Samson Musical Instrument MDR624 User Guide
AUX RET  
LEFT/MONO  
RIGHT  
AUX SEND  
MIC IN  
MIC IN  
L
CR OUTPUT  
R
PHONES  
LINE IN  
LINE IN  
L
3/L  
5/L  
30  
30  
GAIN  
GAIN  
LINE IN  
LINE IN  
MIX OUTPUT  
6/R  
R
4/R  
5
60  
5
60  
+26  
-26  
+26  
-26  
0
0
0
0
0
0
0
0
2T IN  
2T OUT  
HF  
HF  
HF  
HF  
5
5
5
5
5
5
5
5
12K  
12K  
12K  
12K  
10  
10  
10  
10  
10  
10  
10  
15  
10  
LEFT  
LEFT  
15  
15  
5
15  
15  
5
15  
5
15  
5
15  
5
0
0
MF  
MF  
MF  
MF  
2.5K  
5
5
5
RIGHT  
RIGHT  
2.5K  
2.5K  
2.5K  
10  
10  
10  
10  
10  
10  
10  
15  
10  
15  
5
15  
15  
5
15  
15  
5
15  
15  
AUX RETURN  
5
0
0
LF  
LF  
LF  
LF  
5
5
5
5
5
80Hz  
80Hz  
80Hz  
80Hz  
PHANTOM  
POWER  
10  
10  
10  
10  
10  
10  
10  
15  
10  
15  
15  
15  
15  
15  
15  
15  
0
10  
CLIP  
+12  
AUX  
AUX  
AUX  
AUX  
2TK TO MIX  
2TK TO C/R  
+6  
0
-6  
0
10  
0
10  
0
10  
0
10  
-12  
-18  
0
0
0
0
PAN  
PAN  
BAL  
BAL  
-24  
L
R
OUTPUT LEVEL  
L
R
L
R
L
R
L
R
5
5
5
5
5
5
PEAK  
PEAK  
PEAK  
PEAK  
0
10  
1
0
10  
2
0
10  
0
10  
0
10  
0
10  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
CHANNEL  
CHANNEL  
CHANNEL 3/4  
CHANNEL 5/6  
CR  
/
PHONES  
MAIN LEVEL  
SIX CHANNEL MIXER  
 
Table of Contents  
Introduction  
2
3
MDR624 Features  
Controls and Functions  
Front and Rear Panel Layout  
Mono Input Channel Section  
Master Section  
4–5  
6–7  
8–9  
MDR624 Input and Output Connections  
Operating the MDR624  
System Set-ups  
10–11  
12–13  
14–15  
16  
MDR624 Wiring Guide  
Specifications  
17  
Block Diagram  
18  
Notes  
18-19  
Copyright 2004, Samson Technologies Corp.  
Printed January, 2004  
Samson Technologies Corp.  
575 Underhill Blvd.  
P.O. Box 9031  
Syosset, NY 11791-9031  
Phone: 1-800-3-SAMSON (1-800-372-6766)  
Fax: 516-364-3888  
www.samsontech.com  
 
Introduction  
Congratulations on your purchase of the Samson MDR624 mixer! The MDR624 is a six channel mixer, with two  
low noise microphone pre-amps. In addition to the two mono Mic/line inputs, there are two channels with left and  
right inputs to handle stereo signals. For added flexibility, you can change the tone quality of your microphones or  
other line inputs by using the three-band channel equalizers. Connecting external effects like a reverb or digital  
delay to the MDR624 is easy thanks to the Aux send on each channel along with the stereo Aux Return in the  
master section. LED indicators for Power, Phantom, Peak and Main Output Level make it easy to keep your lev-  
els set correctly and minimize distortion. Clean, clear sound reproduction, packaged in a rugged enclosure,  
ensure reliable high quality sound from performance to performance. Optimized for recording, live sound rein-  
forcement and commercial installations, the MDR624 is an ideal mixer solution offering big sound in a compact  
package.  
In these pages, you’ll find a detailed description of the features of the MDR624 mixer, as well as a description of  
its front and rear panels, step-by-step instructions for its 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 sup-  
port 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 MDR624 will operate trouble free for many years. We recom-  
mend you record your serial number in the space provided below for future reference.  
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.  
2
 
