Sennheiser Ventilation Hood EK3253 User Manual

EK 3253  
Instructions for use  
 
If problems occur ... ....................................................................... 31  
Error checklist .......................................................................... 31  
Recommendations and tips ........................................................ 32  
Maintenance and care .................................................................. 32  
Additional information ................................................................ 33  
Squelch ..................................................................................... 34  
Specifications ................................................................................. 35  
Connector assignment ........................................................... 36  
Accessories .............................................................................. 36  
Thank you for choosing Sennheiser!  
We have designed this product to give you reliable operation  
over many years. Over sixty years of accumulated expertise in  
the design and manufacture of high-quality electro-acoustic  
equipment have made Sennheiser a world-leading company in  
this field.  
Please take a few moments to read these instructions carefully,  
as we want you to enjoy your new Sennheiser products quickly  
and to the fullest.  
 
Safety instructions  
y Please read these instructions carefully and completely  
before using the receiver.  
y Make these instructions easily accessible to all users at all  
times. Always include these instructions when passing the  
receiver on to third parties.  
y Never open electronic units! If units are opened by customers  
in breach of this instruction, the warranty becomes null and  
void.  
y Water entering the housing of the receiver can cause a short-  
circuit and damage the electronics. Protect the receiver from  
damp and wet. Only use a slightly damp cloth to clean the  
receiver.  
y Follow the safety instructions on the receiver.  
Attention! High volume!  
This is  
a
professional transmission system.  
Commercial use is subject to the safety-at-work  
regulations. Sennheiser, as the manufacturer, is  
therefore obliged to expressly point out possible  
health risks arising from use.  
This system is capable of producing sound pressure exceeding  
85 dB(A). 85 dB(A) is the sound pressure corresponding to the  
maximum permissible volume which is by law (in some  
countries) allowed to affect your hearing for the duration of a  
working day. It is used as a basis according to the specifications  
of industrial medicine. Higher volumes or longer durations can  
damage your hearing. At higher volumes, the duration must be  
shortened in order to prevent damage. The following are sure  
signs that you have been subjected to excessive noise for too  
long a time:  
y You can hear ringing or whistling sounds in your ears.  
y You have the impression (even for a short time only) that  
you can no longer hear high notes.  
6
 
Intended use of the receiver  
Intended use includes  
y having read these instructions especially the chapter “Safety  
instructions”.  
y using the receiver within the operating conditions as  
described in these instructions.  
Improper use  
Improper use is when you use the receiver other than described  
in these instructions or when you use the receiver under  
operating conditions different from those described in these  
instructions.  
Delivery includes  
y 1 EK 3253 bodypack receiver  
y 2 batteries  
y 1 pair of IE 4 earphones  
y Instructions for use  
7
 
EK 3253 bodypack receiver  
With the wireless in-ear monitoring system, consisting of the  
SR 3254 or SR 3256 stereo transmitter and the EK 3253  
bodypack receiver, musicians, video and sound amateurs,  
reporters/broadcasters, etc. can directly monitor the received  
sound signals without troublesome cables or monitor speakers  
being required. In addition, the system can also be used for any  
application where talkback signals are to be transmitted.  
The system has superb audio quality with an increased signal-  
to-noise ratio and dynamic range due to the inclusion of  
Sennheiser’s HDX noise reduction system.  
The EK 3253 bodypack receiver has the following features:  
y Easy to use  
y FOCUS function for individual audio mix  
y Pilot tone squelch control (during stereo operation)  
y Receiving frequencies tunable in steps of 5 kHz  
y Scan function for scanning the channel banks for free  
channels  
The channel bank system  
The EK 3253 receiver is available in five UHF frequency ranges:  
Range A:  
Range B:  
Range C:  
Range D:  
Range E:  
518 to 554 MHz  
626 to 662 MHz  
740 to 776 MHz  
786 to 822 MHz  
830 to 866 MHz  
The receiver has two channel banks with up to 16 switchable  
channels each. The channels of the channel bank “F“ (fixed  
bank) have been factory-preset to customer-specific receiving  
frequencies. These frequencies cannot be changed.  
The channel bank “U” (user bank) allows you to freely select  
and store frequencies.  
Recommended transmitters  
y SR 3254/SR 3256  
8
 
