Robert Keeley
New Member
Howdy Folks!
I have read through most of the comments and analysis and its truly been a delight. The Halo sound developed from what Andy Timmons showed us he enjoyed, namely the Strymon Timeline and Memory Men, and discussions about how he wanted the sound characteristics to improve. Craighton Hale developed the schematic and circuit board and Aaron Tackett was the DSP programmer. After reading this thread I thought it would be best if we gave a very transparent and revealing description of our process, especially since there were so many creative approaches in trying to replicate the sound. So, I asked Aaron to produce a block diagram of the Halo effect.
Enjoy!
rk
[text from the pdf attached file is copied below]
The input signal is ran into a non-linearity for saturation control and then
low pass filtered. The cutoff frequency of the filter is dependent upon the
amount of saturation, ranging from 2725Hz to 8750Hz.
The saturated and filtered input is ran into Del1 which has a delay time
ratio of 0.75:1 to Del2. The output of the delay is ran through two single-
order filters, an HPF ranging from 0Hz to 300Hz and an LPF ranging
from 1000Hz to 8750Hz.
The filtered output is then modulated up to 9ms at full depth. The left
Del1 is modulated using a cosine while the right Del1 is modulated with a
sine lfo whose rate ranges from 0.1Hz to 10Hz. This modulated output
is then scaled by the feedback control and fed back to the input of Del1.
The saturated and filtered input is combined with the Del1 output. The
sum of these signals’ phase is changed by 180 degrees and ran into
Del2. The output of the delay is ran through two single-order filters, an
HPF ranging from 0Hz to 300Hz and an LPF ranging from 1000Hz to
8750Hz.
The filtered output is then modulated up to 15ms at full depth. Del2’s lfo
is based on the rate control, with the lfo cross-fading between sine and
cosine for the left and right. Essentially at certain points throughout the
sweep of the rate control the lfos for Del2 left and right will either be in
sync or 90 degrees out of phase. This modulated output is then scaled
by the feedback control and fed back to the input of Del2.
I have read through most of the comments and analysis and its truly been a delight. The Halo sound developed from what Andy Timmons showed us he enjoyed, namely the Strymon Timeline and Memory Men, and discussions about how he wanted the sound characteristics to improve. Craighton Hale developed the schematic and circuit board and Aaron Tackett was the DSP programmer. After reading this thread I thought it would be best if we gave a very transparent and revealing description of our process, especially since there were so many creative approaches in trying to replicate the sound. So, I asked Aaron to produce a block diagram of the Halo effect.
Enjoy!
rk
[text from the pdf attached file is copied below]
The input signal is ran into a non-linearity for saturation control and then
low pass filtered. The cutoff frequency of the filter is dependent upon the
amount of saturation, ranging from 2725Hz to 8750Hz.
The saturated and filtered input is ran into Del1 which has a delay time
ratio of 0.75:1 to Del2. The output of the delay is ran through two single-
order filters, an HPF ranging from 0Hz to 300Hz and an LPF ranging
from 1000Hz to 8750Hz.
The filtered output is then modulated up to 9ms at full depth. The left
Del1 is modulated using a cosine while the right Del1 is modulated with a
sine lfo whose rate ranges from 0.1Hz to 10Hz. This modulated output
is then scaled by the feedback control and fed back to the input of Del1.
The saturated and filtered input is combined with the Del1 output. The
sum of these signals’ phase is changed by 180 degrees and ran into
Del2. The output of the delay is ran through two single-order filters, an
HPF ranging from 0Hz to 300Hz and an LPF ranging from 1000Hz to
8750Hz.
The filtered output is then modulated up to 15ms at full depth. Del2’s lfo
is based on the rate control, with the lfo cross-fading between sine and
cosine for the left and right. Essentially at certain points throughout the
sweep of the rate control the lfos for Del2 left and right will either be in
sync or 90 degrees out of phase. This modulated output is then scaled
by the feedback control and fed back to the input of Del2.