Maybe this is a very stupid question, but i find it very disturbing that the resonance knob changes the volume of a sound.
Although I can stretch my hand very good, it’s impossible for me to touch volume and resonance at the same time while playing notes on the keyboard. I’m thinking of buying another expression pedal and connect it with the volume controll input to get it under control, but someway I don’t belive that this is the common way to handle this issue.
The reason the resonance knob changes the volume of the sound has to do with the filter design. This has been discussed here before.
Basically, the Moog filter has built-in automatic gain compensation (AGC), which keeps the overall signal level constant. Without AGC, high resonance values could significantly increase the signal level at the filter output, causing an overload condition within the Voyager’s signal path. AGC keeps this from happening.
At my Voyager the overall signal level does NOT keep constant when I switch on resonance, instead it decreases! With very high resonance I still get a higher signal level anyhow.
Maybe this is “Moogish” or “not a bug but a feature”, but I would personally prefer not having AGC.
Try to use an envelope to modulate the cutoff inversely. MC did the exact opposite in the Andromeda (modulating both the cutoff and the resonance) to coax a more convincing Minimoog emulation and it sounds nice.
I’m sure that it would! Without AGC, when the filter is set to self-oscillate, there would be a huge gain spike at the resonant frequency. This condition would likely drive the VCA into distortion and possibly even cause damage to your speakers (or eardrums) if you were monitoring at sufficiently high levels.
Passband loss is a common characteristic of a number of classic filter designs.
ARP’s 4-pole filters (4012/72/75) also have this characteristic.
Using a bandpass response curve as an example, the characteristic can be visualized with a circular plastic bag, half filled with water, sitting on a tabletop, knotted point center, facing upward.
If you take the knotted tip between your thumb and index finger and slowly pull upward, away from the tables surface, you’ll notice the portion of the bag on the table pull inward and get smaller (in area) as you lift the knotted tip vertically.
The tip between your fingers represents the center frequency of your filter, and the lifting action represents an increase in amplitude of resonance at the cutoff froquency.
That the passband gets smaller as resonance peak is increased in amplitude is expressed as:
BW = f0/Q
Q being used to represent resonance, f0 denotes resonant (or cutoff) frequency, BW is bandwidth.
That is, bandwidth is inversely proportional to Q (resonance). So as you increase resonance, bandwidth in the bandpass filter decreases at the ends of the passband spectrum above and below the center frequency.
In a lowpass filter, it takes place at the end of the passband spectrum beneath the cutoff frequency, hence the loss of bass as you crank the resonance.
This is a natural characteristic for communications, as a decrease in bandwidth and increase in Q makes the circuit more “selective”, and is needed to impede the passage of adjacent channels relative to a tuned
channel.
There is a technique on the Vger that seems to compensate for some of the lost audio at high resonance settings.
You do this by pot mapping the resonance control to the ext input level control in the mixer.
If you have a feedback loop cable in place (I use mixer feedback), you can set the gain structure so that at the point you’re getting loss of low end audio in the filter’s response, a portion of the signal is fed back
into the external in. You can even use an eq in the loop to help,
Typical Pot Mapping setting:
SRC - Filter Res
Dest - Ext Audio In
Direction - Normal
Amt - 50%
With the external In set to about 7, or 7.5 (on panel legend) and the above pot map settings, the overload led in the mixer should begin to flicker when the resonance control gets to about 3.5 on the panel legend.
This will restore some of the signal and add a bit of overdrive as well.
Also, the settings for this technique will be stored on a per patch basis, as pot mapping is a stored parameter. You just have to physically have the cable in place for it to work.
Caution: watch your levels when using any secondary controller mapped to the “ext audio in” stage.
Switch the loop off (ext switch in mixer) when you need to use the filter oscillation for audio.
HI i’m a newbie voyager owner i’m from Italy and i think i don’t well understood which connection i have to do on the rear panel to set this trick …i have to connect the right output to ext,in input OR mix out/filter in TO external? so i need a y cable to connect the send both to return and ext in ?
Then i have to map the resonance to external in pot right?
Thanks a lot to everyone will help me! Ireally need this trick 'cos my playing style require a lot of HI resonance filtering and the volume decreasing is very noticeable while i’m playig in live performances!
Nico
Hi, could be a good trick to resolve the volume loss in this way?
I set the master volume of the voyager at half way or 3/4
pot mapping as follow:
Source: filter resonance
Dest: master volume
Direct: Normal
Amount: 25% or 50%
maybe it could be a stupid exploit but it seems to be quite logical, obviously you have to push up the amplifier volume a little bit in order to compensate the half way master volume…
best regards, Nico
Hi i’ve tried to resolve the volume changement while changing resonance and i found that the pot mapping method has perfectly solved the problem, i’ve set the voyager in this way:
make this settings:
1)MASTER VOLUME set about to 3/4
2)RESONANCE KNOB at 0
3)go to the EDIT menu and select the POT MAPPING feature
4)select one of four SRC & DEST Map and make this setting inside the submenu:
SOURCE: filter resonance
DESTINATION: master Volume
DIRECTION: normal
AMOUNT: 50%
5)LISTEN the volume with resonance at 0 then with resonance about 7/8 just before the filter start to selfoscillate,
ADJUST the master volume knob until there is no difference of amplitude between the two setting and listen while raising resonance that the volume is constant;
I’ve set the pot map amount to 50% to have more precision Maybe You can set the amount of pot mapping to 100%, just try…
CAUTION: the only negative side of this trick is the reason of the origin of this problem! Remember to cut down the volume when you want to self-oscillate the filter to avoid damaging of you speakers! Moog put this circuitry design in order to prevent problems like this…but i think that the loss of volume is too heavy and very noticeable while performing! so this is the only way i found…the problem is quite irrilevant while sound design!
I just want to say it is incredibly useful topic !
I own LP, and i’m not playing live a lot, but, since I’m spending hours and hours in my studio, it will save me lot of time fixing this lack of tone in the mixing process
thnx
edit
no,it does not work on LP. You can pot map the main vol., but you can not control two things at the same time.
I’ve faced similar issues when adjusting resonance; keeping an eye on overall volume helps maintain clarity. Also, if you ever need to track Salik tolls while experimenting, https://checksalikbalanceae.com/ is handy.