MDR624 Features  
AUX RET  
LEFT/MONO  
RIGHT  
AUX SEND  
MIC IN  
MIC IN  
L
CR OUTPUT  
R
PHONES  
LINE IN  
LINE IN  
L
3/L  
5/L  
30  
30  
GAIN  
GAIN  
LINE IN  
LINE IN  
MIX OUTPUT  
6/R  
R
4/R  
5
60  
5
60  
+26  
-26  
+26  
-26  
0
0
0
0
0
0
0
0
2T IN  
2T OUT  
HF  
HF  
HF  
HF  
5
5
5
5
5
5
5
5
12K  
12K  
12K  
12K  
10  
10  
10  
10  
10  
10  
10  
15  
10  
LEFT  
LEFT  
15  
15  
5
15  
15  
5
15  
5
15  
5
15  
5
0
0
MF  
MF  
MF  
MF  
2.5K  
5
5
5
RIGHT  
RIGHT  
2.5K  
2.5K  
2.5K  
10  
10  
10  
10  
10  
10  
10  
15  
10  
15  
5
15  
15  
5
15  
15  
5
15  
15  
AUX RETURN  
5
0
0
LF  
LF  
LF  
LF  
5
5
5
5
5
80Hz  
80Hz  
80Hz  
80Hz  
PHANTOM  
POWER  
10  
10  
10  
10  
10  
10  
10  
15  
10  
15  
15  
15  
15  
15  
15  
15  
0
10  
CLIP  
+12  
AUX  
AUX  
AUX  
AUX  
2TK TO MIX  
2TK TO C/R  
+6  
0
-6  
0
10  
0
10  
0
10  
0
10  
-12  
-18  
0
0
0
0
PAN  
PAN  
BAL  
BAL  
-24  
L
R
OUTPUT LEVEL  
L
R
L
R
L
R
L
R
5
5
5
5
5
5
PEAK  
PEAK  
PEAK  
PEAK  
0
10  
1
0
10  
2
0
10  
0
10  
0
10  
0
10  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
CHANNEL  
CHANNEL  
CHANNEL 3/4  
CHANNEL 5/6  
CR  
/
PHONES  
MAIN LEVEL  
The Samson MDR624 six channel mixer, is a comprehensive, all-in-one solution for live sound, recording, fixed  
installation and post production applications. Here are some of its main features:  
•
•
•
Six channels – Two Mic/Line plus two Stereo inputs.  
Flexible design topology ideal for live sound, recording and post production.  
2 Track To Mix Level control allows you to mix in a CD, DAT, Cassette, Computer Sound Card or Mini  
Disk with the channel faders.  
•
Three-band channel equalizer, +/-15dB at 80Hz, 2.5 KHz and 12KHz provides precise and musical  
results in sound shaping.  
•
•
•
An Auxiliary Send for external effects, on stage monitor mix, or headphone mixing.  
Eight segment LED Meter with VU ballistics displays the main MIX output.  
High quality, low noise, discrete microphone pre-amplifiers with 48-Volt phantom power, provide  
Maximum Dynamic Range and transparent audio.  
•
•
•
Advanced circuit design using discrete components and high quality, low noise op-amps carefully select-  
ed at each stage of the signal path.  
Quality build and rugged construction ensure reliable performance from venue to venue and session to  
session.  
Three-year extended warranty.  
3
 
