TWELVEꢀANDꢀSIXTEENꢀCHANNELꢀMIXER
WITHꢀ24-bitꢀDSPꢀEFFECTSꢀ
Instrucciones de seguridad / Istruzioni di Sicurezza
PRECAUCION: Para reducir el riesgo de incendios o descargas, no permita que este aparato quede expuesto a la lluvia o la humedad. Para reducir el riesgo de descarga
eléctrica, nunca quite la tapa ni el chasis. Dentro del aparato no hay piezas susceptibles de ser reparadas por el usuario. Dirija cualquier reparación al servicio técnico oficial.
El símbolo del relámpago dentro del triángulo equilátero pretende advertir al usuario de la presencia de “voltajes peligrosos”no aislados dentro de la carcasa del producto,
que pueden ser de la magnitud suficiente como para constituir un riesgo de descarga eléctrica a las personas. El símbolo de exclamación dentro del triángulo equilátero
quiere advertirle de la existencia de importantes instrucciones de manejo y mantenimiento (reparaciones) en los documentos que se adjuntan con este aparato.
Instrucciones importantes de seguridad
1.
2.
3.
4.
5.
6.
7.
8.
9.
Lea todo este manual de instrucciones antes de comenzar a usar la unidad.
Conserve estas instrucciones para cualquier consulta en el futuro.
Cumpla con todo lo indicado en las precauciones de seguridad.
Observe y siga todas las instrucciones del fabricante.
Nunca utilice este aparato cerca del agua o en lugares húmedos.
Limpie este aparato solo con un trapo suave y ligeramente humedecido.
No bloquee ninguna de las aberturas de ventilación. Instale este aparato de acuerdo a las instrucciones del fabricante.
No instale este aparato cerca de fuentes de calor como radiadores, calentadores, hornos u otros aparatos (incluyendo amplificadores) que produzcan calor.
No anule el sistema de seguridad del enchufe de tipo polarizado o con toma de tierra. Un enchufe polarizado tiene dos bornes, uno más ancho que el otro. Uno con
toma de tierra tiene dos bornes normales y un tercero para la conexión a tierra. El borne ancho o el tercero se incluyen como medida de seguridad. Cuando el enchufe
no encaje en su salida de corriente, llame a un electricista para que le cambie su salida anticuada.
10. Evite que el cable de corriente quede en una posición en la que pueda ser pisado o aplastado, especialmente en los enchufes, receptáculos y en el punto en el que
salen de la unidad.
11. Desconecte de la corriente este aparato durante las tormentas eléctricas o cuando no lo vaya a usar durante un periodo de tiempo largo.
12. Dirija cualquier posible reparación solo al servicio técnico oficial. Deberá hacer que su aparato sea reparado cuando esté dañado de alguna forma, como si el cable de
corriente o el enchufe están dañados, o si se han derramado líquidos o se ha introducido algún objeto dentro de la unidad, si esta ha quedado expuesta a la lluvia o la
humedad, si no funciona normalmente o si ha caído al suelo.
ATTENZIONE: per ridurre il rischio di incendio o di scariche elettriche, non esponete questo apparecchio a pioggia o umidità. Per ridurre il pericolo di scariche elettriche evitate
di rimuoverne il coperchio o il pannello posteriore. Non esistono all'interno dell'apparecchio parti la cui regolazione è a cura dell'utente. Per eventuale assistenza, fate riferimento
esclusivamente a personale qualificato. Il fulmine con la punta a freccia all'interno di un triangolo equilatero avvisa l'utente della presenza di "tensioni pericolose" non isolate
all'interno dell'apparecchio, tali da costituire un possibile rischio di scariche elettriche dannose per le persone. Il punto esclamativo all'interno di un triangolo equilatero avvisa
l'utente della presenza di importanti istruzioni di manutenzione (assistenza) nella documentazione che accompagna il prodotto.
Importanti Istruzioni di Sicurezza
1. Prima di usare l'apparecchio, vi preghiamo di leggerne per intero le istruzioni.
2. Conservate tali istruzioni per una eventuale consultazione futura.
3. Vi preghiamo di rispettare tutte le istruzioni di sicurezza.
4. Seguite tutte le istruzioni del costruttore.
5. Non usate questo apparecchio vicino ad acqua o umidità.
6. Pulite l'apparecchio esclusivamente con un panno asciutto.
7. Evitate di ostruire una qualsiasi delle aperture di ventilazione. Posizionatelo seguendo le istruzioni del costruttore.
8. Non posizionatelo vicino a sorgenti di calore come radiatori, scambiatori di calore, forni o altri apparecchi (amplificatori compresi) in grado di generare calore.
9. Non disattivate la protezione di sicurezza costituita dalla spina polarizzata o dotata di collegamento a terra. Una spina polarizzata è dotata di due spinotti, uno più
piccolo ed uno più grande. Una spina dotata di collegamento a terra è dotata di due spinotti più un terzo spinotto di collegamento a terra. Questo terzo spinotto,
eventualmente anche più grande, viene fornito per la vostra sicurezza. Se la spina fornita in dotazione non si adatta alla vostra presa, consultate un elettricista per la
sostituzione della presa obsoleta.
10. Proteggete il cavo di alimentazione in modo che non sia possibile camminarci sopra né piegarlo, con particolare attenzione alle prese, ai punti di collegamento e al punto
in cui esce dall'apparecchio.
11. Staccate l'apparecchio dalla alimentazione in caso di temporali o tempeste o se non lo usate per un lungo periodo.
12. Per l'assistenza, fate riferimento esclusivamente a personale qualificato. È necessaria l'assistenza se l'apparecchio ha subito un qualsiasi tipo di danno, come danni al cavo
o alla spina di alimentazione, nel caso in cui sia stato versato del liquido o siano caduti oggetti al suo interno, sia stato esposto a pioggia o umidità, non funzioni corretta-
mente o sia stato fatto cadere.
Copyright 2006, Samson Technologies Corp.
Printed September, 2006 v1.1
Samson Technologies Corp.
45 Gilpin Avenue
Hauppauge, New York 11788-8816
Phone: 1-800-3-SAMSON (1-800-372-6766)
Fax: 631-784-2201
Table of Contents
MDR1248 and MDR1688 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Front Panel Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Front and Rear Panel Layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Controls and Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 12
MONO INPUT CHANNEL SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
MDR1248 and MDR1688 Input and Output Connections . . . . . . . . .13 - 14
Operating the MDR1248 and MDR1688 . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 18
BASIC OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Operating the MDR1248 and MDR1688 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
USING THE DIGITAL EFFECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
SENDING AN INDEPENDENT MIX TO THE MONITOR SPEAKERS . . . . . . . . 17
USING THE CHANNEL INSERT JACKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
USING AN EXTERNAL EFFECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
PLAYING BACK A CD USING 2T TO MIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
RECORDING A MIX FROM THE MDR1248 and MDR1688. . . . . . . . . . . . . . . 18
MDR1248 and MDR1688 System Set-Ups . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
MDR1248 and MDR1688 LIVE SOUND SET-UP . . . . . . . . . . . . . . . . . . . . . . . . 19
MDR1248 and MDR1688 RECORDING SET-UP . . . . . . . . . . . . . . . . . . . . . . . . 20
MDR1248 and MDR1688 Wiring Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
MDR1248 and MDR1688 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Introduction
Congratulations on your purchase of the Samson
MDR1248 or MDR1688 mixer! The MDR1248 and
MDR1688 are great sounding mixers with a lot of
inputs, flexible routing and stunning on-board digi-
tal effects. Connecting all your microphones and
instruments is simple, with four mic/line inputs plus
FOUR additional stereo channels on the MDR1248,
and eight mic/line inputs plus four additional stereo
channels on the MDR1688. There are also dedicated
stereo effects returns for the onboard digital effects.
And the effects! You can add one of the MDR's 256
dazzling digital studio quality effects, which include
Delays, Chorus, Flanging, and lush Reverbs to your
vocals or instruments, using the onboard 24-bit
Multi-Effects Processor.
