Filter for synth

[Vokbuz]

Hello KVR,

I'm working on my first software synth and want to add filter to it. I found a lot of implementations 1-pole, 1-pole ladder, biquad etc. but still not sure which one is better choice to use. Every filter has its drawbacks:

I like the power of biquad but it requires a lot of computations for coefficients (what makes modulation very expensive) and it's stability is very poor (a least in direct form 1).

1-pole have no resonance and slope is not that good.

1-pole ladder sounds not so good to me (maybe I'm failed somewhere with implementation).

So I would ask for your advice. What is best filter choice for synth and how do you deal with its drawbacks? I know this is a very broad question but I think a lot of people have a similar question.

If this topic was already discussed here please point me to discussion.

Regards,
Nikita.

PS. I'm new one here and if this question is incorrect please excuse me.

[Ichad.c]

Well, you're in the right sub-forum, welcome! Just search "TPT" and "ZDF", there are many examples and excellent discussions on the topic. Your question isn't very descriptive though -> so I assume you want a simple linear 12dB filter that is light on CPU; a linear TPT State Variable filter sounds like the thing you're after. There is plenty of examples here - just search.

[davidguda]

welcome to the forum vokbuz. This is definitely the right subforum for discussing filter implementaions. Filters are discussed a lot here so look back at old threads and I'm sure you'll find good info.
Either I misunderstand you or or you have misunderstood the concept of ladder filters. 1-pole ladder does not make sense, a ladder is multiple one poles in series with some feedback to make resonance.

There is a nice pdf about synth filters you could read.
http://noisehack.com/research/VAFilterDesign_1.0.3.pdf

There you'll have the basics and then some...quite some

[Vokbuz]

Well, you're in the right sub-forum, welcome! Just search "TPT" and "ZDF", there are many examples and excellent discussions on the topic. Your question isn't very descriptive though -> so I assume you want a simple linear 12dB filter that is light on CPU; a linear TPT State Variable filter sounds like the thing you're after. There is plenty of examples here - just search.

Hi, Ichad.c. To ask a good question one should know 50% of answer. My knowledge on filters is closer to 0% and I'm not sure what to look for.

Thanks for pointing on TPT SVF. I will look for it.

[Vokbuz]

welcome to the forum vokbuz. This is definitely the right subforum for discussing filter implementaions. Filters are discussed a lot here so look back at old threads and I'm sure you'll find good info.
Either I misunderstand you or or you have misunderstood the concept of ladder filters. 1-pole ladder does not make sense, a ladder is multiple one poles in series with some feedback to make resonance.

There is a nice pdf about synth filters you could read.
http://noisehack.com/research/VAFilterDesign_1.0.3.pdf

There you'll have the basics and then some...quite some

Hi davidguda,

By 1-pole ladder I meant a ladder of 1-poles.

Thanks for pointing to the great Vadim Zavalishin work. I've tried to read it already but a lot of material is hard for me to understand for now.

So based on yours and Ichad.c's comment I will try to implement TPT SVF.