Saturday, January 14, 2012

HOW TO USE IMPULSES (free VST plugins included)

Hello and welcome to another post of this blog! Today we're going to talk about Convolution Impulses. 
Convolution impulses are digital simulations of the reverberation of a physical or virtual space. 
Why do we need them? Because today those are the best replacement for guitar cabinet simulation. In facts, you may have noticed that the main issue of Guitar Amp Simulators (both hardware, like Pods, or software, like Amplitube) is the cabinet simulation and microphone response: they sound harsh, fizzy and plastic, because although they are impulse-based, their response is not accurate enough.
The web nowadays is full of impulses free to download and to experiment, and many of them are really accurate and realistic, that is the reason why many studios use them instead of microphoning a real cabinet. They are great for Reamping too, and can be used with any kind of preamp (a preamp vst, a digital multieffect or a real tube head, through its preamp out), taking the place of power amp, cabinet and microphone.
Just connect the preamp/pedal output into your soundcard, load one of the programs made to play them (for example on this guide we're gonna take a look to VOXENGO BOOGEX), load an impulse and play: if you hear a normal tone, with no harshness/fizzyness, you're done.

WARNING: Do not connect the power amp output of your head to your audio interface! Use the preamp output or the Fx-Send. If you have a tube power amp, you have to connect it to the cabinet anyway in order to prevent tube damages! 

Here's how to load an Impulse on Voxengo Boogex

First off turn off the cabinet simulation of your software or hardware (for example, with Amplitube 2: go into the cab section and activate the BYPASS switch you see in the upper right corner, or with the Pod Hd just take the cab icon away from the chain of your preset, setting it to No Cab), if you have bypassed the cab correctly, when you play a distorted preset you'll hear an awful sound, fizzy as hell, no bass, harsh... You're hearing how an amp sounds like without a cab

Now load Voxengo Boogex (I chose to explain this among the others because it's free, not too heavy for the ram and with zero latency, but there are many others around for free, as KeFir),
Boogex is an amp-sim, if you want to use it ONLY for cab simulation, you have to set all the parameters FLAT, or it will change your eq/sound.
So, open it and set, from the left: Lows Mids and Highs to 0db, Tone to 0%, Drive to 0db, Dynamics to 0%, Phase to 0%, The "Out" control it's the volume control, Dry Pre Cab and Dry Post Cab to "-inf" (knob all the way down).
The "Speaker Cabinet Impulse Response" button MUST be ON, obviously, then click on "file" and select your impulse (a .wav file).
Another interesting thing about Boogex: this software features a built in Low Pass Filter and High Pass Filter. Since they can't be totally bypassed, the best thing to do is to open them to the max, by clicking on the green point in the right area of the graphic section of the interface and move it all the way to the right, then click on the white point in the left area and move it all the way to the left. This will deactivate the filters.

Here are some great free impulses to load:

If you have or know some other interesting impulse to suggest to our readers feel free to tell us!

Additional Awesomeness: some speaker simulator plugin (such as Poulin's LeCab2) gives you the opportunity to load more than one impulse and blend them together, as if the speaker is microphoned with two or more mics. This opens up a very interesting world of variables, if carefully managed, but can also harm your final result, so use it carefully :)

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  1. un plugin che ho usato spesso è il LeCab, lo trovi sul sito di lepou:
    poi c'è il LeCab2 che non ho ancora provato, mi fa paura, è un mostro dove puoi caricare 6 impulsi e mixarli a piacimento!

  2. è un buon plugin, anzi ottimo, ma ho avuto l'impressione che questo mangi meno risorse.