Space Designer global parameters in Logic Pro for iPad

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 benefit 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.

• In Logic Pro, choose one of the following from the Quality pop-up menu to set the sample rate of an impulse response:

  • Lo-Fi: This setting divides the sample rate by four. If the project sample rate is 96 kHz, the impulse response sample rate is converted to 24 kHz. If the project sample rate is 44.1 kHz, the impulse response sample rate is converted to 11.025 kHz, and so on.

  • Low: This setting effectively halves the sample rate. If the project sample rate is 96 kHz, the impulse response sample rate is converted to 48 kHz. If the project sample rate is 44.1 kHz, the impulse response sample rate is converted to 22.05 kHz, and so on.

    When you select a half 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 the volume of a room by eight. The Low (and Lo-Fi) setting can also be used for interesting tempo, pitch, and retro digital effects. Another benefit of reducing the sample rate is that processing requirements drop significantly, making the lower quality settings useful for large, open spaces.

    This behavior also applies when you choose Lo-Fi, but the sample rate is divided by four and the impulse response is multiplied in length four times.

  • Medium: Space Designer uses the current project sample rate. The sample rate of a loaded impulse response is automatically converted 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.

  • High: Space Designer uses the highest possible sample rate.

• To retain the original length of the impulse response when the sample rate is changed: Adjust the Size knob value. Using this parameter with your Quality pop-up menu choice can lead to interesting results.

  If you’re 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. Adjust the Size knob value to reduce 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 contain an excessive amount of high frequency content. If your project is running at 96 kHz, for example, you would need to use lowpass filtering to obtain the mellow frequency response characteristics of many reverb sounds. A better approach would be to first reduce the high frequencies by choosing a lower rate from the Quality pop-up menu, followed by using the lowpass filter, thus conserving significant CPU resources. It is also worth noting that longer impulse responses (sampled or synthesized) place a higher strain on the CPU.

The Definition parameter emulates the diffusion of natural reverb patterns when in Synthesized IR mode.

Natural reverbs contain most of their spatial information in the first few milliseconds. Toward the end of the reverb, the pattern of reflections—signals bouncing off walls, and so on—becomes more diffuse. In other words, the reflected signals become quieter and increasingly nondirectional, containing far less spatial information. To emulate this phenomenon, use the full impulse response resolution only at the onset of the reverb, then use a reduced impulse response resolution toward the end of the reverb.

• In Logic Pro, vertically drag the Definition field to set the crossover point—where the switch to the reduced impulse response resolution occurs.

  The Definition field is shown as a percentage, where 100% is equal to the length of the full resolution impulse response.

In Logic Pro, use the output parameters to adjust the balance between the direct (dry) signals and the processed (wet) signals.

Space Designer provides two output sliders—the Dry slider for the direct signal, and the Wet slider for the reverb signal—when you insert it as a mono, mono to stereo, or stereo effect.

• Set the level of the Dry slider: Move to set the level of the non-effect, or dry, signal. Move the slider to a value of 0 (mute) if Space Designer is inserted in a bus channel or when you’re using modeling impulse responses, such as speaker simulations.

• Set the level of the Wet slider: Move to adjust the level of the effect signal.