Demonstrating Atomic Amplifire's Parametric EQ

Matticus

Member
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1,250
The What, the Why, and What It All Means

I've heard the voice of the people -- and most of you sing flat. Sorry. Anyways, there's good news! I think I can help show you what's going when you tweak those knobs in the Atomic Amplifire's parametric EQ section.

I've actually been meaning to do this for some time now, but, for whatever reason, haven't. Well, today I was able to take a few hours to knock this out. (So, I hope it's helpful.) I used pink noise (-3dBFS) into a clean Deluxe Reverb preset in order to ensure consistency. I don't know if this is the best or most scientific way to do this, but I think it will suit our purposes just fine. Every screenshot will include our baseline frequency response. I will refer to the latest manual (v4.0) where necessary.

Let's get to it...


Cabinet EQ
Amplifire%20Cab%20Rolloff.png

Rolloff

Think your cabinet is bright? Have the digital fizz trolls tracked you down? Do you have enough Chipotle receipts for the crystal lattice giveaway? You could start here. Never mind that some of your favorite records have guitar tracks that push way beyond 5-7 kHz. (But that's probably just room reflections, right, and not overtones?) Anyways. Say we wanted to tweak around 5 kHz ... what happens when we adjust the Q?

Peak Q
The image above demonstrates how significantly the Q affects what happens around your rolloff point. It doesn't take much at all.

Amplifire%20Cab%20Bottom.png

Bottom
Jay Mitchell has given us this information before, but it wasn't with any visuals. The corner frequency is about 250 Hz. We could think of kind of like a pivot point. My guess, trying this on a few different amps, is that some of them like this a little more than others. It may be focused on the amp or, perhaps, the IR you're using.

Amplifire%20Cab%20Air.png

Air
This one is really subtle by comparison. Jay Mitchell said that this is also a first-order shelving filter, with a corner frequency of 6.7 kHz.


Filters That Affect Higher Frequencies
As the graphs will demonstrate, unless otherwise noted, I used 1 kHz as our test frequency for this set.

Amplifire%20EQ%20LPF.png

Lowpass Filter 1 (LPF 1)

Notice how much below the frequency is affected. This is pretty typical (unless you’ve never seen it before). If you want to change it to affect hardly anything below the target frequency, you will need to raise the frequency. I have demonstrated this on the orange line by raising it to 1.5 kHz (and, yes, using the LPF 2 -- apologies).

Q doesn't affect anything there, as the manual states. I didn't show what happens when you change that parameter for that reason. (Also, as far as I can tell, "Level" is a general level parameter and does not appear to affect how the filter works.)

Amplifire%20EQ%20LPF2%20Q.png

Lowpass Filter 2
As opposed to LPF1, Q affects peaking (quite a bit). (Remember the Cab Rolloff Peak Q?) Notice how its rolloff is more pronounced.

Amplifire%20EQ%20HSF%201.png

High Shelf 1
With lowpass (and, as we'll see, highpass) filters, you don't have to change the level to see any change. We will have to change the level parameter to see a change with these shelving filters. Notice how much below the frequency is affected. I chose 3.0 and 9.0 dB to demonstrate the effect. You might not choose values these extreme, of course.

Amplifire%20EQ%20HSF2%20Q.png

High Shelf 2
As opposed to HSF1, Q affects peaking (quite a bit).


Filters That Affect Low Frequencies
As the graphs will demonstrate, unless otherwise noted, I used 200 Hz as our test frequency for this set.

Amplifire%20EQ%20HPF.png

Highpass Filter 1, 2
I think you're beginning to get the picture, so I'll let my words be few. If you want to get closer to your corner frequency, perhaps that you're seeing in your DAW or something, remember that we had to adjust the frequency. Whereas for the lowpass filter we raised our corner from 1 kHz to 1.5 kHz, here we are lowering it just a mere 50 Hz.

Amplifire%20EQ%20HPF2%20Q.png

Highpass Filter 2
This works much like we saw with the LPF2. Notice how much a high Q affects our corner frequency.


Peaking and Notch Filters
Have you wondered how to use these? Me too (especially the notch!). Here is what they actually look like -- and it includes some behavior that you might not expect. We'll use 200 Hz and 1 kHz again.

