770 Prototype 3 with granite enclosure.
Quantity in Basket:
Shipping Weight: 35.00 pounds
This is the third generation Model 770 Prototype. This
is the first prototype to have a printed circuit board.
The MSRP on the Production version of this preamp is
$5,000.00 with the granite enclosure.
The MSRP on the granite enclosure is $1,000.00 by
itself. This prototype comes complete as pictured and is
in working condition. The preamp comes with a schematic
and owner's manual, but of course is SOLD AS-IS.
No Warranty. No Return.
This amp is loaded with audiophile quality parts.
The selector switch and tape monitor switch are solid
silver contacts and rated for 50,000 cycles without any
degradation of the contacts. The chassis is loaded with
Holco Precision copper lead resistors in the signal and
B+ plate circuits. The volume control is an ALPS BLACK
BEAUTY. The main PCB is a 4-layer board and will require
advance DIY skills to change any of the parts on this
board. This amp is sold AS-IS.
This prototype will be shipped with an ALPS Black Beauty
balance control that is not installed on the PCB. This
is because the pin-out on the PCB does not match the actual
control. So, to use the balance control, you would have
to hardwire the control to the PCB and find a way to mount
it above the board, as it will not mount directly to the
PCB. You will notice there is a balance control
knob on the front panel and
it is connected to a shaft that just spins.
The Production version of this preamp has two chokes in
the filament power supply. You can add chokes to this
prototype and you can see there is room for them in the
power supply area. The chokes are not included.
Tubes are included. 1 - 6X4 Rectifier and 6 - 12AX7.
Tubes are NOS JAN Phillips and the same as we ship in
the Production model.
The amp has 4-line level inputs, 1-MM phono input, 1-tape
input, tape monitor loop, and true isolated buffered
bi-amp outputs. Measurements 18.75" x 11.75" x 4.75" high
and weighs 25 pounds with the granite.
Use these links to view larger photos.
Chassis top Hi-Rez.
Front with granite.
Back with granite.