a tip for nice speaker simulation

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pz
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Post by pz »

Here's a small tip how to get a decent guitar sound without tens of analogue filters and complicated hardware speaker simulators, without need to buy any digital modeller, plugins etc. It's completely freeware.
We all know that the sound offered by most commercial and DIY analogue speaker simulators is quite different than a typical sound got with miked guitar cab. Even a big number of filters cannot get us close to the structure of the distorted sound, this "grit" that one can hear when playing with the real amp and cab. One of the reasons behind this is that analogue speakersims mimic mostly only a small part of things that happen in the real world. The frequency characteristic, with a lot of dips and peaks is not only hard to implement, but it is also not everything. For example: what about the room acoustics, the dynamic parameters of the speaker, type of microphone and its position (well, that is sometimes implemented).
What helps here is mathematics, digital domain and something called "convultion". Without getting too deep in details, a convultion process combines the input signal with a "signature" of other signal called the impulse response. Ant that we'll use to get a large variety of speaker simulated sounds.
To perform a convultion we need a special program, a convolver which will do all math. There are VST plugins doing this job, and the one we'll use is the freeware SIR 1
SIR 1 homepage

Then we need a VST host. I'm using freeware version of the multitrack recording program Reaper
Reaper homepage

We also need a sound card with ASIO drivers to get a low latency. If you have a soundblaster card, try KX audio drivers, i didn't try that, but there's an universal ASIO driver for all WDM audio cards : ASIO4ALL.

We need some impulse responses, too. Here you can download some:
Noisevault homepage

In Reaper start new project, add a track select recording source, record something. Then add FX, choose SIR, load the speaker cab impulse response, turn off the dry signal and set the wet signal gain to 0dB.
Press play and you can hear the recorded track with speaker simulation added. SIR1 has one disadvantage, a quite long latency time, which is in most causes compensated by the host software (when you press play). But live playing and listening to the convolved signal is quite uncomfortable or even unacceptable. But hey, it's all freeware! And you can change the type of the cab, microphone, its position with only one click.
It can be very helpful with recording the sound samples of the things we build here. Here's some soundsamples i recorded with this method. It was just my breadboard with new project on it plugged into the audiophile2496s line in. I recorded a short two guitar track, changed the impulse responses and rendered the projects. The drums and bass guitar in "crunch" file are also made with freeware sampler and edited as midi tracks.
sound samples

I hope some of you will find it usefull. If something is unclear due to lack of my english skills please ask. I'll try to explain or maybe post some screenshots. Any suggestions are welcomed, too :)
Piotr
Last edited by pz on 11 Jan 2008, 15:05, edited 1 time in total.

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Supafuzz
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Post by Supafuzz »

Convulsion is what epileptics do. You want convolution.

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Post by vanessa »

That's pretty much what I do with bass guitar in the studio instead of just going direct to the board like has been done for aeons. When at home and just getting a demo going I have a little champ on a dummy load, line out to pre. Then speaker sym using an impulse response program such as this. It's as convincing as it gets.

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Post by pz »

Supafuzz wrote:Convulsion is what epileptics do. You want convolution.
Of course! Thanks fot pointing out the mistake. Edited..

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