Amplifire%20EQ%20Notch%20Q.png

Notch Filter
When you select the notch filter, it will notch out your selected frequency regardless of where you have the Q or the level set. Now, what happens when you do mess with the Q or the level? Above, I kept the level the same (0.0 dB), but changed the Q (0.71, 2.5, 5.0). Increasing the Q does narrow the band, but it also decreases the level. So if you want to notch out a very specific, narrow band of frequencies, this is your tool; but you need to increase the Q quite a bit. I may do some further testing on this one to see what happens when you increase the Q over 5.0.

What if I wanted to -- for whatever odd reason -- notch out the same amount as we see with 0.0 dB and Q0.71?

Amplifire%20EQ%20Notch%20dB%20match.png

Well, if we do that with the notch filter, here's what ensues. Changing the level affects the rest of your signal -- and it is not subtle. I'm not saying that anyone would want to do it, but it does demonstrate what happens with the notch filter when you use both the Q and level parameters. (Note: the -9.0 dB was actually -10.0 dB, but I just remembered that I forgot to change that in the legend. My apologies.)


Amplifire%20EQ%20Peak%20Q10.png

Peaking Filter
Here's what happens with the Amplifire's peaking filter, if we want to use it to cut frequencies.

Again, we'll start by looking what happens when we change the Q. Since the peaking filter does not automatically notch out our target frequency like the notching filter does, we will need to give it a level. I have chosen -6.0 dB to demonstrate here how the Q affects the results. I have also shown three different Q values here, although the last one isn't represented on the legend. The solid green portion is showing a Q of 10.0, which is the highest Q offered. Notice how decreasing or increasing the Q affects the results.

Amplifire%20EQ%20Peak%20dB.png

Now let's see what happens with the peaking filter when the Q is constant and we change the level. Notice the width of the Q in relationship to the level change.

Amplifire%20EQ%20Peaking%201kHz.png

But what about if we want to, you know, actually use the peaking filter for, you know, like, peaking? Here's what that looks like...

Edit 3 Apr 2017: updated links
 
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dbagchee

Silver Supporting Member
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2,036
This is great info! Thanks for taking the time to document all of this!
 

crazyForce

Silver Supporting Member
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1,021
What an effort! This is great resource to someone trying to understand what's happening inside the box. Excellent job, Matticus.
 

Matticus

Member
Messages
1,250
Thanks, everyone. Let me know if there's anything else I could explain or demonstrate.

I was also thinking of taking the same raw Deluxe Reverb tone and applying some actual EQ to it. Maybe tackle answering questions like, "If I hear something that needs to be changed, how would I go about doing it?"


So that's what a notch filter is.

Yeah, it's sort of the opposite of a bandpass filter (which I didn't demonstrate in this thread).
 

CapnRex

Member
Messages
2,259
Thanks, everyone. Let me know if there's anything else I could explain or demonstrate.

I was also thinking of taking the same raw Deluxe Reverb tone and applying some actual EQ to it. Maybe tackle answering questions like, "If I hear something that needs to be changed, how would I go about doing it?"




Yeah, it's sort of the opposite of a bandpass filter (which I didn't demonstrate in this thread).

Hate to trouble you, but I would be quite interested
 

erikm5150

Member
Messages
565
Thanks for sharing this! good to 'see' what is going on coz my old ringing ears aren't so reliable anymore!
 

Guitar1969

Member
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2,253
What do you want to know about them?
I'm having a hard time with some of the more obscure parameters such Flutter, Diffusion, etc. Aside from the normal delays, I am into more modulation and ambient type delays and love the sounds such as Boss' Terra Echo, or Strymon's Ice Delay , Eventide Space Hole,, Echorec, etc and was thinking that with all these settings in the AF along with the other effect blocks some of them could be approximated in the AF. Right now I keep a Boss DD-500 Delay and a Zoom MS-70CDR in the loop of my AF for these sounds.
 
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Matticus

Member
Messages
1,250
I'm having a hard time with some of the more obscure parameters such Flutter, Diffusion, etc. Aside from the normal delays, I am into more modulation and ambient type delays and love the sounds such as Boss' Terra Echo, or Strymon's Ice Delay , Eventide Space Hole,, Echorec, etc and was thinking that with all these settings in the AF along with the other effect blocks some of them could be approximated in the AF. Right now I keep a Boss DD-500 Delay and a Zoom MS-70CDR in the loop of my AF for these sounds.

Think of the diffusion parameter as a second feedback control. The manual uses the term "cross-coupling", which means, if I understand it correctly, that the output of A is fed into B and vice versa. It can be another tool to create a pseudo-reverb wash or another source for oscillation.

