This week I wrote 2 blogposts on aliasing in amp simulation. I focussed on Reason for part 1 and focussed on Ableton Live for part 2. Aliasing is ruining perfect sound, making digital sound uhm… digital!
For today, for part 3 of what seems to have become an aliasing series, I want to focus on all the Reason rack devices which can saturate an audio signal. Testing both the native Reason devices as well as the rack extensions I have bought. To see (hear!) if they are prone to produce these annoying aliasing sounds. This time I didn’t make samples.
What I found out is that all standard Reason devices are producing aliasing sounds. Yes ALL of them!
Here’s the list of all the default Reason devices I have tested:
Pulveriser (Dirt module): aliasing!
The Echo (Color module): aliasing!
Aligator (Drive module): aliasing!
Audiomatic (VHS & Cracked modes): aliasing!
Scream 4 (all modes): aliasing!
D-11 Foldback Distortion: aliasing!
Synchronus (DIST module): aliasing!
Thor (Shaper: all modes): aliasing!
Malström (Shaper: all modes): aliasing!
And here’s the list of the additional rack extensions:
Cakewalk RE-2A: no aliasing
Primal Audio ACID Diode Ladder Filter: no aliasing
Primal Audio Ladder Multimode Filter: no aliasing
Primal Audio PMS-20: aliasing in both modes, see back of the device
Softube Saturation Knob: no aliasing
Battle-Axe Sound Destroyer: aliasing on all saturation modes (Cleave, Trash, Decap)
Conclusion
The Primal Audio PM-20 and the Battle-Axe Sound Destroyer REs are bummers! I hope the companies add an oversampling switch to these devices one day. Possibly with a switch on the back of the devices. 2 times oversampling is often enough to prevent them from aliasing. So it should be a super easy fix right?
It is 2016, stuff shouldn’t sound low res digital anymore. Simple as that.
image by Moxfyre / under Creative Commons BY-SA (Wikimedia)
P.S. these tests are done using a sample rate of 44.1 kHz. Sometimes I use 48 kHz for video projects.
UPDATE (Nov 18, 2020): By email someone asked me if the Sononics Revival RE is causing aliasing errors. I am very fond of its sound. Not only for retro organ sounds, but also as an effects processor. See my review:
Today I decided to put my nerd hat on.
When pushing the drive of the Gold, Red and Brown modes on the Preamp section to the max I could not detect any noticeable aliasing. However with the SilverHG and BlueHG (high gain) modes aliasing became very much noticeable.
I think this device doesn’t use oversampling techniques. The Gold, Red and Brown are filtered overdrives so the filtering in combination with the moderate amount of saturation seem to be a safe combination.
I tested this in a project at 44.1. At 96 kHz the aliasing errors shift to a higher frequency spectrum which might solve the issue you might have when using the HG modes. See my post:
I must say I never use the HG modes, only the Gold, Red and Brown modes. So for me this isn’t a problem at all.
5 Comments
would be very interested to see results of testing at 48k and even more interested to know results at 96k would stepping up to these higher sampling rates avoid possible aliasing in track devices ? 96k is like using 2x oversampling at 48k
I am planning to write another article on this subject. Indeed 96 kHz would be a solution to prevent aliasing. But even so, oversampling is still very much needed imo.
By Post Author
Even at 192k some saturators would have aliasing. Not only high sample rates, but also anti-alias filter is needed.
192 kHz is 4 times oversampling when working in 44.1 kHz. On my guitar plugins (amps and overdrives) I am using 8 times oversampling just to be sure. Some equipment offer 32 times oversampling. You can only use it when rendering. CPU usage is the main issue here.
When working at 96 kHz aliasing should not really be an issue, except when using some serious distortion.
By Post Author
I just tested the Softube Saturation Knob (latest VST version April 2022). It DOES have aliasing. I used a 8372hz (C9 note) Sine Wave signal and reasonable settings and the aliasing became visible. Unfortunately there is no oversampling setting, even though the aliasing is not that severe, but moderate enough to matter in the context of a full mix.