November 5th, 2013

This sound is a 1-sample long impulse at 48 kHz.
It covers the whole frequency range with equal power.

This is a perfect sample for exciting your guitar amp or reverb unit to capture it's impulse response (IR). You can also play it through a speaker in a reverbant room to capture it's reverb characteristics. Remember that the IR sample will be no flatter than your speaker's performance multiplied by your microphone's performance (frequency response characteristics).

The sample has exaclty 1 second of silence, then the impulse, then another second of silence to ensure the impulse will be played clean and untruncated on any sound system or device.

My test with IR LV2 convolution plugin have proven, that this sample has absolutely flat frequency response - convolved signal was identical to the source signal. After normalization and sample-alignment of the sound clips I have inverted the polarisatin of one of them and summed them - result was absolute silence, even no hiss was present as a result. This shows the accuracy of the convolution process and proves this sound to be perfect for sampling IR.

The impusle was generated with C* Dirac LADSPA plugin.
Created using Audacity.


  • avatar
    patrickmmartin 9 months, 2 weeks ago

    Looks like it does what it exactly says on the tin: 1 sample only.

    I almost cracked up a python shell to write a simple WAV file with a few bytes in it. Almost, but this looks to be just the ticket, and also incredibly rare?


  • avatar
    Eneroscu 11 months, 3 weeks ago

    "Big_assy and Motoservo", this is produced by the antialiasing filter: pre-ringing and post-ringing. The sample of Unfa is perfect, verified on Reaper. Thanks!

  • avatar
    big_assy 11 months, 3 weeks ago

    Thanks for this! To what motoservo said, that is due to the gibbs phenomenon I believe. Some programs will show the samples and values, but not the actual curve of frequency and amplitude that will be followed. It is interesting that the ringing starts to occur before the sample is even read though.

  • avatar
    BoaMixtura 4 years ago


  • avatar
    motoservo 4 years, 11 months ago

    I had another Dirac spike I found on the web, (a whole package in differing bit and samples rates) but I noticed they weren't appearing as a single sample spike after I imported and zoomed in with Logic, but instead appeared as a spike followed by a small envelope of about 8 more waves, quickly diminishing in magnitude.

    So, I downloaded yours and was surprised to see something even stranger. Yours has the spike in the center of a cluster of waves, the the buildup hitting the spike in the center, then the similar type of release characteristic described with that other spike (described above). The pre and post waves are in perfect symmetry with yours. Curious to know what I'm seeing and why Logic is rendering this way, does anybody know?

    Is this some sort of "pre-ringing" artifact? What's causing it?

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Wave (.wav)
187.6 KB
48000.0 Hz
16 bit
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