In these pages, you’ll find a detailed description of
the features of the MDR1248 and MDR1688 mixers,
as well as a description of their front and rear panels,
step-by-step instructions for their setup and use, and
full specifications. You’ll also find a warranty card
enclosed—please don’t forget to fill it out and mail
it in so that you can receive online technical support
and so we can send you updated information about
these and other Samson products in the future.
With proper care and adequate air circulation, your
MDR1248 or MDR1688 will operate trouble free for
many years. We recommend you record your serial
number in the space provided below for future refer-
ence.
The Mic/line inputs feature a 3-band equalizer with
sweepable midrange control and there is a four
band fixed equalizer on each of the stereo input
channels. Each of the stereo and mono input chan-
nels have two Aux sends, plus you can switch one
from Pre to Post. The MDR1248 and MDR1688’s
master section includes two stereo Aux returns and
a 2-track Input and Output for playing back stereo
devices and for recording your mix. Clean, clear
sound reproduction with sweet equalization and
signal flexible routing in a rugged enclosure, ensure
reliable high quality sound from performance to
performance. Optimized for recording, live sound
reinforcement and commercial installations, the
MDR1248 and MDR1688 are ideal mixer solutions,
offering big sound in a compact package.
Serial number: ____________________________
Date of purchase: __________________________
Should your unit ever require servicing, a Return
Authorization number (RA) must be obtained before
shipping your unit to Samson. Without this number,
the unit will not be accepted. Please call Samson
at 1-800-3SAMSON (1-800-372-6766) for a Return
Authorization number prior to shipping your unit.
Please retain the original packing materials and if
possible, return the unit in the original carton and
packing materials.
If you purchased your Samson product outside the
United States, please contact your local distributor
for warranty information and service.
tech.com) for complete information about our full
product line.
2
MDR1248 and MDR1688 Features
The Samson MDR1248 and MDR1688, twelve and
mixing. For added flexibility, AUX 1 can be con-
figured as a Pre or Post fader send.
sixteen channel mixers are a comprehensive, all-in-
one solution for live sound, recording, fixed instal-
lation and post production applications. Here are
some of its main features:
•
High quality, low noise, discrete microphone
pre-amplifiers with 48-Volt phantom power, pro-
vide Maximum Dynamic Range and transparent
audio.
•
The mixers offer plenty of inputs with four Mic/
Line plus four Stereo inputs for the MDR1248
and eight Mic/Line plus four Stereo inputs for
the MDR1688.
•
•
Twelve segment LED Meter with VU ballistics dis-
plays the main MIX output.
•
•
Flexible design topology ideal for live sound,
recording and post production.
High quality 60mm faders on the mono and
stereo inputs, plus the Main and Control Room/
Headphone outputs.
The MDR1248 and MDR1688 has a built-in, 24-
bit DSP (Digital Signal Processor) Multi-effects
Processor with 256 selectable presets offering
dazzling studio quality effects including Reverb,
Delay, Chorus and Flanging.
•
•
Advanced circuit design using discrete compo-
nents and high quality, low noise op-amps care-
fully selected at each stage of the signal path.
Quality build and rugged construction ensure
reliable performance from venue to venue and
session to session.
•
•
2 Track Input and Output allows you to con-
nect a CD, DAT, Cassette, Mini Disk or Computer
Sound Card.
•
•
Standard 19-inch rackmount kit included.
Three-year extended warranty.
Three-band channel equalizer with sweepable
mids on the mono input channels, along with
four band fixed equalizer on the stereo channels,
provide precise and musical results in contour-
ing the tone of any signal.
•
Two Auxiliary Sends for built-in or external
effects, on-stage monitor mix, or headphone
3
Front Panel Layout
21
37
38
39
40
41
42
43
44
45
46
47
48
49 50 51 52 53 54 55 56 57 58
59
4
Front Panel Controls
FRONT PANEL
right line input for the stereo channels.
1
MIC IN – Input connector for Low-Noise Microphone
pre-amp.
22 LEFT/MONO LINE - 1/4-inch phone input connec-
tor for the Left Line input for the stereo channels or a
mono input.
2
3
LINE IN–Input connector for Line level inputs.
INSERT – 1/4-inch TRS (TIP/RING/SLEEVE) connector
providing send and receive channel patch point for
outboard effects.
23 ALT 3/4 OUTPUTS jacks – Balanced, 1/4-inch phone
connectors carrying the signal from the ALT 3/4 bus.
24 CONTROL ROOM OUTPUT– Left and Right Control
Room output connectors for connecting a monitor
system.
4
5
6
7
GAIN – Used to set the input level of the mic pre and
line input.
LOW CUT – Bass roll off switch at 75Hz used to elimi-
nate unwanted low end rumble and hum.
25 MAIN MIX OUTPUT (1/4-inch) – Left and Right Main
Mix balanced output 1/4-inch TRS connectors.
HIGH FREQUENCY – Controls the high band of the
Channel Equalizer, +/- 15 dB at 12KHz.
26 MAIN MIX OUTPUT (XLR) – Left and Right Main Mix
balanced output XLR connectors.
MID CUT/BOOST – This control knob provides +/- 15
dB of boost or cut at the frequency set on the MID
SWEEP control on the mono input channels.
27 AUX RETURN 1 – Left and right input jacks for con-
necting to the outputs of external line level sources
like those from effects processors.
8
MID SWEEP – Control knob used to set the center
28 AUX RETURN 2 – Left and right input jacks for con-
necting to the outputs of external line level sources
like those from effects processors.
frequency of the mid band of the Channel Equalizer.
9
LOW FREQUENCY – Controls the low band of the
Channel Equalizer, +/- 15 dB at 80Hz.
29 FOOTSWITCH JACK – 1/4-inch phone jack for con-
necting a standard footswitch used to turn the inter-
nal DSP effects on and off.
10 AUX 1 – Auxiliary send that can be used with an
external effects processor, or to create a cue or moni-
tor mix.
30 PHONES JACK – Connect stereo headphones here.
11 PRE / POST switch – Used to configure Aux 1 signal
31 AUX SEND 2 – Line level output from the Auxiliary 2
routing from a Pre fader to a post fader send.
bus.
12 AUX 2/DSP – Post-fader auxiliary send that can be
used with an external effects processor, or to create a
cue or monitor mix, or to send a signal to the internal
DSP.
32 AUX SEND 1 – Line level output from the Auxiliary 1
bus.
33 2 TRACK OUTPUTS – Connect to the input of a DAT,
Cassette, Mini Disk or Hard Disk Recording system.
13 PAN – Controls the channel’s position between left
and right in the stereo bus.
34 2 TRACK INPUTS – Connect the output from a DAT,
Cassette, Mini Disk or Hard Disk Recording system.
14 3/4 MUTE LED – When illuminated, the display indi-
cates that the input channel is assigned to the ALT3/4
bus and is muted in the Left /Right Main Mix bus.
35 2 TRK LEVEL – Control knob used to set the level of
the source connected to the 2-track input.
15 3/4 / MUTE switch – When engaged, the input chan-
nel is assigned to the ALT3/4 bus and is muted in the
Left / Right MAIN MIX bus.
36 VARIATIONS – Control knob used to select one of the
sixteen variations for each of the sixteen DSP effect
programs.
16 SOLO LED – When illuminated, the display indicates
37 PROGRAMS – Control knob used to select one of the
that the input channel is assigned to the SOLO bus.
sixteen DSP effect programs.
17 SOLO switch – When engaged, the input channel is
38 DSP PEAK – LED indicator illuminates when the input
signal to the internal DSP is reaching an overload
level.
assigned to the SOLO bus.
18 PEAK – Red LED will illuminate indicating when the
GAIN has been adjusted too high.
39 DSP MUTE switch – Used to turn the internal DSP
effects on and off.
19 LEVEL – Audio taper fader provides smooth control
of level changes.
40 ALT 3/4 TO MIX – Routes the ALT 3/4 to the Left /
Right MAIN MIX outputs. Use the ALT3/4 Level (55) to
set the volume.
20 +4 / -10 switch – Used to set the line input sensitiv-
ity from –10dB when the switch is pressed in to +4dB
when this switch is out.
