Ashly MX-508 User manual

MX-508
Stereo
Microphone/Line
Mixer
Operating Manual
ASHLY AUDIO INC.
847 Holt Road Webster, NY 14580-9103 Phone: [phone]
Toll-Free: [phone] Fax: [phone] Internet: http://www.ashly.com/

2
Operating Manual -MX-508 Stereo Microphone/Line Mixer
Table Of Contents
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 UNPACKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 AC POWER REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4 CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
5 CONNECTIONS AND CABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-7
6 TYPICAL APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1 Small Sound Reinforcement System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.2 Meeting Room, Board Room, Church, etc. Using Remote Control . . . . . . . . . . 8
6.3 Location Recording or Broadcast Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.4 Submixer In Larger Sound System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7 CHANGING FACTORY CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1 Changing the Aux Pre/Post Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.2 Installation of Input Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8 TROUBLESHOOTING TIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1 No Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.2 Distorted Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.3 Excessive Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.4 Excessive Hum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9 DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
11 WARRANTY INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
12 SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-15

3
Operating Manual - MX-508 Stereo Microphone/Line Mixer
1. INTRODUCTION
Congratulations on your purchase of an Ashly
MX-508 stereo mixer. In one compact rack-mount pack-
age we have combined features, reliability, and sonic per-
formance previously found only in larger and more
expensive mixing consoles. This second generation mixer
is similar to the MM-508, with the addition of output mute
switches on stereo outputs and double or single jack in-
sert points on all input channels.
Other features include optional plug-in isolation
transformers on all inputs, switchable +48V phantom
power, and front panel switching on each channel select-
ing between mic or line input. Three-band equalization
with a fixed frequency low and high shelf and a tunable
mid-range control provides perfect true-reciprocal equal-
ization curves. A concentric level and pan control com-
bined with a concentric pair of auxiliary sends complete
each input channel.
Ultra low-noise summing amplifiers combine the
channel signals for the main and send outputs. Two 10-
segment LED arrays monitor main or aux outputs. Stan-
dard line level outputs on 1/4" connectors, tape outputs
on RCA connectors, and transformer isolated 600 ohm out-
puts on XLR connectors are provided as standard equip-
ment. Ashly still uses professional quality 16mm metal
shaft potentiometers on all controls for greater accuracy
and long life.
2. UNPACKING
As a part of our system of quality control, every
Ashly product is carefully inspected before leaving the
factory to ensure flawless appearance. After unpacking,
please inspect for any physical damage. Save the ship-
ping carton and all packing materials , as they were care-
fully designed to reduce to minimum the possibility of
transportation damage should the unit again require pack-
ing and shipping. In the event that damage has occurred,
immediately notify your dealer so that a written claim to
cover the damages can be initiated.
The right to any claim against a public carrier
can be forfeited if the carrier is not notified promptly and
if the shipping carton and packing materials are not avail-
able for inspection by the carrier. Save all packing mate-
rials until the claim has been settled.
3. AC POWER REQUIREMENTS
The MX-508 mixer will perform normally from
93 to 125 volts AC, 50-60Hz (some export models are
wired for 240 Volts and are labeled accordingly). Use
only properly grounded AC receptacles. To reduce the
risk of ground loop hum, use a central point for system
AC power distribution. In the event of fuse failure, re-
place only with same type fuse. Power consumption is
less than 50 watts.