Think of the flutter parameter, as well as the filter speed, as a chorus in the repeats of the delay. This is where you could add your "wow and flutter" for a tape echo like the Echorec, the chorus and vibrato settings for a Deluxe Memory Man, the modulation for a Carbon Copy. For example, the modulation rate has a range from 0.20 to 2.20 Hz in the Carbon Copy.




Here are some examples of this.

All delays are post and parallel, set to 100% width, but without ping pong enabled. The echo EQ was set to 150 Hz and 15.0 kHz. Drive was set to 0%. 32 bits. Flutter and speed were set to 40% and 0.90 Hz, respectively, unless otherwise noted. Diffusion was set to 90%, unless otherwise noted. Each delay was set to 75% feedback, unless otherwise noted. Delay 1 is set to a half note, set center (0.0). Delay 2 is set to a quarter note, set right (1.0). Delay 3 is set to a dotted eighth note, set left (-1.0). The delay tempo was 97 bpm.

0:00 - 0:43 | Analog | 100% feedback for delay 3, 100% diffusion
0:43 - 1:50 | Tape
1:50 - 2:29 | Dark Tape
2:29 - 3:34 | Soft Digital
3:34 - 4:03 | Soft Digital | 60% flutter, 4.40 Hz
4:03 - 4:22 | Soft Digital | 75% flutter, 4.40 Hz
4:22 - 4:59 | Soft Digital | 75% flutter, 0.45 Hz, 75% diffusion
 

Guitar1969

Member
Messages
2,253
Think of the diffusion parameter as a second feedback control. The manual uses the term "cross-coupling", which means, if I understand it correctly, that the output of A is fed into B and vice versa. It can be another tool to create a pseudo-reverb wash or another source for oscillation.

Think of the flutter parameter, as well as the filter speed, as a chorus in the repeats of the delay. This is where you could add your "wow and flutter" for a tape echo like the Echorec, the chorus and vibrato settings for a Deluxe Memory Man, the modulation for a Carbon Copy. For example, the modulation rate has a range from 0.20 to 2.20 Hz in the Carbon Copy.




Here are some examples of this.

All delays are post and parallel, set to 100% width, but without ping pong enabled. The echo EQ was set to 150 Hz and 15.0 kHz. Drive was set to 0%. 32 bits. Flutter and speed were set to 40% and 0.90 Hz, respectively, unless otherwise noted. Diffusion was set to 90%, unless otherwise noted. Each delay was set to 75% feedback, unless otherwise noted. Delay 1 is set to a half note, set center (0.0). Delay 2 is set to a quarter note, set right (1.0). Delay 3 is set to a dotted eighth note, set left (-1.0). The delay tempo was 97 bpm.

0:00 - 0:43 | Analog | 100% feedback for delay 3, 100% diffusion
0:43 - 1:50 | Tape
1:50 - 2:29 | Dark Tape
2:29 - 3:34 | Soft Digital
3:34 - 4:03 | Soft Digital | 60% flutter, 4.40 Hz
4:03 - 4:22 | Soft Digital | 75% flutter, 4.40 Hz
4:22 - 4:59 | Soft Digital | 75% flutter, 0.45 Hz, 75% diffusion

That's what I am talking about... Sounds excellent. I am going to have to really break this down and try to recreate it. That Self Oscillation on the Soft Digital (2:29) is pretty cool.
 
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Matticus

Member
Messages
1,250
Thanks, guys.

If you want to try it out, give this a shot:
Code:
Insert      Post
Type        Soft Digital
Config      Parallel (4 Tap if you want more feedback)
Level       to taste (try -15.0 dB for a "solo" thing)
Width       100% (for stereo)
Dry Lvl     0.0 dB
1 Tempo     Half
1 Fdbk      75%
1 Mix       0.0 dB
1 Pan       0.00
Lowcut      150 Hz
Hicut       4.0 kHz (play with this setting too)
Flutter     40%
FltrSpd     0.90 Hz
Diffusion   80% (try 40-80, past that be mindful of feedback)
Drive       0%
Bits        32
2 Tempo     Quarter
2 Fdbk      75%
2 Mix       0.0 dB
2 Pan       1.00
3 Tempo     Dotted Eighth
3 Fdbk      75%
3 Mix       0.0 dB
3 Pan       -1.00
Buckets     8192
 




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