Sound Techniques ZR Sidecar Console with Z Pod master section
currently available as 8 or 16 channels
Artists that recorded with Sound Techniques consoles include: Pink Floyd, The Who, David Bowie, Elton John, Jimi Hendrix, Queen, The Doors, The Rolling Stones, The Beatles, Led Zeppelin and many more.
The new Sound Techniques ZR Recording Console is a fully analog console. Custom Transformer balanced input and output, 4 band equalizer and complete routing capabilities. The ZR Console is based on the original Sound Techniques design from Elektra Sound Recorders, Sunset Sound and Trident Studios, London. No detail was spared in faithfully recreating the historic Sound Techniques sound as well as paying considerable attention to the modern recording facilities needed today.
Features
Mic/Line input with Z Match Variable impedance, 48V Phantom Power, Polarity Inverse
I/O module signal present LED
Sound Techniques Hybrid Coil and Active Equalizer
2 Stereo Folback Sends
6 Mono Echo sends
Direct Output on the Channel Path
8 Group output Busses
Inline Monitor Console with 2 Distinct Signal Paths. Channel and Monitor
Z Pod Master Section
Features
Global switching of console Master Modes
Solo functions
I/O Meter Designation, Channel IN, Monitor IN, Channel OUT
Global Pre/Post Assignments of Foldback and Echo Sends
Signal Level Threshold
Meters 7&8 Can function as Stereo Buss Output Meter
1 External Source Input
Control Room Level
Stereo Master Fader
Z-POD OPERATIONAL DESCRIPTION Rev 01 GJC. 14 August 2018
The Z-Pod connects to the console via a pair of 37-way D-connector cables. The connectors are
arranged so as to ensure correct connection.
It is recommended that all connections are plugged-up prior to switching on power to the console.
CONSOLE MODES:
The pod has internal switches to pre-determine the default operating modes that the console will go
into at power-up. The user can re-configure the console modes via the front panel mode switches.
MIC RECORD.
This is the primary mode for a recording console with all channels set to MIC input (and fader
reverse). Inputs can be flipped between Mic & Line locally on the channels.
MIC RECORD also sets both the channel path and monitor path SOLO MODE to be SAFE.
The reason for this is to disable all destructive solos when in MIC RECORD mode.
Fader Reverse places the large fader in the channel (Mic input) path and the small fader in
the monitor path.
MIXDOWN.
This sets the channel inputs to all be LINE. Faders are set so that the small fader is in the monitor
path and the large fader is in the channel (Line input) path.
FADER REVERSE.
The normal fader location is for the small fader to be in the channel (Mic or Line input) path, and the
large fader to be in the monitor path.
The reversed fader location is for the large fader to be in the channel (Mic or Line input) path, and
the small fader to be in the monitor path.
Fader reverse can be locally changed on each channel.
SOLO MODES:
CHAN SAFE (SW4), MON SAFE (SW5) and PFL (SW6) – all safe – enables/disables destructive
solo when in the safe modes.
If SAFE is selected, individual channels cannot be made un-SAFE; however, when SAFE is not
selected, individual channels can be made safe.
For any channels that are SAFE, operating a SOLO switch will force a PFL/AFL, routing the channel
signal to the monitor speakers, but without destructively muting the other channels.
CHAN METER SOURCE:
The signal source for the channel meters can only be globally selected. Source options are:
CHAN IN. Channel Input (SW7) selects the output of the mic/line input stage.
MON IN. Monitor Input (SW8) selects the output of the channel’s monitor input stage.
CH OUT. Channel Output (SW9) selects the post-fader, post-mute signal.
J1, J2 & J3 are used to select the power-up default signal source. Set only one jumper to the ON
position; the other two jumpers must be set to be OFF
On such small consoles with limited panel space, some things must serve a dual purpose – meters 7
& 8 being the case here. Normally these meters look at the selected channel signal, however, it is
necessary to be able to monitor the mix left & right outputs, so the meter sources are swapped by
the Meters 7&8 From MIX switch (SW10). Furthermore, when in MIX mode, the meters will
automatically be switched over to PFL or AFL when a channel SOLO switch is operated. The meters
normally look at the PFL signal, but are switched to be able to look at AFL by SW11. AFL is a stereo
post-fader post-pan signal.
MUTE BUSES:
The console has 2 mute buses, A and B. Any channel selected to either or both of these buses will
be muted when the appropriate master switches SW12 & SW13 are operated.
ECHO & FOLDBACK PRE/POST:
All of the console’s echo & foldback buses can be selected to have their sources as pre or post fade.
In this implementation, pre/post selection is in pairs of buses. Echo 1&2 selection is via SW14 PRE
and SW15 POST. Power-up default is set by J4. Channels can locally swap between pre & post by
pressing the top of the appropriate pot.
Echo 3&4, 5&6, Foldback 1 & Foldback 2 are similarly controlled.
SIGNAL LED THRESHOLD:
The illumination point of the channel’s signal LED is set by a rotary switch connecting to PL3,
location in the top centre of the schematic.
