Dc Servos; Input/Output Connections; System Grounding; System Polarity - Klyne 7PX3.5 Operating Manual

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NOTE 1: After the initial turn-on delay, the panel muting control activates a CMOS logic
circuit to invert the muting mode from its previous state. There is a delay built into this
control to eliminate false triggering due to bounce of the switch contacts. Thus, after the
initial change, it is necessary to wait a couple of seconds before the next change is possible.
DC Servos · In order to maintain the DC level of the outputs as zero volts without using
large blocking capacitors, DC servos are used in the 7PX3.5. The servo senses the DC voltage of
the output and if different from zero, applies an inverse DC correction to the amplifier stage to
return the output to zero. The servo, however, must ignore the audio signal which ideally
comes very close to DC. Thus, the servo must be taken out of the circuit at a very low point to
still enable the best bass performance. For the 7PX3.5, we have chosen a very low frequency to
disengage the servos. For this reason it takes several minutes for the servo to finally settle at
DC. If you are using direct coupled amplifiers and turn them on shortly after (or before) the
preamp is turned on; you may observe some slow "breathing" of your woofers while the
servos are settling. To avoid this situation leave the 7PX3.5 always on (which we highly
recommend); or, allow several minutes to pass before turning on your power amplifier. Once
the servos have settled. they can only be disturbed by improper operation of the system. Thus
the following conditions should be avoided:
1) Changing the gain switches with the preamp power on.
2) Driving the output stage into clipping.

Input/Output Connections

· Inputs and outputs are marked accordingly on the rear
panel. A separate set of buffered tape outputs is provided for direct connection to a tape
recorder without the need to route the signal through the line level preamplifier for recording.
Also, an extra set of unused holes are provided for the experimenter who may wish to install a
different set of chassis jacks in parallel with the original set.
NOTE: The quality of the interconnect cables is extremely critical in realizing the full sonic
potential of the 7PX3.5. This is particularly important between the tonearm and the preamp
where the signal is at a very low level and unequalized for the RIAA compensation. We
recommend that you use the very best interconnect cables available. Where there is a choice,
use the shortest possible cable that will conveniently connect you components.
System Grounding · The chassis of the 7PX3.5 is connected internally to the circuit ground
plane at a single point. (Located at the left rear circuit board mounting bracket) To properly
ground your pick-up system, simply connect the ground wire from your turntable/tonearm to
the grounding post on the rear panel marked "chassis ground". Always plug the AC power cord
into a grounded outlet if available. Do not attempt to defeat the power grounding pin as it
connects your system to "earth" ground and greatly aids in minimizing noise problem due to
static charges or RFI.

System Polarity

· All amplifier modules (except the balanced output inverters in the
7PX3.5/B) are non-inverting. Thus all signals processed will retain their correct polarity. XLR
connectors used on the 7PX3.5/B are wired as follows: pin 1 - circuit ground (neutral), pin 2 -
positive polarity and pin 3 - negative polarity. (The XLR connector body is mechanically and
electrically connected to chassis ground.)