Keeley Halo Take 2

AlbertA said:
I got my Keeley Halo Pedal yesterday - I made some measurements as I was curious about the settings the default preset (1A) uses for the Halo sound.

Thanks to the block diagram posted by @Robert Keeley himself here: https://forum.fractalaudio.com/threads/keeley-halo.185333/page-4#post-2288551, we know the pedal uses 4 delay lines, Del1L, Del1R, Del2L, Del2R.
Del1L feeds into Del2L and Del1R feeds into Del2R.

Measurements

Here's what I measured for the default preset (The Halo sound), with the pedal in wet only mode and hooked into In3/Out3 of the Axe-Fx III set to unity gain:
  • The modulation rate is set to around 0.252Hz
  • The modulation depth is set to around 46%.
  • There's two LFOs, which I'll call LFO1A = sin, LFO1B = cos, both in sync with each other and 90 degrees apart (naturally).
  • Del1L is modulated with LFO1B.
  • Del1R is modulated with LFO1A.
  • Del2L is modulated with LFO1B.
  • Del2R is modulated with a mix of 0.5*LFO1B + 0.1*LFO1A which results in a LFO output that's about half the depth of Del2L LFO and about a 11.25 degree shift.
  • The output of Del1 into Del2 is lowered by -6dB (50%).
  • Del1 time is set to around 362ms
  • Del2 time is set to around 480ms.
  • The wet level is set to around -11dBFS
  • Feedback for Del1 and Del2 is around 43%

  • With the depth knob at max - I measured around 10ms variation in Del1 L/R and around 15ms for Del2L and around 7ms for Del2R.

To emulate this on the Axe-Fx III, we can use two delay blocks set to Dual Delay Type
  • Del1L = Delay Block 1 L
  • Del2L = Delay Block 1 R
  • Del1R = Delay Block 2 L
  • Del2R = Delay Block 2 R
  • Delay Block 1 Pan L and Pan R can be set to -100 as they are emulating the delay lines for the left channel
  • Delay Block 2 Pan L and Pan R can be set to to 100 as they are emulating the delay lines for the right channel

Feedback

Following the block diagram, we can see that the feed from Del1 to Del2 is phase inverted, so we can use the negative feedback feature of the delay block to invert the phase - since I measured 50% reduction, we can set it to -50%
  • On Both delay blocks, set Feedback L>R to -50%
  • Set Feedback R>L to 0% as Del2 does not feed into Del1.
  • Set Feedback L>L and Feedback R>R on both delay blocks to 43% to match the measured value.

Time and Modulation

  • We can use LFO 1 in the controllers section, mainly because we can map which side A or B we can use and can control the depth more accurately (unsure how the depth scaling works for the built-in delay block LFOs).
    • Output B Phase is set to 90 degrees
  • Delay 1 Time L (Del1L) is mapped to LFO1B, with a parameter range of 357-367ms (approximates the setting of 362ms, with +-5ms)
  • Delay 1 Time R (Del2L) is mapped to LFO1B, since I measured that Del1L and Del2L LFOs are in sync, with a parameter range of 473ms to 488ms, approximating the 15ms depth around 480ms.
  • Delay 2 Time L (Del1R) is mapped to LFO1A, since Del1L and Del1R LFOs are 90 degrees apart, with the same parameter range map as Delay 1 Time L.
  • Delay 2 Time R (Del2R) is mapped to use both LFO1B and LFO1A, with a 50% and 10% mix respectively
    • The tricky part here is that the LFO1A/B outputs go from 0 to 1 - for periodic signals like the sin type, this means the mean is 0.5. When scaling however, the mean is impacted, for example for Scale 1 set to 50% the mean becomes 0.25.
    • So we need to compensate with Offset to keep the same mean.
    • The measurements show the mean for Del2R LFO matches the mean for Del2L LFO.
  • We use the Scale parameter in the mapping section of the modifiers to simulate the measured depth of 46% for all (Delay 1 Time L/R, Delay 2 Time L/R)

Filtering
Saturation

Attached is a patch with all these parameters set.
Edit: Attached preset v3 which attempts to match saturation and filtering.

Here's a comparison between the Halo pedal and the Axe-Fx III - first is the Axe-Fx III, then the Halo pedal.