The operating controls  
·
»
³
Ƹ
¹
¸
¿
´
²
º
¾
µ
³ Headphone output  
(PHONES), 3.5 mm jack  
socket  
̆/̄ rocker button  
(UP/DOWN)  
º Battery compartment  
· Antenna  
¾ Battery compartment  
» Red LED for operation and  
battery status indication  
(LOW BAT/ON)  
cover  
µ Unlocking button  
¸ ESC button  
¹ LC display  
¿ Green LED for RF signal  
indication (RF)  
Ƹ On/off/volume control  
´ Charging contacts  
² SET button  
9
 
Indications and displays  
The LC display  
ቩ ቪ  
Alphanumeric display  
“B.CH“ – appears when the channel bank and the channel  
number are displayed  
“MHz“ – appears when the frequency is displayed  
4-step battery status display  
Lock mode icon (lock mode is activated)  
“PILOT” display (pilot tone evaluation is activated)  
“MUTE” display (audio output is muted)  
7-step level display for audio signal “AF”  
7-step level display for RF signal “RF”  
Operation and battery status indication  
The red LED (LOW BAT/ON) provides information on the  
current operating state of the receiver:  
»
10  
 
Red LED lit up:  
The receiver is switched on and the capacity  
of the batteries/accupack is sufficient.  
Red LED flashing: The batteries are/the accupack is going flat  
(LOW BAT)!  
In addition, the 4-step battery status display on the display  
panel provides information on the remaining battery/accupack  
capacity:  
3 segments:  
capacity approx. 100 %  
capacity approx. 70 %  
capacity approx. 30 %  
LOW BAT  
2 segments:  
1 segment:  
Battery icon flashing:  
Modulation display of the received transmitter  
The level display for audio signal “AF” shows the modulation of  
the received transmitter. When the transmitter’s audio input  
level is excessively high, the level display for audio signal “AF”  
shows full deflection.  
“MUTE” display  
The “MUTE” display appears on the display panel when the  
RF signal of the received transmitter is too weak.  
11  
 
“PILOT” display  
The “PILOT” display appears on the display panel when the  
pilot tone evaluation is activated (see “Activating/deactivating  
RF signal indication  
The level display for RF signal “RF” shows the strength of the  
received RF signal. In addition, the green LED (RF) ¿ at the  
front of the receiver lights up when an RF signal is being  
received.  
¿
However, the green LED (RF) does not light up when the audio  
output is muted because  
y the RF signal of the received transmitter is too weak,  
y the transmitter is set to mono operation and the receiver’s  
pilot tone evaluation is deactivated.  
Display backlighting  
After pressing a button, the display remains backlit for approx.  
10 seconds.  
12  
 
Preparing the receiver for use  
Inserting and replacing the batteries  
For powering the EK 3253 receiver, two 1.5 V AA size batteries  
are required.  
̈ Press the two unlocking buttons µ and open the battery  
compartment cover .  
¾ µ  
¾
´
̈ Insert the two batteries as shown in the diagram above.  
Please observe correct polarity when inserting the  
batteries.  
̈ Close the battery compartment. The battery compartment  
cover locks into place with an audible click.  
13  
 
Inserting and charging the accupack  
The receiver can also be powered via the rechargeable  
Sennheiser BA 2015 accupack. Insert the accupack into the  
battery compartment as described above.  
The receiver has two charging contacts and a sensing  
contact on its short sides. The accupack can be recharged while  
remaining in the receiver. Insert the receiver into the L 2015  
charger (see operating manual of the L 2015 charger).  
Note:  
For accupack operation of the receiver, only use the  
BA 2015 accupack in order to ensure optimum operational  
reliability. Batteries and rechargeable battery cells have  
different discharging curves. The receiver is able to identify  
the BA 2015 accupack and to use its capacity to the full.  
Individual rechargeable battery cells will not be identified  
as accupacks.  
14  
 
