Yamaha DSP-A1 Owner's Manual page 62

REV. DELAY (Reverberation Delay)
This parameter sets the time difference between the beginning of
the direct sound and the beginning of the reverberation sound.
The larger the value, the later the reverberation sound will begin.
A later reverberation sound makes you feel like the space of the
acoustic environment has become larger.
Control Range:
0 – 250 milliseconds
Level
Direct sound
Reverberations
REV.DELAY
REV. LEVEL (Reverberation Level)
This parameter adjusts the volume of the reverberation sound.
The larger the value, the stronger the reverberation becomes.
Control Range:
0 – 100%
Level
Direct sound
60
60 dB
Time
REV.TIME
REV. LEVEL
Time
EFCT TRIM (Effect Trim)
Performs fine adjustment of the level of all the effect sounds.
Control Range:
–3 dB to 3 dB
S. DELAY (Surround Delay)
Adjusts the delay between the direct sound and the first reflection
on the rear surround side sound field. The larger the value, the
later the surround sound field is generated.
Control Range:
When the Dolby Pro Logic Surround is decoded:
15 – 30 milliseconds
When the Dolby Digital (AC-3) or the DTS is decoded:
0 – 15 milliseconds
When a program without the Dolby Surround or the DTS
encoded is used:
0 – 15 milliseconds