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What plugin synth has the least aliasing (especially in the oscs)?
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psytendo
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Posted : Mar 1, 2008 22:56:56
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Hi there peeps,
I've been having a lot of problems with getting clean alias-free high frequencies out of synths and sampler plugs.
It seems the high freqs are hurt, sounding harsh.
I'm working in logic so AU is my option, but other suggestions are ok.
Anyone knows some good ones?
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MadScientist
IsraTrance Full Member
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Posted : Mar 1, 2008 23:13
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what synths are you talking about that give you harsh aliasing?
 https://soundcloud.com/hazak
"Have you ever had that feeling where you're not sure if you're awake or still dreaming?"
"Hmm, yeah... All the time, man - it's called mescaline. The only way to fly!" |
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psytendo
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Posted : Mar 2, 2008 00:09
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Just did a bit of testing so i could produce a list.
arturia cs-80v
cakewalk rapture
all of the logic instruments
linplug alpha
NI absynth
NI Massive (i could only verify by ear that it didnt sound clean (enough) , doesnt show any reflections on spectrum analyzer tho), but Massive is too heavy to use on my computer anyway:) )
NI kontakt (might be ok, but again, setting a sample to 'perfect' quality renders the plugin unusable)
Clavia Nord Modular
These are just a few synths i have installed atm.
But it seems most software synths i have tried have this problem in some way. Some more than others.
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MadScientist
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Posted : Mar 2, 2008 00:56
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ok so how did you figure out that its really aliasing what you mean?
you can always raise the sample-rate btw 
https://soundcloud.com/hazak
"Have you ever had that feeling where you're not sure if you're awake or still dreaming?"
"Hmm, yeah... All the time, man - it's called mescaline. The only way to fly!" |
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psytendo
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Posted : Mar 2, 2008 01:18
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I tested it by using a single saw as osc , no filter, no fx.
Played it around 10khz.
Then i have a spectrum analyzer after that (logic eq).
The spec analyzer clearly shows harmonics folding back.
This was not the case with Massive so it seems to be a good way to measure this phenomenon.
Increasing the samplingrate is just moving the problem. 
The bandwidth of a saw wave is enormous (theoretically infinite?).
So it doesnt solve it, just gives you a better chance of not hearing it as a problem
Also, i want to screw with fm and am at those freqs so any inharmonics are unwanted as a starting point.
And it takes at least double the cpu cycles. I cant afford that on my mac.
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OhmLine
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Posted : Mar 2, 2008 01:31
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what sampling rate you're normally working in ?
Also, if a hardware synth (Nord Modular) showed this symptom the problem might be somewhere else in the audio chain, maybe the soundcard or cables? (audio/data)
Is there a time you don't hear this problem ? like playing cds or something ?
YEEEEES! |
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MadScientist
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Posted : Mar 2, 2008 01:59
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sure but you shouldnt hear any reflections anymore with sample-rates like 88.2 and above
anyway, I dont use the logic synths much, especially for high frequency stuff...but rapture and absynth I use, and I've never recognized what you re talking about...
would you mind posting some screenshots with the folding back harmonics marked?
https://soundcloud.com/hazak
"Have you ever had that feeling where you're not sure if you're awake or still dreaming?"
"Hmm, yeah... All the time, man - it's called mescaline. The only way to fly!" |
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UnderTow
Started Topics :
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Posted : Mar 2, 2008 02:22
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Quote:
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On 2008-03-02 01:18, psytendo wrote:
I tested it by using a single saw as osc , no filter, no fx.
Played it around 10khz.
Then i have a spectrum analyzer after that (logic eq).
The spec analyzer clearly shows harmonics folding back.
This was not the case with Massive so it seems to be a good way to measure this phenomenon.
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When you play a 10 Khz SAW, look at the analyzer and pitch the pitch up, do the folded back harmonics go up or down?
Assuming I am thinking about this correctly, if the harmonics go up with the pitch, this isn't aliasing but something else. If they go down (the opposite of what the fundamental is doing) then it is aliasing.
I just checked with a few synths:
Rapture using the Zeta+ wave: The lower peaks in the analyser go up when I pitch up the fundamental pitch.
Vanguard: The lower peaks go down even with "alias free Oscillators" turned on. (No real surprise here. This synth always sounds aliased).
Massive: There are no lower peaks.
Dicovery: There are no lower peaks. (Surprised that it doesn't seem to alias considering its reputation).
Predator with 16X oversampling turned on: Hard to tell, there are many peaks that are not stable but they seem to be going down when the pitch is turned up.
Conclusions? I don't know. I don't know if not having peaks below the fundamental are a good or a bad thing. In general, mathematical waveforms are not considered to be the most musical.
Often waveforms will be intentionally less than perfect because they sound better that way. So are you observing aliasing or something else that is intentional or just a different by-product of the synth design? I don't know.
UnderTow
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psytendo
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Posted : Mar 2, 2008 06:35
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@OhmLine:
The nord modular is still a software synth (altho running on dedicated hardware) as is every other virtual analog synth.