41 2 TRK TO MIX - Routes the Left / Right 2 track inputs
to the Left / Right MAIN MIX outputs. Use the 2 TRK
21 RIGHT LINE – 1/4-inch phone input connector for the
5
Front and Rear Panel Layout
FRONT PANEL CONTROLS - continued
LEVEL control (35) to set the volume.
50 AUX RETURN 1 – Used to mix in the level of AUX
Return 1.
42 POWER LED – Indicates the MDR1248 or MDR1688 is
powered up.
51 AUX RETURN 2 – Used to mix in the level of AUX
Return 2.
43 PHANTOM LED – Indicates that the 48 Volt Phantom
Power is on.
52 AUX RETURN 2 TO AUX 1 - Switch used to route AUX
RETURN 2 into the AUX 1 output so that effects can be
heard in the monitor mix.
44 MAIN MIX – Routes the Left / Right MAIN MIX bus to
the CONTROL ROOM / PHONES outputs. Use the Left
/ Right MAIN MIX Level faders (58) and PHONES level
fader (59) to set the volume.
53 AUX SEND 1 – Control knob used to set the master
level of the AUX1 SEND.
45 ALT 3/4 – Routes the ALT 3/4 bus to the CONTROL
ROOM / PHONES outputs. Use the ALT3/4 Level (55)
and PHONES level fader (59) to set the volume.
54 AUX SEND 2 – Control knob used to set the master
level of the AUX2 SEND.
55 ALT 3/4 LEVEL – Control knob used to set the level of
46 2 TRK IN – Routes the Left / Right 2 track input to the
CONTROL ROOM / PHONES outputs. Use the 2 TRK
LEVEL control (35) and PHONES level fader (59) to set
the volume.
the ALT 3/4 bus.
56 SOLO LED – Indicates that one or more channels are
assigned to the SOLO bus.
57 SOLO MODE – Selects the SOLO mode from AFL (After
Fader Level) when the switch is pressed in, and PFL
(Pre Fader Level) when the switch is pressed out.
47 OUTPUT METER - Twelve segment LED display with
VU ballistics indicates main Mix level.
48 LEVEL SET LED – When an input channel is in SOLO,
this indicator will illuminate to show that the chan-
nel’s input gain level is displayed on the Main Level
Meter.
58 MAIN LEVEL faders – Used to control the overall vol-
ume of the Left and Right main Mix output
59 CONTROL ROOM / PHONES fader – Adjusts the
volume of the control room speakers and/or head-
phones.
49 BALANCE – Controls the channel’s position between
left and right of the stereo inputs.
l
o
REAR PANEL
A
B
C
POWER – Switches on the MDR1248 and MDR1688’s main
power.
PHANTOM – Engages the 48-Volt Phantom power supply to
microphone pre-amps.
AC ADAPTOR INLET – Connect External AC power supply
here.
6
Controls and Functions
2 - LOW CUT FILTER - switch
MONO INPUT CHANNEL SECTION
The following section details each part of the MDR1248
and MDR1688’s MONO INPUT CHANNELS including the
GAIN control, LOW CUT switch, 3-BAND EQ, AUX sends,
PEAK LED, PAN, SOLO, ALT 3/4 bus and LEVEL controls.
The input channels one through four on the MDR1248
and on through eight on the MDR1688 feature high
quality, discrete transistor pre-amps providing transpar-
ency and extended dynamic range.
Each of the MDR1248 and MDR1688’s mono input chan-
nels include a LOW CUT (or high pass) filter which rolls off
the low frequencies from 75Hz and below at the rate of
18dB per octave. The LOW CUT filter allows you to remove
the lower frequencies that you sometime just don’t want
to pick up. For example, when you are miking a high-hat
you only want to capture the frequencies that the hi-hat is
producing. Therefore, by using the LOW CUT filter, you can
reduce the amount of pick-up from the low toms and bass
drum that may leak into the hi-hat mic. You can use the
same technique on other instruments like acoustic guitar,
violin, piano and even on vocals. In live sound applica-
tions, the LOW CUT filter is especially useful for removing
stage rumble.
1 - GAIN - control knob
The MDR1248 and MDR1688’s pre-amp stage has a vari-
able GAIN control with a range of 0 to 40dB on the MIC
input and –15 to +25dB on the LINE input.
ꢁ
ꢀ
3 - Channel Equalizer
The MDR1248 and MDR1688 mic/line input channels
incorporate a 3-band equalizer, with sweepable Mid-
range, allowing you to adjust the high, mid-range, and
low frequencies independently on each channel. The fre-
quency centers, range of boost or cut, and equalizer type
for each band are described in the following section.
HF (HIGH FREQUENCY) 12kHz +/- 15dB Shelving type
The channel’s HIGH frequency response is flat when the
knob is in the “12:00”position. Rotating the knob towards
the right will boost the channel's high frequency response
at 12 kHz by 15dB, and rotating it towards the left will cut
the high frequency by 15dB.
ꢂ
MF (MID FREQUENCY) CUT & BOOST
The MID CUT & BOOST knob is used in conjunction with
the MID FREQUENCY knob to create the tonal shape in
the mid-range frequency when using the mono channel’s
equalizers. You can adjust the frequency on the mid-range
control with the FREQ knob, and use the MF CUT & BOOST
to either boost or cut that frequency by plus or minus
15dB. The channel’s MID frequency response is flat when
the MF knob is in the “12:00”position.
ꢃ
ꢄ
ꢅ
FREQ (MID FREQUENCY) Variable 100Hz – 5K
The MID FREQUENCY is a control enabling you enhanced
capabilities in the tonal shaping of the input channel
signal. Thanks to the MID FREQUENCY control, you have
a variable mid-range equalizer, allowing you to pin point
the exact frequency you want to boost or cut. The MID
SWEEP has a “fixed Q”of two octaves (the amount, or
width, of frequencies around the center point that are
effected by the MID CUT & BOOST control) and can be set
in a range from 100Hz to 5Khz.
ꢆ
ꢈ
ꢇ
ꢁꢁ
ꢁꢀ
ꢁꢉ
LF (LOW FREQUENCY) 80Hz +/- 15dB shelving type
The channel’s LOW frequency response is flat when the
knob is in the “12:00”position. Rotating the knob towards
the right will boost the channel's low frequency response
at 80 Hertz by 15dB, and rotating it towards the left will
cut the frequency by 15dB.
ꢁꢂ
7
Controls and Functions
MONO INPUT CHANNEL SECTION - continued
Auxiliary Busses ( 4 - 6 )
a monitor send. When the PRE/POST switch is set to POST,
the signal feeding AUX 1 is sent after the fader, so the
channel Fader has an effect on that level, meaning the
Aux level tracks up and down with the channel Fader. This
is the normal setting for using AUX 1 as an effects send,
since when you set the channel louder, you normally
want the effect to get louder.
NOTE: The channel’s effects signal is sent to the AUX 1
bus from a location in the signal path after the VOLUME
control.
The MDR series include two auxiliary signal paths, or
buses, that can be used to create independent mixes for
sending to the internal or external effects processors, or
to an external monitor system. The flow of these buses
start by sending the signal from each individual channel,
which is set with one of the auxiliary control knobs. Then,
the mix of all the channels auxiliary level is ultimately sent
to either an internal effects processors, or to an output
jack to connect to an external effect or monitor system. To
help you control your effects and monitor mixes, the MDR
mixers have two auxiliary buses. Plus, for added flexabil-
ity, AUX1 can be configured as a Pre or Post fader send.
6 - AUX 2/DSP
The channel’s AUX 2/DSP knob controls the amount of
signal that is sent to the AUX 2 bus. The AUX 2 signal can
be sent to an external effects device connected to the
AUX 2 OUT jack located in the MASTER SECTION jack field.
NOTE: The channel’s AUX 2 signal is sent to the AUX 2
bus from a location in the signal path after the channel’s
LEVEL control. This is commonly referred to as a POST
FADER send. This means that the amount of signal that is
sent to the AUX 2 bus will be affected not only by the set-
ting of the AUX 2 knob control, but it will also be affected
by the setting of the LEVEL control.
PRE….? POST….? What’s That?
