hey guys long time no post! just wondering whats the fuzz about reverb impulse? what is it? how does it work? how do you make it on N?


an impulse is the recorded information of a room, usually done with a loud and quick sound.

for example, someone will take a starter gun, and a microphone…
they set the mic up in the room, press record, and shoot the gun.

the mic captures the sound of the gun and records the reverberation as well.

an impulse program reads this sound file and uses it to apply the same echoes and such to a signal-thereby giving you that particular room’s reverb on whatever sound file you run through it.

very basic explanation, but that’s about it. you can use a program called SIR for free I believe that does impulses.

you can impulse most anything even, want the sound of a 4x12 cabinet on your guitar? use an impulse from one…

pretty neat really.

A couple of months ago I recorded an overdub in a church - yes, a real church organ :D - using my MR-8 and a bit of outboard gear. I brought along with me some friends, a couple of balloons and a needle - it served me nicely in getting good impulses of the room. I actually ended up using the church acoustics as (SIR) reverb in the mixdown. Quite nice, really…

regards, Nils

may i suggest that you look at the Voxengo website they do two convolution reverbs, an 8 channel and a new 2 channel one - they also do a de-convolution program which extracts the reverb only from the room/hall/church sample, leaving behind the sound that created the sample - this gives a cleaner reverb - its right at the bottom of their website, just a single line of text in blue. download the beta version (its fully functional) and free -

you can download a lot of manuals there that explain a lot about how convolution reverb works

dr j

If anyone is interested, I’m selling a CD full of high-quality impulses made by Studio Cat - see 32 Bit Float IR CD. They’re great but I just don’t use them anymore.

an impulse is the recorded information of a room, usually done with a loud and quick sound.

Basically correct. Here's the theory and what it means.

Theory: Any infinite impulse response (IIR) filter can be totally characterized by its response to an impulse. The impulse response is used to derive a filter kernel, which, when used to convolve another input signal, reproduces the response of the original system.

What this means, literally:
- Most natural processes that affect sound, including many analog devices, are IIR filters.
- "Characterize" means "you can completely model it and simulate its response to arbitrary inputs".
- "Impulse", in theory, means a step in the input from the maximum value to zero, at time zero. (In the case of sound, the values here are pressures, and zero is the background atmospheric pressure.) Of course, you can't really go from a higher pressure to "zero" in no time at all, so in reality, impulse response filters are approximations. A starter pistol is a good enough approximation to an impulse. There are other reasons it's only an approximation -- for example, the response recording isn't infinite in length, nor is the resulting filter kernel.
"Convolve" and "filter kernel" -- the mathmatical algorith & its parameters. "Convolution" is the kind of magic in the black box, and the "filter kernel" is the proper incantation to perform the magic. The object being magically transformed is the input signal (your track).

What this really means: You can use SIR and similar programs to model a wide variety of things, not just rooms. You can model tube amps, fuzz boxes, plate reverbs, spring reverbs, the grand canyon, your PC's speakers, all sorts of stuff.

Not that the results are ideal in all cases. For example, if you run an impulse through a tube amp that isn't high enough to overdrive it, your model won't ever saturate and give you distortion. So, "max value" is important!

PS: I don't know whether a tube amp really is an IIR filter! I suspect so.

For more information, the classic treatment is in R.L. Hamming's "Digital Filters". Warning: math required; up to elementary differential equations. Over my head, actually. I'm still amazed I got a C in my DiffEQ course all those decades ago, learning as little as I did! Thank goodness for curves.

Oh – some “convolution reverb” programs do reverb-specific stuff in addition to convolutions.

Convolutions are very general purpose & can do amazing things. But some plugins might not be able to, since they have “additional features”.

Hey Dean

I knew nothing about impulse response reverb and following some advice on this site I did the following.

A) Download SIR, a free Impulse Response plugin.
B) Download some impulses.

Follow the instruction to install SIR (easy). Unzip some impulses into an easily accessable location. Then add SIR to a track and load up a wav (IE: impulse) from where you stored your unzipped impulses.

Just play around from there - you’ll be able to see how it all works. Works for a MUCH more natural sounding reverb… depending on the impulse of course.