Page 1
Short explanation of RIAA equalization.
INPUT 2 OUTPUT
15 VDC
+
-
PA550
MADE IN USA
PHONO
The RIAA equalization curve was intended to operate as the
global industry standard for records since 1954. However, it
is almost impossible to say when the change actually took
place.
PA550 Pre Amplier with RIAA Phono preamp
RIAA equalization is a form of pre-emphasis on recording
and de-emphasis on playback. A recording is made with the
low frequencies reduced and the high frequencies boosted,
and on playback the opposite occurs. The net result is a at
frequency response, but with attenuation of high frequency
noise such as hiss and clicks that arise from the recording
medium. Reducing the low frequencies also limits the excursions the cutter needs to make when cutting a groove.
Groove width is thus reduced, allowing more grooves to t
into a given surface area, permitting longer recording times.
This also reduces physical stresses on the stylus which
might otherwise cause distortion or groove damage during
playback.
What's in the box?
1 - Made in USA PA550
1 - 15V power supply PN PS27s
1 - This owners manual
1 - Love for great audio
and Headphone Amp
PWR
Headphone
PHONO
PA550
0 10
Volume
MADE IN USA
0
+
-
Bass
INPUT 2 OUTPUT
MADE IN USA
0
+
-
Treble
Preamplifier
Ch2
Phono
Ch1
In 1
PA550
15 VDC
+
-
SPECIFICATIONS:
Gain: Line 16.4 dB gain @ 1kHz
Phono 56.6 dB gain @ 1kHz
Input Impedance: 22k line and 47k Phono
Output Impedance: 8 to 600 ohms Headphone,47 ohms RCA
Frequency Response: 3Hz to 36kHz
Equalization: RIAA +/- 1 dB, 14Hz to 23kHz
THD: .005% @ 1KHz
S/N Ratio: >94 dB unweighted
PWR: 15 VDC
Size: 5.5"w x 3.5"d x 1.25"h
Weight: .8 lbs
Indicator: 1 Power LED
Bellari is a division of Rolls Corporation
Salt Lake City, UT
6/18
Connection guide
Page 2
INPUT 2 OUTPUT
15 VDC
+
-
PA550
MADE IN USA
PHONO
Thank you for purchasing the Bellari PA550. We hope you enjoy using
the PA550, and that it makes listening to your music collection rewarding.
We sincerely appreciate the opportunity to build a product for you and
participate in your love of quality music and sound. We love what we do
and we’re happy to help. All Bellari products are hand built in Salt Lake
City, Utah by people who care about high quality music.
INTRODUCTION
The PA550 audio Pre Amplier has three selectable stereo inputs: phonograph,
RCA and 3.5mm (1/8") jack for phones, tablets or other. It features a very power-
ful headphone amplier so it can be used as a stand alone headphone amp.
Designed to have the highest level of sound quality, whether you are using it as
a headphone amp or sending music to your amplier. At every design stage we
spent a considerable amount of time focused on one thing, sound quality.
OPERATION
The inputs and outputs of the PA550 are easy to understand. Plug a signal in,
select the source, and connect to your desired headphones or amplier.
One thing to note about the PA550 is that the RCA output's are the default output. When you plug a pair of headphones into the headphone jack on the front of
the unit the RCA output section is then completely disconnected from the circuit.
Meaning that when using the headphone output of the PA550 the unit is only
functioning as a headphone amplier.
Connecting to your Turntable
RCA phono input on the rear connects to your turntable. The ground post
is where things can get complicated. Ground hums have always plagued
the turntable. We recommend using the ground post to connect to your
turntable's ground connection. In our experience we have never seen a
situation where not using the ground would sound better than using it.
Ground loops are a very common occurrence with audio. The more
equipment you use, the higher likelihood you will have a ground loop.
The term "loop" refers to your ground generating unwanted noise from
traveling back and forth in a loop. The turntable is usually the most likely
component to have a ground issue. Another thing to try if you have a
ground loop is connecting the turntable ground to the RCA jack's ground
if the ground post is not remedying the issue. One thing to keep in mind
is that ground loops can be anywhere in a system, so try and isolate the
components that are the issue before spending a lot of time looking at
just one component.
The phono input of the PA550 requires that a turntable be connected to
it to complete the circuit. If you do not have a turntable hooked up to the
phono input do not select phono on the selector switch, as unwanted
noise will be present.
FRONT PANEL
VOLUME: Adjusts the level of signal.
IN 1: 3.5mm jack for connection to a phone, music player or computer. TRS
Stereo (left, right and ground).
HEADPHONE: 3.5mm stereo headphone output jack.
INPUT SELECTOR SWITCH: Selects the channel being used.
BASS and TREBLE: Perform as labeled. If you would like the tone not aected
by the unit, set the controls at the '0' (half way up). This will then be the original
signal.
PWR
Headphone
0 10
Volume
MADE IN USA
0
+
-
Bass
0
+
-
Treble
Preamplifier
Ch2
Phono
In 1
Ch1
PA550
REAR PANEL
RCA OUTPUT: For connection to your amplier or other device.
PHONO: RCA for connection to a turntable.
INPUT 2: RCA stereo input.
15 VDC: For connection to the included power supply.
GROUND POST: Standard phono grounding post.
PHONO
PA550
INPUT 2 OUTPUT
MADE IN USA
15 VDC
+
-
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