Using the receiver  
Switching the receiver on/off  
̈ To switch the receiver on, turn the volume control Ƹ to the  
right until it clicks. The red LED lights up.  
Ƹ
»
̈ To switch the receiver off, turn the volume control Ƹ to the  
left until it clicks. The red LED goes off.  
Note:  
y The receiver has a short switch-on delay.  
y Remove the batteries or the accupack when the receiver  
will not be used for extended periods of time.  
Connecting the headphones  
Attention! High volume!  
Even short exposure to high volume levels can damage your  
hearing! Set the volume for the connected headphones to  
the minimum before putting the headphones on. Do not  
listen at higher volume levels than with loudspeakers.  
15  
 
̈
Connect the supplied earphones or any Sennheiser stereo  
headphones with 3.5 mm stereo jack plug to the  
headphone output (PHONES) .  
³
·
̈
First, set the volume control to the lowest volume by  
turning it to the left as far as possible. Then gradually turn  
up the volume.  
Adjusting the volume  
̈
Use the volume control Ƹ to adjust the volume of the con-  
nected headphones.  
Ƹ
16  
 
Adjusting the balance/FOCUS  
During stereo operation – and provided that the standard  
display is shown – the ̆/̄ rocker button serves to adjust  
the balance between the left and right stereo signal.  
During FOCUS operation, the ̆/̄ rocker button serves to  
adjust the relative levels of the two separate channels in the  
page 27).  
Activating/deactivating the lock mode  
The receiver has a lock mode that can be activated or  
deactivated via the operating menu (see “Activating/  
Attaching the receiver to clothing  
The receiver is attached to clothing (e.g. belt, waistband) with  
the supplied belt clip.  
The clip is detachable so that you can also attach the receiver  
with the antenna pointing downwards. To do so, withdraw the  
clip from its fixing points and attach it the other way round.  
17  
 
 
The operating menu  
The buttons  
Buttons Mode  
To ...  
SET  
Standard  
display  
get into the operating menu  
Operating get into the setting mode of the  
menu  
selected menu  
Setting  
mode  
store the settings and return to the  
previous menu level  
̆/̄  
Standard  
display  
In stereo operation:  
adjust the balance between the left  
and right stereo signal  
In FOCUS operation:  
adjust the relative levels of the two  
separate channels in the mixed  
Operating change to the previous menu (̆) or  
menu  
change to the next menu (̄)  
Setting  
mode  
adjust the setting of the selected  
menu: option (̆/̄)  
Standard  
display  
without function  
ESC  
Operating cancel the entry and return to the  
menu  
standard display  
Setting  
mode  
cancel the entry and return to the  
standard display  
18  
 
Overview of menus  
Display  
CHAN  
TUNE  
Function of the menu  
Selecting a channel  
Setting a receiving frequency for the  
channel bank “U” (user bank)  
SCAN  
Scanning the channel bank for free channels  
Adjusting the squelch threshold  
Stereo/FOCUS selection  
SQELCH  
ST-FOC  
LTD  
Limiting the volume at the headphone output  
Activating/deactivating the frequency boost  
Selecting the standard display  
HI-BST  
DISPLY  
NAME  
RESET  
PILOT  
Entering a name  
Loading the factory-preset default settings  
Activating/deactivating the pilot tone  
evaluation  
LOCK  
EXIT  
Activating/deactivating the lock mode  
Exiting the operating menu and returning to  
the standard display  
19  
 
Working with the operating menu  
By way of example of the “TUNE” menu, this section describes  
how to use the operating menu.  
After switching on the receiver, the standard display is shown  
on the display panel.  
Getting into the operating menu  
̈
Press the SET button to get from the standard display into  
the operating menu.  
The last menu selected flashes on the display.  
Selecting a menu  
̈
̈
Press the ̆/̄ rocker button to select a menu.  
Press the SET button to get into the setting mode of the  
selected menu. The current setting that can be adjusted  
flashes on the display.  
20  
 
