Safe Sound Audio P1 User manual

P1 Audio Processor User Manual Safe Sound Audio
Model P1 Audio Processor : User Manual
Safe Sound Audio, UK
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Page 2 User Manual P1 Audio Processor
P1 Audio Processor Features
Advanced audio compressor wit peakride w ic utilises multiple side-c ains
allowing t e compressor to ‘ride’ t e crests of t e audio so t at control of fast audio
peaks, especially vocals, may be as fast as desired w ilst release from
compression compliments t e natural decay of t e audio waveform. Exceptionally
low levels of ripple distortion.
Limiter featuring multi-stage dynamic threshold control w ic provides a very ig
degree of overload protection wit out t e undesirable side effects of traditional
‘brick wall’ limiters.
The limiter has three side-chains each utilising zero delay ‘look ahead’ dynamic
control of limiter threshold. This allows the ‘natural’ limiter threshold to be
dynamically adjusted to match the dynamics of the incoming audio signal and
provides for very safe control of maximum audio level without the need for ultra fast
attack times all accomplished with 100% analogue processing.
Single knob expander wit ‘follow-audio’ release time w ic tracks t e natural
decay of t e audio; useful for post recording noise reduction and adding punc to
drum sounds.
Hig quality balanced microp one input using t e latest Burr-Brown INA217 c ip.
Balanced line input.
Hig impedance (1 MΩ) instrument input.
Balanced line output offering +21dBu drive capability.
Balanced and unbalanced stereo monitor inputs wit separate source level control
providing zero latency eadp one monitoring of t e source/replay mix.
100% linear internal mains power supply (t row away t ose wall warts for good!)
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P1 Audio Processor User Manual Page 3
Contents Page
P1 Audio Processor Features ………………………………….. 2
Safety Information; READ THIS FIRST ………………………. 4
Quick Start Guide ……………………………………………….. 5
Audio Connector wiring information …………………………… 8
Detailed Operational Guide …………………………………….. 12
Power on …………………………………………………. 12
Typical audio connections ……………………………… 13
+48V P antom Power for microp ones ………………. 14
Setting t e input gain ……………………………………. 14
Overload warning ………………………………………... 15
Setting up t e output gain ………………………………. 16
Hig pass filter …………………………………………… 19
Expander operation ……………………………………... 19
peakride compressor operation ……………………….. 22
peakride compressor t eory …………………………… 24
Limiter wit dynamic threshold control operation ……. 26
How t e P1 limiter manages dynamic range …………. 27
Answers to some common questions …………………. 29
Monitoring facilities ………………………………………. 31
Tec nical Specification ………………………………………….. 33
Fault finding ……………………………………………………… 35
Customer Care …………………………………………………... 37
Warranty conditions ……………………………………………... 37
How to contact us ……………………………………………… 38
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Page 4 User Manual P1 Audio Processor
Important Safety Information : Read this first!
There are dangerous vo tages present within the unit. Do not open the unit
and refer a servicing to qua ified service personne .
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T e lig tning flas wit arrow ead symbol, wit in an equilateral
triangle, is intended to alert t e user to dangerous voltages
wit in t e unit.
T e exclamation point wit in an equilateral triangle is intended to
alert t e user to important operating and safety instructions in
t is user andbook.
T is unit s ould only be connected to a mains supply of t e type
marked on t e rear of t e appliance. Take special note of t e required
mains voltage.
T is unit must be eart ed.
T e IEC mains connecting lead originally supplied wit t is unit as
been fitted wit a 3A mains fuse. Always replace wit a fuse of t e
same rating.
T is unit is fitted wit an externally accessible fuse. Always replace
wit a fuse of t e same type and rating. T e fuse type and rating are
s own on t e rear of t e appliance just below t e fuse receptacle.
Always disconnect t e unit from t e mains supply before replacing t is
fuse.

