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Forums - Synths & synthesis
Subject: virus filter
Viewing all 32 messages - View by pages of 10: 1 2 3 4
Original Message 1/32 24-Sep-02 @ 03:37 AM - virus filter
Thanks in advance.
Message 2/32 24-Sep-02 @ 04:04 AM - RE: virus filter
dunno...rez seems quite rezzy on mine!
Message 3/32 24-Sep-02 @ 05:43 AM - RE: virus filter
After you do all of that sweep the Resonance.
Thanks!
Message 5/32 24-Sep-02 @ 06:32 AM - RE: virus filter
Are you talking about the "whistle" you get, like when you crank a supernova? When you say the sound is "attenuated" do you mean actually quieter or just darker, like the filter isn't open the whole way?
I know the Nova has a parameter (Q norm amount) that can dynamically control the output of the filter depending on how much resonance you set (kind of like pseudo-compression... resonance squawks can get really loud). Perhaps the Virus has something similar? Just guessing here...
psylichon
Message 6/32 24-Sep-02 @ 02:33 PM - RE: virus filter
At least that's the explanation I've come up with
-Craig
Message 7/32 25-Sep-02 @ 05:58 AM - RE: virus filter
One thing I do know is that all the VA's accept the Virus will not self oscillate. Perhaps that is why those other filters sound differently with high res.
Now if you bring down the cutoff just enough to were you can hear the resonance peak then you can hear the resonance gaining. Otherwise your full cutoff peak is higher then the res peak.
Now if you can hear the res peak over the full cutoff then like you can hear on the Jp 8000/8080 then that probably means that if you can give the res enough gain you can self oscillate.
BTW Does anyone know exactly what the Virus's filter is modeled after?
Message 8/32 25-Sep-02 @ 07:32 AM - RE: virus filter
A 24 dB/octave filter would allow more of the saw wave through than a 2- or 3-pole filter.
A s/nova's filter will self oscillate. I don't own any other VA's, but I'd reckon most others self oscillate, too.
I think what we have here is a failure to communicate.
psylichon
Message 9/32 25-Sep-02 @ 08:50 AM - RE: virus filter
Thanks again!
P.S. BTW, this isn't of any importance, I'm just curious
Message 10/32 25-Sep-02 @ 09:53 AM - RE: virus filter
Also, those other synths might have the cutoff only go up to 16khz or something.
(it's all guesswork)
Message 11/32 25-Sep-02 @ 11:29 AM - RE: virus filter
Steve Roughley
Posts: 1178
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regards.
steve.
Message 12/32 25-Sep-02 @ 07:30 PM - RE: virus filter
uh....
Message 13/32 25-Sep-02 @ 07:36 PM - RE: virus filter
I meant a fully opened 24 dB/oct lowpass filter fully opened would most likely pass more signal than a LP filter with a gentler slope.
In fact, I'm playing a raw saw patch on me Nova right now and switching between the 12/18/24 dB filter. I'm right! Nyah nyah! :}
psylichon
Message 14/32 25-Sep-02 @ 08:53 PM - RE: virus filter
Message 15/32 25-Sep-02 @ 10:12 PM - RE: virus filter
wouldnt any filter sound the same as the next wide open?
Message 16/32 25-Sep-02 @ 10:18 PM - RE: virus filter
[image file]
Check it ^^^^
I didn't say it would pass higher frequencies, I said it would pass more signal.
Think about it: An fully open lowpass filter should pass all signal. The only thing is filters have slope, so some hf signal will always be attenuated (unless it's somehow calibrated to compensate for the slope.. on the Nova this doesn't appear to be the case). Hence a gentler slope, less signal.
None of this is even remotely important, I just don't have a job right now.
psylichon
Message 18/32 25-Sep-02 @ 11:00 PM - RE: virus filter
The filters on these synths actually lose frequency or signal when your at 24 db mode. Now if you have the filter wide open with no resonance both the Jp 8080 and the Virus will see no loss in signal or freq quality no matter if its 12 or 24 db mode. On the Jp 8080 if you turn up the res with the filter wide open the waveform will start to atenuate and you will also hear the Q gain or res gain if you like. On the Virus if the filter is wide open and you turn up the q gain it will not atenuate the waveform but instead act more like a volume control. The more res you give the quiter the waveform gets.
Now if you have the filter half way open with no resonance and you switch from 12 db mode to 24 db mode you will notice that in 24 db mode on both the Virus and the Jp 8080 the waveform sounds alittle quiter and as well less quality meaning the 24 db mode is not letting all the signal out of the waveform. The waveform in 24 db mode sounds darker in tone in 12 db mode the waveform will sound brighter.
Now add some resonance and you will here the attenuation as well the Q gain. Both synth will sound more and more raspier as you add more Q. The difference is on 24 db mode the JP 8080 goes to self oscillation becuase the Q gain is greater than the cutoff slope. So when you move the cut off with full gain on the JP at 24 db mode it will sound like a whistle. This is the full feedback of the Q. I can say even though the JP 8080 can self oscillate it is still not perfect oscillation becuase you can still hear very little of the waveform. Its just in the background very quitely. But its close enough to be considered self osc.
The Virus with full q wont self osc becuase its filter cutoff is greater then the Q factor. Yes you can create a self osc like sound on the Virus if you programe it right but all it is is shapeing the waveform with the cut off slope to fit that self osc quality of sound. which is totaly different then that of what the JP 8080 does.
