Systems AVM-1, a 300W flat response power amp. The result were very similar with either setup. 

 

(As an aside, I have also measured the effects of the sag control and it does have some effect even before the power amp audibly distorts. It can help give something like a twin reverb a degree of life even when it sounds clean.) 

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Sag, Bias and Bias X won’t do much unless the power amp is distorting. If the master is turned down and the gain turned up, the preamps will be contributing the distortion and Sag, Bias and Bias X won’t do much of anything. If the master is turned all the way up, the the initial distortion will be in the poweramp and then these controls will have some impact.

 

Rather than talk about cold/hot bias, I’ll use the parameter values. Bias at 0 will make the power amp a bit cleaner, brighter (it will take more drive to make it distort) and possibly harsher. Bias at 50 will be how the amp was generally intended to run and is a good starting point. Bias at 10 will make the amp distort earlier and make it harder to clean up as you turn the drive or guitar volume down. Some amps might distort all the time if the bias is set really high.

 

BiasX is like sag - it controls how much the bias changes as the amp is driven harder. If the power amp isn’t clipping, BiasX will have no effect. If the power amp is clipping a lot, the BiasX will have more effect. BiasX at 0 will not change the amp tone much as the power amp is driven harder. BiasX at 10 will cause the Bias to change more as the amp is driven harder.

 

Now how that matters and effects the sound is a bit less clear to me. Here’s a guess. As the power amp is driven harder, the power supply sags under the load - plate voltages go down while the bias voltage goes up (since the bias voltage is negative). Having the bias voltage go up makes the bias hotter as the amp is driven harder. So the amp will distort a bit more. But it will also get warmer, there will be less highs and fizz as you drive the amp harder. So BiasX might act somewhat like a dynamic hi cut - as the amp is driven harder and distorts more, there’s a bit more high cut to tame the fizz. This can be very useful.

Thanks! It's a very interesting and practical information.

Much better than the usual explanation I already read many times without understanding the effects.

 

Even if I could not put together such a good understanding, I can say that mostly on my presets, I prefer: high master volume, low sag, medium or low bias, and high bias-X.

And I mainly use the Soldano crunch, the Litigator, the DC-30 and the Archon Clean; I still have to try the latest amp sims (added with 2.30 fw).

I mean everything at loud volume (practice room or live). With headphones or low volume monitors, it could be different.

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i may be wrong but in my experience when i turned the bias up (higher numbers) it seemed to clean up the amp a little more .. but that is the opposite to what was mentioned a post or two ago.. now i'm confused and as i've just moved house today i cant race to my helix to check

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i may be wrong but in my experience when i turned the bias up (higher numbers) it seemed to clean up the amp a little more .. but that is the opposite to what was mentioned a post or two ago.. now i'm confused and as i've just moved house today i cant race to my helix to check

Not wrong, I think - but it depends on several factors.   The beauty of the Helix is how the controls seem to change slightly, depending on the amp model.  It truly seems to react like a bias adjustment.  

 

If you've every played around with adjusting bias on an amp where you tweak, then play, then tweak then play, you'll find most amps have a "Sweet Spot" on the bias settings... more like a "Sweet Window"... where it seems to sound better, but not night and day.   Helix appears to have this as well.  Each different amp - to my ears - has a different reaction to the bias, bias X, hum, ripple, sag, etc.... One amp may sound best with bias set higher, while others may sound best with bias set lower, etc... and since all 5 of these parameters are somewhat interactive, that setting may move around based on how you have the other 4 set.    

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Hi all - does anyone use these amp controls and can anyone give a simple guide on how to use them - I usually leave them at default as I only hear a difference in sound on higher hum settings, the ripple & bias X seem to do nothing to my ears 

 

all advice welcome - thanks 

Half the problem is line 6 and their bugs. The ripple control doesnt even work half the time.

 

Listen, if you want to hear the ripple control working, load up line 6 elektrik and load a darkish sounding IR with that amp. Crank the ripple parameter. Play some single note stuff higher up the neck. G minor pentatonic on the 15th fret will be perfect. If the effect is not completely evident to you at that point, something is not working right for you. It should sound a bit like a low level harmony or octaver. 

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Better yet just load L6 Elektrik from the Amp+Cab blocks, because as soon as you switch the cabinet the ripple control stops working.

 

EDIT: No it doesnt quit working....It just turns it into the bias control or something lol...Oh boy.

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