In order to operate your mixer correctly, it is important
to understand the concept of PRE and POST Fader Aux
sends. An auxiliary bus that is set up as PRE Fader routes,
or sends, the signal to its output from a point in the chan-
nels’circuit that is electronically before the channel Fader.
That means the channel Fader has no effect on the PRE
aux level. A Pre Fader send is what you want to use for a
monitor mix, so when the level is changed for the mix in
the main PA speakers using the channel Fader, the level
in the monitor set by the aux control knob remains the
same. An auxiliary bus that is set up as POST Fader routes,
or sends, the signal to its output from a point in the chan-
nels’circuit that is electronically after the channel Fader.
That means that the channel Fader also affects the level of
a POST aux send. A POST Aux bus is what you want to use
(almost always) for sending to an effects processor, either
internal or external. When using the POST aux sends,
(while turning the channel Fader up or down) the level of
effects will track the channel level correctly.
7 - PAN
The MDR1248 and MDR1688’s PAN control is used to
place or position the mono signal into the stereo main
Left and Right MIX bus. You can create a stereo image
by panning some input signals to the left and others to
the right. The MDR1248 and MDR1688’s PAN control is a
Power-Pan circuit, which includes a 3dB dip in the center
position. This is desirable since there’s a 3dB increase in
gain when the mono input signal is heard in both the Left
and Right MIX bus.
8 - 3/4 MUTE switch
The Mono Input channels feature a 3/4 MUTE switch
allowing you to easily turn that channel on or off. When
3/4 MUTE LED is illuminated, the channel is off, converse-
ly, when the backlight is off, the channel is on. The switch
also has a second purpose. When the switch is pressed
down, signal from the selected channels is sent to the
3/4 Outputs. This lets you use 3/4 as a second stereo bus
which can be mixed in with the main left and right mix
bus or sent out the 3/4 outputs without being heard in
the main Left and Right mix.
4 - AUX 1
The MDR1248 and MDR1688 have two auxiliary sends
which can be used for sending signals to external effects
devices or for creating a monitor mix. The AUX1 section
is often used for a monitor mix in a live sound mixing, or
for a headphone mix in a recording application. AUX 1
can also be used as a Pre Fader effect send by setting the
Pre/Post switch to the Post postion. Each input channel
includes an AUX 1 send which controls the amount of that
channel’s signal that is sent to the AUX bus.
NOTE: If the AUX1Pre/Post switch is set to Pre, the Aux
controls are "PRE-FADER SENDS" which means they are
not affected by the FADER level settings of each channel.
This allows you to create a mix for the monitors that is
independent of the main LEFT and RIGHT MIX.
9 – 3/4 MUTE LED
The MDR1248 and MDR1688’s has a 3/4 Mute LED indica-
tor allowing you to easily see if the channel is muted or
assigned to the 3/4 mix bus. When 3/4 MUTE LED is illu-
minated, the channel is off and assigned to the 3/4 bus,
conversely, when the backlight is off, the channel is on
and not assigned to the 3/4 mix bus.
5 - PRE/POST - switch
The PRE/POST switch is used to select the point that the
AUX 1 bus uses to send the signal. When the PRE/POST
switch is set to PRE, the signal feeding AUX 1 is sent
before the fader, so the channel Fader has no effect on
that level. This is the normal setting when using AUX 1 as
10 - Solo switch
The Mono Input channel’s Solo switch allows you to
listen, or “solo”a channel or group of channels in the
headphones. When the SOLO switch is pressed down, the
channel is assigned to the solo bus and can be heard
8
Controls and Functions
in any optional headphones plugged in to the PHONES
connector located in the front panel jack field. If the
AFL/PFL MODE switch, located in the master section, is
switched out, the signal is sent pre fader, so you can hear
the signal regardless of the position of the channel vol-
ume Fader. This allows you to listen to a channel by itself:
(let's say) to see if an artist is out of tune, or to cue up a
channel without having to play it through the main PA
speakers. If the AFL/PFL MODE switch is switched in, the
signal is sent post fader, the signal you hear is dependant
on the position of the channel volume Fader. This allows
you to hear if there is any distortion on a channel added
by the level of the channel fader.
it towards the left will cut the frequency by 15dB. The fre-
quency centers, range of boost or cut, and equalizer type
for each band are as follows:
High: 12kHz +/- 15dB shelving type
High Mid: 3kHz +/- 15dB peaking type
Low Mid: 500Hz +/- 15dB peaking type
Low: 80Hz +/- 15dB shelving type
ꢀꢁ
ꢀꢂ
11- SOLO LED
The MDR1248 and MDR1688’s Mono Input channels
include a SOLO LED which, when illuminated, indicates
that the signal is assigned to the SOLO bus.
12 - PEAK LED
The MDR1248 and MDR1688’s MIC/LINE pre-amp also
includes a PEAK LED which, when illuminated, indicates
that the signal is peaking or overloading. To reduce dis-
tortion, lower the GAIN control to keep this LED from stay-
ing on.
13 - CHANNEL LEVEL
The MDR1248 and MDR1688’s LEVEL control knobs are
used to adjust the overall channel volume.
ꢀꢃ
STEREO INPUT CHANNEL SECTION
The MDR1248 and MDR1688 feature stereo input chan-
nels for connected stereo line level devices like keyboards
and drum machines, as well as the outputs from effects
processors and digital guitar modelers. The MDR1248 has
four sets of stereo inputs which make up channels 5/6,
7/8, 9/10 and 11/12, while the MDR1688 has four sets of
stereo inputs which make up channels 9/10, 11/12, 13/14
and 15/16. The Stereo input channels have a four-band
fixed equalizer and AUX 1 and 2 sends and are laid out the
same as the mono inputs. The following section details
the stereo input controls:
ꢀꢅ
ꢀꢄ
ꢀꢈ
ꢆꢀ
ꢆꢉ
ꢆꢇ
14- GAIN switch
ꢆꢆ
The MDR1248 and MDR1688’s pre-amp stage has a vari-
able GAIN switch with a range of -10 to +4dB on the ste-
reo LINE input.
ꢆꢁ
15 - LOW/LOW MID/HIGH MID/HIGH - Channel
Equalizer
ꢆꢂ
The MDR1248 and MDR1688 Stereo input channels fea-
ture a 4-band equalizer allowing you to adjust the high,
mid, and low frequencies independently on each channel.
The stereo channel equalizer is laid out like a mono input
on the control panel input strip, but internally, the equal-
izer is effecting a stereo signal path. The channel’s fre-
quency response is flat when the knobs are in the “12:00”
position. Rotating the knob towards the right will boost
the corresponding frequency band by 15dB, and rotating
9
Controls and Functions
Auxiliary Busses ( 16 - 18 )
Right stereo mix field. You can create a stereo image by
panning some input signals to the left and others to the
right.
The MDR series include two auxiliary signal paths, or
buses, that can be used to create independent mixes for
sending to the internal or external effects processors, or
to an external monitor system. The signal flow from these
buses start by sending the signal from each individual
channel, which is set with one of the auxiliary control
knobs. Then, the mix of all the channels auxiliary level is
ultimately sent to either an internal effects processors or
to an output jack to connect to an external effect or moni-
tor system. To help you control your effects and monitor
mixes, the MDR's have two auxiliary buses.
20 - 3/4 MUTE switch
The Stereo Input channels feature a 3/4 MUTE switch
allowing you to easily turn that channel on or off. When
3/4 MUTE LED is illuminated, the channel is off, con-
versely, when the LED is off, the channel is on. The switch
also has a second purpose. When the switch is pressed
down, signal from the selected channels is sent to the
3/4 Outputs. This lets you use 3/4 as a second stereo bus
which can be mixed in with the main left and right mix
bus or sent out the 3/4 outputs without being heard in
the main Left and Right mix.
In order to operate your mixer correctly it is important
to understand the concept of PRE and POST fader sends.
For more information on Pre and Post aux sends, see the
previous section “Pre…?, Post?… What’s that?”Located on
page 8 of this manual.
