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Setting the Master Volume

PumpkinKing86

Inspired
Listen to Cliff!

So far the only two amp models I've found that benefit from increasing the MV have been the JCM800 and the SLO. With most everything else that has a MV (i.e., not defaulting to 10), lowering the MV is a good place to start before fiddling with the tone controls.
 

sskkmm

Experienced
Wow this is good to know. Explains some issues I have been having - like why I wasn't getting the clean tones I expected. Thanks.
 

6stringscott

Inspired
Thank you Cliff!

Wile on the topic of MV adjustments...

I would like to see an "Automatic Gain Control" checkbox that dynamically changed the Output Level value as a function of changes in the Master Volume. Actually, it would be nice if the algorithm wasn't just a function of MV value, but was actually looking at the amplitude of the output signal after MV and then adjusting the Level parameter to make the post-Level output the same as that stored at the moment of enabling the Auto-Gain-Control feature.

I can see this would actually get ugly and impractical because the system has no way to know what source is being played, and a person can play a section quietly right after playing something loudly...

So maybe it does actually need to be a function of MV and maybe a few other parameters in the amp configuration. The function would look a little different for each amp, and depend on stuff like changes in output compression, negative feedback, and a bazillion other parameters I don't really understand. But if there's a a way to make something that honors the spirit of this request, it would be a huge USABILITY improvement.

Maybe even something that worked in a way similar to a tone-match block where you push a button then play something very loudly with big dynamics, and that sets the ceiling for input signal level and can adjust the output level to a predetermined DB level to optimize signal to noise ratio and give equal output level. I exclusively use the Level parameter in Amp to try to compensate and make all amp outputs equal level. Folks can always use EQ or VOL or FIL blocks or the end of chain per-scene controls to adjust per-scene volume if they need different sounds to have different output levels.
 
One common theme with new users is the "blanket over the sound" complaint. Often this is due to excessive Master Volume values.

The Master Volume behaves just like the actual amps. However, unlike an actual amp, if you put it on 5.0 it won't cause your cat to hide for several days. This can cause the user to set the value too high as the physical feedback of painfully loud sound is not present.

As you turn up the Master Volume many amps get darker and the bass gets mushy. The key is to find the sweet spot.

Do this exercise:
Take an amp like the HBE. Set the MV to around 2.5 and turn the Level to a comfortable volume. Turn the Presence up to around 8.0. Copy the settings to "Y" by double-clicking the "Y" button. Now you have the same amp model and values in X and Y. Turn up the MV in Y to, say, 6.0 and lower the Level until the volume is the same. Go back and forth between X and Y and notice how much darker Y is.

This occurs because the virtual power amp is distorting, and quite heavily. Due to the impedance curve of the virtual speaker load this causes the bass and high treble frequencies to clip but not the midrange. The result is, naturally, compressed bass and high treble which can sound muddy and indistinct. Modern MV amps are not designed to overdrive the power amp considerably. They are designed to get most of their distortion from the preamp and then adjust the MV until the power amp just starts to clip which is the "sweet spot".

Some amps, like the Recto Modern, will distort the power amp at very low MV values, around 2.0. In real life these amps are painfully loud at these settings but in our virtual world we are unaware of this because the Level control allows us to adjust the volume to any arbitrary level.

Some modeling products intentionally limit how hard their virtual power amps can be overdriven. Even with the MV on 10 the virtual power amp is not being overdriven that much. Of course this is unrealistic. Our modeling is accurate and with the MV on 10 you will get the same amount of power amp distortion as the real amp when set to 10. With this great power comes great responsibility and that responsibility is understanding how the control works and how to set it properly.
Thanks a lot for this great explanation! Now I understand many things! :)
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
A little trick you can do to get the "bounce" of high MV without the muddy bass is to reduce the LF Res value on the Spkr tab. This will reduce the amount of bass clipping in the virtual power amp allowing you to turn the MV up. You can also reduce the HF Res to reduce the amount of treble clipping.
 

ChrisCG

Experienced
A little trick you can do to get the "bounce" of high MV without the muddy bass is to reduce the LF Res value on the Spkr tab. This will reduce the amount of bass clipping in the virtual power amp allowing you to turn the MV up. You can also reduce the HF Res to reduce the amount of treble clipping.
I learn something new everyday I'm on this forum, thanks Cliff this is a cool little nugget of info.
 

codyraptor

Inspired
So question...I tried messing with MV and Gain on the Friedman BE V1 last night....MV around 3-4...and Gain around 6-7ish....it sounds thick and almost like it has too much low end even though that model is described as the brighter bass cut version. I doesn't sound 'open'. However, I turn gain down to around 3 and turn MV up to around 6-7 (almost the exact opposite) and I get a way more open sound that seems way more versatile and sensitive to touch. Am I doing something wrong? I'm not a high gain player...but I'm covering some 80's tunes..so I wanted to dial it in for some of those tones. My ear tends to want to hear more MV and lower gain...so more power amp distortion and less preamp I'm guessing. Is that ok on these models or am I doing something incorrect to get the proper sound from these models?
 