Adjusting a setting  
̈ Press the ̆/̄ rocker button to adjust the setting.  
By briefly pressing the ̆/̄ rocker button, the display jumps  
either forwards or backwards to the next setting. In the  
CHAN”, “TUNE”, “NAME” and “BAL/FOC” menu, the ̆/̄  
rocker button features a “fast search” function. If you hold  
down a button, the display cycles continuously. The “fast  
search” function allows you to get fast and easily to your  
desired setting.  
The new setting flashes on the display until it is stored.  
Storing a setting  
̈ Press the SET button to store the setting. “STORED”  
appears on the display, indicating that the setting has been  
stored. The display then returns to the previous menu level.  
With most menus, new settings become effective  
immediately without having to be stored. An exception is  
the “RESET” menu. With this menu, new settings only  
become effective after they have been stored (“STORED”  
appears on the display, indicating that the setting has been  
stored).  
Exiting the operating menu  
̈ Select the “EXIT” menu to exit the operating menu and to  
return to the standard display.  
21  
 
The operating menu of the receiver  
EXIT  
SET  
SET  
B.CH  
B.CH  
CHAN  
F.01  
Current channel or current  
frequency  
F.02  
Changing the channel  
Channel U.01 …  
U.16  
Selects the channel  
STORED  
Press SET  
for 1 sec.  
B.CH  
TUNE  
U.01  
U.02  
Setting the frequency  
for channel bank “U”  
Channel  
Current channel  
Selects the channel  
SET  
SET  
MHz  
530.100  
530.050  
MHz  
Receiving frequency  
in steps of 5 kHz  
Stores the setting  
Current frequency  
im  
SET  
STORED  
eingestellten Kanal  
CLEAR  
START  
SCAN  
/
:
CLEAR, START  
Scanning  
for free channels  
Start scan = START  
SET: Scans for free  
channels  
09 CH FREE  
SET  
Delete result = CLEAR  
SET: Releases locked  
channels  
STORED  
SQ LO  
SET  
SQ HI  
SQELCH  
Setting the squelch  
threshold  
Current squelch  
threshold  
/
:
LO, MID, HI  
SET: Stores the setting  
STORED  
SET  
SET  
STEREO  
FOCUS  
ST--FOC  
Switching between stereo  
and FOCUS operation  
Current setting  
/
:
Stereo, Focus  
SET: Stores the setting  
STORED  
LTD.OFF  
Limiter activated or  
deactivated  
LTD. ON  
LTD  
Limiting the volume at  
the headphone output  
Stores the setting  
STORED  
SET  
HI--BST  
Boosting the  
AF frequency response  
HB.OFF  
HB. ON  
Frequency boost  
activated or deactivated  
Stores the setting  
STORED  
DISPLAY  
22  
 
HI-BST  
SET  
CHAN  
Current standard  
display  
NAME  
DISPLY  
Switching between the  
standard displays  
/
:
FREQ, NAME,  
CHAN  
SET: Stores the setting  
STORED  
SET  
NAME  
VOCAL  
GUCAL  
Assigning the receiver  
a name  
Current receiver name  
/
:
Name (6 characters)  
Letters w/o pronounciation  
marks, numbers from 0…9,  
special characters, spaces  
SET: next character,  
then store  
STORED  
SET  
RST. OK  
RST. NO  
RESET  
Security check  
Loading the factory-  
preset default values  
"reset" = OK  
SET: Receiver loads  
factory-preset default  
settings, (only pilot tone  
setting is kept),  
receiver is restarted,  
standard display appears  
"reset" = NO  
SET: Reset is cancelled  
SET  
PLT. ON  
PLT. OFF  
PILOT  
Activating/deactivating  
the pilot tone evaluation  
Pilot tone evaluation  
activated or deactivated  
Stores the setting  
STORED  
LOC.OFF  
SET  
LOC. ON  
LOCK  
Lock mode activated or  
deactivated  
Activating/deactivating  
the lock mode  
"Lock mode" = ON  
SET: Stores the setting  
(“STORED”), returns to  
standard display  
"Lock mode" = OFF  
STORED  
Stores the setting  
SET  
EXIT  
Exiting the operating  
menu  
CHAN  
Stereo  
selection  
BAL.L15  
Current balance setting  
BAL.-0-  
/
:
BAL.L 1...15,  
BAL.--0--, BAL.R 1...15  
Focus  
selection  
FOC.L15  
Current Focus setting  
FOC.-0-  
Adjusting the balance/  
Focus  
SET  
23  
 