4
Operating Manual -MX-508 Stereo Microphone/Line Mixer
4. CONTROLS
4.1 Input Level (Gain)
This control sets the operating level of the Microphone preamp and
Line Input. Best signal to noise ratio is obtained with higher gain settings. It
is therefore desirable to set the Gain control as high as possible while still
leaving enough headroom (usually 20dB) to prevent distortion.
4.2 Mic-Line Switch
This switch selects between the XLR microphone input or the 1/4"
line input jack as the signal source. It can also serve as a "channel mute"
switch when selected to the unused input.
4.3 Channel Clip Indicator
This peak sensitive indicator monitors all level critical points in the
input channel and illuminates if any of them reach levels 3 dB below clip-
ping.
4.4 Equalization
Channel EQ consists of a high shelf control at 15KHz (middle of
shelf), a sweepable mid control, and a 70Hz low shelf control. The mid
control is sweepable from 140Hz to 8KHz with a bandwidth of approximately
1 octave.
4.5 Aux Sends
These are an additional pair of level con-
trols to adjust the feed to monitors or effects units.
Aux 1 is factory preset to pre-fader, pre-EQ, while
Aux 2 is post-fader, post-EQ. Both Aux sends can
be internally switched to pre or post fader/EQ. Note:
See section on changing factory configurations.
4.6 Level and Pan
This concentric pair of controls adjusts the
level and stereo position of the channel.
4.7 Aux Master Sends
These controls adjust the overall gain of the output stages for the Aux 1 and Aux 2
outputs.
4.8 Aux Master Returns With Pan
These concentric level and pan controls adjust the returning signal from effects units
or auxiliary inputs to the Main Left and Right outputs. Return 1 is stereo and return
2 is mono. If only the right connection to return 1 is made, this return will function
as mono with pan.
4.9 Tape/CD Input and Send
This stereo level control adjusts the Tape/CD input to the Main Stereo outputs. The
outer concentric control labeled "To Aux 1" sums the left and right Tape/CD inputs
to a mono signal and applies it to the Aux 1 Master group for use with monitors or
effects. It is "pre-fader", or independent of the stereo level control.
100PanLevel
100Aux 2Aux 1
+12-12
+12-12 5K
2.5K
1.2K
630 +12-12
-60-20dB
-50
-40
0
-30
+22 -24
Clip
M
L
Ch.1
3
1
-
Input
Level
High EQ
Low EQ
Aux1
Aux2
Mid EQ
Frequency
Level
Pan
p
Mic
Line
100
100
To Aux 1
T
ape/CD In
PanReturn 2
PanReturn 1
100
100
100
(Stereo)
Aux 2 Send
Aux 1 Send
Aux Master

5
Operating Manual - MX-508 Stereo Microphone/Line Mixer
4.10 Output Meters
A pair of peak
reading 10 segment LED
meters are used to indicate
output level. Green LED's
are used below 0 VU, yel-
low above 0 VU and red
LED's indicate clipping. 0
VU is equivalent to +4 dBu
(1.228Vrms). This meter
pair is switchable (with the
headphone output) to either
the Main Left and Right
outputs or the Aux 1 and 2
outputs. The red clip LED's
will illuminate if the sum-
ming amplifiers are clip-
ping even if the main output
controls are off, in which
case one or more inputs
must be turned down. Note:
The output meters are accu-
rately calibrated to the
transformerless output lev-
els, but not necessarily the
transformer-balanced out-
puts. See note on Trans-
former Balanced Outputs.
4.11 Main Output Level
These controls de-
termine the level of both
transformer balanced and
transformerless output stages for the Main Left and Right
outputs.
4.12 Main Output Mutes
These switches turn off both the transformer-bal-
anced outputs as well as the transformerless 1/4" stereo
outputs, and indicate the mute mode by lighting the red
LED near the switch. The headphone and metering func-
tions continue uninterrupted even though there is no sig-
nal on the mixer's main outputs.
4.13 Phantom Power Switch
This front panel switch enables the 48 Volt phan-
tom power supply for condenser microphones which can
use this feature. One switch controls all the inputs. If you
have a mix of condenser and dynamic microphones, the
phantom power will not affect the operation of the dy-
namic mics.
4.14 Mono Output Level
This control adjusts the level of the summed mono
output. It is completely independent of the Main Left and
Right masters.
4.15 Headphones Level
This control adjusts the level of the designated
output signal (Mains or Aux) to the headphone jack.
4.16 Meter/Phones Select
This switch selects either the Main Left/Right
outputs or theAux 1/Aux 2 outputs to the LED meters and
the headphone jack.
4.17 Headphone Output
This front panel 1/4"TRS connector feeds a stan-
dard set of stereo headphones. A selector switch that also
controls the level meter allows monitoring the main orAux
outputs.
100
1
2
3
456
7
8
9
100
1
2
3
456
7
8
9
Main
Outputs
Left Right
Clip
+6
+3
0
-3
-6
-9
-12
-15
-18
-21
VU -R--L-
MX508
Stereo
Eight Channel
Mixer
100
Headphones
Mono Output
L/R
Aux 1/Aux 2
Meter/
Phones
Select
Power
Off On
Phantom (+48V)
010
9
8
7
6
5
4
3
2
1
MuteMute
(Aux1) (Aux2)

