Product Description
(shown with £2 coin for scale!)
Industry standard
Miniature Stereo PPM
Ideal for NLE Monitoring
PICO has been designed specifically for Professional applications that require stereo metering to PPM specification,
and the Murraypro PICO has been adopted as the Industry Standard in NLE Applications where a physically small
Unit is either desirable, or essential.
As with all Murraypro audio metering, that vital parameter ‘STEREO PHASE’, is continuously monitored by
our "Traffic Light" logic; a normally GREEN LED snapping to RED immediately trouble is detected, to instantly
flag the danger to busy Operators. The phase indication is extremely reliable, and is vital in an editing
environment, where full quality audio monitoring is often compromised by operational pressures. The "Pico's"
deceptively simple traffic light logic unambiguously presents this vital phase information instantly and
automatically, preventing embarrassing (and very expensive!) mistakes that may only become apparent much
later.
Each channel is monitored by an ultra-bright red LED, which gives clear warning should the audio level
exceed the +8dB peak level (="6" on the PPM scale), the threshold is internally adjustable and is set to trigger
at +8.15dBU (equivalent to -10.15dBFS, with EBU Reference Level).
The thousands of PICOs in service have carved a niche for themselves in "audio-for-editing" equipment, and it is to
be found in both ‘High End’ and more basic installations throughout the Industry. PPM monitoring is provided on 2
illuminated miniature meters. True PPM scaling (4dB/division) together with the classic very fast attack characteristic
(with minimal overshoot!) and slow decay times are ensured by the full specification precision meter drive amplifier.
The miniature movements that are fitted in this 1 U height boast a surprisingly large 42 x 20 mm scale, and have a
very slightly relaxed specification which closely emulate the full-sized BS 6840 meters, now been discontinues by
their original Torquay manufacturer. (Please note that Murraypro’s COMPACT PPM range continues to offer ‘full
sized’ PPM metering.
PICO's bright white LED illumination means the PPM's pointer and scale are clearly visible, even in subdued
Operational Area lighting; and it’s extremely low external magnetic field means that it can be located adjacent to CRT
equipment without any effect on either colour purity or scan geometry.
Installation Engineers are particularly pleased with the PICO’s high impedance looping inputs (each with a pair of
complimentary sex XLR-3s), ensuring that the Unit can be "dropped in" to virtually any circuit configuration. Input
signals may be balanced or unbalanced, and although the "Pico" is supplied pre-aligned so that 0dBU/ 0dBV.7/
0.775V RMS = "4" on the PPM scale, the absolute sensitivity of the instrument may be adjusted on internal multi-turn
preset controls to cover a range of about +/-12dBU. This flexibility embraces the rather low level unbalanced audio
output of some PC audio cards (perhaps -6 to -10dBU), and the somewhat higher ‘+4dBU’ Reference levels that are
in use within certain sections of the Audio Industry.
The PICO is housed in a compact case only 157w x 44h x 187mm deep (which precisely matches that of our CAGE
Safe Area Cursor Generator too), and it is fitted with a set of non-scratch resilient plastic feet making the PICO ideal
for free standing use. In some applications it may be necessary to mount the 1U high PICO in either a standard Rack
or a desk-cutout, and Murraypro offer a rack mount kit for this purpose.
Mains power to the PICO’s internal PSU is fed via an earthed 3 pin IEC-320 connector, which eliminates external
"wall warts".
AES Operation
The basic PICO is designed for use with analogue sources, and operation with AES inputs is not possible.
A Factory fitted AES input card option is available, and when specified, the PICO sensitivity will normally be preset so
that the standard EBU AES input signal level of -18dBFS = “PPM4”. Upon request, we can supply the PICO aligned
so that the SMPTE -20dBFS Reference level = “PPM4”.
Note that the AES Card, when fitted, also provides a very useful high quality ‘Utility’ demodulated balanced stereo
audio output, on the rear panel XLR3s at line level, for use elsewhere.
FAQ
Adjustment of PICO’s input sensitivity, a Caution.
The PICO has been designed so that it is simple and easy to adjust it’s input sensitivity if required, and full
instructions for this procedure are given below in a later passage, and also as a separate PDF.
HOWEVER, BEFORE you start, we can not over-stress the importance of:-
1) Fully understanding precisely what it is that is actually required!
2) KNOWING precisely what signal level the PICO is actually receiving!
3) Being aware that an analogue source that claims to be “-18dBFS” is an oxymoron, and does not exist!
4) You require separate Test equipment that can accurately measure balanced audio level to +0.1dB.
5) Carefully reading the procedure below, and ONLY make the adjustments in the order described.
6) By NOT adhering to the above, the PICO will be hopelessly misaligned, with disastrous Operational results.
First let it be understood that we never make recommendations regarding interfacing Murraypro Equipment with
specific (User) Equipment. We are of course very happy to offer detailed advice on all aspects of Murraypro
Equipment and it's particular capabilities, subject to the usual commercial confidences.
That said, it is usually very easy to interface our cost effective PICO PPM Unit with other Equipment, hence it's well
deserved popularity. The standard PICO is designed for use with analogue IP signals, and functions with either
Balanced (XLR) audio, or unbalanced (Phono connector) audio. The audio signal levels for these two different audio
connection protocols are usually quite different, but the PICO PPM is easily adjusted from the Factory Set standard
"0dBU" level (which is how it is supplied), to accommodate the (invariably lower) 'Phono' audio level.
