bhi 37-033 Desktop MKII Amplified DSP Noise Cancelling Base Station Speaker User Manual
- June 6, 2024
- bhi
Table of Contents
bhi 37-033 Desktop MKII Amplified DSP Noise Cancelling Base Station Speaker
User Manual
Important Information
Copyright
This publication, including all photographs and illustrations is protected
under international copyright laws, with all rights reserved. Neither this
manual, nor any of the material within, may be copied or reproduced without
the written consent of bhi Ltd.
Disclaimer
The information in this document is subject to change without notice. bhi Ltd
makes no representations or warranties with respect to the contents hereof and
specifically disclaims any implied warranties of merchantability or fitness
for any particular purpose.Furthermore, bhi Ltd reserves the right to revise
this publication and to make changes from time to time in the content hereof
without obligation of bhi Ltd to notify any person of such
revision or changes.
Packing List
The bhi DESKTOP MKII is shipped with the following items:
- DESKTOP MKII DSP noise cancelling speaker
- 3.5mm mono plug audio lead
- Speaker mounting bracket
- Fused DC power lead (1030-FPL with 2.1mm power plug centre +ve)
- User manual
- Customer feedback card
Introduction
The bhi DESKTOP MKII speaker is a microprocessor controlled amplified DSP
noise cancelling base station speaker that removes noise and interference to
improve the quality of speech in noisy radio and voice communications. It is
suitable for use in base station applications where background noise and
interference mean that you cannot clearly hear what is being said. The speaker
will enable the user to listen and concentrate “stressfree”. Suitable
applications where the speaker will be of great benefit are: amateur radio,
two-way radios, HF radios, marine communications, scanners, taxi base stations
etc. The DESKTOP MKII speaker incorporates the latest bhi Digital Signal
Processing technology (DSP) which can differentiate the speech signal from the
unwanted background noise and interference. The DESKTOP MKII speaker has
separate line level and speaker level inputs allowing it to be used with a
wide range of radio and audio equipment including SDR radios. There is also a
3.5mm headphone socket on the side of the speaker. The DESKTOP MKII speaker
comprises a 4” bass driver and a 1” tweeter unit, with an amplified bhi DSP
noise cancelling unit capable of producing up to 10Watts audio (peak). The
speaker requires an audio input signal of between 160mV and 1.6mV peak-to-peak
for line level, and 350mV and 3.5V peak-to-peak for speaker level input, and
requires a DC power supply of between 12 and 18 Volts (2.5A peak). The unit is
supplied with a quality moulded 3.5mm mono jack plug lead terminated with 4mm
banana plugs, a 2.1mm fused DC power lead and a user manual. Accessories are
available see section 10.
Note: The speaker is mainly designed for speech signals and is not really
suitable for music. CW signals will be improved when using the speaker.
bhi DSP Noise Cancellation
The bhi DSP processes the incoming signal and differentiates the speech from the noise. The unwanted noise and interference is then attenuated to leave only the speech. The following diagrams are taken from actual audio signals and illustrate how the signal is processed.
Original signal.
Speech with a lot of background noise
Processed speech.
Speech with reduced noise
The DESKTOP MKII speaker includes the latest bhi DSP noise cancelling technology which means that the processed audio is clearer and more intelligible, especially when working with weak signals. When you switch on the DESKTOP MKII speaker you may hear an audio noise just after the start-up beeps. This is normal and only happens when powering up the speaker and is nothing to be concerned about. It will not affect the operation and your enjoyment of the speaker.
Installation
The speaker is supplied with a mounting bracket that can be left on in case of permanent fixing, or removed altogether depending on personal choice.
Connections to your radio equipment can be made via audio sockets on the rear of the speaker using either the red/black speaker level terminals (audio lead supplied) or the 3.5mm stereo line level socket (requires an ALD-007 stereo audio lead not supplied).
Set the volume on your radio or audio source to the normal listening level prior to using the DESKTOP MKII speaker.
Connect the audio lead to your radio, and then connect the other end to the relevant input connection on the rear of the DESKTOP MKII speaker.
Connect the 1030-FPL fused DC power lead supplied to a power supply capable of providing 12 – 18VDC @ 2A (2.5A peak), or connect a suitable DC power supply. The centre pin of the 2.1mm power connector is positive, and the red lead or the black leadwith the white stripe is positive.
