Log InCreate An Account
  1. Plugins
  2. »
  3. SIR Audio Tools
  4. »
  5. SIR1
  6. »
  7. Details
SIR1 by SIR Audio Tools is a Virtual Effect Audio Plugin for Windows. It functions as a VST Plugin.
Sample Formats
Loads and/or Saves
Copy Protection
My KVR - Groups, Versions, & More
148 KVR members have added SIR1 to 18 My KVR groups 167 times.
Not In Your MY KVR Groups
(or group limitation prevents versioning)
+18 in private groups

KVR Rank

Overall: 1230   1199

30-Day: 1257; 7-Day: 1586; Yesterday: 3832

SIR1 is a reverb device that works with "impulse-responses". Impulse-responses are generated by recording short, broadband signals and their corresponding room-reflections, and by cutting out the initial signal. What is left contains the information needed to reproduce the same room with other signals.


  • Works with a fixed latency of 8960 samples (possibly compensated by VST-Host).
  • You can adjust predelay, attack-time, length and stereo width of the impulse response.
  • Stretch (up & downsampling of impulse response).
  • FFT EQ (to adjust the frequency spectrum of the impulse-response).
  • Auto Gain (automatic volume compensation).
  • Dynamic CPU Consumption (use only the CPU power that is needed to get the result).

Latest User Reviews

Average user rating of 4.25 from 4 reviews

Reviewed By gmore [all]
August 5th, 2006
Version reviewed: XP on Windows

Given all the chatroom talk about SIR, I'm surprised there's only 3 reviews here.
I've been a hardware based recorder for over 6 years, and went DAW about 4 months ago. Aside from all of the obvious reasons to switch, the #1 reason was to get 'that sound' especially on vocals. It had been a fairly frustrating few months, aside from the learning curve - I never really got close to 'that sound' until I found this plugin - I'm a convert now !

I was a little intimidated to try this program because of all the latency talk, but Tracktion 2 automatically compensates for it ! I left a 9 for 'stability', not because it has been 'unstable', but the latency and CPU draw (not quite as bad as I expected) can make using multiple plugins or an aux-buss applications a little taxing and tricky - there have been times I've wanted to use it, but went with a more basic reverb to avoid issues, but given the price - no complaints.

At any price, sonically this is a 10 and the free IR's online have covered every application I've needed thus far. I don't use it everytime I need reverb, but it's my go-to for most vocal applications and anytime an instrument is 'naked' in the mix - it can really fill a void without being overbearing.

Didn't want to bring an overall rating down so I left 10's but in reality - N/A's for documents and support - if they exist, I haven't needed them, and in the software world, I'm just a bit beyond novice. For newbies its not a plug-and-go, you need to download IR's and load them into the program to get different sounds(NA really for presets too, although the 2 available are pretty good).

The GUI gets a 10 too - there's nothing more that I've needed, and its been a breeze to navigate without a manual.

BOTTOM LINE - DOWLOAD THIS PLUGIN - its worth a try. Its the best one I have and ITS FREE !
Read Review

Reviewed By jopy [all]
January 5th, 2006
Version reviewed: 1.011 on Windows

For starters, it's worth considering what a convolution reverb is (and my review was too short, so I need to pad it a little). Convolution reverbs use impulses usually collected from natural spaces by people popping balloons or using other meants to get a basic example of how the space affects sounds. Then the reverb unit emulates the behavior of the natural space by filtering/damping the sound consistent with the response pattern of the reverberation of the natural space. Convolution reverb is the next step in reverb for those interested in rich, natural sounds.

In my opinion, SIR is the undisputed king of free reverb effects, and I've tried quite a few. There's nothing else in the same class as SIR. The sound is gorgeous, natural, and very morphable in a hurry. One can find dozens of free impulses online to enhance choices. Because most commercial convolution reverbs are quite expensive, this free version is all the more impressive. I've had minor stability issues and it doesn't work for live recording because it has too much latency, so it's not perfect, but it is outstanding for a free product.
Read Review

Reviewed By benwalker [all]
April 12th, 2004
Version reviewed: on Windows

Reverb is one of those things, along with a compressor, that's used all over the place - which kind of means you need to find a really good one, or have lots for different jobs...

