The procedure for capturing the acoustics of a room (completely described in Making Post Pro IR's.pdf):

1. playback 10 second sine sweeps (included) via a speaker in a room
2. record the sweep with microphones in the room
3. feed the recordings to the IR Pre Processor Application, and you have a sample of a room for use in altiverb.

In order to make impulse response recording as easy as possible, portable self powered equipment can be used for playing back the sine wave sweep CD. Portable gear allows you to sample on a filmset or even outdoors. But the more portable it is, the uglier the sound. Audio Ease has sampled some portable gear to be able to make up (eq) for their frequency characteristics.

Below you can playback audio samples that were treated using Altiverb. The impulse responses (acoustic samples) were made using the depicted gear. The Genelec S30 is our reference monitor. In the samples the genelec has not been corrected by the automatic corrector eq in the IR Pre Processor Application. In the case of the starter pistol and the Panasonic bombox, the uncorrected (un equalised) samples are also given, so you can evaluate what the corrector eq does.

playback device (click to enlarge)	2 voices (no dynamic compression) Dry (untreated at all):	Tabla's Dry (untreated at all):
Genelec S30 (D)
Tannoy reveal (+car cd, and battery)
Sony CFD G70
Panasonic RXES 22/27	With correction EQ: Without correction EQ:	With correction EQ: Without correction EQ:
6mmm flobert starter pistol	With correction EQ: Without correction EQ:	With correction EQ: Without correction EQ:

Notes:

• Generally high quality studio monitors can be used without a specific correction EQ.
• Availability and description of the playback gear is listed in Portable sweep gear.pdf
• A step by step sampling instruction using portable gear is in Making Post Pro IR's.pdf
• A step by step instruction in making impulse Responses for music is in Making IR's for music.pdf
• More about using the starter pistol is in: Making starter pistol IR's.pdf

• A major problem using separate gear for playing back and recording the sine wave sweep is that they normally do not share a digital word clock. To overcome this the IR Pre Processor Application automatically corrects playback and recording speed deviations, by examining and sample rate converting the recordings prior to processing them.

• Audio Ease is not sponsored by any of the manufacturers or resellers mentioned.

• All Impulse Response recordings were made at Audio Ease in the central hall (below), using DPA (formerly B&K) omnidirectional microphones.