P1 Audio Processor User Manual Page 5
Quick Start Guide
After reading t e important safety information, you may wis to ‘plug and go’. If, at
any time, you are in doubt as to t e correct operation of t e unit, all operational
points are covered in detail later in t is manual, but as a quick start;
Basic functions
T e P1 is a mono audio pat processor wit separate stereo monitoring facility, as
s own below;
T e t ree audio inputs ave separate connectors but only one of t ese inputs is
connected to t e main processing c ain at any one time. T is is controlled by a
simple priority system t roug t e actual plugging of t e connectors.
T e balanced LINE input (3 pole ¼” jack plug) will always ave t e ig est priority.
T e unbalanced INSTRUMENT input (2 pole ¼” jack plug) as priority over t e
MICROPHONE input.
T e balanced MICROPHONE input (3 pole XLR plug) as t e lowest priority.
T e connector wiring follows normal audio convention. Details are given later in t is
manual.
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Page 6 User Manual P1 Audio Processor
Alt oug t e t ree inputs s are a common input gain control, t e gain range
available to eac input is different and appropriate to t at input;
MICROPHONE GAIN 0dB to +70dB
INSTRUMENT GAIN 0dB to +30dB
LINE INPUT GAIN -10dB to +20dB
Phantom Power
T e microp one input as switc able +48V p antom power suitable for powering
most types of studio condenser microp ones.
ALWAYS CONNECT THE MICROPHONE FIRST BEFORE
SWITCHING ON THE +48V ot erwise damage to t e microp one amplifier is a
possibility. In a similar way, always switc off t e +48V and wait for 10 seconds
before disconnecting t e microp one. If you are unsure w et er a microp one
requires +48V p antom powering always c eck wit t e microp one manufacturer
first. DON’T GUESS!
Most professional BALANCED dynamic microp ones will not be damaged t roug
t e accidental application of p antom power.
HI Pass Filter
T e switc able ig pass filter as a -3dB point at 80Hz and a slope of 18dB per
octave.
Peak indicator
Lig ts w en t e main signal pat (before t e limiter) comes wit in 3dB of clipping.
Expander
Variable t res old expander wit a fixed expansion ratio of 1:3, fixed attack time of
around 3ms and variable ‘follow-audio’ release time.
Compressor with peakride
A sop isticated multi side-c ain compressor wit variable t res old, attack and ratio.
‘Follow-audio’ release time. LED bargrap s ows gain reduction in dB’s.
Limiter with dynamic threshold control and output level control
T e most sop isticated part of t e processing c ain but it as no user controls! Full
explanation later in t e manual, but for now a brief set-up procedure;
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P1 Audio Processor User Manual Page 7
T e limiter is actually t e last signal processing element and sits just before t e
preset output gain control. T e limiter t res old is fixed, so for quick set-up;
•Ensure t e expander and compressor are switc ed OUT of circuit
•Apply a fixed level test signal (s ould be a 50% duty square wave) to t e line
input and adjust t e input gain control until t e red LIM LED just lig ts (a
suitable test signal is available to download from our web site,
www.safesoundaudio.com)
•Adjust t e preset output gain control (screwdriver adjustment) until t e desired
recording level is s own on your recording device metering; best to allow 1dB
below 0dBFS.
Main Output
T e balanced main output is fed via t e preset level control described above to a
3 pole balanced ¼” jack labelled ‘LINE OUT (BAL)’.
An LED bargrap s ows t e output level prior to t e output gain control.
he Monitoring Chain
Stereo input designed to be fed from t e replay c ain of your recording device. Can
accept eit er a single 3 pole ¼” jack for unbalanced stereo connection OR two 3 pole
¼” jacks for balanced stereo connection. Plug as s own on t e unit’s rear panel.
T e monitoring c ain feeds t e front panel ¼” stereo jack socket best connected to
eadp ones wit an impedance of 600 o ms or above. It is safe to connect low
impedance eadp ones but monitor audio quality will degrade.
