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Sag, Hum, Bias, Bias Excursion and master volume
by Pezza on 2011-04-06 02:42:34

Ok, so we can adjust the sag, hum, bias, bias excursion and master volume in the upcoming update, but what are they? I understand master volume and have a vague idea on sag but I'm sure the amp gurus here could enlighten me (and others) some more.

Thanks



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Vettaville-nl on 2011-04-06 02:47:15

May this enlighten you

http://www.aikenamps.com/Sag.html

regards

-Hans



Re: Sag, Hum, Bias, Bias Excursion and master volume
by mesaz on 2011-04-06 04:47:20

I'm all ready to get excited about a new update, but what do they mean by master volume? Each amp model already has one  i believe.

Stupid question perhaps but do they mean we will be able to set a maximum volume and all the patches you make will be automatically that volume if you want so. The bassman model is way to quiet to my taste if you compare it to the bogner or something.

Bias, bais excursion hope... it doesn't get to comlplicated, it's good as it is now i believe.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Vettaville-nl on 2011-04-06 04:50:56

The master volume (labeled as master) on POD HD series is an overal volume, applied to everything in the total chain.

Master Volume in the update is the Master Volume of the amp section only



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Rowbi on 2011-04-06 04:54:05

mesaz wrote:

I'm all ready to get excited about a new update, but what do they mean by master volume? Each amp model already has one  i believe.

Stupid question perhaps but do they mean we will be able to set a maximum volume and all the patches you make will be automatically that volume if you want so. The bassman model is way to quiet to my taste if you compare it to the bogner or something.

Bias, bais excursion hope... it doesn't get to comlplicated, it's good as it is now i believe.

the existing amp models are modelled with the master volume at full (i.e. no master volume) for NMV amps or low gain amps, and with the amster at 50% for high gain amps.

imagine for example that you think the uber is too fizzy, you can turn up the bias more, so that you get more class A tone and less CLass A/B crossover distortion.  also you can turn down the master volume parameter to get less power tube sizzle (as in real high gain amps that's what is sometimes the cause of what people call fizz... it's in real high gain amps only when you crank them up to ear bleeding volumes).

I think by the time the update is released L6 will release a statement on all this to better describe these for all to understand, so do not fret



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Crusty_Old_Rocker on 2011-04-06 04:55:42

If you don't know what those things are, you can just leave them alone without adjusting them.

Basically, you will be able to change things within the valve amp modelling in the same was as modifying the real amp.  You will be able to adjust the bias down which will lead to more power amp crossover distortion characteristics or you can raise the bias right up to the point of driving the power amp valves into class A.  You really wouldn't do that with a real amp because your valves would burn out in no time at all, but with modelling, anything's possible.

The master volume is like installing a master volume within the modelled amp's circuitry.

Cheers,

Crusty



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Texxxxx on 2011-04-06 07:07:23

Rowbi wrote:

I think by the time the update is released L6 will release a statement on all this to better describe these for all to understand, so do not fret

Yes, I hope they do release some detailed notes on these subjects for those of us (me) that don't understand them.

It the meantime, thanks to all you guys that do know for explaining them to us.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by lowyaw on 2011-04-06 07:22:49

being able to turn MV dowan on full models would be very, very handy, that will allwo you to have less dirt and less poweramp coloration(less 'farty" so to speak)



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Crusty_Old_Rocker on 2011-04-06 07:32:12

Bias excursion, as the name implies, is movement of the bias.  Driving power amp valves hard actually has an affect that moves the bias and it takes some time for it to shift and to return.  It simple terms the bias on a pair of heavily driven valves can shift toward a lower bias and introduce more distortion to the power amp valves.  Having control over this could make it occur at various levels lower or higher which would result in the characteristic being introduced at a different point.

This is an over simplified version of the phenomenon.

A very sound understanding of valve theory and class A/B power amp circuit design is required to understand how and why this phenomenon occurs.

Cheers,

Crusty



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Crusty_Old_Rocker on 2011-04-06 07:34:42

lowyaw wrote:

being able to turn MV dowan on full models would be very, very handy, that will allwo you to have less dirt and less poweramp coloration(less 'farty" so to speak)

The bias and bias excursion controls will be the controls for that splatty/f@rty power amp characteristic rather than a master volume control.

