Technical Design Features - Rockford Fosgate 250.1 Operation & Installation

T
ECHNICAL
Many of the solutions to common design problems encountered by Rockford Fosgate engineers created entire
new circuit designs as well as new ways to construct the Punch 250.
amplifiers, no expense was spared in design and construction from the unique circuitry design to the
manufacturing process that has proven to be the industry reference for many years. Described below are just some
of the accomplishments achieved by our engineering and manufacturing staff.
trans• nova
The trans• nova (TRANS conductance NOdal Voltage Amplifier) is a patented circuit (U.S. Patent 4,467,288) that
allows the audio signal to pass through the amplifier at low voltage . Each amplifier channel utilizes its own "fully
floating" power supply and is configured to increase power gain. The increase in power gain allows the drive
stage to operate at a lower voltage. A low voltage drive stage is the same principle used in high quality
preamplifiers to produce high linearity and wide bandwidth.
The resulting design utilizes an output stage with a simpler gain structure and a shorter total signal path than
conventional high voltage (bi-polar) designs. The number of stages is reduced from five or more to three. The
output stage is further refined into a trans-impedance stage (current to voltage converter) to achieve a short loop
(fast) negative feedback. The output stage is driven cooperatively by a transconductance stage (voltage to current
converter).
THE RESULT: Superior sound quality, greater efficiency and higher reliability.
DIABLO
DIABLO (Dynamically Invariant A-B Linear Operation - patent application in process) is an important advance
in circuit design which reduces high frequency distortion. Amplifiers which utilize a large array of output
MOSFETs cause a high capacitive load on the driver stage. This load can make the high frequencies sound harsh.
The DIABLO circuit eliminates high frequency distortion by allowing the driver to operate with 20dB or more
of current headroom, whereas traditional drives have only 6dB of current headroom.
THE RESULT: Lower distortion and greater inherent stability.
TOPAZ
The TOPAZ (Tracking Operation Pre-Amplifier Zone) circuitry solves ground loop noise problems common to
automotive amplifier design. This innovative new development allows vastly improved isolation of the input
signal grounds from the power supply ground of the amplifier. This is accomplished by allowing the source unit
to control the potential "environment" of the entire input structure or "zone" of the amplifier. This process
improves the noise rejection of the amplifier by 30-40dB – an astounding 20-100 times better than amplifiers
without TOPAZ.
THE RESULT: Elimination of troublesome ground loop noise between source and amplifier.
D F
ESIGN
(TRANSconductance NOdal Voltage Amplifier)
E-I
trans•nova circuitry
(Dynamically Invariant A-B Linear Operation)
(Tracking Operation Pre-Amplifier Zone)
EATURES
and 250.
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Power Amplifiers. In our flagship
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