Rex

Legend!
So question...I tried messing with MV and Gain on the Friedman BE V1 last night....MV around 3-4...and Gain around 6-7ish....it sounds thick and almost like it has too much low end even though that model is described as the brighter bass cut version. I doesn't sound 'open'. However, I turn gain down to around 3 and turn MV up to around 6-7 (almost the exact opposite) and I get a way more open sound that seems way more versatile and sensitive to touch. Am I doing something wrong? I'm not a high gain player...but I'm covering some 80's tunes..so I wanted to dial it in for some of those tones. My ear tends to want to hear more MV and lower gain...so more power amp distortion and less preamp I'm guessing. Is that ok on these models or am I doing something incorrect to get the proper sound from these models?
You like what you like. There's no right or wrong. A couple of thoughts, though:

Are you listening at low volume? At higher volumes, you may find that the higher MV sounds muddier.

Have you tried the Cut switch in the Amp block?
 

codyraptor

Inspired
I haven't tried the 'cut' switch. I might try that. I'm running through custom in-ears. They're high dollar quad in-ears...so I'm hoping I am getting a true sound from them. I do hear a difference when turning up of course...but more pre-amp and less power amp sounds like a wall of gain and less responsive.
 

Rex

Legend!
I haven't tried the 'cut' switch. I might try that.
Do try it. It's three seconds out of your life, and it's often an instant cure for mud.

I'm running through custom in-ears. They're high dollar quad in-ears...so I'm hoping I am getting a true sound from them. [/quore]
Even the best in-ears wont sound the same as playing with room volume. And the feel/responsiveness won't be anything like it. There's no substitute for having your guitar "hear" thee same sound you're hearing.
 

Stratoblaster

Fractal Fanatic
So far the only two amp models I've found that benefit from increasing the MV have been the JCM800 and the SLO.
Agree with being able to crank the MV on the 800 higher then most amps in the AFX; that's because the MV pot interacts with the surrounding circuitry in a real JCM 800 which acts as a high-pass filter; turning it up lowers the cutoff giving more low end and fattens things up. I do a simple mod on my 800's to swamp out the effect of the MV interaction which really improves it a great deal overall.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Agree with being able to crank the MV on the 800 higher then most amps in the AFX; that's because the MV pot interacts with the surrounding circuitry in a real JCM 800 which acts as a high-pass filter; turning it up lowers the cutoff giving more low end and fattens things up. I do a simple mod on my 800's to swamp out the effect of the MV interaction which really improves it a great deal overall.
It also reduces the lowpass filtering due to the Miller capacitance of the PI. At low MV the source resistance into the PI is low which raises the highpass frequency due to the coupling cap and raises the lowpass frequency due to the Miller capacitance and snubber. As you increase the MV the source resistance increases which decreases both of these things.

As you keep raising the MV the source resistance then starts to decrease as you get above 50% of the pot value.
 

H3O2

Experienced
From Cliff: "A little trick you can do to get the "bounce" of high MV without the muddy bass is to reduce the LF Res value on the Spkr tab. This will reduce the amount of bass clipping in the virtual power amp allowing you to turn the MV up. You can also reduce the HF Res to reduce the amount of treble clipping."

Small adjusts improved clarity in my goto preset. Very helpful. Thanks for another very useful tip.
 

GuttaLaser

Power User
A little trick you can do to get the "bounce" of high MV without the muddy bass is to reduce the LF Res value on the Spkr tab. This will reduce the amount of bass clipping in the virtual power amp allowing you to turn the MV up. You can also reduce the HF Res to reduce the amount of treble clipping.
This is a little counter-intuitive to me!
I mean... Cliff said that the MV is just like real amp so the MV distort and clip Low and High freqs @ high values!
So how an external parameter (I mean out the amp circuitry model) like the spkr res can limit the bass and treble clipping?
This to me sounds more like saving a recorded track in post-prod and/or putting an emergency lo/cut filter on the channel by the FOH guy!
Second: You say also this work even with the HF! But if the HF clipping because the MV results in an Hi-cut... and you apply and HF reduction... you ends with a double HF-cut-cut!
 

Rex

Legend!
This is a little counter-intuitive to me!
I mean... Cliff said that the MV is just like real amp so the MV distort and clip Low and High freqs @ high values!
So how an external parameter (I mean out the amp circuitry model) like the spkr res can limit the bass and treble clipping?
The SPKR res parameters are part of the amp model.


Second: You say also this work even with the HF! But if the HF clipping because the MV results in an Hi-cut... and you apply and HF reduction... you ends with a double HF-cut-cut!
The SPKR parameters in the Amp block are not EQ filters. They represent the virtual speaker's impedance curve. Reducing HF Resonance will reduce treble clipping in the power amp. That can clean up the highs.
 

GuttaLaser

Power User
The SPKR res parameters are part of the amp model.
The SPKR parameters in the Amp block are not EQ filters. They represent the virtual speaker's impedance curve. Reducing HF Resonance will reduce treble clipping in the power amp. That can clean up the highs.
Uh! Ok... this make sense! :p
 

George Koerich

Inspired
@FractalAudio, thanks for these technical posts! It´s a great pleasure to read them!
They are very informative and well written articles.

I did some awesome improvents in my AFX2 presets using properly some advanced controls because I knew what I was doing.

I'm new to community, but I've read all tech notes available here.
Problem is that I'm now addicted to them and always seeking for new ones. :D

Please, keep up writing! ;)
 
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