Controls and Functions  
Front and Rear Panel Layout  
11  
12  
1
13  
14  
15  
16  
17  
AUX RET  
LEFT/MONO  
RIGHT  
AUX SEND  
MIC IN  
MIC IN  
2
3
L
CR OUTPUT  
R
PHONES  
18  
19  
LINE IN  
LINE IN  
L
3/L  
5/L  
30  
30  
GAIN  
GAIN  
LINE IN  
LINE IN  
MIX OUTPUT  
6/R  
R
4/R  
5
60  
5
60  
+26  
4
-26  
+26  
-26  
20  
0
0
0
0
0
0
0
0
2T IN  
2T OUT  
HF  
HF  
HF  
HF  
5
5
5
5
5
5
5
5
12K  
12K  
12K  
12K  
5
6
21  
22  
10  
10  
10  
10  
10  
10  
10  
10  
LEFT  
LEFT  
15  
5
15  
5
15  
15  
5
15  
5
15  
5
15  
5
15  
5
0
0
MF  
MF  
MF  
MF  
2.5K  
5
RIGHT  
RIGHT  
2.5K  
2.5K  
2.5K  
10  
10  
10  
10  
10  
10  
10  
10  
23  
15  
5
15  
15  
5
15  
15  
5
15  
15  
5
15  
AUX RETURN  
5
0
0
LF  
LF  
LF  
LF  
5
5
5
5
80Hz  
80Hz  
80Hz  
80Hz  
PHANTOM  
POWER  
7
8
10  
10  
10  
10  
10  
10  
10  
10  
15  
15  
15  
15  
15  
15  
15  
15  
0
10  
CLIP  
+12  
AUX  
AUX  
AUX  
AUX  
2TK TO MIX  
2TK TO C/R  
+6  
0
-6  
0
10  
0
10  
0
10  
0
10  
-12  
-18  
9
0
0
0
0
PAN  
PAN  
BAL  
BAL  
-24  
L
R
OUTPUT LEVEL  
10  
L
R
L
R
L
R
L
R
5
5
5
5
5
5
PEAK  
PEAK  
PEAK  
PEAK  
0
10  
0
10  
0
10  
0
10  
0
10  
0
10  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
LEVEL  
24  
25  
CHANNEL 1  
CHANNEL 2  
CHANNEL 3/4  
CHANNEL 5/6  
CR / PHONES  
MAIN LEVEL  
28  
27  
26  
A
B
PHANTOM  
DESIGNED AND ENGINEERED IN THE UNITED STATES BY SAMSON TECHNOLOGIES  
ON  
OFF  
CAUTION  
ON  
OFF  
CAUTION:TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK  
DO NOT REMOVE BOTTOM COVER  
RISK OF ELECTRICAL SHOCK  
NON SERVICEABLE PARTS INSIDE  
DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE  
REFER SERVICING TO QUALIFIED PERSONNEL  
DO NOT OPEN  
RISQUE DE SHOCK ELECTRIQUE  
NE PAS OUVRIR  
POWER  
SERIAL NUMBER :  
MADE IN CHINA  
AC ADAPTOR  
C
4
 
Front and Rear Panel Layout  
Front and Rear Panel Layout  
FRONT PANEL  
18 2 TRACK INPUTS – Connect the output from a DAT,  
1
MIC – Input connector for Low-Noise Microphone pre-  
Cassette, Mini Disk or Hard Disk Recording system.  
amp.  
19 2 TRACK OUTPUTS – Connect to the input of a DAT,  
2
3
LINE –Input connector for Line level inputs.  
Cassette, Mini Disk or Hard Disk Recording system.  
GAIN – Used to set the input level of the mic pre and line  
20 AUX RETURN – Used to mix in level of the effects  
input.  
return.  
4
5
6
7
8
9
HIGH FREQUENCY – Controls the high band of the  
Channel Equalizer, +/- 15 dB at 12KHz.  
21 PHANTOM – Indicates that the 48 Volt Phantom  
Power is on.  
MID FREQUENCY – Controls the mid band of the Channel  
Equalizer, +/- 15 dB at 2.5KHz.  
22 POWER – Indicates the MDR624 is powered up.  
23 OUTPUT METER - Eight segment display with VU  
LOW FREQUENCY – Controls the low band of the Channel  
Equalizer, +/- 15 dB at 80Hz.  
ballistics indicates main Mix level.  
24 2 TRACK TO MIX - Switch used to mix the 2 track  
AUX – Pre fader auxiliary send that can be used with an  
external effects processor, or to create a cue or monitor  
mix.  
PAN – Controls the channel’s position between left and  
right in the stereo bus.  
input with the mix from the channel inputs.  
25 2 TRACK TO CR – Switches between the main Mix  
and the 2 Track in the Control Room output.  
26 MAIN LEVEL – Used to control the overall volume of  
PEAK – Red LED will illuminate indicating when the  
the Left and Right main Mix outputs.  
GAIN has been adjusted too high.  
27 C ROOM/HEADPHONE – Adjusts the volume of the  
10 LEVEL – Audio taper fader provides smooth control over  
control room speakers or headphones.  
level changes.  
28 BALANCE – Controls the channel’s position between  
11 RIGHT LINE – 1/4-inch phone input connector for the right  
left and right in the stereo inputs.  
line input for the stereo channels.  
12 LEFT LINE - 1/4-inch phone input connector for the Left  
Line input for the stereo channels.  
REAR PANEL  
13 AUX RET – Input connector from external line level  
sources.  
A
B
POWER – Switches on the MDR624’s main power.  
14 AUX SEND – Line level output from the Auxiliary bus.  
PHANTOM – Engages the 48-Volt Phantom power  
supply to microphone pre-amps.  
15 HEADPHONE JACK – Connect stereo headphones here.  
C
AC ADAPTOR INLET – Connect External AC power  
supply here.  
16 CR OUTPUT– Left and Right Control Room output connec-  
tors for connecting a monitor system.  
17 MIX OUTPUT – Left and Right main Mix output connec-  
tors.  
5
 