DESKTOP MKII controls:
Speaker Operation
Once installed and connected, switch the power on. The LED behind the grille
will illuminate either green or red, and a rising audio tone will be heard.
You should hear audio through the speaker now. Turning the “Volume” control
clockwise or anticlockwise will increase or decrease the volume level, at the
same time you will hear a low frequency audio sound through the speaker when
the volume control is turned. The volume of this audio “blip“ sound will vary
as you rotate the volume level control knob. Momentarily press the “Volume”
control knob to turn the speaker on and off. When switching back on the
speaker will go to the last stored setting when switched off. Pressing the
filter level control knob switches the DSP noise cancelling filter on and off,
a red LED indicates filter off, and a green LED filter on. The filter level is
simply changed by turning the filter level control knob clockwise or
anticlockwise. There are 8 filter levels indicated by 8 different frequency
tones. The lowest tone indicates the lowest filter level and the highest tone
indicates the maximum filter level. You can easily adjust the filter level in
“real time” to suit the current operating conditions.
Note: If the power is on and the DSP is switched off (red LED), the audio
passes through the DSP filter, but without any signal processing.
Speaker Tone Level Volume Adjustment
There are four volume settings for the audible volume “blips” and filter level tones; off, low, medium and high. To change these audible tones to your preferred setting press and hold the volume control until you hear an audible tone and the LED flashes continuously. Release the volume control to select the current level, otherwise press and hold the volume knob again until you hear the next tone level (Note that with the audio tone in position off, only the LED will flash when the volume control is pressed).
Sleep Mode
The DESKTOP MKII speaker has a built-in sleep mode feature whereby it will be
put into standby mode when there is no signal present after approx 60 minutes.
This is indicated by falling tones. In this mode the speaker only draws a
small amount of current (approx 10mA). The speaker will be woken up if a
signal is received whilst in sleep mode. This is indicated by rising tones. If
the speaker is switched off manually by pressing the volume control knob
momentarily with power still applied, the sleep mode is inactive and to wake
the speaker up in this instance, press the volume control knob again and the
speaker will switch on, with the last known settings restored.
The sleep mode function can be turned off and on by pressing and holding the
filter level control knob for approx 4 seconds. Falling tones indicate that
the sleep mode is enabled, and rising tones indicate that the sleep mode is
disabled.
Input Overload
The DESKTOP MKII has audio input overload protection for both the line level and speaker level inputs. If the signal peaks go over the limits set out in the specification, the LED will change red and flash 3 times. If the audio level is constantly above the overload threshold, the red LED will flash continuously. Reducing the audio input level will bring the speaker back in to normal operation.
Specification
DC Power
Connector type: 2.1mm DC power jack (centre positive)
Input voltage: 12 to 18 Volts DC
Input current: 10mA standby (typical) 125mA active (no signal) 2.5A peak
Line Level Audio Input
Connector type: 3.5mm Mono or Stereo line level
Input voltage range: 160mV to 1.6mV pk-pk
Input impedance: 10kΩ (±2kΩ) nominal
Speaker Level Audio Input
Connector type: 2 x 4mm socket/screw binding posts (mono)
Input voltage range: 350mV to 3.5V pk-pk
Input impedance: 8Ω (±2Ω) nominal
Input power rating: 1.5W max
Audio Output
Speaker Output power: 10W peak (supply voltage of 18V)
Bandwidth: 50Hz to 4.3kHz
Volume levels: 16 levels (3dB steps)
Headphone output: 3.5mm mono or stereo (8 to 64 Ohms)
DSP Noise Cancellation
Levels: 8 levels + off
Noise reduction: 9dB to 35dB
Tone reduction: 4dB to 65dB
Indications
Status LED: Multicolour LED (red, amber, green).
Audio tones: Power-up, power-down, DSP level, volume and memory store.
Controls
Power/Volume: Digital rotary encoder with push function
DSP level Digital: rotary encoder with push function
Physical
Weight (packed): 1.90kg
Dimensions: 200(H) x 150(D) x 160(W) mm
Accessories
PSU12-2A-WW 12V 2A DC world-wide mains plug-in power supply, with centre
+ve 2.1mm DC output connector. This power supply is high quality and very
reliable. It has built in Short, over voltage & over current and over
temperature protection.