Cheers,

Crusty



Re: Sag, Hum, Bias, Bias Excursion and master volume
by chimp_spanner on 2011-04-06 07:46:01

So, just so I understand, this will allow me to use power amp modelling, with the ability to control the volume (and in turn, I guess, drive) of the power amp/master volume? I find that the power amp models add a fatness to the sound that the pres lack. But they currently also bring a lot of extra stuff that I feel I have no control over. I said in another thread that these kind of controls have been in GR4 for a long time, and they're really the key to dialling out the fart from the high gain amps. Not having been a tube amp owner, I'll have to do some real research into what these other controls do.

It's too early to say without having tried it but I certainly welcome these kind of additions to the POD. My hope is that they'll unlock the full potential of some of the high gain amps, and allow for some more pristine sounding cleans. So yes, being careful not to get too excited but it seems like L6 have really listened to their customers on this one. Think I'll just get one of those bobbing bird toys and set it to tap the F5 key until a "1.3 is out!" thread appears.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by TheRealZap on 2011-04-06 07:51:58

i just want to add to this thread that... just because a control exists doesn't mean you should monkey with it...

pay attention to crusty, and any other valuable resources you can find that explain these things...

keep in mind that the models will still sound great as is... and that you'll have 6 more models to play with before you start making adjustments to the new DEP's

(deep edit parameters)

not saying they aren't valuable in the right hands... as well as a great opportunity for the rest of us to learn...

just throwing a little caution out there....



Re: Sag, Hum, Bias, Bias Excursion and master volume
by chimp_spanner on 2011-04-06 07:54:29

One thing I wonder...is will these parameters be set on a per patch basis? Or will we effectively be altering the model 'file' itself?? You're making the whole thing sound kinda...dangerous lol



Re: Sag, Hum, Bias, Bias Excursion and master volume
by TheRealZap on 2011-04-06 08:00:35

not dangerous in the typical sense...

but imagine the frustration when someone cant get the sound they want... and those things are all messed about with.....

no idea if they will be global for the amp model... or patch specific



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Vettaville-nl on 2011-04-06 08:02:36

Logic would be on a per patch basis, so you also experiment with one model and experience what settings of these extra parameters fits your playing style, feel, behaviour or pleases your ears..

Whadda you call em Zap  DEP's??

Deep Edit Parameters, nice naming

cheers

- Hans



Re: Sag, Hum, Bias, Bias Excursion and master volume
by chimp_spanner on 2011-04-06 08:02:55

Gotcha. I mean realistically I think the most useful thing for me is just gonna be the master volume thing. So, I'll just wait and see



Re: Sag, Hum, Bias, Bias Excursion and master volume
by silverhead on 2011-04-06 08:05:05

These terms are all new to me in the context of amp modeling. As an aging (aspiring to crusty) old rocker, here's what they mean to me:

Sag - inevitably happens at the most inappropriate moments. Requires little blue pill in advance.

Hum -  'cuz I forget the words

Bias - with every passing year the back of my neck gets more and more red

Bias Excursion - my redneck symptoms get worse when I travel

Master Volume - the control on my hearing aid

Can't wait to learn new meanings!!



Re: Sag, Hum, Bias, Bias Excursion and master volume
by TheRealZap on 2011-04-06 08:15:02

yes i called them DEP's although it's actually copyright rowbinet



Re: Sag, Hum, Bias, Bias Excursion and master volume
by chimp_spanner on 2011-04-06 08:35:51

Deep Edit Rig Parameters. DERP!

Or we could make an acronym using the available tweaks.

Line 6's revolutionary SHMEB system. Rolls off the tongue.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by tommasi on 2011-04-06 08:37:19

To *me*, SAG is just GAS spelled backwards.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by mesaz on 2011-04-06 09:16:07

That's a good one, OK thanks for explaining.

The patches i've made so far are sounding good as they are, gonna make some miles with the new update before i touch them.

Thanks!



Re: Sag, Hum, Bias, Bias Excursion and master volume
by TheRealZap on 2011-04-06 09:40:38

damn i just shmebed all over my girlfriends face... hope my wife doesnt find out!



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Vettaville-nl on 2011-04-06 10:30:22

TheRealZap wrote:

damn i just shmebed all over my girlfriends face... hope my wife doesnt find out!

LOL



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Pezza on 2011-04-06 13:20:30

Thanks for the contributions everyone!

I'm assuming that when we pull up an amp model in 1.3 it's default DEPs will be set as in the original models so that, if we don't want to mess with them, the amp will have it's original sound. I'm sure ignorance of the parameters won't stop 99% of us fiddling with them though! I can't believe I'm getting so excited about sag and bias...will it really make the world a better place?!

Just another question...these parameters all relate to the power amp don't they? Does this mean that the pre models (and DT50 function) are unaffected?



