Peavey LT Series TourClass protection, safety, AutoRamp, Thermal Protect, Short Circuit

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TourClass® protection

Just like Crest Audio’s highly acclaimed Pro series amps, LT and ST amps incorporate TourClass protection features. Derived from Crest Audio’s extensive experience with the world’s largest sound rental companies, the TourClass group of circuits sets the industry standard for assured protection of internal amplifier circuits and all connected loads.

ACL ACTIVE CLIP LIMITING

At the amplifier’s full power limit, or clipping point, ACL will be activated.This is indicated by illumination of the ACL / IGM LED.The channel gain is automatically reduced, protecting the loudspeakers from potential damage from the high power, continuous square waves that would otherwise be produced. ACL may be activated by uncontrolled feedback, oscillations, improper equipment gain settings, or an equipment malfunction upstream from the amplifi- er. Only steady or excessive clipping (not normal program transients) will trigger ACL. The circuit is virtually transparent in operation and full signal bandwidth is maintained.

IGM INSTANTANEOUS GAIN MODULATION

IGM is an innovative circuit that allows the amplifier to operate safely into loads as low as 2 ohms.When the amplifier sees a load that overstresses the output stage,the IGM circuit adjusts the channel gain to a safe level. This gain control circuit is inaudible in normal use. In addition, if extreme and sustained low impedance is encountered, the amplifier’s output relay will open.

AutoRamp

Auto Ramp operates every time the amplifier is turned on or is reactivated after a protect condition is corrected.This exclusive Crest Audio feature gradually increases gain to the atten- uator setting avoiding unnecessary stress on the loudspeakers.

Thermal Protect

Abnormally high heat sink temperatures will engage the Protect circuit and disconnects the output relays. During this time the Prot LEDs will light red.The cooling fan will continue run- ning at high speed. Normal operation resumes once the amplifier cools to a safe level.

Short Circuit

If an output is shorted (i.e. defective speakers or crossed speaker wires) the channel will shut- down and can be re-set by turning the amplifier off, then on.

DC Voltage

If an amplifier channel detects DC voltage at its output terminals, the output relay will immediately open to prevent loudspeaker damage. The protect LEDs illuminate.

Subsonic Frequencies

Built-in high pass filtering provides subsonic frequency protection for each channel. In addition, a relay will open if excessive subsonic energy appears at the output.

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