21 – 3/4 MUTE LED
The MDR1248 and MDR1688’s has a 3/4 Mute LED indica-
tor allowing you to easily see if the channel is muted or
assigned to the 3/4 mix bus. When 3/4 MUTE LED is illu-
minated, the channel is off and assigned to the 3/4 bus,
conversely, when the LED is off, the channel is on and not
assigned to the 3/4 mix bus.
16 – AUX 1
Each of the MDR1248 and MDR1688’s stereo input chan-
nels include an AUX 1 send, which controls the amount of
that channel’s signal that is sent to the AUX 1 Output. The
AUX1 section is often used for a monitor mix in live sound
mixing, or for a headphone mix in a recording applica-
tion. AUX 1 can also be used as a Post Fader effect send
by setting the Pre/Post switch to the Post postion. Each
input channel includes an AUX 1 send which controls the
amount of that channel’s signal that is sent to the AUX
bus.
22 - Solo switch
The Stereo Input channel’s Solo switch allows you to
listen, or “solo”a channel or group of channels in the
headphones. When the SOLO switch is pressed down, the
channel is assigned to the solo bus and can be heard in
any optional headphones plugged in to the PHONES con-
nector located in the front panel jack field. If the AFL/PFL
MODE switch, located in the master section, is switched
out, the signal is sent pre fader, so you can hear the signal
regardless of the position of the channel volume Fader.
This allows you to listen to a channel by itself: (let's say)
to see if an artist is out of tune, or to cue up a channel
without having to play it through the main PA speakers. If
the AFL/PFL MODE switch is switched in, the signal is sent
post fader, the signal you hear is dependant on the posi-
tion of the channel volume Fader. This allows you to hear
if there is any distortion on a channel added by the level
of the channel fader.
17 - PRE/POST - switch
The PRE/POST switch is used to select the point that the
AUX 1 bus uses to send the signal. When the PRE/POST
switch is set to PRE, the signal feeding AUX 1 is sent before
the fader, so the channel Fader has no effect on that level.
This is the normal setting when using AUX 1 as a monitor
send. When the PRE/POST switch is set to POST, the signal
feeding AUX 1 is sent after the channel fader, meaning the
Aux level tracks up and down with the channel Fader. This
is the normal setting for using Aux1 as an effects send,
since when you set the channel louder, you normally want
the effect to get louder.
23- SOLO LED
The MDR1248 and MDR1688’s Stereo Input channels
include a SOLO LED which, when illuminated, indicates
that the signal is assigned to the SOLO bus.
18 – AUX 2 /DSP
Each of the MDR1248 and MDR1688’s stereo input chan-
nels include an AUX 2/DSP send, which controls the
amount of that channel’s signal that is sent to the internal
DSP and/or AUX 2 Output. The signal that feeds Aux 2 is
sent after, or post, the channel Fader, so the channel Fader
has an effect on the Aux 2 level. This is the normal setting
for an effects send, since when you set the channel loud-
er, you normally want the effect to get louder.
24 – PEAK LED
The MDR1248 and MDR1688’s MIC/LINE pre-amp also
includes a PEAK LED which, when illuminated, indicates
that the signal is peaking or overloading. To reduce dis-
tortion, lower the GAIN control to keep this LED from stay-
ing on.
19 - BALANCE - Control
The MDR1248 and MDR1688’s BALANCE control is used to
place, or position, the stereo signal into the main Left and
25- VOLUME - Fader Level Control
The VOLUME Fader control adjusts the level of the stereo
channel.
10
Controls and Functions
27 - AUX RET 1 control knob
MASTER SECTION
26 - 2 TRK LEVEL
The 2TK LEVEL control knob is used to set the volume
level of the source connected to the 2-track input. If you
want to mix in a CD, tape or MP3 player with your input
channels connected to the 2TK inputs, use the 2TK LEVEL
to adjust the level.
This adjusts the amount of signal that is sent from the AUX
1 RET jacks to the MAIN bus.
28 - AUX RET 2 control knob
The AUX RETURN 2 adjusts the level of the signal present
at the AUX 2 RET jacks. This signal is summed, or mixed in
to the main L/R MIX bus.
29 - AUX 2 RETURN TO AUX 1 switch
This routes the signal that is present on the AUX 2 RETURN
jacks to AUX 1 so that the effects can be heard in the
monitor mix.
ꢀꢁ
ꢀꢂ
30 - AUX 1 SEND control knob
The master AUX SEND control is used to send the effect
mix bus to an external effect device connected to the AUX
SEND 2 jack.
ꢅꢁ
ꢅꢂ
ꢅꢃ
ꢀꢃ
ꢀꢄ
31 - AUX 2 SEND control knob
The master EFX SEND control is used to send the effect
mix bus to an external effect device connected to the AUX
SEND 2 jack.
ꢅꢄ
32 - ALT 3/4 Level control knob
ꢅꢆ
ꢅꢇ
Use this control knob to set the level of the mix created
from the channels assigned to the 3/4 bus. The ALT 3/4
level control will control the level of the signal being
sent to the 3/4 Output jacks. When the Master ALT 3/4
switch(43) is switched in, the ALT 3/4 level control will con-
trol the level of the ALT 3/4 mix that is heard in the Main
Left and Right mix. Remember, the ALT 3/4 TO MIX switch
must be set to the on or down position in order to hear
the 3/4 mix in the main Left and Right mix.
ꢉꢆ
ꢉꢈ
ꢉꢁ
ꢉꢇ
ꢅꢀ
ꢉꢂ
ꢉꢀ
ꢉꢅ
ꢉꢉ
ꢅꢉ
ꢅꢅ
ꢅꢈ
33 - SOLO LED
The LED will illuminate when any one or more channel's
SOLO switch is engaged, indicating that there is a channel
in solo.
34 - LEVEL SET LED
When a channel's SOLO switch is pressed, the LEVEL SET
LED will illuminate and flash indicting that the channels
input level is now being measured by the main VU meter.
35 - MODE (AFL/PFL) switch
You can change the mode of the SOLO bus from Pre fader
listen to After, or Post fader listen using the MODE switch.
When the switch is pressed in, the SOLO mode is set to
AFL (After Fader Listen), so the channels signal is sent after
or post fader. When the switch is pressed out, the SOLO
mode is set to PFL (Pre Fader Listen), so the channels sig-
nal is sent before or pre fader.
ꢉꢃ
Auxiliary Returns
ꢉꢄ
36 - PROGRAM control knob
The MDR1248 and MDR1688 feature an internal 24-bit
DSP with 256 presets. The presets are organized in sixteen
Program banks, each with sixteen variations. The Program
control knob used to select one of the sixteen DSP effect
programs.
The MDR1248 and MDR1688 have two stereo auxiliary
returns, which can be accessed via the two pairs of 1/4-
inch phone jacks located on the master section jack field.
The auxiliary returns can be used to connect any stereo
line level signal, but they are primarily used to connect
the output of external effects processors.
37 - VARIATION control knob
The MDR1248 and MDR1688 feature an internal 24-bit
11
Controls and Functions
MASTER SECTION (continued)
output and will be adjusted by the CR / PHONES control
fader.
DSP with 256 presets. The presets are organized in sixteen
Program banks, each with sixteen variations. The Variation
control knob is used to select one of the sixteen variations
for each of the sixteen DSP effect Programs.
45 - Phantom Power LED
This LED illuminates indicating that the 48 volt phantom
power is applied to the microphone pre-amps enabling
use with condenser microphones. The +48V LED will light
up when the Phantom Power switch (located on the rear
panel) is switched to the ON position.
38 - PEAK (DSP INPUT) LED
LED indicator illuminates when the input signal to the
internal DSP is reaching a clipping level.
46 - POWER LED
39 - DSP MUTE switch
The Power LED lights up to indicate that the main POWER
switch (located on the rear panel) is on.
This switch is used to turn the internal DSP effects on and
off. When the DSP MUTE switch is pressed in, the internal
DSP effects are turned off and when the switch is pressed
out, the DSP effects are on.
47 - Output Level Meters
The OUTPUT LEVEL METERS allows you to monitor the
level of the signal which is being sent to the MAIN MIX
jacks.