Re: Sag, Hum, Bias, Bias Excursion and master volume
by markbrid on 2011-04-06 14:28:27

The master volume is exciting for one use at least; the JCM800 model.  To me that model is currently useless as you have no way to adjust it like it would be used in a real world situation.  For instance, players like Zakk Wylde will take a JCM800 2204 and run the gain on 6 or 7, boost the high gain input with a booster, and adjust the master volume to fit the hall (usually around 5 or 6).  You then get a powerful sound that is mostly preamp distortion but has lots of punch as the power amp is working hard but not clipping too much.  In the current JCM800 model, you can't really get this tone as it sounds like the master volume is on 10 and you can only adjust the high input gain.  Marshalls can sound muddy and indistinct if the power amp is clipped too much and the preamp is distorting.  I'm hoping the master volume control will allow the JCM800 to be set with lots of preamp distortion and just a touch of power amp distortion, then the goodies might pop out.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by kevmomuny on 2011-04-06 15:23:23

derp-derp.jpg



Re: Sag, Hum, Bias, Bias Excursion and master volume
by chimp_spanner on 2011-04-06 18:01:59

You've just ruined like...two things for me right there Nice. Real nice.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by johnnyayyy on 2011-04-06 21:45:16

chimp_spanner wrote:

Line 6's revolutionary SHMEB system. Rolls off the tongue.

Ewwww...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by MGblade on 2011-04-07 00:19:04

maybe line6 gonna make us buy virtual tubes, as they virtualy burn out, that will make things even more realistic



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Pezza on 2011-04-07 05:13:35

This site has some interesting stuff on sag:

http://www.mavenpeal.com/sag.html



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Crusty_Old_Rocker on 2011-04-07 05:35:50

Pezza wrote:

Just another question...these parameters all relate to the power amp don't they? Does this mean that the pre models (and DT50 function) are unaffected?

Yes.

Sag has the greatest effect in the power amp section where the big demand for electrons comes from.

Bias exists in all valves from triodes up (not diodes or rectifiers).  But the adjustable bias in the amps itypically relates to moving the point at which two power amp valves crossover when they share the load from the preamp from the phase splitter/inverter (I'm trying to keep this explanation simple).

The bias excursion refers to that bias level moving by itself when the valve is working hard, another term that gets thrown around this is power amp saturation.

A master volume can exist in several places within the amp circuit but the role it plays is affects the power amp section of the amp.

So, this would mean that the PREs should be left as is because they take care of the guitar signal before being affected by these other things.

Cheers,

Crusty



Re: Sag, Hum, Bias, Bias Excursion and master volume
by meambobbo on 2011-04-07 10:02:08

Here's a related question - the master volume parameter should affect the power amp distortion/compression.  But shouldn't it also affect the amount of speaker/cab distortion?



Re: Sag, Hum, Bias, Bias Excursion and master volume
by spaceatl on 2011-04-07 10:37:33

Quite the contrary...With "Virtual Bias" control there is less danger of killing yourself...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by meambobbo on 2011-04-07 10:54:48

But unlike a real amp, you have to keep the Pod plugged in and powered on to adjust the bias...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by KozMcCharlie on 2011-04-07 12:07:54

meambobbo wrote:

But unlike a real amp, you have to keep the Pod plugged in and powered on to adjust the bias...

There should be a disclaimer, then, for those who decide to sell the POD because the update doesn't address some imaginary issue and go back to toob amps. I mean we wouldn't want people who hear strange noises running around trying to fiddle with bias and electrocuting themselves...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by spaceatl on 2011-04-07 13:20:59

hmmm....I never adjusted bias with an amplifier turned off...A little difficult to get a reading when it's off...There is also the problem of stabilization...The amp needs to get to operating temp before finalizing adjustment...

Perhaps Line 6 could add a "shock" feature whereby the POD will shock you when you adjust the bias....

Pretty cool to see these features coming out...Where's my "Jump To Conclusions" matt?



Re: Sag, Hum, Bias, Bias Excursion and master volume
by antonior7724 on 2011-04-07 17:30:14

Is this going to make a difference in the live setting? or in a live situation using the HD as preamp?



Re: Sag, Hum, Bias, Bias Excursion and master volume
by meambobbo on 2011-04-07 17:54:51

yes, as long as you use the "full" amp, rather than the "pre", I am assuming.  Hum might be effective on both - not sure.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Pstrat on 2011-04-08 20:32:13

I'm not sure why,but this update is reminding me of variax Workbench like crazy. 