Adjustment tips for the operating  
menu  
Selecting a channel – CHAN  
Via the “CHAN” menu, you can switch between the channels in the  
channel banks “F” (fixed bank) or “U” (user bank). The channel  
bank “F“ has up to 16 switchable channels that are factory-preset  
to customer-specific receiving frequencies. These frequencies  
cannot be changed.  
The channel bank “U” also has up to 16 switchable channels to store  
frequencies that are freely selectable within the preset frequency  
range.  
Always set the transmitter and the receiver of a transmission link to  
the same channel. After scanning the channel bank (see “Scanning  
free channels are displayed. Set the transmitter to one of the free  
channels.  
Selecting the frequencies to be stored in the  
channel bank “U” – TUNE  
Via the “TUNE” menu, you can freely select the frequencies to be  
stored in the channel bank “U” (user bank).  
̈
Press the SET button to get into the setting mode of the “TUNE”  
menu.  
Note:  
When pressing the SET button for one second, you can use the  
̆/̄ rocker button to select a different channel for which you  
can then change the frequency.  
When you have selected the channel bank “F” and then select the  
TUNE” menu, the receiver automatically switches to channel 01 of  
the channel bank “U”  
̈
Press the ̆/̄ rocker button to select the desired receiving  
frequency. Receiving frequencies are tunable in 5-kHz steps  
within a switching bandwidth of 36 MHz max.  
24  
 
̈ Press the SET button to confirm your selection. The receiver  
changes immediately to the new frequency.  
Scanning the channel bank for free channels –  
SCAN  
Before putting one or several transmission links into operation,  
you should scan the channel bank for free channels.  
Starting the scan and storing the scan result  
̈ Before starting the scan, switch all transmitters of your  
system off, since channels used by switched-on  
transmitters will not be displayed as “free channels”.  
̈ Select the “SCAN” menu.  
̈ Select “START” and confirm your selection by pressing the  
SET button. After the scan is completed, the number of free  
channels is displayed. Pressing the SET button once more  
will store the scan result and lock all channels that are used  
or subject to interference.  
Releasing locked channels  
̈ Select the “SCAN” menu.  
̈ Select “CLEAR” and confirm your selection by pressing the  
SET button. All channels can now be selected again.  
Adjusting the squelch threshold – SQELCH  
The receiver is equipped with a squelch that can be adjusted via  
the “SQELCH” menu (see “Squelch” on page 34). The squelch  
eliminates annoying noise when the transmitter is switched  
off. It also suppresses sudden noise when there is no longer  
sufficient transmitter power received by the receiver.  
25  
 
   
Note:  
Before adjusting the squelch threshold to a different  
setting, use the volume control Ƹ to set the volume for the  
connected headphones to the minimum.  
Ƹ
There are three possible squelch setting:  
y LO = low  
y MID = middle  
y HI = high  
High volume levels can damage your hearing!  
CAUTION!  
When in the setting mode of the “SQELCH”  
menu, pressing the ̄ button for more than  
three seconds will switch off the squelch.  
“SQ.OFF” appears on the display. If no RF signal  
is being received, hissing noise will occur.  
̈
This setting is for test purposes only and  
must only be used by service technicians.  
Selecting the setting “LO” reduces the squelch threshold,  
selecting the setting “HI” increases the squelch threshold.  
Adjust the squelch threshold – with the transmitter switched  
off – to the lowest possible setting that suppresses hissing  
noise.  
Important note:  
y If the squelch threshold is adjusted too high, the trans-  
mission range will be reduced. Therefore, always adjust  
the squelch threshold to the lowest possible setting.  
26  
 
