Nexo PS8 User Manual

Also see for PS10: User manual User manual Quick start guide

Nexo PS8 User Manual Manual pdf 26 page image

AMPLIFIERS___________________________________________________________________________________________________PS SERIES MANUAL REV3 10/10/05P.26cover on the front panel (lower right corner).Earth-Lift configuration can be accessed without removing the safety panel by pushing with a smallscrewdriver the earth lift switch through two tiny holes in the safety cover. The upper hole switches to“Ground on”, the lower hole to “Ground off” (earth lifted).Changing the Voltage configuration or the fuses requires the opening of the safety cover (2 outerscrews). 115/230 V mains configuration is made by pushing a switch (according to the silk screenpainting) through two holes. The main fuses are the same in both configurations (no change is required).If the event of a main fuse failure both fuses shall be changed. The fuses are 5x20mm type temporized.Fuse reference: T6.3AH250Note: Two other fuses are located inside the unit on the PCB. Those fuses should never fail in normaloperation. In the event of a failure do not replace those fuses yourself, as something else could be faulty.Contact an authorized dealer.The mains power cable can be located on the front or on the back of the PSAmp. Changing the mainscable from the front to the back shall be made by an authorized dealer. No other control or connectionexists on the back of the amplifier. At installation nothing else is required than sufficient air flow path onthe back of the PS10Amp.Stand alone AmplifiersRecommended PowerNEXO recommends high power amplifiers in all cases, budget constraints being the only reason to selectlower power amplifiers. If a problem occurs on an installation without protection, the use of a lower poweramplifier generating half their rated output power (-3dB) will not prevent possible damage. This is due tothe fact that the RMS power handling of the weakest component in the system is always 6 to 10 dB lowerthan the amps' ratingCurrent RatingIt is very important that the selected amplifier behaves correctly under low load conditions. A speakersystem is reactive by nature, on transient signals like music it will require much higher instantaneouscurrent than its nominal impedance would indicate (four to ten times more). Amplifiers are usuallyspecified by their continuous RMS power into resistive loads (which is irrelevant); the only usefulinformation in that regard is the specification into a 2 ohms load. It is possible to make an amplifierlistening test by loading the amplifier with twice the number of cabinets considered for the application (2speakers per channel instead of one, 4 instead of 2…) and modulating at high level (onset of clipping). Ifthe signal does not noticeably deteriorate the amplifier is well adapted (overheating after approximatelyten minutes is normal but thermal protection must not operate too quickly after starting this test).GainIt is very important to know the voltage gain of all amplifiers present in your set-up. This will ensure thecorrect alignment of your system and may be obligatory (for reliability) in cases where only oneTDcontroller drives several amps. The tolerance should be about ±0,5 dB. In practice this can be difficultto achieve:Some amplifier brands have an identical input sensitivity for models of different power ratings (this meansDIFFERENT VOLTAGE GAIN for each model). This problematic practice, inherited from non-