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Post subject: Re: Information on sag, bias and effect parameters
Posted: Tue Dec 13, 2011 3:33 pm
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Aspiring Musician
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If these amps were not such great value, I wouldn't have bought two of them.

Nor do I have any problem whatsoever with a company with a healthy profit motive that needs to pay its own bills.

I just can't swallow the line that they cut corners for 'musical' reasons through a philosophical desire to make us better guitar players.


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Wed Dec 14, 2011 8:22 am
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Yep, just low cost amps that do a ton of stuff.

I wonder how the documentation compares to similar offerings from Vox/Peavy etc.


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Wed Dec 14, 2011 6:45 pm
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Aspiring Musician
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I have never disputed any of the points you make.

The ONLY simple point I ever made was that the level of documentation provided with these - and no doubt many other amps as well - is a function of cost, not the musical altruism suggested by another poster.

Apparently that constitutes a savage and unwarranted attack on Western capitalism requiring that I be put back in my box.

I consider myself duly knuckle-wrapped.


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Wed Dec 14, 2011 9:04 pm
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If you're talking to me depepat you're reading way too much into what I wrote. I literally was wondering about how docs compared.


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Thu Dec 22, 2011 12:10 pm
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depepat wrote:
Orcatraz

Noodling around as a way to learn how an amp works and listening to the outcomes is a great thing to do, especially if someone is savvy enough to keep notes so that they can reproduce what they did.

But I still maintain that a basic written explanation by a manufacturer of how the many control and effect options on their amps might contribute to/affect a tone, including how they inter-relate, is not a completely unreasonable expectation when someone hands over their hard-earned.


Absolutely, it's not unreasonable. It would indeed be nice to have an actual manual. One nice thing about Fuse and the Mustangs is that you don't really have to write anything down if you save the sounds you like on the computer. Fuse can show you exactly what all the settings are for each preset.

O.


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Tue Dec 27, 2011 11:17 pm
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Since not a single person has answered the OP's question, I'll give it a shot. This is the dumbed down version but it will at least give you an idea of what bias and sag are supposed to emulate.

Bias - This is the amount of current flowing through the tube. Think of it in terms of hot and cold. Turn it up and it emulates running the tubes hotter. This will give you more saturation or distortion and compression. In real life it's a balancing act. Get too hot and you cook the tubes prematurely, you can also get to a point where things start to get mushy sounding. As you turn it down and run colder, things start to tighten up and become less distorted and compressed. Turn it down too much and the distortion starts to sound crappy.

Sag - This is all about the power supply. In a tube amp the incoming AC power is rectified to DC by a rectifier. This rectifier can either be tube or solid state (silicon diode). Sag is the effect of the ability of the rectifier to supply power on demand to the tubes. Tube rectifiers are not as fast as silicon so you get what is known as sag. when you hit a note, the power tubes draw current to amplify the note. With a silicon based rectifier the needed power is supplied pretty much instantaneously so the attack of the note is quick and sharp. The tube rectifier can't supply the power as quickly so the attack is a little softer and spongier. Sag is more about feel than sound.

Like I said, this is a dumbed down version so please don't break my balls :D

To learn about it in depth, here are some good links.
http://www.aikenamps.com/WhatIsBiasing.htm
http://www.aikenamps.com/Sag.html


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Wed Dec 28, 2011 2:35 pm
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Aspiring Musician
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donnievaz wrote:
Since not a single person has answered the OP's question, I'll give it a shot. This is the dumbed down version but it will at least give you an idea of what bias and sag are supposed to emulate.

Bias - This is the amount of current flowing through the tube. Think of it in terms of hot and cold. Turn it up and it emulates running the tubes hotter. This will give you more saturation or distortion and compression. In real life it's a balancing act. Get too hot and you cook the tubes prematurely, you can also get to a point where things start to get mushy sounding. As you turn it down and run colder, things start to tighten up and become less distorted and compressed. Turn it down too much and the distortion starts to sound crappy.