S
tereo/FOCUS selection – ST-FOC  
Via the “ST-FOC” menu, you can switch between stereo and  
FOCUS operation.  
In both operating modes, the corresponding transmitter has to  
be set to stereo operation.  
When the receiver is set to stereo operation, the left-right  
signals are available as usual.  
When the receiver is set to FOCUS operation, the left-right  
signals are mixed and are available as a mono signal in both  
headphone channels. With the ̆/̄ rocker button you can  
adjust the relative levels of the two separate channels in the  
page 17).  
Limiting the volume at the headphone output –  
LTD  
Via the “LTD” menu, you can switch the limiter on or off. With  
the limiter switched on, the volume at the headphone output  
will be reduced.  
Activating/deactivating the frequency boost –  
HI-BST  
Via the “HI-BST” menu, you can boost the AF frequency  
response at 10 kHz by approx. 6 dB. As a result, headphones  
with magnetic transducers sound better.  
27  
 
 
Selecting the standard display – DISLPY  
Via the “DISPLY” menu, you can select the standard display:  
Selectable standard display  
Contents of standard  
display  
“FREQ”  
“NAME”  
“CHAN”  
Entering a name – NAME  
Via the “NAME” menu, you can enter a freely selectable name  
for the receiver. You can, for example, enter the name of the  
performer for whom the adjustments have been made.  
This name can be displayed on the standard display and can  
consist of up to six characters such as:  
y letters (without pronounciation marks),  
y numbers from 0 to 9,  
y special characters and spaces.  
To enter a name, proceed as follows:  
̈
Press the SET button to get into the setting mode of the  
NAME” menu. The first segment starts flashing on the  
display.  
̈
With the ̆/̄ rocker button you can now select a  
character. By briefly pressing a button, the display jumps  
either forwards or backwards to the next character. If you  
hold down a button, the display starts cycling continuously.  
28  
 
̈ Press the SET button to change to the next segment and  
select the next character.  
̈ Have you entered the name completely? Press the SET  
button to store your setting and to return to the previous  
menu level.  
Loading the factory-preset default settings –  
RESET  
Via the “RESET” menu, you can load the factory-preset default  
settings. Only the selected setting for the pilot tone remains  
unchanged. After the reset, the receiver is restarted and the  
standard display is shown on the display panel.  
Activating/deactivating the pilot tone  
evaluation – PILOT  
Via the “PILOT” menu, you can activate or deactivate the pilot  
tone evaluation.  
The pilot tone has two functions:  
y Stereo identification  
y Squelch control  
When used with a suitable transmitter which adds a pilot tone  
to the transmitted stereo signal, the receiver can evaluate this  
pilot tone. When the transmitter is set to mono operation, you  
have to deactivate the pilot tone evaluation on the receiver.  
Activating/deactivating the lock mode – LOCK  
Via the “LOCK” menu, you can activate or deactivate the lock  
mode.  
The lock mode prevents that the receiver is accidentally  
programmed during operation. However, the volume can be  
adjusted at any time.  
29  
 
   
¾
µ
²
̈
̈
̈
̈
Press the two unlocking buttons µ and open the battery  
compartment cover .  
Press the SET button ². “LOC.ON” and the lock mode icon  
appear on the display.  
Press the ̆/̄ rocker button . “LOC.OFF” flashes on the  
display.  
Confirm your selection by pressing the SET button ².  
“STORED” appears on the display and the lock mode is  
deactivated.  
Exiting the operating menu – EXIT  
Via the “EXIT” menu, you can exit the operating menu and  
return to the standard display.  
30  
 
