User Manual

27
No.25 employs an advanced lter circuit which provides exceponal performance when coupled to the rest
of the signal chain of the Sub-Bass System. A second-order variable low-pass lter approximang a Bessel
funcon was chosen for its linear phase response, which equates to at group delay. This means that, unlike
other lter funcons, the amount of delay the signal is subjected to during processing is constant through
the enre pass-band, which improves the frequency response and allows for beer integraon of the sub
with the main speakers. An addional xed second-order Bessel lter follows the variable lter, removing
unwanted midrange signals that, if le unltered, cause the midrange of the main speakers to become
muddy or congested. All ltering is performed in the analog domain using high-quality components with
ght tolerances to ensure the highest possible performance and consistency.
The amplier is inherently stable and will retain its characteriscs over very long periods of me – important
in a unit designed for an exceponally long working life. These ampliers are designed to withstand reasonable
abuse and overloads. If in doubt, please contact your dealer.
We believe that the importance of the electronics, cabinet and drivers being designed to work in harmony is
paramount. This belief allows No.25 to achieve the highest possible level of delity.
Overload Protecon
All REL Sub-Bass Systems are designed as true sub bass speakers. They are designed to reproduce those
exceponally deep notes that are felt as well as heard. This it will aempt to do at whatever volume level
you set. If set too high no damage should result because the built-in electronics will limit the cone movement.
This electronic control is called Set-Safe™. It constantly and instantaneously monitors the output from the
power amplier and is totally transparent in operaon unl required. This means it has absolutely no eect
on the sound quality of your REL unl an overload is detected.
Ordinarily an overload would cause the power amplier to go into clipping with resultant loss of control
over the drive unit. This can cause drive unit damage, and always sounds nasty. Set-Safe™ detects the point
of incipient clipping and gently so-clips the waveform of the signal to ensure actual clipping does not occur.
This is a necessarily simplied descripon of what actually happens, but in eect, Set-Safe™ controls the
amplier and ensures there is minimum risk of amplier and driver damage caused by over-driving.
Technical