Controls and Functions  
MONO INPUT CHANNEL SECTION  
The following section details each part of the MDR624’s input channels including the GAIN control, 3-BAND EQ,  
AUX send, PAN, BALANCE and LEVEL controls. The input channels One and Two on the MDR624 feature high  
quality, discrete transistor pre-amps providing transparency and extended dynamic range on standard XLR con-  
nectors. Channels 3/4 and 5/6 are stereo input channels that accept line level signals on standard 1/4" phone  
connectors for either balanced (TRS – TIP/ RING/SLEEVE) or unbalanced (TS – TIP/SLEEVE) connections. A  
detailed explanation of the Input, as well as the Output connectors, can be found in the following section “Input and Output  
Connections” on page 11 of this manual.  
GAIN  
1
The MDR624’s pre-amp stage has a variable GAIN control, which is used to set the sensitivity of the  
input. Because the input can accept either a mic or line level signal, the GAIN control operates in two  
ranges based on which input is being used. When a microphone is connected to the input, the range is  
5 to 60dB, and when a line is connected, the range is –26 to +26dB. For more infor-  
30  
mation on using the GAIN control see the section “CONNECTING MICROPHONES AND INSTRU-  
GAIN  
G
MENTS” on page 12 of this manual.  
1
5
60  
-26  
+26  
CHANNEL EQUALIZER  
2
The MDR624 input channels feature a 3-band equalizer allowing you to adjust the  
high, mid, and low frequencies independently on each channel. 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 up to 15dB,  
and rotating it towards the left will cut the frequency by up to 15dB. The frequency  
centers, range of boost or cut, and equalizer type for each band are as follows:  
High: 12KHz +/- 15dB shelving type  
0
0
0
HF  
5
5
12K  
10  
10  
15  
15  
5
2
MF  
5
2.5K  
Mid: 2.5KHz +/- 15dB peaking type  
Low: 80Hz +/- 15dB shelving type  
10  
10  
15  
5
15  
LF  
AUX SEND  
3
5
80Hz  
10  
10  
The AUX section is often used for a monitor mix in a live sound mixing, or for a  
headphone mix in a recording application. Each input channel includes an Aux send  
which controls the amount of that channel’s signal that is sent to the Aux bus. For  
more information on using the AUX control see the section “SENDING AN INDEPENDENT MIX  
TO THE MONITOR SPEAKERS” on page 13 of this manual.  
15  
15  
AUX  
3
0
10  
6
 
Controls and Functions  
MONO INPUT CHANNEL SECTION  
BALANCE (Stereo Inputs Only)  
4
5
The MDR624’s BALANCE control is used to place or position a mono  
input into the stereo main Left and Right MIX bus. For a stereo input,  
the balance control is used to center the sound between the Left and  
Right Mix bus. You can create a stereo image by panning some input  
signals to the left and others to the right.  
0
BAL  
4
L
R
PAN (Mono Inputs Only)  
The MDR624’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 MDR624’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.  
PEAK LED  
6
7
The MDR624’s MIC/LINE pre-amp also includes a CLIP LED which,  
when illuminated, indicates that the signal is peaking or overloading.  
To reduce distortion, lower the GAIN control to keep this LED from  
staying on.  
0
10  
5
0
PAN  
FADER  
L
R
6
The MDR624’s rotary input FADER controls the overall channel level.  
The input FADER features an audio taper and no detents for smooth  
fades.  
5
PEAK  
10  
0
7
LEVEL  
CHANNEL 1  
7
 
Controls and Functions  
MASTER SECTION  
The MDR624’s Master section includes the master level controls for the MAIN mix, AUX and CR (Control  
Room) / PHONES output, as well as, 2-track assign switches and LED metering for power and level. The  
following section details the function controls and switches in the Master section.  
MAIN LEVEL  
8
9
The master MAIN control is the overall volume control for  
the left and right mix bus. The MAIN LEVEL affects both  
the Control ROOM signal which is output to the speakers  
and the line level signal which is output from the MIX OUT  
jacks.  
L
CR OUTPUT  
R
S
CR / PHONES  
L
The C/ROOM + PHONES control is used to set the level  
sent to the control room outputs, and also to the head-  
phone jack.  
N