If problems occur ...  
Error checklist  
Problem  
Possible cause  
Possible solution  
No  
operation  
indication  
Batteries are flat or  
accupack is flat  
Replace the batteries  
or recharge the  
accupack  
No RF signal Transmitter and  
Set transmitter and  
receiver are not on the receiver to the same  
same channel  
channel  
Transmitter is out of  
range  
Check the squelch  
threshold setting  
or change the position  
of the transmitting  
antenna  
RF signal  
available,  
no audio  
signal,  
“MUTE”  
display  
appears on  
the display  
panel  
Receiver’s squelch  
See “Adjusting the  
threshold is adjusted squelch threshold –  
Transmitter does not Set the transmitter to  
transmit a pilot tone  
stereo operation or  
deactivate the pilot  
tone evaluation on the  
receiver  
No access to During scanning, an RF See “Scanning the  
a certain  
channel  
signal has been  
detected on this  
channel and the  
channel has been  
locked  
channels – SCAN” on  
If problems occur that are not listed in the above table or if the  
problems cannot be solved with the proposed solutions, please  
contact your local Sennheiser agent for assistance.  
31  
 
Recommendations and tips  
... for the receiver  
y The antenna must not be in direct contact with the body.  
... for optimum reception  
y Reception range depends to a large extent on location. There  
should be a “free line of sight” between transmitting and  
receiving antennas.  
y To avoid overmodulating the receiver, observe a minimum  
distance of 5 m between transmitting and receiving antennas.  
... for multi-channel operation  
y When operating a multi-channel system, make sure to only  
use intermodulation-free frequencies.  
Maintenance and care  
Water can damage the electronics of the  
receiver!  
CAUTION!  
Water entering the housing of the receiver can  
cause  
a
short-circuit and damage the  
electronics.  
̈
Only use a slightly damp cloth to clean the  
receiver.  
̈
If necessary, you can clean the receiver with a slightly damp  
cloth. Do not use any cleansing agents or solvents.  
32  
 
Additional information  
HDX noise reduction  
RF link  
Inherent  
noise  
of the  
RF link  
Receiver  
Transmitter  
Progress you can hear:  
The product family is equipped with HDX, the Sennheiser noise  
reduction system that reduces RF interference. It increases the  
signal-to-noise ratio in wireless audio transmission to more  
than 90 dB.  
HDX is a wideband compander system which compresses the  
audio signal in the transmitter in a 2:1 ratio (related to dB) to  
lift it above the inherent noise floor of the RF link. In the  
receiver the signal is expanded in an identical and opposite way  
in a 1:2 ratio to restore the original signal, at the same time  
reducing the RF noise to below the noise floor of the receiver.  
HDX has been specially developed for high quality radio  
microphone systems.  
Note:  
Only transmitters and receivers that are equipped with HDX  
can work correctly with each other. If non HDX equipment  
was mixed with HDX, the dynamic range would be  
drastically reduced and the transmission would sound  
blunt and flat.  
33  
 
Squelch  
Pilot tone squelch  
When set to stereo operation, the transmitter adds a 19-kHz  
pilot tone to the audio signal. The receiver checks incoming  
audio signals to see if the pilot tone is present. In the absence  
of the 19-kHz signal, the receiver’s audio output will remain  
muted, even if a strong RF signal is present.  
This prevents strong interfering signals from causing hissing  
noise in the receiver when the transmitter is switched off.  
Field strength-dependent squelch  
Depending on the strength of the received RF signal, the  
receiver’s audio output is opened or muted. Via the “SQELCH”  
menu of the receiver, the squelch threshold can be adjusted in  
three steps (LO, MID, HI).  
34  
 