I admit im no signal expert but I can tell you what my ears are hearing. And this is how those filters sound to me.
Message 19/32 25-Sep-02 @ 11:08 PM - RE: virus filter
___________________________________
I had an idea for a script once. It's basically Jaws except when the guys in the boat are going after Jaws, they look around and there's an even bigger Jaws. The guys have to team up with Jaws to get Bigger Jaws.... I call it... Big Jaws!!!
Message 20/32 25-Sep-02 @ 11:58 PM - RE: virus filter
[image file]
umm psylichon... take a look at this, and tell me why dont i have your job, mr. professional engineer? eh?
m ;)
Message 21/32 26-Sep-02 @ 01:15 AM - RE: virus filter
me - "some hf signal will always be attenuated (unless it's somehow calibrated to compensate for the slope.. on the Nova this doesn't appear to be the case). "
I can only comment on the gear I have. On the Nova there seems to be an absolute top throw for the filter, and using a filter of gentler slope attnuates more high frequencies. If you have a Nova, check it out yer damn self. It makes sense logically, it just depends on how the filter is designed. So fuck off.
psylichon
"professional" means I get paid occasionally, it doesn't imply skill. I've been known to make mistakes, too.
Message 22/32 26-Sep-02 @ 02:23 AM - RE: virus filter
and Im NOT!
Message 23/32 26-Sep-02 @ 03:35 AM - RE: virus filter
SCORPION, you hit the nail on the head, on the Virus, with a filter fully open Resonance starts acting like volume control. And you explained everything in a very clear manner. Thank you!
Peace!
Message 25/32 26-Sep-02 @ 04:45 AM - RE: virus filter
Your welcome!
Message 26/32 26-Sep-02 @ 12:52 PM - RE: virus filter
___________________________________
I had an idea for a script once. It's basically Jaws except when the guys in the boat are going after Jaws, they look around and there's an even bigger Jaws. The guys have to team up with Jaws to get Bigger Jaws.... I call it... Big Jaws!!!
Message 27/32 26-Sep-02 @ 01:01 PM - RE: virus filter
Message 28/32 26-Sep-02 @ 02:47 PM - RE: virus filter
a 24dB slope is steeper than a a 12dB slope, so it cuts more high frequencies for a given cutoff point than does a 12dB filter.
the bottom line is that a 12dB LPF lets more high freqs through than a 24dB LPF for a given cutoff point.
As for Q (=resonance), boosting the Q (cranking up the resonance) causes LPFs to tend towards band-pass behaviour as the freqs around the cutoff point are boosted (note how bass disappears when you crank the res). in effect, the slope of the filter becomes steeper and steeper. you change the Q of the filter when you increase the res. Q is the Quality of the filter. novations have the Q-norm feature which seems to avert the detrimental side-effects (loss of bass).
Message 29/32 26-Sep-02 @ 06:39 PM - RE: virus filter
I ran my Nova experiement again and found I was wrong. I actually restored a totally vanilla patch from ROM and used that. There must have had some other parameter in yesterday's test patch that I was hearing. Sorry for the confusion.
psylichon
Message 30/32 26-Sep-02 @ 07:08 PM - RE: virus filter
anyways, Q is often interchanged with resonance, because they're about the same thing; just usually, for those 'out there' not in the music world, they're not designing filters to sound good with the resonance up, actually they're trying to design filters with the maximum cutoff and no ringing whatsoever. most practical non-musical reasons for filtering (and there are many) have totally different goals. Q=quality comes from the internal gain structure; as you increase feedback in the system, you can make the cutoff steeper, in exchange for some 'ripple' or 'ringing' at the point of cutoff.
so, in a real filter, it's not really a strict '12 db' or '24 db' response. the poles do have a large influence on the filter response, but so does Q - when Q is low, we have no ringing, but the frequency slope isn't as steep. as we bring Q up, the filter slope gets steeper, but we start 'ringing'. ringing equals that traditional boost around the cutoff. the higher Q, the steeper the cutoff still but the boost is higher. so there really is more going on than just a boost.
another interesting feature of this is that in a real analog filter, you don't just get one boost right at the cutoff. it's more like a ripple in a pond.. a large boost right at the cutoff, a smaller boost a little lower in frequency, an even smaller boost farther down, fading away (these 'ripples' as they are called also go above the cutoff frequency, but we are generally so far down at this point they are irrelevant). the smaller ripples do not affect the signal near as much as the main ripple, but they could have some effect...
Message 31/32 26-Sep-02 @ 07:11 PM - RE: virus filter
psylichon
Message 32/32 27-Sep-02 @ 01:17 PM - RE: virus filter
OnAcid
Posts: 18
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"Self oscillation is, when the resonance control - which is a sort of Feedback actually - can be set to values above 1, so the filter amplitude is increasing by itself until it hits the headroom, and than sticks there. This is identical in analog and digital domain. For the exitation, you need some signal. In the analog domain noise is always apparent, in digital domain you can add some dither noise to archive the same effect. But noise is not the reason for self oscillation.
The Virus filters do not allow self oscillation, but still allows very high resonances resp. Q-factors.
Waldorf does more to archive self resonance than simply adding noise. But that makes the filter sound different even on lower resonances ..."
Just turn up a bit of noise on the virus...full resonance...turn down the cutoff...et voila.
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