METER ILLUMINATION BRIGHTNESS:
The brightness of the meter illumination is set by 1-of-5 jumpers (J401-J405). Location is the top
right corner of the schematic.
LOGIC BUS & SOLO CONTROL LOOPS:
The location is top right quadrant on the schematic.
The output drive from the Master card to the console is provided on the Logic Bus, a 34-way flat
ribbon cable.
Channel Solo Loop.
Pressing a channel SOLO switch takes the normally logic high (+5V) channel solo enable
(CH_SOLO_EN) low to 0V. This low is inverted and buffered by Q401 & Q402 respectively, with the
resulting high (+5V) being applied to the channel solo mute bus (CH SMT). The solo mute bus will
mute any channels that are not set to be SAFE.
Monitor Solo Loop.
Pressing a monitor SOLO switch takes the normally logic high (+5V) monitor solo enable
(MON_SOLO_EN) low to 0V. This low is inverted and buffered by Q403 & Q404 respectively, with
the resulting high (+5V) being applied to the monitor solo mute bus (MON SMT). The solo mute bus
will mute any monitors that are not set to be SAFE.
Channel PFL and AFL enable are combined as CH APFL EN, is normally high, but goes low when a
channel solo operated. Similarly, Monitor PFL and AFL enable are combined as MON APFL EN, is
normally high, but goes low when a monitor solo operated.
The purpose of the PFL & AFL enables is to switch over the monitor speakers from Mix output to the
PFL or AFL signal.
Q50 inverts the channel APFL enable from low to high.
Q51 inverts the monitor APFL enable from low to high.
These high signals are diode OR-ed by D27 & D28 to form a combined APFL active drive which
goes to the monitor control logic (IC36 & IC37) to switch audio away from Mix or External and over
to APFL. The APFL active is also used to switch on the PFL/AFL LED, LD1
AUDIO PATH:
Overview:
The audio paths through the pod are stereo.
The L&R bus mix amp outputs are brought onto the master card, passed through the Mix fader,
buffered and output via a pair of balanced output stages. (This is in addition to the fixed-level blind
outputs available from the channel backplane’s balanced mix outputs).
The monitor path has 4 stereo sources: Mix, PFL, AFL, and External. Selection is via logic controlled
CMOS switches.
The output of the monitor selector goes to the meter driver on the Pod interface card located in the
console where it is switched to meters 7&8. Within the Pod, it also goes to the monitor level pot.
The monitor pot buffer feeds the balanced speaker outputs. These have output mute relays
controlled by SW24, the Speakers ON switch. A power-up delay circuit ensures that the output
relays only turn on after the console’s DC voltages have stabilised.
The monitor pot output also feeds the headphones amplifier which is always active.
Circuit Description:
Only left-path components will be referred to.
The mix L&R inputs are derived from differential outputs of the channel backplane’s Mix Amp card,
and are converted to single-ended in the pod by IC45. This IC is followed by the fader driver, fader,
post-amp and level trimmers, PR5 & PR6. The fader post-amp (IC39) feeds the Mix monitor selector
(IC42a, IC42b) and the mix balanced output drivers (IC29 & IC30) whose outputs are returned to the
console for presenting to a DB25 output connector..
The PFL & AFL inputs to the Pod are derived from the differential outputs of the channel backplane’s
Mix Amp cards, and are converted to single-ended in the pod prior to going to the monitor selector
ICs (IC40, IC41)
The External monitor source is balanced and enters the monitor system via a DB25 connector in the
console. It is then fed to the Pod’s input chip, IC27. Monitor selection switching is via IC41.
The headphones amp is a hybrid based around a driver (IC35) and a triple set of output transistors.
The output is available on a 3-pin Molex connector feeding a standard headphones jack on the back
of the Pod.
Power Supply & Control:
DC power entry and distribution is via the Pod Interface Card (located in the console, circuit details
shown in the top right quadrant of the schematic).
Protection via polyfuses is provided for the Pod and two buckets (usually only one is connected).
48V for phantom power can either be fed in from an external PSU, or be locally generated by a 12V
to 48V converter card, SB401.
Various logic functions in the channels and on the Master card are soft-logic and a battery-backup
system is provided on subcard, SB402
Power control and distribution for the Pod circuitry is important as regards presenting the correct
voltages to the circuitry, and at power-up ensuring that the various supplies are switched on in the
correct sequence.
On the Pod interface card, the +/-16.5V audio incoming rails need to power-up first and become
stable. These rails are fused by re-settable polyswitches PF411 & PF412.
RG401 down-converts +16V to logic voltage +5L. On the Pod interface card, this is used to control
the relay power-up delay (Q408, Q409) and the solo logic loops.
+/-16V is fed to the pod where RG1 is used to down-regulate to +5A, a clean supply for the 4053
CMOS audio switch chips.
Correct power-up sequencing for the logic circuitry is important; audio power needs to be up and
stable before logic power is activated. +5VL for the logic chips is derived via REG1. The REG1 input
(from the 12V delayed power rail) is switched by Q55.
Audio switch chips require a -1V bias voltage to ensure full “offness” of the switch elements when in
the off state; this is derived through R242 and R254.