Edit: After matching filtering and saturation:
Click to expand...

Dude, you are awesome! Thank you!
 
AlbertA said:
I got my Keeley Halo Pedal yesterday - I made some measurements as I was curious about the settings the default preset (1A) uses for the Halo sound.

Thanks to the block diagram posted by @Robert Keeley himself here: https://forum.fractalaudio.com/threads/keeley-halo.185333/page-4#post-2288551, we know the pedal uses 4 delay lines, Del1L, Del1R, Del2L, Del2R.
Del1L feeds into Del2L and Del1R feeds into Del2R.

Measurements

Here's what I measured for the default preset (The Halo sound), with the pedal in wet only mode and hooked into In3/Out3 of the Axe-Fx III set to unity gain:
  • The modulation rate is set to around 0.252Hz
  • The modulation depth is set to around 46%.
  • There's two LFOs, which I'll call LFO1A = sin, LFO1B = cos, both in sync with each other and 90 degrees apart (naturally).
  • Del1L is modulated with LFO1B.
  • Del1R is modulated with LFO1A.
  • Del2L is modulated with LFO1B.
  • Del2R is modulated with a mix of 0.5*LFO1B + 0.1*LFO1A which results in a LFO output that's about half the depth of Del2L LFO and about a 11.25 degree shift.
  • The output of Del1 into Del2 is lowered by -6dB (50%).
  • Del1 time is set to around 362ms
  • Del2 time is set to around 480ms.
  • The wet level is set to around -11dBFS
  • Feedback for Del1 and Del2 is around 43%

  • With the depth knob at max - I measured around 10ms variation in Del1 L/R and around 15ms for Del2L and around 7ms for Del2R.

To emulate this on the Axe-Fx III, we can use two delay blocks set to Dual Delay Type
  • Del1L = Delay Block 1 L
  • Del2L = Delay Block 1 R
  • Del1R = Delay Block 2 L
  • Del2R = Delay Block 2 R
  • Delay Block 1 Pan L and Pan R can be set to -100 as they are emulating the delay lines for the left channel
  • Delay Block 2 Pan L and Pan R can be set to to 100 as they are emulating the delay lines for the right channel

Feedback

Following the block diagram, we can see that the feed from Del1 to Del2 is phase inverted, so we can use the negative feedback feature of the delay block to invert the phase - since I measured 50% reduction, we can set it to -50%
  • On Both delay blocks, set Feedback L>R to -50%
  • Set Feedback R>L to 0% as Del2 does not feed into Del1.
  • Set Feedback L>L and Feedback R>R on both delay blocks to 43% to match the measured value.

Time and Modulation

  • We can use LFO 1 in the controllers section, mainly because we can map which side A or B we can use and can control the depth more accurately (unsure how the depth scaling works for the built-in delay block LFOs).
    • Output B Phase is set to 90 degrees
  • Delay 1 Time L (Del1L) is mapped to LFO1B, with a parameter range of 357-367ms (approximates the setting of 362ms, with +-5ms)
  • Delay 1 Time R (Del2L) is mapped to LFO1B, since I measured that Del1L and Del2L LFOs are in sync, with a parameter range of 473ms to 488ms, approximating the 15ms depth around 480ms.
  • Delay 2 Time L (Del1R) is mapped to LFO1A, since Del1L and Del1R LFOs are 90 degrees apart, with the same parameter range map as Delay 1 Time L.
  • Delay 2 Time R (Del2R) is mapped to use both LFO1B and LFO1A, with a 50% and 10% mix respectively
    • The tricky part here is that the LFO1A/B outputs go from 0 to 1 - for periodic signals like the sin type, this means the mean is 0.5. When scaling however, the mean is impacted, for example for Scale 1 set to 50% the mean becomes 0.25.
    • So we need to compensate with Offset to keep the same mean.
    • The measurements show the mean for Del2R LFO matches the mean for Del2L LFO.
  • We use the Scale parameter in the mapping section of the modifiers to simulate the measured depth of 46% for all (Delay 1 Time L/R, Delay 2 Time L/R)

Filtering
Saturation

Attached is a patch with all these parameters set.
Edit: Attached preset v3 which attempts to match saturation and filtering.

