INSTALLING EQUALIZER JACK IN THE AC-300

Serial Numbers ___1764 and above.

INSTALLING AN EQUALIZER JACK IN YOUR AMPLIFIER COULD REDUCE THE RESALE VALUE OF YOUR UNIT. HILTON AUDIO PRODUCTS WILL NOT ACCEPT FOR TRADE-IN A UNIT THAT HAS BEEN SO MODIFIED.

Other than mounting the jack the wiring is very simple. The jack should be located near the volume control to keep the wire length as short as possible reducing the chance of hum pickup.

Remove the unit from the case as follows: Remove the handle by sliding a screwdriver under the chrome cover and pry it off, exposing the two screws that hold the handle on. Remove these two screws. On the opposite side of the case remove the two rubber feet, held in place by screws. The entire unit will now slide out of the carrying case. Stand the unit up so that you have access to the underneath side. Remove the bottom heat plate.

In order to mount the jack it will be necessary to drill a large hole (approx. ½" diam.) in the outer chassis, and a 3/8" jack mounting hole in the preamp sub-chassis. These holes must line up with each other. (drilling a small locator hole through both chassis panels, before disassembling, will help line them up).

To mount the EQ jack it will be necessary to remove the preamp. Remove all the knobs from the controls on the front panel. Remove the small grounding springs underneath knobs if any. Remove the hex nuts from each of the control shafts and mac. jacks.

Remove the plug-in connector at the end of the preamp board. (It will be necessary to loosen the spot of clear plastic that holds it in place). The entire preamp assembly will come out. Now drill the holes in the chassis and sub-chassis for mounting the EQ jack.

Place a small jumper wire on the EQ jack from the (X) terminal to the ring terminal. See drawing 1.

Wiring the music EQ jack

The phono volume control has three wires attached:

Ground: goes from one end of the control to the wide trace that runs about ½ inch from the top of the PC.

Signal out: from the center of the control.

Signal in: the other end from ground. This is the one we will work with.

Remove the signal in wire from the main phono control, and attach it to the lug for the Tip. (see drawing)

Run a wire from the Ring to the phono control, where you removed the old wire.

Run a wire from the ground lug to the control ground.

If you wish to effect both main and monitor, cut the signal in wire going to the monitor music control and attach it to the ring also.