For track laying and overdubbing, it is also possible to mix in a feed of t e unit’s main
processor pat w ic as it’s own ‘source monitor’ level control. T is level control
does not affect t e processor’s main audio pat level.
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Page 8 User Manual P1 Audio Processor
Audio Connector wiring information
Note : All connector wiring information refers to t e cable end connecting to t e P1
audio processor unless ot erwise stated.
Balanced Microphone input
Any standard balanced XLR-3 to XLR-3 microp one cable s ould be suitable.
At t e P1 end, use a cable type XLR-3 pin plug wired as follows;
You s ould not use t is input to connect unbalanced ig impedance microp ones
w ic in any case are normally supplied terminated in a 2-pole ¼” jack plug.
Balanced Line input
Any standard ‘off t e s elf’ balanced line level cable s ould be suitable. T ese will
be typically eit er jack to jack or jack to XLR depending on t e type of equipment you
are connecting to t e line input. If wiring your own, at t e P1 end use a standard ¼”
3-pole jack plug wired as follows;
It is also possible to feed t is input from an unbalanced source w ic may be t e
case w en feeding t e P1’s line input from some keyboard instruments or
unbalanced sound card outputs.
If you want to use an ‘off t e s elf’ cable t en use a standard unbalanced line level
cable (guitar cable) wit standard ¼” 2-pole jacks at eit er end. If wiring your own
unbalanced cable we suggest t e following wiring arrangement w ic will give better
noise and um rejection. (Note t at t e sleeve of t e 3-pole jack is intentionally left
unconnected.)
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Pin 1 = screen
Pin 2 = signal +ve (also called ‘in p ase’ or ‘ ot’)
Pin 3 = signal -ve (also called ‘anti-p ase’ or ‘cold’)

P1 Audio Processor User Manual Page 9
T e balanced line input s ould not be used to directly connect to electric guitars and
basses. Use t e INSTRUMENT input instead.
Unbalanced Instrument input
Any standard unbalanced ¼” to ¼” 2-pole instrument (guitar) cable s ould be
suitable. If wiring your own use standard ¼” 2-pole jack plugs for bot ends wired as
follows;
Insert Point
A ‘Y’ type cable is necessary to access t e processor’s insert point. T e ideal cable
type is a twin ‘figure 8’ unbalanced cable. T ese are available ‘off t e s elf’ but if
wiring your own, a typical wiring sc eme is s own below.
Balanced Line output
Any standard ‘off t e s elf’ balanced line level cable s ould be suitable. If wiring
your own, at t e P1 end use a standard ¼” 3-pole jack plug wired as follows;
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Page 10 User Manual P1 Audio Processor
It is also possible to feed t is output to an unbalanced destination w ic may be t e
case w en feeding t e P1’s line output to some unbalanced PC sound card inputs.
In t is case use a standard ‘off t e s elf’ unbalanced line level cable. If wiring your
own, at t e P1 end use a standard ¼” 2-pole jack plug wired as follows;
It is possible t at t e input jack on some unbalanced sound cards will be for a stereo
input typically via a 3.5mm stereo jacket socket. Assuming you are feeding only one
P1 unit into t is soundcard’s stereo input t en it is important to ground t e unused
input of t e soundcard to prevent crosstalk. A typical wiring sc eme is s own below.
Monitor inputs
T e P1 as t e option to accept eit er unbalanced or balanced monitor inputs w ic
allows standard cables to be used in bot cases. T e monitor inputs will most
commonly be fed from a stereo output of t e recording device or PC sound card.
Unbalanced connection : plugs into t e jack labelled ‘MONITOR INPUT L/R
(UNBAL)’.
If you want to use a standard ‘off t e s elf’ cable t en use a standard stereo twin
‘figure 8’ unbalanced cable wit a single 3-pole jack plug at eit er end. If wiring your
own, at t e P1 end use a standard ¼” 3-pole jack plug wired as follows;
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