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Chapter 13 Space Designer convolution reverb 242
Set the impulse response sample rate and preserve length
Changing the sample rate upward increases—or changing it downward decreases—the
frequency response (and length) of the impulse response, and to a degree the overall sound
quality of the reverb. Upward sample rate changes are of benet only if the original impulse
response sample actually contains higher frequencies. When reducing the sample rate, use your
ears to decide if the sonic quality meets your needs.
Note: Natural room surfaces—except concrete and tiles—tend to have minimal reections
in the higher frequency ranges, making the half-rate and full-rate impulse responses sound
almost identical.
m To determine the sample rate of an impulse response: Move the sample rate slider.
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Orig: Space Designer uses the current project sample rate. When loading an impulse response,
Space Designer automatically converts the sample rate of the impulse response to match
the current project sample rate, if necessary. For example, this allows you to load a 44.1 kHz
impulse response into a project running at 96 kHz, and vice versa.
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/2, /4, /8: These settings are half-divisions of the preceding value—one-half, one-quarter, one-
eighth. For example:
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If the project sample rate is 96 kHz, the options are 48 kHz, 24 kHz, and 12 kHz.
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If the project sample rate is 44.1 kHz, the options are 22.05 kHz, 11.025 kHz, and 5512.5 Hz.
When you select half the sample rate, the impulse response becomes twice as long. The
highest frequency that can be reverberated is halved. This results in a behavior that is much
like doubling every dimension of a virtual room—multiplying a room’s volume by eight. The
lower sample rates can also be used for interesting tempo, pitch, and retro digital sounding
eects. Another benet of reducing the sample rate is that processing requirements drop
signicantly, making half–sample rate settings useful for large, open spaces.
m To retain the original length of the impulse response when the sample rate is changed: Click the
preserve length button. Manipulating this parameter in conjunction with the sample rate
parameter can lead to interesting results.
If you are running Space Designer in a project that uses a higher sample rate than the impulse
response, you may also want to reduce the impulse response sample rate. Make sure the
preserve length button is turned on. This cuts CPU processing time without compromising
reverb quality.
Tip: You can make similar adjustments while running in Synthesized IR mode. Most typical
reverb sounds don’t have an excessive amount of high frequency content. If your project is
running at 96 kHz, for example, you would need to use lowpass ltering to obtain the mellow
frequency response characteristics of many reverb sounds. A better approach would be to rst
reduce the high frequencies by 1/2 or even 1/4 using the “sample rate” slider, followed by using
the lowpass lter, thus conserving signicant CPU resources.