6
Operating Manual -MX-508 Stereo Microphone/Line Mixer
5. CONNECTIONS AND CABLES
The MX-508 mixer is fitted with four types of
audio connectors: 3-pin XLR type male (stereo outputs),
3-pin XLR type female (mic inputs), tip-ring-sleeve (TRS)
phone jack, and RCA jack. Certain 1/4" jack connections
use an unbalanced mono plug, which is also shown.
Two-conductor (twisted pair) shielded cable is
best for all XLR type connections. Belden No. 8412, or
its equivalent, is an excellent cable due to its heavy con-
struction. This type of cable should be used for all por-
table applications. Snake cables containing multiple
shielded pairs must be handled very carefully because the
leads tend to be fragile, and a broken conductor is diffi-
cult to repair.
If low level and high level lines (e.g., microphones
and mixer line outputs), or if either of these lines and
speaker cables are run parallel for long distances, crosstalk
may be significant. In fact, the crosstalk (signal leakage
between cables) can cause an electronic feedback loop,
oscillation, and possibly damage to the equipment. To
minimize crosstalk, physically separate low level (micro-
phone) cables from speaker cables by the greatest feasible
distance. At any point where cables meet, run low level
cables perpendicular to high level or speaker cables. If
low and high level or speaker cables must be run parallel
and in close proximity to one another, they should be
bundled separately.
5.1 Microphone Input
The microphone input is an
active balanced type with a nominal
impedance of 1200 ohms. Its noise
performance is best with a 200 ohm
microphone. A plug-in transformer
option is available if you need the
isolation. The Mic input connector
is a standard 3-pin XLR female with
the shield on pin 1, the (+) in-phase
connection on pin 2, and the (-) out-
of-phase connection on pin 3.
5.2 Input Pad
The Pad is a 20dB attenua-
tion switch on the rear panel for use
with the XLR microphone input. It
has no effect on the line input. It
should normally be left in the "out"
position for best signal to noise ra-
tio and should only be used when the
input is being overdriven with the
Gain control at its minimum setting.
5.3 Line Input
The line input is a standard
1/4" TRS active balanced connec-
tion, with a balanced input imped-
ance of 20KΩ. It will accommodate
a wide range of input levels.
5.4 Channel Send And Return Patch
A channel patch point allows a device such as graphic
equalizer, noise gate, compressor/limiter, remote level con-
troller, or direct out recording device to be used on individual
channels. The MX-508 has both single jack insert capabili-
ties as well as separate send and return jacks.
- To use separate send and return jacks, use the
send jack to feed the input of the device to be inserted, and
use the return jack for the output of the inserted device. You
must use unbalanced (tip-sleeve) mono plugs for this con-
figuration.
- To use the single jack insert, use a TRS (stereo)
plug in the send jack only, where the send output signal is on
the tip, and the return signal is applied to the ring. This
convention is most common among mixers.
- To use the send jack as a Direct Line Output
(pre EQ), you must use a special cable with tip and ring con-
nected at the MX-508 Send and a tip-sleeve mono plug at
the other end. Connecting tip and ring at the mixer send
jack is necessary for uninterrupted signal within the mixer
when using direct line outputs.
Ch.1
Pad (-20dB)
Mic
Input
Return
TRS
Insertion
( )
Send*
Line
Input
PUSH
PUSH
Stereo Phone Plug
used for balanced
Mono Phone Plug
used for unbalanced
Tip (+)
Ring (-)
Sleeve (Ground)
Tip (+)
Sleeve (Ground)
XLR
Male
2 = (+)
3 = (-)
1 = (gnd)
XLR pins are
numbered
in the
connector
insert.
XLR
Female
RCA Plug
Tip = (+)
Sleeve = ground

