Yruama_Lairba wrote:To be short, i discovered an aliasing probleme with guitarix witch is probably present in all effect that introduce non-linearities like overdrive, distortion, tube preamp ... a very noticeable example is with the 12ax7 alone with pregain and drive at maximum. If you put sinusoid signal (I use Invada Test tones) inside guitarix, and if you use different frequency, you can hear dissonnant tones (try every test tones from 1khz :p). You can put a spectrum analyzer on guitarix output (calf analyzer but i prefer the ugly jaaa because you can have very high precision when using a very low "bandwith" value and it's easier to see harmonics with a linear scale of frequency).
Yruama_Lairba wrote:The reason of this problems is because non-linearities produces harmonics, even above the half of sampling frequency. if care is not taken, all harmonics the half of sampling frequency are aliased and dirty your signal. Even if it's impossible to totally supress the aliasing, you can reduce this by oversampling before non-linear effect, put appropriate lowpass filter after and finally "undersampling" to go back to the original frequency.
Yruama_Lairba wrote: a very noticeable example is with the 12ax7 alone with pregain and drive at maximum
brummer10 wrote:True, the distortion introduce harmonics into the signal, and so does the tube when it is driven hard by pregain, but I'm not able to hear aliasing artifacts when I play guitarix with my guitar.
ssj71 wrote:a very noticeable example is with the 12ax7 alone with pregain and drive at maximum
ssj71 wrote:Have you measured any aliasing when using your guitar
brummer10 wrote: guitarix is able to produce nice metal distortion sounds
brummer10 wrote:Using oversampling will be a easy task, but, it will use a lot more processing power
brummer wrote:I could, if you like, add a new branch "oversampling" to guitarix-git with oversampled non-linear effects and amp simulations.
Yruama_Lairba wrote:Only if it not involve not much effort. I'd like to test oversampling on guitarix but i'm not sure to hear difference and i don't want to bother you.
Yruama_Lairba wrote:I tried the oversampling branch, but i was unable to compile anything, even after cleaning everthin using ./waf clean and git clean -f. I fact, when I launch "./waf build" it complete without any errors, but it does'nt seem to do anything ?
git checkout oversampling
./waf configure --includeresampler --convolver-ffmpeg --optimization
Yruama_Lairba wrote:I also confirm that there something wrong with my config, I found presets giving me horrible sensation (https://musical-artifacts.com/artifacts/83), It feel like "bitdowner effect". Maybe, part of the "high frequencies" i hear sometimes is the same problem ? I don't know if it's guitarix or my soundcard driver, i don't have enought points of comparison.
Maybe, ensure that your mic isn't connected to the speakers, means, there should be no monitoring without you connect the mic to the speakers, or any other app, like guitarix, within jack. Turn down to zero, the PCM value of your input in Alsamixer, Select your soundcard(F6) and press F4 to get access to the input controllers.
Instead the PCM you should use the Mic, which will capture without monitoring the signal direct.
In file included from default/src/LV2/faust/fuzzface.cc:4:0,
../src/LV2/DSP/trany.h:64:22: fatal error: SVEL34t.cc: Aucun fichier ou dossier de ce type
Yruama_Lairba wrote:maybe it's because i don't have the right version of faust ? i'm using the --no-faust flag during configure.
note : the error means "no file or folder of this type"
Yruama_Lairba wrote:I'm using the pod studio UX2, and even if its drivers was integrated in linux kernel V4, the driver is not fully functionnal and sometime buggy.
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