Question regarding Preamp Dynamics

lj045637

Inspired
Dear all,

Was tweaking a high gain tone last night and notices the following...
When I increase Preamp Dynamics in the Amp Block I can turn off my noise gate at a certain level as an increase of the Preamp Dynamics leads to significant noise reduction.
Can anybody kindly explain the correlation of the this effect? Have googled but did not find any reasonable explanation.

Thanks.
John
 
Dear all,

Was tweaking a high gain tone last night and notices the following...
When I increase Preamp Dynamics in the Amp Block I can turn off my noise gate at a certain level as an increase of the Preamp Dynamics leads to significant noise reduction.
Can anybody kindly explain the correlation of the this effect? Have googled but did not find any reasonable explanation.

Thanks.
John

Because with higher values it works as expander
http://wiki.fractalaudio.com/axefx2/index.php?title=AMP_block_parameters#PREAMP_DYNAMICS
 
Got it, thanks !!!

My first impression after this "discovery" is that this "expander effect" seems to be less "brutal" than a noise gate...and it seems to be very efficient for getting amp buzz under control. Especially as a gate is a static gain control while an expander is a variable gain control.

So wouldn't the "expander effect" be the better approach for high gain presets or are there any negative side effects?

One positive side effect with this approach is that the CPU usage can be reduced by est. 3% by turning off the noise gate or GateExp block :)
 
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Both are variable gain controls. The difference is the ratio of the action. It's sort of like the difference between a compressor and a limiter, but working in the opposite direction. A hard limiter is a compressor with an infinite upward ratio. The input signal can raise infinitely above the threshold, yet the output will only increase a set amount. A gate works the other way and is simply an expander with an infinite downward ratio. Any signal level below the threshold is reduced infinitely and you get silence. That gives you the biggest drop in noise floor, but also has the negative side effect of chopping off all signals below the threshold so quiet sustained notes get cut short.
 
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Both are variable gain controls. The difference is the ratio of the action. It's sort of like the difference between a compressor and a limiter, but working in the opposite direction. A hard limiter is a compressor with an infinite upward ratio. The input signal can raise infinitely above the threshold, yet the output will only increase a set amount. A gate works the other way and is simply an expander with an infinite downward ratio. Any signal level below the threshold is reduced infinitely and you get silence. That gives you the biggest drop in noise floor, but also has the negative side effect of chopping off all signals below the threshold so quiet sustained notes get cut short.

Thanks, Mr Fender...so do the advantages of the expander approach prevail from your perspective in order to get rid of noise and leave the tone unchanged? Could not identify any negative aspects for the expander approach up to now.
 
I need to learn more, I have experienced this effect too and found nothing negative about it.
I always noticed a tone impact of the noise gate especially with my high gain presets, this seems to be gone with the expander approach.

I really start to appreciate preamp dynamics :)
 
It's a trade off. An expander will preserve more of the low level signal, but will be less effective at eliminating the noise. A gate will remove all of the noise, but can affect sustain and quiet parts. You have to decide on the balance that suits your needs. It also depends on how both are setup. You have to set the threshold higher than the noise level, but low enough to not drastically affect the tone or sustain. The lower your initial noise level, the more gentle your reductions can be. If your preset is very noisy, more drastic settings are required.

A big thing with gates is to put them in the right location in the signal chain. That is determined by the source of the noise. If the noise is coming from your guitar, like 60 cycle hum from single coils, the gate should be at the very front of the chain. If the noise comes from the amp, like hiss from high gain settings, but your guitar signal is not noisy, the gate should go after the amp in order to preserve the input dynamics from the guitar as best as possible.
 
All I know is I HATE gates, although the axe has an extremely good one, I know it's there, digital or real amp. I cannot stand the way they suck tone and chop off tails etc..
 
It's a trade off. An expander will preserve more of the low level signal, but will be less effective at eliminating the noise. A gate will remove all of the noise, but can affect sustain and quiet parts. You have to decide on the balance that suits your needs. It also depends on how both are setup. You have to set the threshold higher than the noise level, but low enough to not drastically affect the tone or sustain. The lower your initial noise level, the more gentle your reductions can be. If your preset is very noisy, more drastic settings are required.

A big thing with gates is to put them in the right location in the signal chain. That is determined by the source of the noise. If the noise is coming from your guitar, like 60 cycle hum from single coils, the gate should be at the very front of the chain. If the noise comes from the amp, like hiss from high gain settings, but your guitar signal is not noisy, the gate should go after the amp in order to preserve the input dynamics from the guitar as best as possible.
Thanks, up to now I did not notice any difference between noise gate and expander regarding noise elimination.
 
All I know is I HATE gates, although the axe has an extremely good one, I know it's there, digital or real amp. I cannot stand the way they suck tone and chop off tails etc..
Hehe...So you are also elimininating noise via preamp dynamics ?
 
That depends on how loud the noise is to start with. If your noise level is 10 dB above your threshold of hearing, any reduction greater than 10 dB will drop the noise level to where you can no longer hear it.
 
That depends on how loud the noise is to start with. If your noise level is 10 dB above your threshold of hearing, any reduction greater than 10 dB will drop the noise level to where you can no longer hear it.
Right...so a reasonable trade off would be keep and reduce NG and increase preamp dynamics :)
 
A big thing with gates is to put them in the right location in the signal chain. That is determined by the source of the noise. If the noise is coming from your guitar, like 60 cycle hum from single coils, the gate should be at the very front of the chain. If the noise comes from the amp, like hiss from high gain settings, but your guitar signal is not noisy, the gate should go after the amp in order to preserve the input dynamics from the guitar as best as possible.
I'll just add here, it's a perfect situation in the latter example to use the side-chain feature, to have the gate respond to your input signal (but shut on your post-gain signal).
 
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