7
Operating Manual - MX-508 Stereo Microphone/Line Mixer
5.10 Sub Outputs
These outputs are generally used to feed another
mixer's Sub Inputs for expanded input capacity. The Main
left and right submaster outputs use unbalanced (mono)
1/4" connectors. TheAux submaster outputs use 1/4"TRS
connectors with Aux 1 on the tip and Aux 2 on the ring.
5.11 Mono Output
This output is a function of the Mono Level Con-
trol, which is a pre-Master summed output from the left
and right mix busses. Like the main outputs, it is pseudo-
balanced with a nominal level of +4dBu.
5.12 Sub Inputs
These inputs are useful for linking together two
or more mixers for expanded input capacity, and include
Main left, Main right, and Aux 1/Aux 2. Signal to the
Sub Inputs is taken from the Sub Outputs of another mixer,
with a nominal level of +4dBu. The Aux submaster input
requires Aux 1 on the tip and Aux 2 on the ring.
5.5 Aux Send Outputs
The Aux Outputs are used to
drive monitors, effects processors, re-
cording devices, or any function
which requires isolated level control
from the main outputs. They are
pseudo-balanced 1/4" tip-ring-sleeve.
5.6 Aux Return Inputs
The return inputs are 1/4" un-
balanced. Return 1 is stereo with a
left and right input, while Return 2 is
mono. To use return 1 as mono, con-
nect only to the Right return 1 input.
5.7 Tape/CD Input - Tape Output
The stereo inputs on RCA
connectors have a nominal operating
level of -10dBu to match most tape
decks and CD players. The tape out-
puts are -10dBu "pre-master", so they
are not affected by the settings of the
Main output controls.
5.8 Transformer Balanced Outputs
The transformer outputs use
male XLR type connectors and pro-
vide total isolation for 600 ohm lines.
Pin 1 is ground, pin 2 is (+), and pin 3
is (-). These outputs are controlled
by the Left and Right Master levels,
with a nominal operating level of
+4dBu.
Note: The transformer-balanced outputs are de-
signed to drive up to +24dBu into 600 ohm loads. Be-
cause of the nature of an output transformer, the output
level increases as the impedance of the terminating load
becomes higher than 600 ohms. Whereas a "direct-
coupled" output stage like that of the transformerless out-
puts will not change as the load changes, any transformer
used in an audio path is affected by its termination im-
pedance. Since line level inputs on audio devices are
typically 10K Ω or higher, expect a slight increase (2.5dB)
in output level when driving high impedance inputs with
the transformer outputs. The output meters will remain
accurately calibrated to the levels present on the
transformerless outputs, regardless of the load on the
transformer outputs.
5.9 Main Outputs
These Main Outputs are also controlled by the
left and right master. They are 1/4" pseudo-balancedTRS
jacks with a nominal operating level of +4dBu into any
load.
C
h
Pa
d
o
f
ot
Aux 1
Send
Aux 2
Send
Return 2
Tape/CD
Input
Tape
Out
-R--L-
Return 1
Right
(Mono)Left
Transformer Balanced
Output -L--R-
Transformerless
Output
-L--R-
R/L
Sub Out
Aux 1
Aux 2
Sub Out
Mono
Output Tip=Aux 1
Ring=Aux 2
R/L
Sub In
-L--R-
-L--R-
Aux 1
Aux 2
Sub In