 
Specifications  
EK 3253 bodypack receiver  
RF characteristics  
Modulation  
FM stereo  
Frequency ranges  
518–554, 626–662,  
740–776, 786–822,  
830–866 MHz  
Receiving frequencies  
1 channel bank with up to 16  
factory-preset channels  
1 channel bank with up to 16  
freely selectable channels  
(frequencies tunable in steps  
of 5 kHz)  
Switching bandwidth  
36 MHz  
Nominal/peak deviation  
24 kHz / 48 kHz  
19 kHz / 5 kHz  
Pilot tone  
(frequency/deviation)  
Frequency stability  
20 ppm (-10 to +55°C)  
Sensitivity  
(with HDX, peak deviation)  
typ. 1.5 μV at 52 dBA  
S/N  
rms  
Adjacent channel rejection  
Intermodulation attenuation  
Blocking  
typ. 75 dB  
typ. 75 dB  
typ. 90 dB  
4 steps: OFF  
Squelch  
LO: 5 dBμV  
MID: 15 dBμV  
HI: 25 dBμV  
AF characteristics  
Noise reduction system  
AF frequency response  
Sennheiser HDX  
40–15,000 Hz  
Signal-to-noise ratio  
(1 mV, peak deviation)  
91 dB(A)  
THD (at nom. deviation, 1 kHz)  
Headphone output  
0.9 %  
3.5 mm jack socket  
35  
 
AF output power (at peak  
2 x 100 mW at 32 Ω  
deviation, 1 kHz ) PHONES  
AF  
Overall unit  
Temperature range  
Power supply  
-10 °C to +55 °C  
2 AA size batteries, 1.5 V  
2.4 V  
Nominal voltage  
Power consumption  
approx. 190 mA  
250 μA  
Power consumption with  
switched-off receiver  
Operating time  
(with batteries)  
6–10 hrs  
(depending on volume)  
Operating time  
6–10 hrs  
(with BA 2015 accupack)  
(depending on volume)  
Dimensions in mm  
Weight (incl. batteries)  
Type approval  
82 x 64 x 24  
approx. 200 g  
Canada: RSS-123  
IC: 2099A-SREK3K  
EU:  
ETSI EN 300 454-1/-2  
IE 4 earphones  
Frequency response  
Max. sound pressure level  
Impedance  
40–20,000 Hz  
118 dB SPL  
32 Ω  
Connector assignment  
3.5 mm jack plug  
for headphone output  
Accessories  
IE 4:  
Earphones  
IES 4:  
BA 2015:  
L 2015:  
1 pair of ear sleeves for IE 4 earphones  
Accupack  
Charger for BA 2015 accupack  
36  
 
Warranty regulations  
The guarantee period for this Sennheiser product is 24 months  
from the date of purchase. Excluded are accessory items,  
rechargeable or disposable batteries that are delivered with  
the product; due to their characteristics these products have a  
shorter service life that is principally dependent on the  
individual frequency of use.  
The guarantee period starts from the date of original purchase.  
For this reason, we recommend that the sales receipt be  
retained as proof of purchase. Without this proof (which is  
checked by the responsible Sennheiser service partner) you will  
not be reimbursed for any repairs that are carried out.  
Depending on our choice, guarantee service comprises, free of  
charge, the removal of material and manufacturing defects  
through repair or replacement of either individual parts or the  
entire device. Inappropriate usage (e.g. operating faults,  
mechanical damages, incorrect operating voltage), wear and  
tear, force majeure and defects which were known at the time  
of purchase are excluded from guarantee claims. The guarantee  
is void if the product is manipulated by non-authorised persons  
or repair stations.  
In the case of a claim under the terms of this guarantee, send  
the device, including accessories and sales receipt, to the  
responsible service partner. To minimise the risk of transport  
damage, we recommend that the original packaging is used.  
Your legal rights against the seller, resulting from the contract  
of sale, are not affected by this guarantee.  
The guarantee can be claimed in all countries outside the U.S.  
provided that no national law limits our terms of guarantee.  
EC Declaration  
of Conformity  
This equipment is in compliance with the essential  
requirements and other relevant provisions of Directives 1999/  
5/EC, 89/336/EC or 73/23/EC. The declaration is available on  
Before putting the device into operation, please observe the  
respective country-specific regulations!  
37  
 
Sennheiser electronic GmbH & Co. KG  
30900 Wedemark, Germany  
Phone +49 (5130) 600 0  
Fax +49 (5130) 600 300  
Printed in Germany  
Publ. 08/05  
512765/A01  
 

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