Karplus Strong

Alexander

Hello everyone,

I have been trying to make this:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

..on my engine, but can't seem to get it to work. I only have internet here at school and haven't brought any patches. But please, can someone patch this up and post a working patch, so I can figure out what I did wrong.

Here's the wiki on karplus strong:

http://en.wikipedia.org/wiki/Karplus-Strong_string_synthesis

thank you.

Roland Kuit · Posted: Thu Sep 04, 2008 8:05 am Post subject:

Hi Alexander, have a look at this one, from Robby. There are more karplus pch's here.
From Rob Hordijk(a Dutchy also:))
http://www.electro-music.com/forum/topic-5213.html

Blue Hell · Posted: Thu Sep 04, 2008 9:32 am Post subject:

Have a look at Chet's stuff and at James' stuff too (even when it is for the NM Classic).

Roland Kuit · Posted: Thu Sep 04, 2008 10:28 am Post subject:

to bad that chat's pages are missing(his links)

Blue Hell · Posted: Thu Sep 04, 2008 10:31 am Post subject:

The links seem to work here, but note that not every underlined text is a link.

Tim Kleinert · Posted: Thu Sep 04, 2008 11:46 am Post subject:

Here's a quick'n dirty Karplus-Strong demo.

Press the "Press!" button (duh Laughing

) to trigger the noise burst going into the resonator. The resonator is just three modules -a delay line, a filter and a mixer for the feedback. That's all there is to that.

As a comparison, you can toggle between the delay-feedback-loop and the String Oscillator module which does exactly the same thing (but with the benefit of exponential tracking (which can be patched with the DIY approach also, although tuning is an issue)).

cheers,
tim

KS demo.pch2

Description:

very basic Karplus-Strong demo for Alexander

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KS demo.pch2

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Alexander · Posted: Fri Sep 05, 2008 5:38 am Post subject:

Thank you, I am now putting everything on my usb stick and will be working with it later this weekend. Thanks to our lovely provider I am again internetless for the next few weeks.

Great for my productivity, but for the g2 I still rely on you guys.

Thanks again for the quick and useful replies!! Very Happy

Antimon · Posted: Sat Sep 06, 2008 4:45 am Post subject:

Tim Kleinert · Posted: Sat Sep 06, 2008 12:31 pm Post subject:

Antimon · Posted: Sat Sep 06, 2008 3:05 pm Post subject:

Hmm, you mean something like this? I guess you mean the LevScaler (couldn't find anything saying -6dB on the NoteScaler)?

I get something like an expected result in some note intervals, but mostly there is just a tiny rise/drop in pitch between notes. I tried running the value through several scalers, but I can't get it right, though it's fun to play these weird tones. I got a better result in a limited interval running the note output from the keyboard through the LevScaler, but then it was backwards.

I've used the controlsequencer approach as well - though looking quickly at Chet's patches it seems he mostly uses them to fine tune comb filter pitch inputs, not pure delay times.

/Stefan

ks_demo_tuning_test.pch2

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ks_demo_tuning_test.pch2

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Blue Hell · Posted: Sat Sep 06, 2008 3:44 pm Post subject:

Your patch is OK Stefan, you must just set the delay fixed time too zero (0.01m) and then tweak E4 in the LevScaler till your range is what you want. Then you can fine tune with the same method Chet is using.

Antimon · Posted: Sat Sep 06, 2008 4:52 pm Post subject:

Aha! Brilliant! Very Happy

Thanks for this revelation, Tim and Jan! The LevScaler was one of those modules that I've looked at and not really thought I had a use for - now I know better.

/Stefan

Antimon · Posted: Sat Sep 06, 2008 5:01 pm Post subject:

OK, so just for reference - here is a tweaked version of Tims example patch above which plays notes from the keyboard. The notes are a bit off if you compare with another keyboard, this can be fixed with Chet's control sequencer fine tuning mentioned above, or maybe you can just fine tune all the other synths instead.

/Stefan

ks_demo_tuning_test.pch2

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ks_demo_tuning_test.pch2

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Blue Hell · Posted: Sat Sep 06, 2008 5:34 pm Post subject:

Or maybe, as the delay loop inserts add linear time delay, you could just subtract a bit from the LevScaler output to compensate for that extra delay.

Like in attached.

ks_demo_tuning_test_bh.pch2

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ks_demo_tuning_test_bh.pch2

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Tim Kleinert · Posted: Sun Sep 07, 2008 1:37 am Post subject:

yeah, doh

, I meant the LevelScaler, sorry. I don't have my stuff here (I'm writing this from a hotel lobby internet station).

Glad you figured it out.

I use this approach not only for PM stuff, but also for DIY oscillators and my granular thingies (which are based on DIY oscillators).

I tried various things in order to correct the tuning issue, but none worked. It's not like a constant linear offset or something. I think it's a calculation precision issue, as the detunings are sometimes sharp, sometimes flat, and quite randomly dispersed over the note range.

Antimon · Posted: Sun Sep 07, 2008 1:49 am Post subject:

Neat! I didn't think that would work across the whole range. Now I've got something to sink my teeth into. clown

/Stefan