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770 Prototype 3 with granite enclosure.
Quantity in Basket: none
Code: 770proto3
Price: $1,490.00
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.