2 TRACK INPUT AND OUTPUT
The MDR1248 and MDR1688’s 2 Track section provides the
connections for playback and recording for an external
device such as a DAT, cassette recorder, CD or Mini Disk.
48 - MAIN MIX - Fader Control
The master MAIN controls are the overall volume controls
for the left and right mix bus. These line level signals are
output from the MAIN MIX jacks.
Main Mix Assign Switches
The next two switch functions are used to select addition-
al sources that can be combined with the Main Left and
Right mix and sent to the main Left and Right Outputs.
49 - PHONES / CR
The PHONES / CR control is used to set the level sent to the
control room outputs, and also to the headphone jack.
40 - ALT 4/3 TO MIX switch
The ALT 3/4 TO MIX switch is used to assign the ALT 3/4
mix bus to the MAIN mix bus. If you push the ALT 3/4 TO
MIX button, all the channels with their ALT 3/4 switch
pressed in will be routed to the left and right MAIN out-
puts and the level will be controlled by the 3/4 LEVEL con-
trol knob and MAIN LEVEL fader.
NOTE: To avoid distortion, adjust the Main Level control so
that the 0 indicator LED lights occasionally.
41 - 2TK TO MIX switch
The 2TR TO MIX switch is used to assign the 2TR input to
the MAIN mix bus. If you push the 2TR TO MIX button, the
signal present at the 2 TRACK IN will be routed to the left
and right MAIN output and the level will be controlled by
the 2TK LEVEL control knob and MAIN LEVEL fader.
Control Room and Headphone Assign Switches
The next three switch functions are used to select addi-
tional sources that can be heard in the headphones and
sent to the Left and Right Control Room Outputs.
42 - MAIN MIX switch
The MAIN MIX switch routes the Left / Right MAIN mix bus
to the CONTROL ROOM / PHONES outputs. Use the Left /
Right MAIN MIX Level faders (48) and PHONES level fader
(49) to set the volume.
43 - ALT 3/4 switch
The ALT 3/4 switch routes the 3/4 mix bus to the CONTROL
ROOM / PHONES outputs. Use the ALT 3/4 LEVEL control
knob (32) and PHONES level fader (49) to set the volume.
44 - 2 TK IN switch
The 2TR IN switch is used to assign the 2TR input to the
Control Room output. If you push down the 2TK IN button,
signal will be routed into the left and right Control Room
12
MDR1248 and MDR1688 Input and Output Connections
equalizer, compressor, noise gate, reverb and other audio
devices. For more information on the channel INSERT
points, see the section, “Using the Channel Insert Jacks”on
page 17 of this manual.
MONO INPUT CHANNELS - MIC and LINE INPUTS
Channels 1 through 4 on the MDR1248 and channels 1
through 8 on the MDR1688 are mono inputs, each pro-
viding a 1/4-inch connector for line level signals and an
XLR connector for the MIC signals. Channels 5/6 through
11/12 on the MDR1248 and channels 9/10 through 15/16
on the MDR1688 are stereo inputs, providing a pair of 1/4-
inch connectors for line level inputs. By using the GAIN
control on the mono channels, you can connect a variety
of signal sources from microphones to line level devices
such as synthesizers, and drum machines. All the LINE
and MIC inputs are balanced. The MIC inputs are compat-
ible with microphones with output impedances of 50-
600 Ohms and the LINE inputs are compatible with line
level devices of 600 Ohms. Following below is a detailed
description of the MDR1248 and MDR1688’s input and
output connectors.
Stereo Input Channels - Line Inputs
You can connect the outputs from stereo devices such as
synthesizers, drum machines, effects processors or any
stereo line-level signal. The LINE inputs have a nominal
operating level of -40dBV through - 10dBV. The 1/4-inch
TRS phone jacks Connector pin-out are as follows; Sleeve:
Ground, Tip: Hot (+), Ring: Cold (-)
%
&
"
D- LEFT MONO
The LEFT MONO jack is used to connect the left output of
a stereo device to the Left input of the MDR’s stereo input
channels or use the LEFT input when connecting a mono
input signal to the Stereo Input channels.
#
$
E - RIGHT
The RIGHT jack is used to connect the Right output of a
stereo device to the Right input of the MDR’s stereo input
channels.
NOTE: It is not possible to simultaneously use both the
LINE and MIC inputs on the same channel. Use only one of
the inputs for the appropriate source on each channel.
A - Microphone Input - Mono Input Channels
Use these inputs to connect Low Impedance micro-
phones and low level signals from direct boxes. The MIC
inputs have a nominal operating level of –50dBu through
-20dBu. The MIC inputs also feature +48V phantom
power, allowing you to use condenser microphones. The
Phantom Power switch (located on the MDR1248 and
MDR1688’s rear panel) enables phantom power on all
the microphone inputs when set to the ON position. XLR
Connector pin-out - Pin 1: Ground, Pin 2: Hot (+), Pin 3:
Cold (-)
MASTER SECTION INPUT AND OUTPUT JACKS
The MDR1248 and MDR1688 features several input and
output connectors allowing you to interface a variety of
external devices. A stereo recording device, such as a cas-
sette recorder, can be connected to the 2 Track jacks, and
power amplifiers or powered monitors can be connected
to the CONTROL ROOM and MAIN output jacks.
*
B - Line Level Input - Mono Input Channels
Use these inputs to connect synthesizers, drum machines,
effects processors or any line-level signal. The LINE
inputs have a nominal operating level of -40dBV through
- 10dBV. TRS phone jacks Connector pin-out - Sleeve:
Ground, Tip: Hot (+), Ring: Cold (-)
'
(
)
F - ALT 3/4 LEFT/RIGHT OUTPUT
The ALT 3/4 outputs are 1/4-inch balanced jacks carrying the
signal from the 3/4 bus. You can assign a channel or a group
of channels to the 3/4 bus using the MUTE 3/4 switch on the
stereo and mono input channels. The 3/4 output connectors
are labeled Left and Right since the 3/4 bus follows the chan-
nels’PAN control allowing it to be used for a second stereo
C - Insert Point Jack - Mono Input Channels
The MDR1248 and MDR1688’s mono input channels fea-
ture a 1/4-inch, TRS INSERT jack providing a patch point to
connect an external processor. You can use these connec-
tions to interface an external signal processor like an
13
MDR1248 and MDR1688 Input and Output Connections
mix. You can also pan the channels hard left and right to cre-
ate two mono buses. Keep in mind that using the 3/4 switch
mutes the channel from the main mix, so use the ALT 3/4 bus
for a separate stereo, or two mono, zone mixes.
L - AUX RETURN 2 LEFT/RIGHT
The AUX RETURN 2 LEFT/RIGHT are stereo inputs that are
generally used to connect the outputs of an effects proces-
sor, but can also accept the signal from any line level source
like a keyboard, recorder and even another mixer. The signal
connected to the AUX RETURN 2 LEFT/RIGHT will feed the
main LEFT/RIGHT MIX bus. The overall level is controlled by
the AUX RET 2 knob located in the master section on the
front panel. Use the LEFT/MONO input when connecting a
mono input signal to the AUX RETURN.
G - CONTROL ROOM LEFT/RIGHT OUTPUT
The Control Room outputs are 1/4-inch balanced jacks used
to connect a studio monitor system. The Control Room out-
puts have the same output as the L/R MIX, however, the level
can be adjusted independently from the main mix using the
C ROOM/HEADPHONES control.
M - AUX Send 2
H - MAIN MIX LEFT/RIGHT 1/4-INCH OUTPUTS
In a live sound application, the LEFT/ RIGHT MIX outputs are
1/4-inch balanced jacks used to connect a power amplifier
or powered speakers. In a recording application, the LEFT/
RIGHT MIX outputs are used to connect to the inputs of a
stereo device such as computer sound card, DAT, or cassette
recorder.
The signal present at the AUX 2 output is sent from the AUX
2 bus, which is fed from all the AUX 2 sends on the input
channels. The AUX 2 output can be used as the MONITOR
MIX bus in a live sound situation by connecting the output to
a power amp and monitor speaker.
N – FOOTSWITCH - 1/4-inch jack
With a footswitch connected to this jack, you can turn on
and off the on-board digital effects by simply stepping on
the footswitch.