8
Operating Manual -MX-508 Stereo Microphone/Line Mixer
6. TYPICAL APPLICATIONS:
6.1 Small Sound Reinforcement System:
In the setup shown here, the MX-508 is used to mix typical sound sources that might be found in a small club, school
theater or similar environment. Six of the input channels are used for microphones for live vocal or instrumental
pickup. The remaining two channels are used for playback from a stereo tape recorder, such as might be used during
intermission, for backup, for special recorded effects, etc. The power amplifier (or any additional equalizers or elec-
tronic crossovers which may be used) is fed from the transformer balanced Output connectors.
6.2 Meeting Room, Board Room, or Church
Mixer Using Remote Control:
In this example, the MX-508's send/
return insert jacks are interfaced with anAshly
VCX-80 eight channel remote level controller,
allowing a full-featured mixer to be operated
from a distance by a non-technical person.
Once initially set up, the RD-8 desk-top remote
controller (or RW-8 if a wall-plate version is
desired) can be located far away (up to 1/4 mile)
from the main audio equipment rack using a
single balanced XLR cable, allowing for sim-
plified sound system operation. Alimited num-
ber of knobs, lights, and buttons saves the VIP
operator from distraction and potential embar-
rassment, while giving them a great deal of
overall system control. While only two zones
are shown, the MX-508 can independantly con-
trol audio to five different zones at once. Each
of these zones could just as easily be controlled
by the VCX-80 by interfacing with the mixer's
outputs.
100-120VAC
50-60Hz 15W
DataInput
231
Data
V+
Ashly AudioInc.
Mode l V CX -80
Made InUSA
INPUTS are Active Balanced (Tip is +, Rin g is -).
OUTPUTS May Be W ired Balanced or Unbalanced.
** TRS Insert ion Is Availab le - See O wner's Manual* *
Ch.2
DC Control
Ch.8 Ch.7 Ch.6 Ch.5 Ch.4 Ch.3
Ch.1InIn Out In Out In Out In Out Out In Out In Out In Out
1 - Ch.1
2 - Ch.2
3 - Ch.3
4 - Ch.4
5 - Ch.5
6 - Ch.6
7 - Ch.7
8 - Ch.8
9 - Master
10 - Control CCW
11 - (Aux Ground)
12 - Cont rol CW
13-14 - (Aux Data In)
15 - NC
1
9
Remote Control
Caution: No User Serviceable Parts Inside.
Re f er A ll Se rvici n g To Qu al ifie d S ervic e Pers o nn el.
To R educe The Ris k Of Fire Or E lectric Shock
Do Not E xpose This Equ ipmen t To Rain O rM oisture.
AVIS: RI SQU E DE
CHO C EL EC TR IQU E.
NE PAS O UV RI R.
1210
Pin 1 -9
10K CW
** ** ** ** ** ** ** **
MasterOutput
+10
-70
+5
0
-5
-10
-20
-30
-50
-
¥¥
-15
+10
-70
+5
0
-5
-10
-20
-30
-
-50
¥¥
-15
RD-8
Remote LevelControl
XLR D ata Connector
OnTop orBack.
DoNotUse
Transformers.
Ch.1
On
Ch.2 Ch.3 Ch.4 Ch.5 Ch.6 Ch.7 Ch.8 Master
Remote
Disabled
Gain(dB) Gain(dB)
V+
13 2
Data
On
Return
TRS
Inse rtio n( )
Sen d*
Line
Input
Ch.1Ch.2Ch.3Ch.4Ch.5Ch.6Ch.7Ch.8
Pad (-20dB)Pad (-20dB)Pad (-20dB)Pad (-20dB)Pad (-20dB)Pad (-20dB)Pad (-20dB)Pad (-20dB)
Mic
Input
Mic
Input
Mic
Input
Mic
Input
Mic
Input
Mic
Input
Mic
Input
Mic
Input
Return
TRS
Inse r tio n( )
Sen d*
Line
Input
Return
TRS
Inse r tio n( )
Sen d*
Line
Input
Return
TRS
Inse r tio n( )
Sen d*
Line
Input
Return
TRS
Inse r tio n( )
Sen d*
Line
Input
Return
TRS
Inse rtio n( )
Sen d*
Line
Input
Return
TRS
Inse r tio n( )
Sen d*
Line
Input
Return
TRS
Inse r tio n( )
Sen d*
Line
Input
*Direct Out Usi ng Send Jack (No Retur n):
Use Mono Plug Only And Insert Dummy Plug Into R eturn Jack.
*Normal Send And Return:
Us e M on o (t ip -s lee ve) P lu gs O nly *TRS Inserti onUs ing Send Jack: Send = Tip, Return = Ring
Ashly Audio I nc.
Made In USA
120 VAC
50-60Hz
Fuse
3AG 1A
CAUTION:
Toreduce the risk of
electric shockdo not
remove c over. No use r
servic eable part s inside.
Re fe r servic ing t o
qualified pers onnel. To
reduce th e risk of f ire
replace with same type
fuse. To reduce the risk of
fireor electric shockdo not
expose this equipment to
rain or mo isture.
Aux 1
Send
Aux 2
Send
Return 2
Tape/CD
Input
Tape
Out
-R-
-L-
Return 1
Right
(Mono)Left
TransformerBalanced
Output -L--R-
Transformerless
Output
-L--R-
R/L
Su b O ut
Aux 1
Aux 2
Sub Out
Mono
Output Tip=Aux 1
Ring=Aux 2
R/L
Sub In
-L--R-
-L--R-
8-Channel
Microphone
Mixer
(Single Jack
Inserts Used)
RD-8 Remote Controller
With 3-Pin XLR Data Cable
VCX-80
Patched Into
Channel
Insert Points
8 Mic/Line
Inputs
Speaker
Zone 2
Amplifier
Speaker
Zone 1
Amplifier

