controls (with no gain). The higher level of these sources should be attenu-
ated, ideally with a passive volume control (a high quality resistor to ground).
Measurements are normally made with a test disc and oscilloscope, but if
the output level and impedance is known, the amount of attenuation can be
calculated. Finally, most recorders provide a level meter, and the appropri-
ate level can be set by watching the level using representative music.
P
HONO
I
NPUT
The Phono Input can only accommodate the type MM cartridge with 2.5
mV/ 47k Ohm. This is the most common type input found on most proces-
sors and receivers. Correct phono connection should also include a ground
connection between the chassis ground of the phono player and the dedi-
cated phono ground screw on the back of the PAD. For true high quality
recordings, a separate preamp should be used on the line level input.
M
ANUAL
C
ONTROL
A DB-15 connector is provided on the back of this product. It can be used
for two functions. It provides an output signal reporting what inputs are
active and an input function allowing manual override of the selected source.
Each source has a dedicated pin that is either Low or High (Ground or
+5V). A low output indicates that the source is not active. A high output
indicates an active source. The highest priority source High is the source
selected.
The unit may be manually controlled by forcing each source line either Low
or High. This can be accomplished with either logic or relay closures. A
Ground and +5V pins are supplied for convenience. Key functions and
power on/off are also accomplished with dedicated pins. The function of
each pin is described in the table below. *NOTE. When selecting an input
high, you must force all other inputs low (ground).
P
IN
#
M
ODE
F
UNCTION
1
High (+5V)
Input 8 Output
2
High
Input 7 Output
3
High
Input 6 Output
4
High
Input 5 Output
5
High
Input 4 Output
6
High
Input 3 Output
7
High
Input 2 Output
8
High
Input 1 Output
9
High
Phono Input Output
10
High
Power On
12 and 15
Ground
14
+5V
1) Power Button and Indicator LED
- The ADD defaults to the power
on position. In actual practice, the ADD is always powered on. The power
button actually activates the front display and calibrates the A/D. Allow
the ADD to warm up for at least 15 minutes when first applying line level
power. Once warm, the ADD can be used immediately after the power
button is pressed. We reccomend always leaving the ADD on.
2) Clipping Indicator Light
- This light indicates that an analog source
has exceeded the input level specifications. Setting the levels too low, to
avoid this possibility reduces the resolution of the output signal so care should
be taken to run the levels as high as possible without clipping.
3) Sample Frequency Button and Indicator Light
- The ADD defaults
to a 48 kHz sampling rate. This is the rate commonly output by DVD, DSS
and many new digital sources. The 44.1 rate is the CD standard. The 96K
rate is common in studios and is used for DAD discs. Select the highest
sampling rate the system will allow.
4) Virtual 3D Option On/Off Button
- When the virtual 3D option is
installed, this buttion turns it on and off. When no option is installed, the
button has no effect.
5) Line Level Input Selector and Indicator Light
- This default setting
activates all the line level inputs with automatic switching. Only the phono
input is not automatically detected.
6) Phono Input Selector and Indicator Light
- Selects only the phono
input
1
2
3
4 5 6
F
RONT
OF
THE
ADD-1
5
4