I - MAIN MIX LEFT/RIGHT XLR OUTPUTS
In a live sound application, the LEFT/ RIGHT MIX outputs are
connected to a power amplifier or powered speakers. In a
recording application, the LEFT/ RIGHT MIX outputs are used
to connect to the inputs of a stereo device such as computer
sound card, DAT, or cassette recorder.
0 - HEADPHONE OUTPUT
You can connect a standard pair of stereo headphones to
the PHONES jack and depending on the position of the 2T
TO CR switch, you will hear either the 2-Track input or the
MAIN mix.
J - AUX RETURN 1 LEFT/RIGHT
The AUX RETURN 1 LEFT/RIGHT are stereo inputs that are
generally used to connect the outputs of an effects processor,
but can also accept the signal from any line level source like
a keyboard, recorder and even another mixer. The signal con-
nected to the AUX RETURN 1 LEFT/RIGHT will feed the main
/
+
-
1
2
P - 2TR INPUT
The MDR1248 and MDR1688 features dual RCA connectors
for the left and right 2-track input. You can use these inputs
to connect a CD, Cassette, Mini Disk, DAT or the output from
a computer sound card. To listen to the input connected to
the 2T IN, be sure to check the position of the 2T To Mix and
2T TO CR switches. For more information on using the 2 Track
inputs, see the section “PLAYING BACK A CD USING 2T TO MIX ”
on page 18 of this manual.
,
.ꢀ
0
LEFT/RIGHT MIX bus. The overall level is controlled by the
AUX RET 1 knob located in the master section on the front
panel. Use the LEFT/MONO input when connecting a mono
input signal to the AUX RETURN.
Q - 2TR OUTPUT
If you want to record the mix from your MDR1248 and
MDR1688, you can use the 2-track OUT connectors. The
dual RCA connectors can be connected to a CD, Cassette,
Mini Disk, DAT or even the input of a computer sound card
for hard disk recording. For more information on using the 2
Track outputs, see the section “RECORDING A MIX FROM THE
MDR1248 and MDR1688 ” on page 18 of this manual.
K - AUX Send 1
The signal present at the AUX1 output is sent from the AUX1
bus, which is fed from all the AUX 1 sends on the input chan-
nels. The AUX 1 output can be used as the EFFECTS SEND
bus in a live sound situation by connecting the output to an
external effects device.
14
Operating the MDR1248 and MDR1688
NOTE: SETTING THE INPUT GAIN - When connecting a
BASIC OPERATION
microphone to channels 1 through 4 on the MDR1244 or
1 through 8 on the MDR1688, it’s a good idea to start with
the Gain Control turned all the way down. Set the input
fader to the "0" position and slowly raise the GAIN control
until you see the PEAK LED turn on. Now, back the GAIN
control down so that the PEAK LED only lights for a short
time during the loudest input the channel will see.
The following section explains the basic operation of the
MDR1248 and MDR1688:
CONNECTING MICROPHONES AND INSTRUMENTS
1. Before connecting mics or instruments, make sure that
the power of all your system's components including
the MDR1248 and MDR1688 is turned off. Also, make
sure that the MAIN LEVEL and PHONES / CR controls are
turned all the way down.
Note. You can also press the channel's PFL switch and
use the LEVEL SET function. When the PFL is switched
on, you'll see the LEVEL SET LED is illuminated and the
channel's input level will now be displayed on the Main
VU meter.
2. Connect the cables to your microphones and instru-
ments, and insert the other end of the cable firmly into
the appropriate input on the MDR1248 and MDR1688.
3. Switch on the power of any peripheral devices, and
then power up the MDR1248 and MDR1688.
NOTE: It is important to remember the Golden Rule of
audio … " LAST ON, FIRST OFF". Translated, this means
that when turning on your system, you should always
turn your power amplifiers or powered monitors on LAST,
and when turning your system off, turn your power amps
off FIRST. This helps avoid any loud pops caused by rush
current at power up, or down, which can sometimes dam-
age loudspeakers.
4. Turn on your power amp or powered monitors and
raise the level control to the manufacturers recom-
mended operating level.
5. Set the MAIN LEVEL control in the MDR1248 and
MDR1688’s master section to the "0" position.
6. While speaking into the mic (or playing the instru-
ment), adjust the channel LEVEL control so that the
"0" LED of the MAIN section VU level meter lights
occasionally.
7. You can shape the tone of each channel by adjusting
the channel equalizer controls as desired.
NOTE: You may need to adjust the channel LEVEL control
to compensate for the slight changes in level after using
the channel equalizer.
15
Operating the MDR1248 and MDR1688
4. Next, locate the AUX SEND 2 knob and turn it about to
USING THE DIGITAL EFFECTS
a little past “5”or half way.
The MDR1248 and MDR1688 mixers feature a built-in,
high quality, 24-bit Multi Effect Processor, offering studio
grade digital effects. The MDR’s Effect section features
clean Delay, lush Reverbs and multi-effects like Chorus
+ Delay, Chorus Flange or Chorus + Reverb. You can add
a broad range of studio quality effects by simply dialing
through the 256 presets.
5. Now, use the AUX RETURN 2 control knob to adjust
the effects return level. The AUX RETURN 2 control
knob sets the overall level control for the DSP effects
processor in the main Left and Right Mix.
6. Now, you can check out different versions of the
PROGRAM presets by using the VARIATIONS control
knob. Each of the 16 effects PROGRAM banks has six-
teen variations providing a total of 256 effects presets.
7. If you want to hear the effects in the monitors, press
the AUX RETURN 2 TO AUX1 switch and you will have
the output of the internal effects routed to the AUX1
output. For more information on setting up a monitor
mix, see the following section.
NOTE: If the DSP PEAK LED lights up and effect sound is
distorted, even though the AUX RETURN 2 is turned down
low, lower the AUX SEND 2 control knob and the AUX2/
DSP controls of each channel.
8. If you want to bypass the effects, you can turn off the
effects processors output by using the DSP MUTE
switch, or an optional footswitch connected to the
FOOTSWITCH jack.
The following details the operation of the internal DSP
effects in the MRD1248 and MDR1688 Effects section:
1. Connect a mic or instrument to the desired channel,
adjust the level and equalizer to your liking and make
sure the MAIN fader level is set so you can hear it in
your speakers.
2. Now select the desired effects program using the
PROGRAM control knob located in the Effects sec-
tion in the middle of the mixer’s Master section.
Set the PROGRAM control knob to one of the 16
effects. You can check the effects Program List below
the PROGRAM knob to find the effect type per-
fect for your performance. The first PROGRAM and
VARIATION banks have been preset with common
effects for live performance, and the following banks
are set up in groups by the types of effects.
3. Once you have selected the desired effects preset,
raise the AUX 2 DSP control on the channels you wish
to apply the digital effect to.
16
Operating the MDR1248 and MDR1688
SENDING AN INDEPENDENT MIX TO THE
USING THE CHANNEL INSERT JACKS
MONITOR SPEAKERS
To further control your signal, channels 1-4 on the
MDR1248 and 1-8 on the MDR1688 feature an inser-
tion point, or “effects loop”, on one 1/4-inch phone jack,
INSERT SEND and RETURN. An insertion point is a patch-
point that interrupts the signal, allowing you to bring that
signal outside to be processed by another device. You
can use these connections to interface an external signal
processor like an equalizer, compressor, noise gate, reverb
and other audio devices. A common application for the
MDR1248 and MDR1688’s insert point is using a compres-
sor.
The MDR1248 and MDR1688’s AUX1 auxiliary send can be
used to feed a separate set of amplifiers and loudspeakers
for stage monitors. This lets you build one mono mix for
the amplifiers and monitor speakers facing the musicians,
and the other stereo mix for the amplifiers and speakers
facing the audience.
1. Connect the AUX1 output to your monitor's power
amplifier or powered monitor.
2. Press the input channels’AUX 1 PRE/POST switches
in, to set AUX 1 up as a pre-fader bus.
