HELIX DSP PC-Tool Software Operating Instructions Manual

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English
HELIX DSP
PC-Tool
Software
Operating Instructions
Version: June 2011
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System requirements ...................................................................................... 3
Installing the HELIX DSP PC-Tool Software .................................................. 4
Connecting the PP50 DSP to the PC ............................................................. 6
Connecting the C-DSP/P-DSP to the PC ....................................................... 7
Starting the software ....................................................................................... 8
Operating controls ........................................................................................ 10
Description of the main navigation menu ..........................................................10
Channel selection .......................................................................................... 12
Linking channels: .............................................................................................. 12
Channel routing - conguring inputs and outputs .....................................13
Naming inputs: .................................................................................................. 13
Naming outputs: ................................................................................................14
Default settings of the individual channel types: ............................................... 14
Allocating inputs to outputs: .............................................................................. 15
High and low-pass lter settings .................................................................17
Crossover frequency .........................................................................................17
Filter characteristics .......................................................................................... 17
Butterworth Bessel Linkwitz Chebyshev
Self-dene
Slope .................................................................................................................19
Q-factor ............................................................................................................. 21
High-pass and low-pass lter bypass function ..................................................22
Adjusting the output levels .......................................................................... 23
Adjusting the phasing and time alignment ................................................. 24
Adjusting the phase .......................................................................................... 24
Adjusting the time alignment .............................................................................25
Adjusting the equalizer ................................................................................. 27
Graphic 1/3 octave equalizer ............................................................................ 27
PP50 DSP: Parametric lter .............................................................................28
P-DSP: Graphic equalizer ne adjustment function ..........................................29
C-DSP: Graphic equalizer ne adjustment function .........................................30
Measuring frequency responses ................................................................. 31
Measuring equipment ....................................................................................... 31
Measuring microphone
Suitable preampliers
Suitable measurement signals
Measurement software ..................................................................................... 32
Appropriate car radio settings for taking readings
Frequency response readings .......................................................................... 34
Important information about the PP50 DSP ......................................................36
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System requirements
PC system requirements:
At least 1 GHz processor
At least 1 GB RAM main memory
At least 25 MB free hard disk space
1 free USB port for connecting the HELIX Optical & USB Interface
Screen resolution of at least 1024 x 768 pixels or greater
The software has been tested on the following operating systems: Windows XP, Windows Vista (32 bit) and Windows 7.
PP50 DSP system requirements:
You require the HELIX Optical & USB Interface (Part No. H424493)
The relevant SETUP FILE must be installed in the PP50 DSPFile name: “PP50 DSP PC-Tool
Software Rev X.X.af1”Detailed instructions are provided in the PP50 DSP user manual.
Recommended equipment for correct in-vehicle sound measurement:
A device is required to measure frequency responses in order to optimize the PP50 DSP to your vehicle. There are now very reasonably priced systems which operate on a PC/Notebook/Netbook and make it affordable for everyone to achieve reliable readings. The following list of components and software have been tested by us and judged to meet the operational requirements.
Behringer ECM8000 measuring microphone
T-BONE Micplug USB microphone-USB interface with phantom power
Praxis measurement software from Liberty Instruments (freeware)
A music CD containing a pink noise test signal
Further information can be found under “Recommended measuring equipment”, “Measuring fre­quency responses” and “Operating the measurement software”.
P-DSP system requirements:
You require the supplied USB cable
The most recent version of the SETUP FILE must be installed in the P-DSPFile name: P-DSP
PC-Tool Software Rev X.X.af1Detailed instructions are provided in the P-DSP user manual.
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Installing the HELIX DSP PC-Tool software
In order to use the HELIX DSP PC-Tool software you must rst install it on your PC according to
the following instructions:
• Important: Ensure that the processor and/or USB interface are not yet connected to your computer. Only connect the processor and/or USB interface once the software has been suc­cessfully installed on the computer!
• Download the compressed zip-le “HELIX DSP PC-Tool.zip” from the Audiotec Fischer website (www.audiotec-scher.de) The le can be found under the “PC-Tool” tab.
