Granite Audio 770 Brochure

Resistors.
High-performance expensive HOLCO resistors with
copper leads in signal path, tube plate, and other
critical circuits.

Filter chokes.
Dual high-inductance high-current filter chokes in
filament power supply. These are extremely impor­tant for a quiet phono section.

Power inlet.
Universal 15 amp IEC power inlet with removable
cord. This gives choice of cord length and option
to upgrade to Granite Audio Model #555 or #560
handcrafted power cords.

Bi-Amp Outputs.
True dual-isolated Bi-amp out­puts. The HI OUTPUT jacks are
3dB louder than the LOW OUT­PUT jacks for more connection
options. Jacks are 24Kt. gold­plated silver on OFC copper base.

Model #770 Preamplifier

Capacitors.
High AC current handling
polypropylene capacitors by
Sprague. These capacitors
give a smooth musical pres­entation, clean details, and
excellent dynamic range.

Vinyl lovers note:
Dual Vishay adjustable resistors for “loading” the
phono cartridge. They’re easily adjusted by the
user to match any brand of phono cartridge. This
adjustment is extremely important to give accurate
flat playback of the RIAA Equalization curve that all
vinyl records are encoded with at the time of mas­tering. The Model #770 Preamp comes with the ad­justment tool and a Model #CD-101 Phono Burn-In
& RIAA Test CD. If you’ve ever thought your favor­ite records sounded too bright on some cartridges,
it’s probably because the wrong value of load resis­tor was used in the preamp. This 15-turn precision
adjustable Vishay resistor can be precisely set to
the exact correct load for any moving magnet or
high-output moving coil cartridge for the ultimate
accurate smooth playback.

Transformer.
Custom laminated transformer for the ultimate tube
sound. It’s grounded to the steel chassis and iso­lated from the main signal circuits in it’s own
shielded compartment for the maximum in low
noise operation. The B+ winding is rated to 400%
over typical current demand.

Chassis.
One piece solid steel powder-coated and welded for
maximum resonance control, durability, noise rejec­tion, EMI/RFI shielding, and strength. Mounting
bolts fit into quality threaded inserts and standoffs.

Vacuum tube rectification.
High-current 6X4 rectifier tube for high voltage B+
circuit. Tube rectification gives a fuller richer bass
response and automatic soft-start to the power sup­ply because it has to warm up slowly before the B+
reaches full voltage of 300VDC. Tube rectifiers also
create a smoother voltage rail without the spikes
and noise often associated with diode rectifiers.

Ultra-Fast Recovery Schottkey Rectifiers.
These give a smoother voltage rail and lower noise
floor to the filament circuits than lesser diodes
would. This contributes to the ultra quiet operation
of the sensitive phono section.

5

6

ALPS

Black Beauty

Balance Control

1

2

3

4

ALPS

Black Beauty

Volume Control

No other preamp in the world has all these high quality features and parts.

Tube Sockets.
Sockets are mil spec quality porcelain with silver
plated pin sockets and are wave soldered directly to
the PC board.

4-Layer PC Board.
Our printed circuit board is actually 4 layers of
traces with a solid copper shield between each of
the layers. The high-voltage low-current B+ circuits
are on the top layer. The low-voltage high-current
filament circuits are on the bottom layer.

The signal traces are on the two middle layers. By
putting the signal traces onto 2 layers, the traces
can cross each other at perpendicular angles which
eliminates the noise and interference found in con­ventional single-layer boards that require the traces
to run parallel to each other.

All the parts, controls, and input/output jacks are
wave-soldered directly on the 100% shielded PC
board. So, every circuit is completely shielded.
The only wires in the main compartment are the
ones that supply the voltage from the power supply
to the main board and the ones that supply the volt­age to the front panel LED indicator lights. None of
which are in the signal path. This no-wire 100%
shielding design gives us the ultimate in low-noise,
black background, and maximum clean signal path
for your favorite music.

B+ Filtration.
There are 3 levels of B+ Pi filtration on the power
supply board and 3 more levels of filtration on the
main PC board, for a total of 6 filters. This gives an
ultra-low noise floor and pure black background for
your favorite music passages.

Main power switch.
Contacts are gold-plated solid silver for
the ultimate in clean signal transfer and
maximum life without signal degradation.
Hermetically sealed body for long mainte­nance-free operation. This Alcoswitch is
rated for 35,000 cycles at 6amps.

Power supply

shielding.
Special steel bulk­head welded in place
for maximum shield­ing of power supply
from signal circuits.

Tape monitor switch.
Contacts are gold-plated solid silver for
the ultimate in clean signal transfer and
maximum life without signal degradation.
Hermetically sealed body for long mainte­nance-free operation. This Alcoswitch is
rated for 50,000 cycles at 6amps.

Shafts.
Custom insulated flexible shaft couplers
give a smooth tactile feel to the front
panel knobs and create an insulation
barrier to hum & noise that might enter
the circuit through the shaft when the
knobs are handled.

Selector switch.
Contacts are gold-plated solid silver for the ultimate
in clean signal transfer and maximum life without
signal degradation. Hermetically sealed body for
long maintenance-free operation. This Alcoswitch
is rated for 35,000 cycles at 6amps.