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PL-2 Analog Peak Limiter Manual

 

Features

· Two independent channels with stereo link 
· JFET (hard) and MOSFET (soft) peak limiting modes
· Limiter circuit 'switched out' of the signal path when below threshold
· Precise readout of peak reduction
· Stepped input and output gain controls ideal for mastering or session recall
· I/O gain stages can be bypassed to shorten signal path
· Multiple units can be linked for multi-channel applications
· Active-balanced inputs and outputs
· Gold-plated switch contacts and I/O connectors 
· Audiophile-grade passive components 
· 120V or 240V ac voltage switch on the rear panel.

 

Introduction

Thank you for purchasing the Pendulum PL-2, a stand-alone two channel
version of the very popular peak limiter in our Quartet II Tube Recording
Channel. It uses a novel approach to brickwall limiting in the analog domain,
one that is fast enough to prevent digital overs without using time delay or
phase-shift delay techniques. This allows us to keep the analog signal path
short, and keep the limiting circuit 'switched out' of the signal path below the
peak limiting threshold. Distortion for all levels below the limiting threshold is
low, and does not rise as the threshold for limiting is approached. Unlike
analog peak clippers, which chop off the top and bottom of the waveform, our
limiter retains dynamic information at the top of the peak. And unlike digital
limiters, there is no latency, so it can be used as an insert on an analog mix!

The PL-2 has two modes of peak limiting, using either junction field-effect
transistors (JFET) or metal-oxide semiconductor field effect transistors
(MOSFET) as the control elements. While both are equally capable of
brickwall limiting, each type has its own characteristic sound. The JFET tends
to be a stiffer, harder mode of limiting, while the MOSFET has a softer, more
compliant response. The resulting waveforms look different, and each device
has its own characteristic sound.

The two channels for the PL-2 can be linked for stereo or used independently.
Multiple units can be linked via the Master/Slave jacks on the rear panel,
making it ideal for multi-channel processing.

In addition, Input and Output gain controls allow the user to scale the gain
structure for a wide range of applications, from driving the front end of an
A/D converter at +20 dBu, to inserting it as an effect into a +4 dBu patch bay.
The I/O gain stages can be bypassed globally to shorten the signal path for
mastering applications. Each channel also has an expanded 13 segment LED
display that accurately indicates peak reduction.

Unpacking

Summary of Contents for PL-2

Page 1: ...shold for limiting is approached Unlike analog peak clippers which chop off the top and bottom of the waveform our limiter retains dynamic information at the top of the peak And unlike digital limiters there is no latency so it can be used as an insert on an analog mix The PL 2 has two modes of peak limiting using either junction field effect transistors JFET or metal oxide semiconductor field eff...

Page 2: ... defeated Unless otherwise stated this unit operates from either 115 120V 60 Hz or 230 240V 50 Hz at 16W Before the unit is plugged in select the correct ac voltage using the switch adjacent to the IEC inlet on the rear panel The ac fuse is accessible within the rear panel IEC input jack and is rated at 1 5A 250V 5x20mm SLO BLO To check or replace the fuse unplug the power cable from the IEC input...

Page 3: ... then making up the difference at the end of the chain by adding level the so called makeup gain The net result is an increase in the average program level which depends on the amount of gain reduction that is applied and the parameters chosen attack an release times ratio etc Since the ear is sensitive to the average program level the overall effect is an increase in apparent level Brickwall peak...

Page 4: ... a certain amount of compliance is built in to the limiting action This means that instead of chopping off the peaks and losing all dynamic information some wiggle is left at the top The JFET and MOSFET devices have differing amounts of compliance which results in differences in the character of limiting The JFET tends to produce harder limiting with less compliance while the MOSFET produces softe...

Page 5: ...digital or analog devices When the OUTPUT control is set at 0 the CEILING control sets the maximum output level JFET MOSFET The JFET MOSFET switch determines which type of device is doing the peak limiting As discussed above the JFET red LED illuminated gives a stiffer form of limiting while the MOSFET blue LED illuminated is more forgiving Due to the differing nature of the JFET and MOSFET device...

Page 6: ...on with yellow 5 and red 6 to 8 indicating caution is required PL 2 Specifications Circuit Type Class A solid state peak limiter with transformerless balanced inputs and outputs and dual mono or stereo operation Input Sensitivity 4dBu Input Impedance 20k Input Gain 0 to 10dB in 1dB steps Freq Response 1 0dB 5Hz and 80kHz Noise 90dB below 4dBu Distortion less than 0 03 THD N 20Hz to 20kHz at all si...

Page 7: ...injure in Pendulum s sole judgment the performance stability or reliability of the unit The warranty does not apply if the unit is connected installed or used otherwise than in accordance with the instructions furnished by Pendulum Audio Inc If the equipment requires warranty repair return authorization must be obtained from Pendulum Audio Inc prior to shipment Equipment should not be shipped to P...

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