To send a signal to an external processor, use a standard
1/4-inch “Y”insert cable to connect the MDR1248 and
MDR1688 channel insert point. Connect the TRS (TIP /
RING / SLEEVE) plug to the channel INSERT point, and
then, connect the 1/4-inch (TIP / SLEEVE), INSERT SEND
plug to the input of the external processor. The signal is
sent back to the MDR1248 or MDR1688, using the 1/4-
inch (TIP / SLEEVE), INSERT RETURN plug connected to the
output of the external processor.
3. Raise the AUX SEND 1 control knob, located in the
Master section, up to a little past “5”or halfway.
4. Raise the AUX 1 controls for the channels that you
wish to hear from the monitor speakers.
The diagram below shows a typical application for using a
compressor (in this example a Samson C com opti) in the
MDR1248 or MDR1688’s insertion point.
NOTE: When the AUX1 PRE/POST switch is pressed in and
set to “PRE”, the AUX 1 controls are "PRE-FADER SENDS"
which means they are not affected by the level settings
of each channel. This allows you to create a mix for the
monitor system that is independent of the main LEFT and
RIGHT MIX.
5. If feedback occurs, turn down the AUX SEND 1 knob
to lower the overall level sending to the monitor.
Then check the AUX1 levels of the individual chan-
nels to see if you need to turn one or more channels
down. Then try to raise the AUX 1 SEND level again.
NOTE: Adjusting the balance between the channel AUX1
control knobs and the AUX SEND 1 is a tricky but neces-
sary part of getting good levels in the monitor system. In
general, try to keep the master AUX SEND 1 higher than
the channel AUX1 levels to achieve a cleaner mix. In order
to get the most gain from your monitor mix, use an exter-
nal graphic equalizer (like a Samson S curve 131or D2500
digital EQ with feedback control) to cut out any frequen-
cies that cause feedback.
Below, is a diagram showing the wire for the TRS‘Y”Insert
cable.
6. If you want to add effects from the internal effect
processor, or the effects from an external proces-
sor connected to the AUX RETURN 2 inputs, engage
the AUX RETURN 2 TO AUX 1 switch, located in the
Master section, by pressing it in.
17
Operating the MDR1248 and MDR1688
USING AN EXTERNAL EFFECT
PLAYING BACK A CD USING 2T TO MIX
If you prefer to use an external device for effects process-
ing, you can easily connect the unit using the MDR1248
and MDR1688 AUX 2 bus. Follow the simple steps below
to interface your processor:
The MDR1248 and MDR1688 has a dedicated input for
playing back a stereo device such as a CD, Tape or Mini
Disk. Below is a description of how you can play back
a CD, Tape or MD using the MDR1248 and MDR1688’s 2
TRACK INPUT.
1. Connect the AUX 2 OUTPUT to the input of the
external effect processor.
1. Turn the MAIN level control all the way down.
2. Press the 2TK TO MIX button down.
2. Connect the outputs of the effect processor to
the AUX 2 RETURN located on the MDR1248 and
MDR1688’s master section.
3. Adjust the MAIN LEVEL control in the master section
to the "0" position.
4. Start playback on the CD, Tape or MD player, and use
the 2 TK LEVEL control to set the desired level.
RECORDING A MIX FROM THE MDR1248 and
MDR1688
You can record the audio from the MDR1248 and
MDR1688’s mixer section including the MIC, LINE, 2T IN
and AUX inputs to a Cassette deck, MD, DAT or any other
type of recorder using the 2T OUT outputs. Simply con-
nect the MDR1248 and MDR1688’s 2 TRACK OUT to the
input jacks of the recorder as shown in the diagram on
the right and follow the steps below.
3. Set the MAIN LEVEL control to the "0" position.
4. Raise the AUX 2 knobs for the channels to which you
want the external effect to be applied.
5. Set the input level of the external effect so that the
sound is not distorted and so that the effect’s input
meter does not indicate a clipped signal.
1. Adjust the MAIN LEVEL control in the master sec-
tion to the "0" position.
2. Set a clean signal using the recorder’s input level
controls and meters.
6. Use the AUX RETURN 2 control to adjust the level of
the effects processed by the external effects device.
3. Press RECORD.
4. Play back using as described in the previous section
"PLAYING BACK A CD USING 2T TO MIX".
NOTE: To avoid feedback, be sure to keep the 2TK LEVEL
control knob all the way down while recording with the
2TK outputs.
18
MDR1248 and MDR1688 System Set-Ups
MDR1248 and MDR1688 LIVE SOUND SET-UP
19
MDR1248 and MDR1688 System Set-Ups
MDR1248 and MDR1688 RECORDING SET-UP
20
MDR1248 and MDR1688 Wiring Guide
CONNECTING THE MDR1248 and MDR1688
The are several ways to interface the MDR1248 and MDR1688 to support a variety of applications. The MDR1248 and
MDR1688 features balanced inputs and outputs, so connecting balanced and unbalanced signals is possible.
Unbalanced 1/4” Connector
Balanced TRS 1/4” Connector
XLR Balanced Wiring Guide
1/4-inch TRS“Y” Insert Cable Wiring Guide
21
MDR1248 and MDR1688 Specifications
Mono input channels
Microphone input
Frequency response
Distortion
Gain range
SNR (Signal to Noise Ratio)
Line input
Frequency response
Distortion (THD & N)
Sensitivity range
electronically balanced, discrete input configuration
10Hz to 45kHz
(THD & N) 0.005% at 4dBu, 1kHz
0dB to +40dB (MIC)
105dB
electronically balanced
10Hz to 45kHz
0.005% at 4dBu, 1kHz
-10dBu to +30dBu
Stereo input Channels
Line input
Balanced
Frequency response
Distortion (THD & N)
10Hz to 45kHz
0.005% at +4dBu, 1kHz
Impedances
Microphone input
Channel Insert return
All other inputs
Tape out
3k Ohm
2.5k Ohm
14.8k Ohm or greater
1k Ohm
All other output
120 Ohm
Equalization
Mono Channels
Hi shelving
Swept Mid bell
Low shelving
Low Cut filter
Stereo Channels
Hi shelving
High Mid bell
Low Mid bell
Low shelving
+/- 15dB @ 12kHz
+/- 15dB @ 100 to 5kHz
+/- 15dB @ 80Hz
75Hz, 18dB/oct.
+/- 15dB @12kHz
+/- 15dB @ 3kHz
+/- 15dB @ 500Hz
+/- 15dB @80Hz
Main Mix Section
Noise (Bus noise)
Max output
Levels full down: -100dBr (ref.:+4dBu)
Level set to 0 dB: -90dBr (ref.:+4dBu)
+28dBu balanced XLR,
+22dBu impedance balanced, 1/4" jacks
3/4 Output Section
Noise (Bus noise)
Levels full down: -100dBr (ref.:+4dBu)
Level set to 0 dB - 90dBr (ref.:+4dBu)
+22dBu impedance balanced, 1/4" jacks
Max output
Control Room Output Section
Noise (Bus noise)
Levels full down: -100dBr (ref.:+4dBu)
Level set to 0 dB - 90dBr (ref.:+4dBu)
+22dBu impedance balanced, 1/4" jacks
Max output
Aux Section
AUX Return gain range
AUX Sends max out
-∞ to +15dB
+22dBu
Power supply (AC/AC Adaptor)
Power Consumption
MDR1248
15W
32W
39W
MDR1688
Main voltage
USA/Canada 108 - 132V, 60Hz
Europe 210 - 230V, 50Hz
U.K./Australia 240V, 50Hz
Physical
Net weight
MDR1248
MDR1688
9.79 lb. (4.45kg)
12.87 lb. (5.85kg)
Shipping weight
MDR1248
MDR1688
13.86 lb. (6.30kg)
18.92 lb. (8.60kg)
Dimension (W D H)
MDR1248
MDR1688
16”x 12.3”x 2.6”(405mm x 313mm x 65mm)
16”x 16.7”x 2.6”(405mm x 425mm x 65mm)
Specifications are subject to change without notice.
22
Samson Technologies Corp.
45 Gilpin Avenue
Hauppauge, New York 11788-8816
Phone: 1-800-3-SAMSON (1-800-372-6766)
Fax: 631-784-2201
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