9
Operating Manual - MX-508 Stereo Microphone/Line Mixer
6.3 Location Recording or Broadcast
Mixing:
In this setup the MX-508 is used to mix
sources typically found in location re-
cording or broadcast situations (mostly
microphones). In this case, two of the
microphones are wireless types, so the
channel input actually comes from the
microphone receivers. Since the out-
put from the mic receivers is at line
level, the input selectivity of the re-
spective channels must be set accord-
ingly. The Tape Out jack feeds a
portable tape recorder, and the tape
recorder's line output is brought back
to the Tape/CD Input connectors for
monitoring. For live remote broadcast applications the Mono Out connector can feed a suitable TELCO interface.
6.4 Submixer In Larger Sound
System:
In this application the MX-508 is used
to provide a drum mix to the main
mixer without tying up a number of
channels on the main console. Up to
eight mics can be "pre-mixed" in ste-
reo, with all drum-specific gating,
compression, and effects controlled
directly by the drummer. Either the
main OUTPUT or the SUB OUT con-
nectors can be used to feed the mixed
drum signal to the main mixer. If
there is significant distance between
the MX-508 and the "master" mixer,
use the pseudo-balanced or trans-
former-balanced Main outputs for
long cable runs, otherwise use the un-
balanced Sub outputs.
7. CHANGING FACTORY CONFIGURATIONS
7.1 Changing the Aux Pre/Post Assignment
The MX-508 is shipped from the factory with Aux 1 assigned Pre-Fader/EQ, and Aux 2 Post-Fader/EQ. Each
channel'sAux Send controls may be independently configured for either pre or post fader/EQ operation with a minimum
of tools and no soldering. To make this change, refer the fol-
lowing procedure to a qualified service technician:
Unplug the unit's AC power cord from the outlet.
Remove the bottom cover which is fastened by seven 6-32
screws. Locate the 3 pin headers labeled Send 1 and Send 2
near the front of each input channel circuit board (see dia-
gram). Remove the shunt bar from the factory installed posi-
tion indicated on the circuit board legend and place the shunt
on the other position of the 3 pin header.
14-PIN CONNECTOR FRONT
PANEL
CONTROLS
MX-508 INPUT CHANNEL CIRCUIT BOARD

