EMG BQS-HZ SYSTEM Service manual

ABC (B125)
BALANCE
CONTROL
BASS
CONTROL
TREBLE
CONTROL
NECK
PICKUP
BRIDGE
PICKUP
ABC
CONTROL
BQS
CONTROL
MASTER
VOLUME
OUTPUT
JACK
MASTER VOLUME AND
BQS CONTROL ORDER
CAN BE REVERSED
MASTER
VOLUME
MID-RANGE
CONTROL
0230-0214rL
INSTALLATION INFORMATION
EMG MODEL: BQS-HZ SYSTEM
(PASSIVE PICKUP INPUT)
Installation notes:
Battery Power:
If you play the instrument very hard, and are boosting the bass, mid, or treble with the BQS, you should consider operating the guitar on +18
Volts (2 Batteries in series, see page 4). If you play mildly and use a minimum of boost the instrument should operate easily on a single 9-Volt
battery. Use an Alkaline or Lithium battery for the best battery life and always unplug your guitar when you’re not using it.
Warranty
All EMG Pickups and accessories are warranted for a period of two years. This warranty does not cover failure due to improper installation, abuse or damage. If
upon examination the pickup is determined to be defective, a replacement will be made. Warranty replacement products are covered by this same warranty. This
warranty covers only those pickups and accessories sold by authorized EMG Dealers. This warranty is not transferable.
© 2021 Copyright EMG INC. All Rights Reserved.
PO BOX 4394
SANTA ROSA, CA
95402 USA
P [phone]
F [phone]
EMGPICKUPS.COM
wiring order:
Below is a diagram of the typical wiring order of the controls. Often the Volume control is closer to the pickups than the BQS Control making it
difficult to wire the instrument. It is preferable to have the Master Volume control last in the signal chain before the output jack. If this isn’t
possible it’s no worry, either wiring order is acceptable.
ABOUT THE BQS-HZ SYSTEM:
The BQS-HZ System is a complete control system for bass guitars. Active Balance, Master Volume and EQ circuits are included. The EQ effects
are illustrated in the graphs on the next page. They allow you separate control over bass, midrange, and treble. Rotate the controls clockwise
to boost, counterclockwise to cut. There is a center detent for flat response.
The mid-range control has a variable frequency knob that allows you to sweep through the mid-frequency range from 100Hz to 1KHz. This
selects the frequency to boost or cut.
Included in the system are:
1) Active Balance Control (B125)
The B125 Active Balance Control is designed for Passive Pickups. It allows loss-free balance between two pickups and has a center detent for
the middle position. If you are using EMG Active pickups you can also use the B125 although the B118 Active Balance Control which features
inputs for Active Pickups has lower noise.
2) BQS Control 3-band equalizer for Bass guitar. The BQS features dual-pole filters for broadband equalization. The primary feature of the BQS
System is the variable mid-range frequency selection from 100 to 1KHz along with boost or cut of the chosen frequency. An additional feature
of the BQS Control is a 2-position dip-switch that controls the slope of the high frequency response. By choosing one of the four combinations
the high frequency response can be tailored to your liking.
3) Master Volume control, output jack, battery buss and clip.
Specifications for each of the EMG products included in the BQS-HZ System are available online.
Go to: http://www.emgpickups.com
PASSIVE
PICKUP
INPUTS

High Frequency (Treble) Response Selection:
The BQC has the added feature of allowing you to choose from 4 different
high frequency response curves. This is a nice feature especially if you are
using the BQC with passive pickups. The following diagrams show the dip-switch
positions and the graphs show the resultant frequency response.
The BQC Control is an equalizer style control, offering both boost and cut
at the same frequency locations. The control also features a center detent
(click) that lets you know when no equalization is in effect.
Low Frequency (Bass) Response:
The BQC has a fairly standard bass response boost and cut. It’s slope is
6dB per octave and is centered at 50Hz. As you can see in the graph
on the left the signal can be boosted by +12db (Red Line) or cut by
-12dB (Green Line). A center detent (click) is provided on the control
to let you know when the frequency response is flat or unaffected
by boosting or cutting.
Mid-Range Frequency Response:
One of the primary features of the BQC is it’s mid-range control. It allows you to
choose the frequency you want to boost or cut from 100 to 1000 Hz. The concentric
mid-range pot has two sections. The lower control chooses the frequency, while the
upper control lets you choose the amount of boost or cut you want. The maximum slope
is 12dB per octave at full gain or cut.. There is also a center detent (click) in the center
of the upper control to let you know when the control is not having any effect.
MID FREQUENCY SELECTION (LOWER CONTROL)
MID BOOST OR CUT (UPPER CONTROL)
BASS BOOST OR CUT (LOWER CONTROL)
TREBLE BOOST OR CUT (UPPER CONTROL)
BASS/TREBLE
CONTROL
BQS-HZ System Page 2
Installation Instructions:
EMG Model: BQS-HZ System
10KHz1KHz
20Hz
10 dB/div
BQC CONTROL BASS RESPONSE
10KHz1KHz
20Hz
10 dB/div
ON/ON
BQC CONTROL (TREBLE RESPONSE: ON/ON)
10KHz1KHz20Hz
10 dB/div
OFF/ON
BQC CONTROL (TREBLE RESPONSE: 1 OFF/2 ON)
10KHz1KHz
20Hz
10 dB/div
OFF/OFF
BQC CONTROL (TREBLE RESPONSE: 1 OFF/2 OFF)
10KHz1KHz
20Hz
10 dB/div
ON/OFF
BQC CONTROL (TREBLE RESPONSE: 1 ON/2 OFF)
VARIABLE MID-RANGE FREQUENCY
1.0KHz100Hz
20Hz
10 dB/div
10KHz1KHz