Order code ALD-007 3.5mm stereo plug to 3.5mm stereo plug lead 1.2m long,
for use with line level input.
Order code: DESKTOP_FEET – Set of 3 Rubber feet for the DESKTOP MKII
speaker (2 x 16mm and 1 x 6mm). 16mm feet fit next to the front plastic feet
and the 6mm fits onto the metal bracket.
Order code: A-DESKTOP_ACBL – Replacement audio lead
3.5mm mono plug to 2 x 4mm banana plug 1.2 M long.
Order code: Mini Switch – Allows connection of two radios to your DESKTOP
MKII GB8M 8 ohm mono, GB8S 8 ohm stereo. GroundBreaker audio isolation units.
A simple solution to RFI and ground loop audio breakthrough problems
Troubleshooting/FAQs
Speaker doesn’t work at all, no sound from the speaker:
- Check that the power connector on your power supply is suitable for the power socket on the speaker (2.1mm, centre positive).
- Check that you have switched your radio communication equipment on and that you have a signal for the speaker to process. To verify this, remove the audio connector from the external speaker socket on your equipment.
- Check that the DESKTOP MKII Power LED is on.
The speaker works but the noise cancellation doesn’t appear to improve the audio quality of the signal:
- Check that the filter is switched on (green or orange LED).
- Increase the filter level to see if this makes a difference.
- Increase the volume on the audio source.
The volume from the speaker is low and cannot be increased:
- The red and black inputs terminals are designed to work with speaker level signals. Try using the line level input socket using a 3.5mm mono or stereo plug to plug lead (ALD-001 or ALD-007
Sometimes there is a short delay before the noise cancellation is active:
- This is due to the time the DSP takes to start processing the signals. This gives you the opportunity to check that the DSP is not taking out any detail from the signal.
Sometimes I can hear a processing sound in the speakers when no signal is present :
- This is caused by the DSP processor and is normal. When a signal is applied you should not be able to hear this in the speaker.
I can hear speech/sounds in the speaker when I transmit:
- The DESKTOP MKII has been designed to minimise against the effects of stray RF. If you do hear speech or sounds in the speaker on transmit this is probably due to increased levels of RF in your station or an earth loop issue. Follow best practice and carry out the standard checks on your setup. Check for earth problems and ground loops. Make sure that the audio leads and the fused DC power lead are routed away from sources of electronic interference or RF cables. Using a separate 12V DC power supply usually solves this problem. Fit ferrites to the power cables and audio leads at outlined on the bhi website FAQ page (http://www.bhiltd.com/index.php/support/faq.html).
- Purchase one of our GroundBreaker audio isolation units. https://www.bhiltd.com/nois- cancelling/accessories/groundbreaker.html. These small passive units connect to the extension speaker unit of your radio or receiver and your DESKTOP MKII plugs into the Ground Breaker unit. It will isolate the audio and remove any ground loops and should reduce the chance of RFI getting in to the audio path.
bhi Support
Every DESKTOP MKII noise eliminating speaker comes with a 12 month guarantee
against defective materials and workmanship. If you have a problem please
refer to the troubleshooting guide (section 11). If this doesn’t resolve your
problem please contact us. Also see our website FAQs for answers to other
common questions, otherwise most queries can be resolved over the telephone.
If you have any suggestions for improvements
or wish to be informed about new products please complete and return the
customer feedback form.
Weee Statement for correct disposal of this product:
(Applicable in the European Union
and other European countries with separate collection systems).
This marking shown on the product or its literature, indicates that it should
not be disposed of with other household wastes at the end of its working life.
To prevent possible harm to the environment or human health from uncontrolled
waste disposal, please separate this from other types of wastes and recycle it
responsibly to promote the sustainable reuse of material resources. Household
users should contact either the retailer where they purchased this product, or
their local government office, for details of where and how they can take this
item for environmentally safe recycling. Business users should contact their
supplier and checkthe terms and conditions of the purchase contract. This
product should not be mixed with other commercial wastes for disposal.
bhi Ltd
PO Box 318, Burgess Hill, West Sussex, RH15 9NR, England
Telephone: + 44 (0)1444 870333
Email: [email protected] Web: www.bhi-
ltd.com