Yorkville Sound AP812 ユーザーズマニュアル

Feature Details & User Tips

Channel Strips

Inputs

Each channel has both a MIC and LINE input (except for channels 9/10 & 11/12

(15/16 & 17/18) which have RCA type inputs as well as 1/4-inch TRS inputs). The

LINE input will accept either balanced or unbalanced signals from all types of sources

and the MIC input is optimized for low-impedance microphones. The LINE input

is Tip-Ring-Sleeve balanced, with the Tip in phase, the Ring reverse phase and the

sleeve, Ground. The XLR is wired Pin 1= Ground, Pin 2 = in phase & Pin 3 = reverse

phase. This configuration is the standard throughout the world.

User tip: Problem; Hum and Buzz When Source is Unbalanced...
Unbalanced connections may be made to the LINE input with an unbalanced shield-

ed cable. However, field or leakage-induced ground currents between separate pieces

of equipment can sometimes produce hum and buzz. Most electronic instruments, for

example, still use unbalanced connections. If the equipment has more than one out-

put feeding the mixer, even floating the circuit ground may not help.
CAUTION: We urge you to NEVER remove the ground-pin on the AC cord or other-

wise disable the earth safety Ground connection as doing so can expose you to a seri-

ous shock hazard. Additionally, your radio interference problems will likely increase

and in some cases your hum problems will get even worse.
What to do: Hum and buzz can be safely reduced or eliminated with the AP812/818’s

input balancing, even when the signal source is unbalanced, Simply use standard

Tip-

Ring-Sleeve balanced patch cables. However, in some worst-case instances it may be

necessary to create a special patch cable. In this case, use a 1/4-inch

TRS (stereo) cable.

Attach a 1/4-inch

TRS (stereo) plug to the end which will plug into the mixer’s

balanced-input as follows;

1) solder shield to Sleeve, 2) solder wire #1 to Tip, 3)

solder

wire #2 to Ring. Now attach the mono plug to the other end of the cable as

follows:

4) solder the shield and wire #2 to the Sleeve, 5) solder wire #1 to the tip.

Now connect this

mono end to the output of the unbalanced piece of equipment and

the

stereo end to the AP812/818’s LINE input.

This technique will always reduce hum, and it can be used to connect any equipment

having a

Balanced INPUT to any other equipment having an Unbalanced OUTPUT.

Phantom Power Button & LED

Located on the back panel near the

SPEAKER outputs, this push-button activates the

24 Volt PHANTOM POWER feature built into the AP812/818. When the PHANTOM

POWER is activated, the +24V LED on the front panel (just below the PHONES jack) will

illuminate. Now you may connect condenser microphones to any channels without the

need for external power supplies. You may also connect

dynamic mics to any channels

with the

PHANTOM POWER activated without any problems or loss of sound quality.

Gain Control

With signal applied to the input, adjust this control so that occasional flashes of the

CLIP LED are observed. This will ensure that the signal level fits comfortably within

the channel strip’s headroom ~ low enough to prevent distortion, and yet high

enough to preserve the signal to noise ratio. This control covers a wide range, so it

may seem rather sensitive until you’re used to it.
Monitor Send

The

MON send control is post-EQ & pre-fader. This means that the bit of channel sig-

nal it sends to the

MASTER MONitor bus is tapped off at a point after the channel EQ

circuitry, and before the level fader. As a result it is not affected by the channel fader.