10
Operating Manual -MX-508 Stereo Microphone/Line Mixer
7.2 Installation of Input Transformers
The MX-508 is designed to accept optional plug-
in input isolation transformers with a minimum of tools
and no soldering. Instructions for installation are included
with the kit when you purchase an Ashly MX-508 ITC-
Kit (no. 40A5902)
8. TROUBLESHOOTING TIPS
8.1 No Sound
Check theAC power. Is the power switch on and
illuminated? Check the level meters. If they are operat-
ing, either the problem is between the mixer and the later
components in the system, or else the Output Mute
switches are pressed. If there is no meter activity, check
to see you really have an input signal and that it is on the
desired channel, or check to see that the meter select switch
is set to Left/Right. Check that you have the master gain
controls at the desired operating level.
8.2 Distorted Sound
Something is being overdriven in the signal path.
If the clip indicators are active, reduce the channel gain
controls and/or press in the pad switch on the rear panel.
If the level meters are constantly in the red, reduce the
Master gain and increase the gain of components follow-
ing the mixer. There are many gain adjustments in the
mixer itself and probably several others in other system
components which makes it possible to overdrive an in-
put section and then incorrectly try to reduce the gain of
the output section. The best way to approach setting gains
is to establish the operating level of input stages first by
setting their gain as high as possible but leaving about
20dB of headroom for loud peaks, then move on to set the
master gain to produce a good meter reading. Proceed to
set the gain of equalizers, limiters, crossovers, and ampli-
fiers following the mixer in the same manner, always work-
ing toward the later stages of the system.
8.3 Excessive Noise
If the noise is in the form of hiss, the problem is
usually due to an input stage set up for low gain and then
compensating by increasing the master gain. Check that
the Pad switch is not enabled unnecessarily. Turn up the
channel gain controls and reduce the master gain.
8.4 Excessive hum
This is usually caused by "ground loops" in the
system wiring. A complex sound system with many
sources separated by significant distance and using sev-
eral power outlets has many opportunities for this prob-
lem to occur. If possible, feed everything in the system
from one power source with a common ground. Use bal-
anced input and output connections between widely sepa-
rated components.
If you need help, get in touch with your Ashly
dealer or call an Ashly technical service representative at
1-800-828-6308 ext. 125.
9. DIMENSIONS:
5.25
2.25
18.38
19.00
1.50 1.3 8.00
17.00

