UX201A Sound Processor, Part 2 : Assembly

Hi!

After the presentation of the circuit in part 1 of the article series about the UX201A Sound Processor, this post will show the assembly steps.

Since this circuit needs massive heatsinks, the usual chassis with wooden frame would not work. So I designed a completely new full metal chassis style. The chassis was sized as compact as possible.

The top metal plate with sub plates for the tube sockets:

The sockets are mounted to sub plates which in turn get attached to the main plate by rubber damping elements as seen in my DHT preamps and phono stages.

The sub plate mounted into the main plate:

Pre assembled main plate:

Adding the Tango NP8 line output transformers. The connection between transformers and plate pins are already in place (done with solid core silver wire and additional insulation sleeve):

Preparation of the heatsinks:

The 3 resistors on the left side are 1.5k/25W types. They will be wired in parallel to get the 500 Ohm resistor through which the filament voltage is derived from B+. It has been split into three resistors to spread out the heat dissipation. The resist on the right is the 22 Ohm filament bias resistor.

Mounting the heatsinks to the top plate :

Wiring of the resistors. The main ground buss is also in place already (wire at the bottom):

Adding the chokes :

The chokes are nice nickel core units wound for me by Dave Slagle

View from the backside before the panel with the connectors is attached:

Preparation of the back panel:

There are two sets of outputs. The NP8 secondary has a tap for extra low output impedance.

Backplate attached to the Sound Processor:

Adding the bottom plate :

Finished:

In the next articles the circuit and assembly of the power supply will be covered. Stay tuned!

Best regards

Thomas