Does anyone else think a podHD workbench is a potential?



Re: Sag, Hum, Bias, Bias Excursion and master volume
by Octo777 on 2011-04-09 03:39:00

Pstrat wrote:

I'm not sure why,but this update is reminding me of variax Workbench like crazy. 

Does anyone else think a podHD workbench is a potential?

I agree, it certainly has that kind of vibe surrounding it although I imagine that these DEP's will be able to be managed via an update to the existing edit system as opposed to an outright Amp Workbench type program.

Looking forward to the update more and more now.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by gtrman100 on 2011-04-09 08:18:38

Crusty_Old_Rocker wrote:

lowyaw wrote:

being able to turn MV dowan on full models would be very, very handy, that will allwo you to have less dirt and less poweramp coloration(less 'farty" so to speak)

The bias and bias excursion controls will be the controls for that splatty/f@rty power amp characteristic rather than a master volume control.

Cheers,

Crusty

Are they going to label the bias excursion knob, "F@rt Control"? If so, my son could use one...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by John_BlisterTip on 2011-04-09 10:13:41

I didnt see the most important word in any of the posts so I'll try and simplify the practical use of this update that matters most.

TIGHT

Pods are notorious, for those with decent ears, to be extremely loose. The comments I hear most are a Cartoonish Tube sound. I dont agree with this but it gives an idea of the problem. It seems Line6 is more in love the spongy mushy sound of tubes than anything else and this causes the dreaded mushy Low E string. I love some of this but its overdone.

So what do people do? They put a dist/overdrive pedal in front that tightens up the E but unfortunately over compresses the midrange into a wah pedal.

When you have control over sag, MV, and bias you can lower their values and Tighten up your sound.

Axefx has exactly the opposite problem. Its cold and clinical--almost like there' s a pedal in front of every amp. Many people have said this.  No tube sponge sound on the low E of any amp I have heard by them(by  default). No tube fatness. The answer is somewhere in the middle. The Pod desperately needed these tools. The question is going to be--are they going to increase other problems Pods have like nasty overtones--especially around 750hz, which can easily be seen on any analyzer.

BTW..I did hear Punch..and that begins to explain it...and Splatty which explains its opposite



Re: Sag, Hum, Bias, Bias Excursion and master volume
by cGil on 2011-04-09 17:19:29

How any of the new tweaks will actually translate for the HD models is SO up for speculation at the moment.   No telling, really.   However,...   

Less sag generally means an amp will have a more punchy response; as opposed to having more sag, which will cause the signal to compress the initial transient spike, and then bloom afterward at the same relative volume, more or less.   More sag also equates to a looser feel in the bottom end.  I'm stoked that the HD's will get a sag control.   Totally stoked!  For me, sag is the one factor that makes some tube amps go beyond being merely something to play my guitar through, and become more of an extension of the guitar, and fun to play in and of themselves!

I expect the bias may wind up being a fairly subtle tweak for the model's power tube distortion character.  It'll all depends on how Line 6 chooses to model it, whether it be a range within normal tube data spec, or to extremes that you really wouldn't do to a real amp unless you just wanted to know where the magic smoke escapes from.

I expect the bias excursion to be a tweak determining just how dirty you can overdrive a power tube before hitting the wall of blocking distortion; which is the splattiest, phartiest possible sound that a Derpy hamster choking on a grapefruit could hope to produce, or something along those lines.   Blocking distortion kills most of the ouput level of tube amps, so it's not even useful as a fugly noise effect in most instances.   Reverend Billy Gibbons does get some use out of blocking distortion, but in that case it's doable because it's from the transistors in a stack of Expandora pedals.

At the other end of the possible bias excursion tweak spectrum, it may be a totally subtle tweak used to set how quickly the tube goes from clean to overdriven.    This could be good for those of us who prefer to set our amps just on the edge of breakup and would like more control over the touch sensitivity that sends the power tubes into clip.    Normally I just do it all with the guitar volume pot, but this, like the sag, could wind up being an addictive new tweak.

All just speculation at this point, though.  Only Line 6 knows what's really in store for the future of the HD's.  

