T
E C H N I C A L
R
E F E R E N C E
– 9 –
FIELD SERVICE CONSIDERATIONS
A primary focus during the design and development of the P1000 was to ensure the dependability of the amplifiers. The
use of MOSFET output transistors and the low voltage trans•
ana input stage combined with careful component selection
for the circuit assembly made the reliability goals achievable. However, a parallel effort was also undertaken to make
sure any down time caused by an amplifier fault was minimized by making the amplifier technician “friendly.” The
modular construction allows exchanging the entire operational portion of either channel quickly and easily without the
need for soldering or specialized equipment.
This section of the manual contains descriptions of circuit operation and block diagrams to assist technicians with
component level repairs.
THEORY AND OPERATION OF trans•
ana
The
trans•
ana
(
TRANS
conductance
A
ctive
N
odal
A
mplifier) circuit is an efficient, short loop amplifier design using
Vertical MOSFET output transistors. The input and pre-driver stages operate at low voltage and the output MOSFETs are
connected in a source-on-rail configuration to deliver their full voltage gain.
Using the output stage to supply voltage gain inherently increases the power gain (for the same bandwidth) of the output
stage by typically ten times over the conventional follower connection, using the same MOSFET devices. This increase
in efficiency allows the use of a much simpler input section than in the more common high voltage designs. The number
of serial stages, from input to output has been reduced from five or more to only four in the P1000.
The transition from the low voltage input processing to the high voltage output operation is handled by a pair of
complementary bipolar driver transistors. The drivers form an
active node at ultrasonic frequencies and couple very
accurately to the gates of the MOSFETs. This results in highly stable and highly linear performance.
The trans•
ana topology is particularly well suited for use in a moderately powered compact amp like the P1000 because
of its simplicity and efficiency. The circuit configuration does not require separate high voltage power supplies thus
reducing the size and complexity of the power transformer. The vertical MOSFETs used in the P1000 have a lower “on
resistance” than the lateral MOSFETs used in our other amplifiers which results in less operating heat. This allows for
a reduction in the size of the heatsinks and makes the single rack size of the P1000 practical.
The sonic character of the P1000 is similar to our larger trans•
nova amplifiers and delivers realism and accuracy which
surpasses any other similarly sized amplifiers.
Summary of Contents for trans-nova P1000
Page 16: ...SC H E M A T I C DI A G R A M 7...
Page 17: ...8 Amplifier Channel...
