Needing help with a filter

stefan · 26 Dec 2005

Two issues: 1) you're mixing "stream" "poly" connections, so that the same component both uses mono4 and poly inputs. All should be generalized stream (or mono4) 2) it's a monophonic section, using the standard adsr won't work, since it's strictly polyphonic. is the filter SUPPOSED to be monophonic or should it really be polyphonic?

MyCo · 26 Dec 2005

It should have a mono4 input and a mono4 output. The Pitch input is a poly.

I don't understand your point 1) because a poly can be converted by connecting it to a mono4.

skOre · 26 Dec 2005

Something is really messed up with your schematic. First of all, as stefan said, directly routing a poly stream into a mono (or mono4 in that case) is a big nono. Use same stream type all the time and if you need to, convert them. I also don't understand why you would want that section to be mono if you want an envelope folower. If you would want polyphonic envelope for them, use poly, if you want a mono envelope, use mono (although you would need a lot more work to accomplish that - there is an example on this in the EA forum).

So basically the same as stefan said, you can't just mash up different streams, especially not mono/poly together. You need to have converting going on in between.

MyCo · 26 Dec 2005

I've already tried a lot, just converting forth and back. But nothing works. Here are 2 versions, as Stefan said:

http://music-drive.com/files/problem2.osm http://music-drive.com/files/problem3.osm

But there the complete filter won't work. There is no sound at all.

The reason for that what I need: I want 2 left-right panned oscillators connect to one filter, so that I don't need to duplicate all filter parts. That would also work when I just convert 2 mono signals back to one poly, but I haven't found a way to do this.

skOre · 26 Dec 2005

I feel that you got a lot of things wrong.

A) There is no connecting mono back to poly. Poly is a means to handle more voices than one at one time, which is done by having your computer duplicating the whole poly stream for each voice. Converting mono back to poly would mean that you want to make more than one voice out of one. How do you think should this work? Try to train a program to get all the poly voices out of a stereo stream, and I buy your patent for 10k bucks.

B)Why do you want two oscillators routed into one filter? Why don't you just take one osc duplicate the output so you have one left and one right channel. Then you could also have a filter before the channel work and you have it poly and in stereo.

Please check with the Documentation and work through all of that. Especially the Tutorial Synth Explaination.

This will clear a lot of errors in your thinking I s'pose. Most of your questions are due to you not knowing how to handle synthesis in general. So please make yourself familiar with these concepts before asking for things that won't work in this dimension.

daze after daze with the families, excuse me for being rude

oddson · 26 Dec 2005

skOre wrote: daze after daze with the families, excuse me for being rude

Shouldn't have small'd that skOre.

I think you're being a little harsh.

That said, MyCo, you do need to get the basics before plunging in.

MyCo · 26 Dec 2005

hm... The Tutorial-Synth and all of the other synth I found in the forum have one realy big problem. They have 2 or more oscillators, but this Oscilatore are everytime centered in the stereo-panorama. That's not typical for VST synths. The reason, why they are only centered is: it is simple.

My Synth needs oscilators on different positions in the stereo panorama. So and now to "why I don't use poly input on the filter". If I would use poly inputs, my filter need 4 of them, 1 for each oscilator. Otherwise I would loose the panorama positions. Then I need to copy each Filter 4 times.

That's not the only problem with that. There will be a lot of effects which need to be 4 times there.

So I look for an easy way to mix 4 stereo oscilators down to 1 stereo line, connect this stereo line to one filter, and different FX, and finaly split the stereo line to 2 mono line for VST output.

I hope that someone understands what I'm looking for.

MyCo · 26 Dec 2005

@Skore, I think I know more about DSP than most of all here. I am a programmer, I studied on the university where they made the mp3 codec. May be that I've lost a lot of information from that what I studied, but I don't think that you have the right to say that I'm a noob to DSP.

The problem is that my english is so bad that nobody understand what I want. 🙂

stefan · 26 Dec 2005

If you want a polyphonic "stereo" synth with filters, you MUST have two filters, one for the left channel and one for the right. Keep the filters as "poly" and nothing will go to waste, when there's four voices playing simultaenously, there's still just two filters active (since they can handle four voices per process).

osc_l -> filter_1 osc_r -> filter_2

osc_l & osc_r is left and right out from the oscillator, filter_1 and filter_2 are two separate filters that can use the same adsr and knobs etc, but must be two different filter instances. so you don't need a separate filter for each oscillator, only for each stereo channel.

the mono connections (mono and mono4) can't be used for polyphonic material, only monophonic. there is no polyphonic stereo stream, so you have to use two poly streams to work with polyphonic stereo signals.

MyCo · 26 Dec 2005

I see... I missunderstood poly and mono.

But it is stupid to duplicate everything behind the Oscs... there should be a better way in SynthMaker in the future.

stefan · 26 Dec 2005

MyCo wrote: I see... I missunderstood poly and mono.

But it is stupid to duplicate everything behind the Oscs... there should be a better way in SynthMaker in the future.

There's usually not _that_ much things going on in the polyphonic section of a synth, especially not that has to be unique for the left and right channel, and you only have to implement for instance a "stereo SVF" once to be able to use it in all your synths. So it's not a big issue, imo. I almost always have two filters in my synths anyway, but instead of having pan on the oscillators I have pan on the filters and can feed different amounts of each oscillator to each filter.