Gil...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by zakkyvenom on 2011-04-09 17:56:46

i can't wait to set the expression pedal to control one or two of these new parameters and make dying amp noises, gonna be rad



Re: Sag, Hum, Bias, Bias Excursion and master volume
by cGil on 2011-04-09 20:22:53

More hopeful thoughts on the Sag Control.  And the Ghost Notes!    Sag, in amps that have it to whatever degree, is most evident when an amp is cranked.  It's a demand vs supply thing involving both the Power Transformers capacity to deliver necessary current on demand, as well as the capacitance value of the filter caps used on the B+ rail high voltage supply.    And it is at the most extreme saggy end of saggy amp design with the gain cranked is where the ghost note phenomenon will normally rear its ugly head.   Assuming the sag model is accurate, and set high, and the amp model is cranked up into healthy power tube distortion,...  then dialing down the model's gain just a hair should reduce the ghost note phenomenon just like it should on a real amp.    I hope this new Sag Control lets the models work exactly like that.  Of course, one should hopefully also be able to dial out the ghost notes by reducing the sag (thereby making the model a little punchier and tighter), but where's the fun in that if you want the sag?    

The Sag Control should not just be for good sag, though.   Punchy and tight is good, too.   Real good.  And absolutely essential for certain tones, of course.   It's good to have all the tools ya need for the proper response from all the tones you gotta have!    Someday soon these HD's are gonna mature into some totally incredible tone monsters.    It's like smelling what's cookin'!    And the suspense is killin' me!  Arrrgh! 

Gil...



Re: Sag, Hum, Bias, Bias Excursion and master volume
by rumrill1 on 2011-04-20 10:20:00

Re the new Master Volume control - seems to me we already have a MV in the Channel Volume (in the software; it's called Volume on the hardware). Adjusting this control and the Drive does exactly what a MV does on a real amp, doesn't it?, i.e. you set the desired level with the Channel Volume (MV on a real amp) then the distortion or gain level with the Drive. What would an added MV do?

I don't use the hi-gain models, usually nothing dirtier than the J-45, so if someone could explain this in terms that would be useful to guys like me I'd appreciate it. . .



Re: Sag, Hum, Bias, Bias Excursion and master volume
by HarryN on 2011-04-20 10:31:47

No the Channel Volume control only controls the output volume of the amp model, it is not a modelling control at all. So it doesn't change the tone - just overral volume. It's a device control - not a modelling function.

That's fine for the none master volume amps simulated, where the gain controls act as they would on the real amp. But on the master volume models Line6 has set the simulated master volume at a certain position that the user cannot edit - until that is v1.30 firmware is released.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by rumrill1 on 2011-04-20 10:56:34

Will this give more clean overhead to models like the Supro? I'd like to be able to turn down the Drive a bit on this & some others and still have enough overall volume to keep up with some of the louder models.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by markbrid on 2011-04-20 11:02:00

rumrill1 wrote:

Will this give more clean overhead to models like the Supro? I'd like to be able to turn down the Drive a bit on this & some others and still have enough overall volume to keep up with some of the louder models.

It might, will have to see.  I'm hoping this added master will allow the adjustment of the ratio of preamp vs. power amp distortion, which is critical on some Marshall amps like the JCM800 Master Volume.  Just guessing here, but if you can get the headroom you want out of the preamp only model of the Supro, but want a bit of power amp along with it, the new master volume might help achieve that.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by daveschutt on 2011-05-02 17:52:37

I did scan the 4 pages of posts before I asked this question so I apologize if I missed this.  But is Hum what I think it is, just the natural hum you'd get from a tube amp?  Maybe I'm missing the boat here but it seems like I'm generally putting noise gates on my patches to get rid of any hum from either the patch or my guitar.  Are there some people out there that are feeling what they are missing is not enough "hum"?



Re: Sag, Hum, Bias, Bias Excursion and master volume
by meambobbo on 2011-05-03 08:33:27

the pod simulates everything, including AC hum.  you can change it from 60 to 50 HZ in the setup menu as well.  i always try to remove it with a noise gate as well.  i would assume the new hum setting will allow you adjust its volume.  i'll be setting it to 0.

however, there are some people that swear that you need the hum to get the killer vintage tone.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by DeanDinosaur on 2011-05-03 08:37:44

I'll be setting the HUM ast zero also and hope to remove it, but I'll have to see if I would actually miss the hum.   It's like dither noise it actually smooths out the quite passages and makes them more intelligable, so maybe hum has a similar effect to dither noise.



Re: Sag, Hum, Bias, Bias Excursion and master volume
by mtreehugger on 2011-05-03 08:57:33

It will be interesting to see what effect hum really has.  If I remember correctly, Line 6 says hum is integral to tone, and they ought to know, right?  But to what extent?  It might be a scenario where if the hum is gone, so is the crunch?  Or it may wind up being a lesser deal, similar to the trade-offs between P-90s and humbuckers.




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