... and so enter SIR. I'll spare the science bit, suffice to say that it doesn't have a sound or characteristic of its own, but rather borrows reverb tails from 'real' effects, rooms, cabinets etc. The upshot of this is that you can add the reverb from a £11k Lexicon, to your sampled/recorded drum track. Brilliant! Impulse reverbs are getting more common now, so there are loads of useable impulses out there on the web, or of course you can always make your own.

Interface - Basic but effective.

Sound - Depends on the impulse. 0/10 for that badly recorded impulse of my bathroom, 10/10 for the 960L, Eclipse, TC 6000 etc...

Features - Not as many knobs as say, Ambience, but then again it doesn't really need it. no damping or anything like that but the EQ is powerful, and the reverb tail can be cut, stretched and so on, so some great sounds can be easily produced.

Documentation - Doesn't really need it. Simple idea and it's easy to use.

Presets - None. But that's kind of the point. I'm giving it 9 because at least the SIR page has links to some impulse hosting sites. Be warned that these impulses can be big...

Customer Support - haven't had to deal with them, but since it seems to be a one-man operation, would expect support to be good.

VFM - No question, it's free...

Stability - Never crashed yet.

Make sure your host has full PDC, and run as a SEND effect. Either that, or only use it when mastering and use a lower latency/CPU reverb for recording. But come on... it's free. It loads top quality impulse responses. Works well and deserves a space on your hard-drive :D you won't be disappointed.
Read Review

Reviewed By RockMaestro [all]
January 27th, 2004
Version reviewed: on Windows

When I want reverb, I think SIR. I’ve practically stopped using any of my other reverb plugins.

SIR is a convoluting reverb. Basically, what happens is someone ‘samples’ a room, or a piece of gear and SIR will apply that tonal response and trail onto other material. So someone makes a reverb ‘impulse’ of a room and SIR will let you put your music in that room.

In addition to simulating rooms, SIR can load impulses of Guitar cabinets, non-linear gear, and other non-reverb things, and it can make your music sound like it’s been through these things. SIR will not produce distortion, so if someone makes an impulse of a guitar amp, it won’t sound distorted, it will merely have the *tonal* response of the amp.

So basically SIR has no sound of it’s own. I put the “Sound” assessment at 10 because I’m judging with my set of impulses.

As for features, it can do most of what I would want it to, although I’d like to see the ability to have negative predelay – basically start the impulse later, so as to cut off predelay in the impulse. Other than that, it’s pretty good for basic applications.

The documentation was enough, but it’s not really a full manual. That said, I didn’t really need one.

It doesn’t come with any presets – there are 2 you can download on the author’s page. Get impulses here http://www.noisevault.com . That’s the best source of real rooms, sampled hardware reverbs, and other gear.

Customer support – well there is none. But it isn’t needed, I’ve had no problems with this plugin. Stability is good, and that’s Cakewalk Home Studio 2002 with DirectiXer 2.5.

VFM – it’s free so it gets 10, no matter what.

It *is* a CPU hog, and it does introduce some latency into the system, but it’s well worth it.

I love this plugin, it’s part of the RockMaestro Cannon of free plugins.
Read Review

Products similar to SIR1...

Comments & Discussion for SIR Audio Tools SIR1

Discussion: Active
9 February 2017 at 11:00pm

Now, this may well be just me not being very knowable, but - how is "fixed latency" a feature? To me, it seems like a bug.

26 April 2017 at 2:47am

This appears to be no longer available. The link redirects to siraudiotools' products page, where you can buy SIR2. There is no entry for (free) SIR1.

@Thohi It's too slow to calculate convolution without latency. The only way to do it without latency is fully in the time domain, where each sample of output requires /n/ multiply-and-add operations (/n/ being the size of the convolution kernel). It's actually faster to FFT the input, multiply by the IR spectrum, and IFFT to get the output... but you have to collect an entire FFT frame's worth of audio before you can do that, hence the latency.

26 April 2017 at 6:33am

The link is now hidden... but remains available. It is this one:



26 April 2017 at 3:26pm

How then do the other IR reverb plugins do it with little to no latency?

Please log in to join the discussion