Diagram #3 (preferred wiring order)
ABC Control
BQS Control
Master Volume
Output Jack
NECK
PICKUP
BRIDGE
PICKUP
ABC
CONTROL
BQS
CONTROL
MASTER
VOLUME
OUTPUT
JACK
NECK PICKUP (White tubing)
(Upper 3-pin header)
BRIDGE PICKUP (Black tubing)
(Lower 3-pin header)
Pin 1
This pin and the one below it supply
9V+ for EMG Active Pickups:
DO NOT use either pin when using
passive pickups.
Diagram #1
EMG-HZ Plug-in Inputs & Output
Pin 2 Ground for pickup
OUTPUT
BOTTOM
VIEW
T
R
S
9V+ POWER BUSS
BATTERY
NEG (-) BLACK
RED
RED
OUTPUT CABLE
- 9V +
BQS
CONTROL
RED
NOTE:
REVERSED
CONNECTOR!
OUTPUT TO
VOLUME CONTROL
RED TO 9V + BUSS
Diagram #2
EMG-HZ Pickups
Soldered Inputs
EMG Neck Pickup
(Upper 3-pin header)
EMG Bridge Pickup
(Lower 3-pin header)
B125
ACTIVE BALANCE
CONTROL
Pin 3 Input for pickup
EMG,INC. B125rC
BRG
NEK
GND
IN
V+
NK IN
BR IN
OUT
GND
V+
GND
GND
BASS
CONTROL
TREBLE
CONTROL
Bridge Pickup Cable
Neck Pickup Cable
Solder Pickup Hot (Red Wire)
to BRG Pad
Solder Pickup Ground (Green/Braid)
to GND Pad
Solder Pickup Ground (Green/Braid)
to GND Pad
Solder Pickup Hot (Red Wire)
to NEK Pad
BQS-HZ System Page 3
Installation Instructions:
EMG Model: BQS-HZ System
Soldered inputs:
On the back side of the ABC PC Board there are 4 pads to solder to.
Solder the signal wire (Hot) of the bridge pickup to the BRG Pad,
and solder the ground wire (shield) of that pickup to the GND Pad.
Do the same for the Neck Pickup, Hot to the NEK Pad, and ground
to the GND Pad.
If you already have EMG Passive Pickups in your instrument you can use
the existing pickup cables.
Diagram #1 illustrates how to connect the pickups to the ABC Control by using
the EMG plug-in connectors.
Installation Instructions:
Plug-in Pickup Inputs:
VOLUME
B122rH
MASTER
VOLUME

B125
ACTIVE BALANCE
CONTROL
Diagram #4 (alternate wiring order)
ABC
Master Volume
BQC Control
Output Jack
NECK
PICKUP
BRIDGE
PICKUP
ABC
CONTROL
BQC
CONTROL
MASTER
VOLUME
OUTPUT
JACK
- 9V +
EMG Active Neck Pickup
(Upper 3-pin header)
EMG Active Bridge Pickup
(Lower 3-pin header)
OUTPUT
BATTERY
NEG (-) BLACK
9V+ POWER BUSS
RED
RED
BOTTOM
VIEW
OUTPUT CABLE
RED NOTE:
REVERSED
CONNECTOR
T
R
S
BQS
CONTROL
Diagram #5
If the instrument has a Battery Holder:
If your instrument has a 9 or 18 Volt battery holder you can still
use the EMG Connectors to supply power to the pickups.
Simply cut and strip the wires from the battery clip provided.
Twist the wires together (Red to Red and Black to Black) and
use the shrink tubing included to cover the connections.
Soldering the wires is recommended.
9/18 VOLT
BATTERY
HOLDER
Cover these connections with the
shrink tubing provided.
BLACK to RING terminal
of the Output Jack
RED to BATTERY OR PICKUP BUSS
BLACK to RING terminal
of the Output Jack
RED TO BATTERY BUSS (+18Volts)
Diagram #6
- 9V +
- 9V +
T
R
S
RED
BLACK
+18 Volt Wiring Option:
If you want to operate your instrument at +18 Volts for more
headroom then use 2 batteries wired as below.
Also, if you are using any type of EQ in your instrument
(EMG-BT, BQ) or anything that boosts the pickup signal then
+18 Volts is recommended.
Solder the Black and Red
wires together and cover
the connection with shrink
tubing, or other insulation.
TIP
RING
SLEEVE
Diagram #7
FROM TONE
OR VOLUME
BATTERY
NEG (-)
RED to BATTERY BUSS
Soldering to the 152B Panel Jack:
If your instrument has a long Panel Jack like the one below
you will have to solder the output cable as shown.
Ground (Black) to the Sleeve
Signal (White) to the Tip
Battery Negative (Black) to the Ring
- 9V +
Diagram #8
13
Soldering to the battery buss:
If your instrument has an older EMG Pickup you can solder the
pickup RED wire to the buss. Simply use some needle nose pliers,
pull out the V+ header and solder the RED Wire from the pickup(s)
to any of the pins and then re-insert the header into the housing.
2
BASS
CONTROL
TREBLE
CONTROL
BQS-HZ System Page 4
VOLUME
B122rH
MASTER
VOLUME