Yamaha SREV1 User Manual 2

SREV1 Sampling Guide

An Introduction to Impulse-response Sampling with the
SREV1 Sampling Reverberator

1

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

What is Sound Field Sampling? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

What is Convolution? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

What is an Impulse Response? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

What are Impulse & TSP Signals? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

What is Averaging? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

What Equipment is Necessary? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Is the Quality of the Equipment Important? . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

How about Microphone & Speaker Placement? . . . . . . . . . . . . . . . . . . . . . . . . 6

2 Sampling Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Configuring IRSampler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Checking the Generator Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Setting Input Levels Automatically . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Actual Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Using Your Data on the SREV1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Data Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Fixing the Roar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Removing the Delay at the Beginning of the Reverberation . . . . . . . . . . . . . . 13

Deleting the Direct Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Adjusting the Reverberation Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Specifying the Reverb Time & Start Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4 Hookup Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 17

MY4-AD/DA I/O System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

AES/EBU I/O System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Sampling with a Digital Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

SREV1 Sampling Guide

Introduction

1 Introduction

This document provides a basic explanation of sound-field sampling, and a tutorial by
which you can actually sample a sound field and audition it on the SREV1.

For more detailed information on the SREV1, IRSampler, or IREdit, please refer to the
relevant documentation.

What is Sound Field Sampling?

No doubt you are already familiar with the technique of audio sampling, made possible
by the ubiquitous sampler? Well, sound-field sampling is similar, except that instead of
capturing sounds, we’re attempting to capture the unique character of an acoustic
space, such as a concert hall or church. When you sample a sound field with the SREV1,
you are in fact sampling the reverberant characteristics of that acoustic space. The
acquired data can then be loaded into the SREV1 to create a reverb program that repro­duces the unique reverberation of the original space.

Let’s take a moment to consider the sounds we hear in an acoustic space such as a hall.
Vocal or instrument sounds (i.e., the audio source) reach the ears of the listener accom­panied by the reverberation of that acoustic space. If we substitute a microphone for the
listener’s ears and record the sound, we capture the vocal or instrument sound together
with the reverberation of that acoustic space. Since the reverberation is unique to that
particular space, until now the only way to add it to a vocal or instrument sound was to
actually perform in that space and record the resulting sound. With the introduction of
the SREV1, however, it’s now possible to sample the reverberation characteristics of an
acoustic space and apply them to any audio signal.

2

In conventional recording, changing the location of the singer or instrument (i.e., the
audio source), or the position of the microphone (i.e., the pickup point) affects the
sound that is recorded. You’ve no doubt experienced how the same audio source can
sound different when heard from a first-floor seat and a balcony seat. In addition, dif­ferent power amplifiers, speakers, microphones, and other equipment can also have an
affect on the recorded sound. These issues also apply to sound-field sampling with the
SREV1. Changing the position of the audio source or the pickup point, for example, or
changing the equipment, all affect the reverberation that is sampled, even in the same
acoustic space. In this respect, sampling a sound field with the SREV1 is similar to nor­mal recording.

Sound-field sampling involves recording the reverberation information that occurs
between an audio source located in the space being sampled and a pickup point. Since
this consists of the information that occurs between these two points, it’s not possible
to capture the reverberation character of an entire acoustic space. By experimenting
and taking a number of samples at various pickup points and sound source positions,
however, you should be able to capture the reverberation character that defines each
and every acoustic space.

SREV1 Sampling Guide

What is Sound Field Sampling?

As you can see from the following diagram, sound-field sampling consists of “firing”
SREV1 test pulses into an acoustic space, thereby energizing the reverberation in that
space, which is then picked up by a number of microphones and returned back to the
SREV1 for processing. The acquired data can be saved onto PC Card, edited as neces­sary using IREdit, and then loaded into the SREV1 to create reverb programs.

SREV1

Generator

Generator output

Trigger output

Internal

D/A A/D

External

Sampler

Trigger input

CH 1 input

CH 2 input

CH 3 input

3

PC running

IRSampler

CH 4 input

Hall

FL FR

RL RR

Power Amp Mic Amp

Firing pulses

SREV1 Sampling Guide