Here's a comparison between the Halo pedal and the Axe-Fx III - first is the Axe-Fx III, then the Halo pedal.



Edit: After matching filtering and saturation:
Click to expand...

What exactly is the Tape Distortion drive block needed for?

Edit: Nvm I saw your other post explaining it. Is it totally necessary?
 
Jipps0525 said:
What exactly is the Tape Distortion drive block needed for?

Edit: Nvm I saw your other post explaining it. Is it totally necessary?
Click to expand...
Depends on what you mean by totally necessary. I think the contribution is fairly subtle on its own - in the pedal the amount of low pass and saturation are linked so I think you end up hearing more of the filter contribution. In any case IMO you are still well within the halo sound if you bypass it but keep the rest of the setup.
 
AlbertA said:
Depends on what you mean by totally necessary. I think the contribution is fairly subtle on its own - in the pedal the amount of low pass and saturation are linked so I think you end up hearing more of the filter contribution. In any case IMO you are still well within the halo sound if you bypass it but keep the rest of the setup.
Click to expand...
This is what i was getting at. I use fm9 so 2 drive blocks is pushing it within my current template
 
Sounds great - the real pedal seems to be clearer, though. The Axe model seems to be pushing into OD but also less of the original signal in the sound.
 
MackieFX said:
Sounds great - the real pedal seems to be clearer, though. The Axe model seems to be pushing into OD but also less of the original signal in the sound.
Click to expand...
Guess it depends what you're after, but I lowered the mix and master feedback on both delay blocks.
Short version is I agree with you, but I'm not comparing the the real pedal, just going for what I like to hear for that sort of ambience effect.
 
Great work AlbertA !

It's my turn to share something. Here's an updated version of my Andy Timmons preset, with these "Halo" settings. The original preset (from my "Rock & Metal vol 1" pack) was made after Vai Academy 5.0, where I got to check Andy's amps and effects settings, and further tweaked after watching many of his Stage It streaming shows (I recorded all of them) and taking an online lesson with him (that was great ! I asked him lot of details on his amp & effects settings, he checked my AT preset, and I even made him improvise over the synth backing of one of my "drones" presets, like "Fremen's drones of Arakis". Wish I could post that video, I recorded the full session :cool: )

My preset uses a custom user cab, which I don't want to share, but you can use channel B of the cab block for the first two scenes instead if you don't already have it from one of my packs.



This short video is not an extensive demo, I made it to show two things : (1) the difference between my custom cab and the stock cab I used (I didn't searched for long, probably another cab will sound closer to mine, I'm not that familiar with stock cabs), (2) the AlbertA "Halo" settings (scene 5, also used in all scenes except scene 6) and the original delay setting of my preset (scene 6). I tend to prefer the stereo bouncing delay spread of scene 6 myself, but kudos to AlbertA and all the guys who worked on the Halo settings !
 

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fremen said:
Great work AlbertA !

It's my turn to share something. Here's an updated version of my Andy Timmons preset, with these "Halo" settings. The original preset (from my "Rock & Metal vol 1" pack) was made after Vai Academy 5.0, where I got to check Andy's amps and effects settings, and further tweaked after watching many of his Stage It streaming shows (I recorded all of them) and taking an online lesson with him (that was great ! I asked him lot of details on his amp & effects settings, he checked my AT preset, and I even made him improvise over the synth backing of one of my "drones" presets, like "Fremen's drones of Arakis". Wish I could post that video, I recorded the full session :cool: )

My preset uses a custom user cab, which I don't want to share, but you can use channel B of the cab block for the first two scenes instead if you don't already have it from one of my packs.



This short video is not an extensive demo, I made it to show two things : (1) the difference between my custom cab and the stock cab I used (I didn't searched for long, probably another cab will sound closer to mine, I'm not that familiar with stock cabs), (2) the AlbertA "Halo" settings (scene 5, also used in all scenes except scene 6) and the original delay setting of my preset (scene 6). I tend to prefer the stereo bouncing delay spread of scene 6 myself, but kudos to AlbertA and all the guys who worked on the Halo settings !
Click to expand...

Cool preset cant wait to try. Different from my normal “Marshall-ey” instincts :)
 
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