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impulse response convolution

For general discussion related FlowStone

impulse response convolution

Postby aombk » Wed Aug 03, 2016 2:52 pm

Hello,

I try to make an impulse response convolution effect for small Impulse response files (less than 1024 samples)
small files like this are used for simulating guitar cabinets and contain detailed EQ data (mostly) and a tiny reverb tail.

i modified an old synthmaker file called 3386_Convo 8000 - 07.osm

i also modified ConvoRev6c.fsm (by Martin Vicanek and the one modified by KG) that i think is better but it (not only the modified, the original too) produces a strange sound (like low bit resolution sound) every other time something else (like a switch for example) changes

but anyway. the thing is that the first schematic doesnt work properly. i compared their results with other commercial or free convolvers like ignite amps nadir or le pou lecab2 etc and the results are not the same. it seems to mess things up, especially high frequencies

the second schematic results seem closer to other convolvers, but it has that low bit resolution sound every other time.

can anyone help with this?

thanks.
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Re: impulse response convolution

Postby martinvicanek » Fri Aug 05, 2016 10:56 pm

Try this schematic. It is derived from ConvoRev7.fsm with the IR size set to 1024.
Attachments
Convo1024.fsm
(205.01 KiB) Downloaded 1020 times
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Re: impulse response convolution

Postby aombk » Sat Aug 06, 2016 12:05 pm

ok i tried it.
check out this schematic.
i removed the dry - wet, delay and filter knobs.

just turn the switch on and off a couple of times.
Attachments
Convo1024 - switch.fsm
(120.91 KiB) Downloaded 983 times
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Re: impulse response convolution

Postby martinvicanek » Sat Aug 06, 2016 4:13 pm

Okay, I see your point. In your last schematic, when switching on/off it seems to work correctly only every other time. Weird. The selectors in FS make the whole schematic recompile while it is still processing, which may lead to unexpected results. I replaced the selectors with soft variants and the problem is gone. The downside is that processing takes place even if you don't need it.
Attachments
Convo1024 - softswitch.fsm
(121.21 KiB) Downloaded 1057 times
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Re: impulse response convolution

Postby aombk » Sat Aug 06, 2016 10:18 pm

thanks, although i cannot make use of the soft selectors solution.

but why the convolver recompiles correctly every other time?
btw, the "Direct Convo 32" doesnt produce a problem with FS selectors.

so you dont think there could be another workaround for this or maybe some change in the FDL assembler code to avoid this problem?
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Re: impulse response convolution

Postby martinvicanek » Thu Sep 01, 2016 6:43 pm

I think I finally fixed it. The issue was when you use the switch, FS will restart the audio and possibly recompile the entire schematic. It will not, however, go through the declarations, so when you have something like
Code: Select all
a = 0;
in the preamble, this will be ignored. Instead, FS will resume operation (starting at stage 0, mind you) with whatever value "a" was when you switched.

Have fun! 8-)
Attachments
Convo1024 - switch fixed.fsm
(116.23 KiB) Downloaded 1171 times
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Re: impulse response convolution

Postby aombk » Thu Sep 29, 2016 8:41 pm

great, yeah, that makes sense. thank you very very much :)
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