Convolution Engine/Impulse Response Processor?

[miketheman]

Hello!

My name is Mike, from Gothenburg (sweden). Being an owner of a Chameleon since some years ago, but unfortunately not a DSP-programmer (some ideas though!). So since I can´t answer this question myself I´m wondering if the Chameleon could be turned into a convolution engine/impulse response processor?

Would love to have a kind of processor where I can switch it (within the same skin) to be a kind of acoustic guitar body simulator for some presets. And to be a (electric guitar) amp cabinet simulator with mic placement and all for some other presets. And perhaps even a kind of reverb or compressor processor for another presets. Thinking it as a impulse response processor with different modes (selectable for each presets) similar to the different EQ-modes in the Infiltrator.

Anyone knows?

/Mike

[DrJustice]

to the forum, Mike!

The chameleon could indeed do convolution. If one wanted long impulse responses, like those of a reverb, then a partitioned convolution based on FFT's would be the way to go. For shorter impulses a simple FIR could be used, limited to say 40ms or so. To my knowledge, there haven't been developed any soundskins to perform these flavours of convolution.

There is the Amp-O-Matic skin for amp/cabinet/multiple-fx simulation. Although not with mic placement, it does some of what you're asking for. I've not tested it yet myself, but now that we're talking about it AND I've taken up the guitar, I shall do so one of these days

As you say, Infiltrator has the freely configurable EQ modes. And of course the vocoder mode is actually a form of convolution, although you have to supply the 'impulse' through an input and it has a low resolution in frequency since it uses an IIR filterbank for the analogue vocoder modelling.

The (very nifty) Chromasonic multi-fx soundskin have EQ's and reverbs in it's arsenal, so it also does some of what you want.

None of these can take an actual impulse response as data and perform convolution though. Since that is a function that requires some management of impulse responses, perhaps it's best suited to computers with monitors and harddrives etc. (although latency is often a bit of a bother in the case of desktop computers).

Perhaps you need one or two more Chameleon to combine multiple soundskins?

DJ
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[miketheman]

Thanks for your reply Are!

Yeah, I´ve checked out those skins. Not so much the Infiltrator yet, but it seems promising for the synth part of my rig!

I haven´t checked out Spin Audios RoomVerb and/or FX designer yet. That may get me somewhat closer. I realize that it´s possible to simulate an acoustic guitar via some extensive filtering onto your electric guitar signal, I believe that´s practically what Boss does with their AC-2/AC-3 pedals.

However, it would be grand if one could take one step further with Impulse Response technologies. I think that´s what Fishman does with their Aura Imaging products, but haven´t read up on these any closer.

Regarding the Amp Cabinets Impulses, that´s not so much of an issue since I´ve already got me an Fractal Audio Ultra. Which handles that very well. User memories are somewhat limited though, with only 10 program slots for custom Impulse Responses. Believe those impulses for Fractal Audio units are allowed to be max 20seconds or something too. But it would be cool to have an Chameleon to be an extra add-on with loads of cabinets aviable.

That would perhaps even boost some interests into the Chameleon platform again. Their forum activities are quite mad sometimes. In the past, the developer/manufacturer have released new OS within hours when someone is asking for a specific feature. Thanks to this the loyality and help from the end-users all around the world is quite unique too.

Any (good) news mentioned on these forums can grow really fast...

/Mike