Sag - This is all about the power supply. In a tube amp the incoming AC power is rectified to DC by a rectifier. This rectifier can either be tube or solid state (silicon diode). Sag is the effect of the ability of the rectifier to supply power on demand to the tubes. Tube rectifiers are not as fast as silicon so you get what is known as sag. when you hit a note, the power tubes draw current to amplify the note. With a silicon based rectifier the needed power is supplied pretty much instantaneously so the attack of the note is quick and sharp. The tube rectifier can't supply the power as quickly so the attack is a little softer and spongier. Sag is more about feel than sound.

Like I said, this is a dumbed down version so please don't break my balls :D

To learn about it in depth, here are some good links.
http://www.aikenamps.com/WhatIsBiasing.htm
http://www.aikenamps.com/Sag.html


Thanks for doing that, donnievaz.

I was a little too unsure of exactly how Bias works to try to explain it and did not want to give out false info... then get flamed. Not that parameter does much for me on the Mustang.

O.


Last edited by Orcatraz on Thu Dec 29, 2011 1:02 am, edited 1 time in total.

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Post subject: Re: Information on sag, bias and effect parameters
Posted: Wed Dec 28, 2011 11:12 pm
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On the kind of tones I mostly use - lightly driven/slightly crunchy tones on the older Fender amp models - I can certainly hear the impact of changes to the Sag setting, and actively use it, but I would tend to agree that the impact of changing the Bias setting seems harder to detect - at least with those tones - and I generally leave it alone.

Maybe it is more apparent with more distorted tones ?


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Thu Dec 29, 2011 1:08 am
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depepat wrote:
On the kind of tones I mostly use - lightly driven/slightly crunchy tones on the older Fender amp models - I can certainly hear the impact of changes to the Sag setting, and actively use it, but I would tend to agree that the impact of changing the Bias setting seems harder to detect - at least with those tones - and I generally leave it alone.

Maybe it is more apparent with more distorted tones ?


That's been my experience as as well. The effects of Bias may also be a bit more difficult to replicate in a modeling amp and fender chose to make it a more subtle effect. Maybe.

O.


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Post subject: Re: Information on sag, bias and effect parameters
Posted: Tue Jan 03, 2012 1:19 am
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Thanks to donnievaz for that nice explaination and useful links.

I've had good results with the two Marshalls (err...British 70s and British 80s) by setting the Bias high (tubes want to run hot) and the Sag low (rectifier stages will be sluggish). The net effet is a more natural sounding crunch than I find by front-loading the preamp with an overdrive box.

If you play around with both controls together you can get some intersting sounds...

The effect is less apparent on cleaner amps like the '65 Deluxe or Twin, but as you can hear the sound get thinner as Sag goes CW and it gets fatter as Sag goes CCW. They just don't naturally overdrive like the others.

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Post subject: Re: Information on sag, bias and effect parameters
Posted: Mon Mar 19, 2012 7:51 pm
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Actually, O, the effects of changes in bias levels should be easier to model mathematically than the effects of changing the sag in the amp. But I am with you, the effect on the MIII I have is certainly more noticable on changes of the SAG than changing the bias. It is probably true on tube amps, too. But my "valve" experience is limited in guitar amps. I am more experienced with amateur radio amplifiers.




Orcatraz wrote:
depepat wrote:
On the kind of tones I mostly use - lightly driven/slightly crunchy tones on the older Fender amp models - I can certainly hear the impact of changes to the Sag setting, and actively use it, but I would tend to agree that the impact of changing the Bias setting seems harder to detect - at least with those tones - and I generally leave it alone.

Maybe it is more apparent with more distorted tones ?


That's been my experience as as well. The effects of Bias may also be a bit more difficult to replicate in a modeling amp and fender chose to make it a more subtle effect. Maybe.

O.

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Post subject: Re: Information on sag, bias and effect parameters
Posted: Tue Mar 20, 2012 6:56 pm
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Yes, I understand it is a business. And one thing that keeps a business open is keeping the customer satisfied.
Here's an idea: how about Fender setting up a "resource library" as a read only type forum?
Lord knows they have the information or where to get it, one would think.
I agree that tweaking and listening are important, and I also believe writing was invented to aid in the transmission of knowledge.
Why reinvent the wheel if someone already has the knowledge?


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