@MadScientist:
well, higher samplerates are not an option for me as it consumes 2x as much cpu. I'm usually near 100% cpu with all tracks frozen so upping the sample rate is realy no option. (just imagine all my fx plugins need to work 2x as hard....)
btw, i should re-examine absynth. I just remembered it has other synthesis algorithms and i only tried one.
@UnderTow:
All my findings were based on the harmonics moving back into the audible spectrum, so moving down in your story. This is definitely aliasing.
the problem with aliasing is that it has no musical relation to the actual waveform. It is in fact inharmonics.
I dont want to say aliasing is bad per se, but you can apply it easily afterward.
Of course aliasing can ocur in different parts of the synth as well but i'd like to concentrate on Oscs first
I have to re-check Rapture, because i did get harmonics moving 'backwards'. So maybe i just need to enable some option or so.
About waveforms being not mathematically perfect, that's not what is happening.
If you see those harmonics moving back on the spectrum analyzer it means that the synth is trying to produce frequencies which cannot exist within the samplerate.
(that's why MadScientists suggestion of a higher samplerate is theoretically a good option, just practically not good for me, or i should make more minimal )
There are basically 2 possible solutions to this problem that i know of: either dont produce those frequencies or filter them out before they enter the rest of the chain.
Anyway, thanks for helping ! |
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OhmLine
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Posted : Mar 2, 2008 12:50
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Dude.
The Nord Modular is not a software synth even though you control it with software. It has it's "brain" and DACs outside the computer and you need to physically record or monitor the sound in your computer, through your sound card.
If you have this problem with recording sounds from the outside, I'll try to check the soundcard as it seems to me this is your culprit.
Good luck.
YEEEEES! |
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MadScientist
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Posted : Mar 2, 2008 14:15
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thanx for your testing undertow! I guessed that vanguard has a lot of aliasing, since its one of the synths that really sound much better at 88.2
anyway, I dont know if its really such a big problem (seems it is for you ), but I've never recognized some disturbing aliasing with most of the synths you mentioned...
seems I got just 1 conclusion for you if its bothering you that much: get a new mac and start working at 88.2
https://soundcloud.com/hazak
"Have you ever had that feeling where you're not sure if you're awake or still dreaming?"
"Hmm, yeah... All the time, man - it's called mescaline. The only way to fly!" |
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UnderTow
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Posted : Mar 2, 2008 14:24
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OhmLine, it is still software. It just runs on dedicated hardware.
UnderTow |
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UnderTow
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Posted : Mar 2, 2008 14:43
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Quote:
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On 2008-03-02 06:35, psytendo wrote:
@UnderTow:
All my findings were based on the harmonics moving back into the audible spectrum, so moving down in your story. This is definitely aliasing.
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We are in agreement.
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I have to re-check Rapture, because i did get harmonics moving 'backwards'. So maybe i just need to enable some option or so.
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Rapture doesn't use sync interpolate when running live. It does when frozen/bounced! (Note that you have to have the Osc Quality set to High to get the best results).
I find it a bit of a shame that the user can't turn on Sync Interpolate when the plugin is running live. Oh well...
UnderTow
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psytendo
Started Topics :
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Posted : Mar 2, 2008 16:59
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@OhmLine:
As me and UnderTow said the nord is still a software synth, bound to a samplerate.
In fact, the Nord Modular runs at 96kHz.
BUT the algorithms for the oscilators do alias and are unable to produce frequencies above about 20kHz.
They have their own internal samplerate which makes them alias.
I dont know how you came up with the story that its my soundcard. Its not.
@MadScientist:
One of the problems i am experiencing is a kindof slight swirly noisy 'feel' to the top end if i have a few things going on in the high freqs. Transparancy is lost for instance. Its as if the highs are not, well, pure enough.
I'm seriously thinking of starting to collect analog gear as they always have the kind of transparant high freqs i am looking for. Its just that i realy like staying 'in the box'.
@UnderTow:
Interesting feature of rapture!
But as i understand interpolation, it doesnt fix aliasing.
Its good for smoothing out waveforms that have a LOWER sample frequency than the main samplefrequency.
It works when you play, for instance, a wave at half speed. It should help make the basses more smooth.
The problem is that oscs can (try to) produce HIGHER frequencies than the samplerate.
One option could be an internal brickwall filter just underneath the main nyquist frequency (samplerate / 2).
But you'd need to oversample the oscs (make them run at a higher samplerate) and filter that down. Also a linear phase FIR brickwall has some latency, not sure how much of a problem that is.
Judging by Massive i'd say that its pretty heavy on the cpu.
Another solution could be to create the waves from some sort of additive synthesis and just never add patials that are higher than the niquist frequency.
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MadScientist
IsraTrance Full Member
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Posted : Mar 2, 2008 17:13
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I think especially analog gear wouldnt help you at 44.1, since (most-of) soundcard's adc's implement some more or less ugly anti-aliasing filters...but again, this depends on the quality of your interface...but from your position where you re after clear highs, I would just record analog stuff with sample rates like 88.2
https://soundcloud.com/hazak
"Have you ever had that feeling where you're not sure if you're awake or still dreaming?"
"Hmm, yeah... All the time, man - it's called mescaline. The only way to fly!" |
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