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Amp Speaker tab versus Amp Graphic EQ

Chris Hurley

Experienced
Can someone spend a moment talking about how using the Amp Speaker Tab differs from using the Amp Graphic EQ or a separate PEQ block?

I think the speaker tab actually affects how the modeled poweramp behaves but I don't really understand in what way the behavior is affected.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
The speaker tab is not an EQ. It allows you to adjust the impedance that the virtual speaker presents to the virtual power tubes. In most cases the resulting EQ is quite different than the impedance curve since negative feedback flattens the response. If you turn the damping all the way down then the EQ will be close to the impedance curve (but still influenced by the transformer).
 

paullypj

Inspired
The speaker tab is not an EQ. It allows you to adjust the impedance that the virtual speaker presents to the virtual power tubes. In most cases the resulting EQ is quite different than the impedance curve since negative feedback flattens the response. If you turn the damping all the way down then the EQ will be close to the impedance curve (but still influenced by the transformer).
What did he say? Could someone please translate this ... In other words how does it affect the sound...
 

paullypj

Inspired
.QUOTE=prometh;623924]Basically, an EQ at a different location in the amp, resulting in a different sound.[/QUOTE]

The speaker tab is not an EQ. what your are saying contradicts what fractal says and i still dont konw what this means and how to use it to ajust my tone... But thanks for the effort
 

Chris Hurley

Experienced
It isn't an EQ in that it isn't boosting or cutting frequencies directly. I believe it is making it harder or easier for the virtual poweramp to drive the virtual speaker load at those frequencies which isn't the same thing as boosting or cutting frequencies directly, even if the result is similar in some ways.
 

Dancing Frog

Inspired
What did he say? Could someone please translate this ... In other words how does it affect the sound...
The amp pushes on the speaker and the speaker pushes back. How the speaker pushes back changes how the amp responds. The speaker tab is adjusting how the speaker pushes back; because unlike a real amp, there is no bi-directional interaction between the amp and cab blocks in the Axe-FX II.
 
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paullypj

Inspired
The amp pushes on the speaker and the speaker pushes back. How the speaker pushes back changes how the amp responds. The speaker tab is adjusting how the speaker pushes back; because unlike a real amp, there is no bi-directional interaction between the amp and cab blocks in the Axe-FX II.
Thanks this and the post before is the kind of intellegent answer that i was looking for . So im guessing that this is one way to get the power amp to change its tone ...
 

javajunkie

Moderator
Moderator
Thanks this and the post before is the kind of intellegent answer that i was looking for . So im guessing that this is one way to get the power amp to change its tone ...
Yes. With lo freq res as you move its frequency, it will change it low frequency resonant peak. A place where there is a spike in the low frequencies. Palm muting and moving the freq slowly up and down will give an idea of its effect.
On the hi end, it is similar only it deals more with the chimyness of the amp.

The low freq res is pretty narrow (covering few frequencies) while the high is broader.

but negative feedback as, Cliff stated, will affect this response.
 

paullypj

Inspired
Yes. With lo freq res as you move its frequency, it will change it low frequency resonant peak. A place where there is a spike in the low frequencies. Palm muting and moving the freq slowly up and down will give an idea of its effect.
On the hi end, it is similar only it deals more with the chimyness of the amp.

The low freq res is pretty narrow (covering few frequencies) while the high is broader.

but negative feedback as, Cliff stated, will affect this response.
Thank you jj another good explanation Im starting to learn something thanks!!!
 

barhrecords

Axe-Master
In the amp block speaker page graph display, the horizonal axis is frequency.

What is the vertical axis?

And the XFormer High Freq setting seems to affect the high freq peak in the graph more than the High Resonance too?

There are two vertical and one horizontal ruler lines but also one vertical line that moves left to right... anyone know what that vertical ruler line that moves is?

Good stuff.

Richard
 

javajunkie

Moderator
Moderator
In the amp block speaker page graph display, the horizonal axis is frequency.

What is the vertical axis?

And the XFormer High Freq setting seems to affect the high freq peak in the graph more than the High Resonance too?

There are two vertical and one horizontal ruler lines but also one vertical line that moves left to right... anyone know what that vertical ruler line that moves is?

Good stuff.

Richard
Graph is just a guide. I assume the vertical axis is db. As Cliff stated the graph (impedance curve) can be quite different from than resulting EQ because the damp and transformer settings have an effect.
He also went on to say when the damp is at 0( no negative feedback to the amp) the curve and resulting EQ should be pretty close.
 

barhrecords

Axe-Master
I saw where Cliff talked about the impedance of the speaker as seen by the power tubes across the frequency spectrum.

So the monitor, aka the graph, is an EQ plot not the impedance plot?

There is that "floating" line too... that moves with the low freq bump... wonder what that is?

Richard
 

javajunkie

Moderator
Moderator
I saw where Cliff talked about the impedance of the speaker as seen by the power tubes across the frequency spectrum. <br>
<br>
So the monitor, aka the graph, is an EQ plot not the impedance plot?<br>
<br>
There is that "floating" line too... that moves with the low freq bump... wonder what that is?<br>
<br>
Richard
Considering the low, mid, and hi res goes from 0 -10. and the mid is listed as db. I would think it is the level of the resonance

Don't know what that line is. Does it exist in hardware?
 

Scott Peterson

Global Moderator
Moderator
Absolutely different beasts - GEQ vs. Speaker Resonance.

Think of the Speaker resonance as 'tuning' the power amp response and speaker cab as one 'thing'. You in essence are dialing up how the power amp responds to the speaker cab and vice versa.

The GEQ is a GEQ. I never use it because it is not needed IMHO. Glad it is there should I want to, never felt the need.

Also piggybacking on JJ's comments - the graph is just a visual representation. It is helpful when dialing things up to 'see' what you 'hear' in order to nail it down faster and 'learn' what you are doing when you change the parameters. I find it exceptionally helpful in that regard.
 
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TheScientist

Inspired
Low End

Practically, I have been using the low end speaker res controls - as well as low freq cut - to deal with any flub I get. After I get that where I want it, I adjust the GEQ stuff to give me the freq envelope I like. Its just easy. I really like a clean, but booming 15" speaker low end.
 

barhrecords

Axe-Master
Also piggybacking on JJ's comments - the graph is just a visual representation. It is helpful when dialing things up to 'see' what you 'hear' in order to nail it down faster and 'learn' what you are doing when you change the parameters. I find it exceptionally helpful in that regard.
+1 I find the graph useful too for sure :)

I just was curious as to what the monitor graph represented.

For instance on another thread, there were speaker cab impedance graphs posted by redwire for some of their cabs.

The monitor graph in the speaker page would *not* represent those graphs or other impedance graphs provided or measured in regards to a particular cab and its associated IR.

Richard
 
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