11
Operating Manual - MX-508 Stereo Microphone/Line Mixer
*unless otherwise stated, specification conditions are: 150 Ω source, Input Level set at "-60", all other controls set at
nominal, XLR outputs into 600 Ω or greater.
11. WARRANTY INFORMATION
Thank you for your expression of confidence in Ashly products. The unit you have just purchased is protected
by a five-year warranty. To establish the warranty, be sure to fill out and mail the warranty card attached to your
product. Fill out the information below for your records.
Model Number _______________________________________________________________________________
Serial Number ________________________________________________________________________________
Dealer ______________________________________________________________________________________
Date of Purchase______________________________________________________________________________
Dealer’s Address______________________________________________________________________________
Dealer’s Phone _______________________________________________________________________________
Salesperson __________________________________________________________________________________
10. SPECIFICATIONS
DISTORTION
THD at +4 dBu, 20Hz-20KHz . . . . . . . . . . . . . . . . . . . .<0.05%
THD at +20dBu, 30Hz-10KHz . . . . . . . . . . . . . . . . . . . .<0.05%
IMD (SMPTE) at +20dBu . . . . . . . . . . . . . . . . . . . . . . . .<0.05%
HUM & NOISE (20Hz-20KHz at max preamp gain)
equivalent input hum and noise . . . . . . . . . . . . . . . . .<-129dBu
equivalent input hum and noise
with input transformer option . . . . . . . . . . . . . . . . . . .<-128dBu
residual output noise, TRS outputs,
all levels at minimum . . . . . . . . . . . . . . . . . . . . . . . . . .<-100dBu
residual output noise, XLR outputs, . . . . . . . . . . . . . . .<-90dBu
Master Level at nominal,
all Ch. Level controls at min . . . . . . . . . . . . . . . . . . . . .<-78dBu
Master Level and one Ch. Level at nom. . . . . . . . . . . .<-67dBu
Aux 1 or 2 Out, Aux Master at nominal
and all Ch. Aux at min, . . . . . . . . . . . . . . . . . . . . . . . . .<-88dBu
Aux 1 or 2 Out, Aux Master and
one Ch. Aux at nom . . . . . . . . . . . . . . . . . . . . . . . . . . . .<-67dBu
MAXIMUM VOLTAGE GAIN (±2dB)
MASTER
Mic Input to Master Output, 600 ohm load . . . . . . . . . . . .84dB
Line Input to Master Output, 600 ohm load . . . . . . . . . . .42dB
AUX SENDS
Mic Input to Aux Master Output, pre ch. level . . . . . . . . .76dB
Mic Input to Aux Master 2 Output, post ch. level . . . . . .92dB
SUB Input to Master Output . . . . . . . . . . . . . . . . . . . . . . . .12dB
AUX RETURNS 1 or 2 to Master Output . . . . . . . . . . . . .30dB
TAPE/CD In to Master Output . . . . . . . . . . . . . . . . . . . . . .34dB
FREQUENCY RESPONSE
20Hz-20KHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.5/-1.0dB
50Hz-10KHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0/-0.5dB
EQUALIZATION
Low . . . . . . . . . . . . . . . . . . . . . . . ±12dB at 70Hz, shelving
Mid . . . . . . . . . . . . . . . . . . .±12dB peaking, 140Hz-8KHz
High . . . . . . . . . . . . . . . . . . . . . ±12dB at 15KHz, shelving
CROSSTALK
adjacent inputs, 20Hz-20KHz . . . . . . . . . . . . . . . . . . . . . <-65dB
Mic Input to Master Output, 1KHz . . . . . . . . . . . . . . . . . <-65dB
Mic Input to Master Output, 20KHz . . . . . . . . . . . . . . . <-55dB
VU METERS
Selectable to Main or Aux Outputs . . . . . . . . . . 0VU = +4dBu
PEAK INDICATORS
Peak Clip indicator on each input channel and left and right out-
puts, illuminates 3dB below clipping
PHANTOM POWER
+48 VDC applied to all Mic Inputs, switchable on front panel.
Maximum total current draw = 80mA. Maximum single chan-
nel current draw = 14mA. Gradual power-up and down to elimi-
nate "pops".
SHIPPING WEIGHT
19 lbs. maximum with 8 input transformer options installed
POWER REQUIREMENTS
120 VAC nominal, 93 VAC minimum, 50-60 Hz,
35 watts (240 VAC available)

12
Operating Manual -MX-508 Stereo Microphone/Line Mixer
MX-508 Power Supply Card Schematic
12. SCHEMATIC DIAGRAMS

13
Operating Manual - MX-508 Stereo Microphone/Line Mixer
MX-508 Left and Right Output Card Schematics

14
Operating Manual -MX-508 Stereo Microphone/Line Mixer
MX-508 Send/Return Card Schematic

15
Operating Manual - MX-508 Stereo Microphone/Line Mixer
MX-508 Input Channel Card Schematic

Printed in USA 9/97 MX508 Rev 1
ASHLY AUDIO INC. 847 Holt Road Webster, NY 14580-9103
Phone: [phone] Fax: [phone]
Toll Free [phone] Internet: http://www.ashly.com/
1997 by Ashly Audio Corporation. All rights reserved worldwide.
Operating Manual - MX-508 Stereo Microphone/Line Mixer