Installation variants.
There are usually 3 installation variants, which are described below:-
1.
Often, Users have existing 'downstream' equipment (perhaps a Recorder) that is fed from the Editor (or Mixer)
on twin XLR-3 cables. In this case installation is very simple, and the existing XLR cables are removed from
the 'downstream' equipment's input, and transferred to the PICO's input. To re-establish that original
connectivity, the Channel 1 & Channel 2 balanced audio is 'looped' THROUGH the PICO, and onwards to the
'downstream' Equipment, using the pair of XLR Utility cables that are included with each PICO. It really is that
simple! Usually NO gain adjustment of the PICO will be required.
2.
If an unused stereo XLR OP is available and there is NO 'downstream' equipment, the loop through capability
will NOT be required, and so the PICO may be conveniently fed direct from this using the supplied XLR
cables. Usually NO gain adjustment, of the PICO, will be required.
Under NO circumstances should any signal line associated with the PICO be 'terminated' in 600 ohms. Such
practice is long obsolete, and will affect severely measurement accuracy!
3.
Where only an (unbalanced) Stereo Phono output is available, the PICO PPM may certainly be used for
metering, but attempts to use the 'loop through' capability may be problematic, and caution is advised.
Usually, the unbalanced stereo phono signal line is connected directly to XLRs’ Pin 3, and XLRs’ 1+2 to
Screen/Ground of the input to the PICO.
Under NO circumstances should any signal line associated with the PICO be 'terminated' in 600 ohms. Such
practice is long obsolete, and will severely affect measurement accuracy!
XLR to Phono connector cables are availably commercially if required. Be aware that adjustment of the PICO's
sensitivity controls will be required for correct function with 'Phono Levels', and that unbalanced 'Phono' audio levels
are usually between -6 and -10dB (about 2 full PPM scale divisions) LOWER than a 'Balanced' audio level, and the
gain setting of the PICO must be adjusted to compensate. This is very straight forward adjustment, PROVIDED the
instructions are followed!
We are pleased to have supplied a very significant number of PICOs over the years, and are NOT aware of a single
Installation where it has not been possible to achieve satisfactory Operation.
How to adjust the PICO's gain:
As shipped, an input signal amplitude of 0dBU (= 0dBV.7 = 0.775V RMS) at 1KHz will produce a meter deflection to
PPM Mark "4"
Adjustment to normalise the PICO's gain for a different operating level is unusual, but not an unknown
requirement. PICO has a readily accessible (internally preset) gain range greater then +/- 10dB, to facilitate
operation in a different environment. Simply remove the 4 screws retaining the top cover, and locate the
MULTI-TURN preset resistors R37 and R38, situated in the front left corner of the main circuit board. Usually
these are small blue RECTANGULAR components with a metal adjusting screw on the top surface. Do NOT
adjust any other of the other (round) preset resistors.
Ensure that your external equipment IS correctly adjusted and operating to your satisfaction (perhaps
producing a 1KHz reference tone at -0dBU, for example), then, and only then, adjust ONLY R37 & R38 to
produce PPM Mark "4" on each meter. Replace, and screw down the top cover.
AFTER gain adjustment, Murraypro strongly recommends that a label is placed on the outside of your
adjusted PICO indicating that the "Operating Level" has been altered. This can save many hours of concern
and worry in the future, if the PICO is subsequently relocated to an area with a different "Operating Level" as,
without your label, your own gain adjustment will not otherwise be immediately obvious to other folk (or indeed
even yourself) in the future!
“Somebody” has had the lid off the PICO, and now it reads audio levels incorrectly!
Ouch! you now have only two courses of action available.
1.
If you have access to accurate audio test equipment, and are content to follow the alignment
instructions via the hyper-link “PICO Alignment” below, you can restore the PICO to rude good health
yourself.
2.
Contact Murraypro “tech@murraypro.com” by email, requesting a Return Material Authorisation (RMA)
docket, and we will undertake the alignment on your behalf following it's return to our Works. Please
note that this re-alignment service is chargeable.
It has to be said that the PICO is normally extremely reliable, and very stable, so "gain drift" is extremely
unlikely to occur naturally if the equipment is left undisturbed. In practice mystical "Fairy Fingers", or the so-
called “screwdriver drift”, are by far the most likely cause of PICO gain problems!
Welcome to Murraypro electronics. With over 45 years experience developing broadcast
television test, monitoring and generation equipment, our products are designed for you.
PICO Program Meter
Testamonials
Our evaluation PICO has been
a great success, you even
included the XLRs. Here is our
Order for a further 4 more.
Really great little Unit!
"D.H", Soho.
I just wanted to say that the
Pico meter arrived safely just
before 10:00 on Saturday.
Thank you very much indeed
for sorting this out for us so
quickly. We really appreciate it.
"T.W.", London
I wanted to say a big
"thank you". The built in phase
monitor in your PICO has
really bailed us out of the
audio poo today. Fantastic
performance, and great value
too.
"FS", Edinburgh.
Test Chest IS the
world’s fastest A+V Tester