Cary Audio CAD 1610 SE Owner's Manual

CAD-1610-SE

OPERATING MANUAL

NOTE:

Before installing your new CAD-1610-SE, please read this manual carefully as it will inform you
of the CAD-1610-SE's specifications, proper installation and operation procedures. Also
included in this manual are guidelines on how to properly service and care for your new CAD­1610-SE.

CAD-1610-SE

SINGLE-ENDED MONO-BLOCS

The new CAD-1610-SE single-ended triode mono-blocs are equipped with the
new KR Enterprises T-1610 triode tube. This vacuum tube has been specifically
engineered and manufactured for the Cary Audio Design CAD-1610-SE
amplifiers. By all indications, this tube will last up to five years or more in the
Cary Audio mono-bloc amplifiers. The basic design of the new CAD-1610-SE is
a time proven circuit used in many of the Cary Audio triode single-ended designs.
These circuit topologies contribute to incredible reliability and enjoyment.

For the technically minded, a review of the circuit is in order. The new CAD­1610-SE mono-blocs operate in pure class A single-ended. The output stage
features the new T-1610, low-mu audio power triode. The T-1610 low-mu
design allows for very low distortion in single-ended designs. The CAD-1610-SE
amplifiers have two special high and low impedance bias supplies. There is no
need to ever worry if the lower amplifier section that contains the T-1610 triode
tube is inadvertently turned on without the bias voltage supplied from the top
300B section. There is a high impedance bias supply that automatically controls
the T-1610 plate current. The actual operating bias is supplied from the driver
section (top unit) to the T-1610 vacuum tube. The output power of the CAD­1610-SE amplifier is over 100 watts peak envelope power. The steady state
continuous sin wave power is 55 watts into either an 8 or 4 ohm load. The class
of operation is pure class A single-ended. The output transformer in the new
CAD-1610-SE is an air gap design with full bias running on a continual basis.
The output transformer in the CAD-1610-SE is the most important component in
the amplifier and has been specifically designed by Cary Audio Design for use in
the CAD-1610’s. We have taken the approach in the output transformer design
the use oxygen free copper wire. The primary and secondary windings on portions
of the output transformer are wound in a bi-filer process with the two inductors
interleaving twenty six times. The bi-filer wind (two conductors wound at the
same time) will yield the closest balance and coupling of any design currently
utilized in vacuum tube output transformers. The E/I laminents used in the
special output transformers on the CAD-1610-SE’s are silicone impregnated
hipersil steel contributing to the extremely low loss and a seductive midrange. The
above process is similar to the single-ended design air-gap transformers found on
all the Cary single-ended output transformers.

An audio drive signal is applied to the control grid of the input 6SN7 dual triode
tube. The second 6SN7 triode is functioning as a anode current device supplying
operating voltage and current to the first 6SN7 triode gain stage. After the signal
is amplified by the 6SN7 the output anode of this section is directly coupled to the
grid of the 300B triode gain stage. The direct coupling eliminates the need for a

coupling capacitor along with supplying bias for the 300B tube. The 300B gain
stage is supplied voltage on the anode by a high inductance voltage choke. This
choke takes the place of a conventional resistor used in most amplifiers. The
choke allows the 300B to swing a much greater amount of amplified AC audio
signal to the output T-1610 tube. The amplified signal from the 300B triode is
coupled through an oil filled .22 at 600 VDC capacitor to the grid of a dual
section low mu 6BL7 triode. The 6BL7 performs two functions. One is to
provide the proper low impedance bias voltage to the T-1610 output tube. The
other function is to couple the amplified AC audio signal directly to the control
grid of the T-1610 output triode. The T-1610 output tube is fed B plus voltage
through the air gapped output transformer.

The power supply in the CAD-1610-SE’s actually consists of eight different
supplies. The power transformers are designed to operate at a 200% continuous
commercial service at the full rated output power. The high voltage power supply
section for the T-1610 output tube is a full wave center tap configuration (not
some cheap voltage doubler as used in many competitors amps) to a PI network.
All filament voltages in the CAD-1610-SE amplifier are DC. The DC filament
supplies will prevent AC ripple from capacitively being coupled to the electrodes
of the input and output tubes.

A great deal of attention during design of the new CAD-1610-SE’s was
concentrated on the “overload recovery” ability of the amplifier. The ability of an
amplifier to instantly recover from clipping is much more important than is
commonly believed. In the power war of amplifier manufacture’s, the mentality
is focused on high and then even higher power output to solve the clipping
problem. When in reality the most critical aspect is how fast a
recovery an amplifier can achieve after overload. With the incredible dynamic
range of live and in turn recorded music, even 2,000 watts of power is not
enough. Most of the music being listened to in an average home listening room is
only requiring about 3 watts of power. It is on the transients of loud low
frequency program material that tremendous signal voltages will appear at the
input of the amplifier. It is in this situation that the overload recovery ability of
an amplifier is of critical concern. The CAD-1610-SE extols its merits in the
ability to handle transients and instantaneously recover from brief or even
extended over loads. The CAD-1610-SE’s will overload symmetrically at any
frequency in the audio bandpass.

The CAD-1610-SE will also yield faithful reproduction of extremely low
frequencies at full output levels. Power transformer, power supply regulation and
output transformer design and careful shaping of the overall frequency response
curve all play a very important part in the ability of the CAD-1610-SE to recover
quickly when over loaded. If one were to monitor the high voltage rail voltage
(550 VDC) at the anode to cathode of the T-1610 output tube during soft and also

loud music passages it would be found there is no more than a volt or so change
from soft to loud passages.

Another technical feature of the new CAD-1610-SE amplifier is stability. The
CAD-1610-SE’s may be operated with no load (without speaker) without damage
to the amplifier, output transformer or tubes.

The CAD-1610-SE mono amplifiers are built from machined aluminum on all
parts of the structure. The amplifiers are built to perform year after year with
trouble free operation. The CAD-1610-SE’s are a classic example of the
“CARY” sound.

Model: CAD-1610-SE

Serial Number: _____________

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