• This zip-le contains a folder called “HELIX DSP PC-Tool”
Unpack the entire folder and save it on your hard driveImportant: This folder must not be sa-
ved to any portable data storage media (e.g. USB stick), but stored on the hard drive.
• If the folder has been successfully unpacked and saved, you will nd it contains the following les, among others:
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• Now double-click on the “USB driver.exe” le to install the USB communication driver. This
driver must be installed before you start the “HELIX DSP PC-Tool Rev X.xx.exe” program!The following window will appear on your PC when you install the USB driver:
Important information:
If this window does not open, please execute the “USB driver.exe” le again.
Installing the driver itself can take up to 1 minute, depending on the PC.
Once the driver has been installed, your PC is ready to use the software.
You may now connect the processor and/or USB interface to a free USB port on your PC.
Information on the PP50 DSP:
The PP50 DSP is supplied as standard with operating software (.af1-le) for adjusting the DSP via the PC-Tool. This le is located in the amplier’s rst memory bank (af1). If communication prob-
lems occur between the PP50 DSP and the interface/PC-Tool, please install the most recent ver-
sion of this le. The le can be found under “Download” under the PC-Tool tab on our homepage. Download the latest version of this le and install the le via a micro SD card. Detailed instructions can be found under “Installing vehicle-specic setups” in the PP50 DSP user manual.
Information on the P-DSP:
The P-DSP is supplied as standard with operating software for conguring the DSP via the PC-
Tool. If communication problems occur between the DSP and the computer, please install the most
recent version of this le. The most recent le can be found under Download under the PC-Tool
tab on our homepage. Detailed instructions on updating the operating software can be found in the P-DSP user manual under “Updating the operating software”.
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Connecting the PP50 DSP to the PC
Connect the red connector of the HELIX Optical & USB Interface to the red “CONTROL IN­PUT” on the PP50 DSP:
Connect the HELIX Optical & USB Interface USB connector to a free USB port on your PC.
Switch on the PP50 DSP via your car radio.
Please note: The interface connector may only be inserted one way up. Do not attempt to force the connector into the “CONTROL IN­PUT” the wrong way up.
Connector to CONTROL INPUT
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Connecting the C-DSP/P-DSP to the PC
Connect the P-DSP directly to the computer using the supplied USB cable.Use the USB port on the P-DSP.
Then insert the USB cable into a free port on the computer.
Now switch on the P-DSP via the radio or the remote input, or via the high level input.
Please note: It is not possible to use the HELIX USB Interface with this processor. Only use the P-DSP USB port to connect to the computer.
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Starting the software
Requirements:
The software and the USB driver have been installed correctly
The PP50 DSP or the C-DSP/P-DSP have been connected correctly to the computer
The most recent version of the operating software has been installed on the PP50 DSP and/or
the C-DSP/P-DSP: instructions can be found in the user manual of the respective device
In order to start the software, please execute the HELIX DSP PC-Tool Rev 1-XX.exe le.
The following window will then appear on your screen:
Now press the “Connect” button. If the PP50 DSP or the C-DSP/P-DSP has been connected cor­rectly, the program user interface will appear within 5-15 seconds:
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The following window will appear if the PP50 DSP or P-DSP is not connected correctly or the USB drive is not installed correctly.
You can still start the software in demo mode. However, it is not possible to make any adjustments in demo mode as the device is not connected.
If you start in demo mode, you then have the option of selecting the user interface for the specic
device. The user interface will open automatically on selection.
Important information about the PP50 DSP:
If you start the software in demo mode, it will not recognize any optical and USB interface sub­sequently connected. It is then necessary to close the program completely and restart it.
• Once the PP50 DSP has been connected to the PC via the HELIX USB Interface, the amplier
will be in PC mode, which deactivates various functions such as the under voltage detector or the automatic switching on/off using High Level or Remote, for example. This status remains active until you close the software again correctly using the “Close” button. It is not enough to
simply break the connection between the PC and the PP50 DSP. If you do this, the amplier
remains in DSP mode for up to an hour and does not switch off, even if you switch off your car radio!
Important information on the P-DSP
Once the P-DSP has been connected to the computer and the PC-Tool started, the P-DSP will be in PC mode. However, it does not remain switched on if the remote input signal or high level signal is switched off. Please ensure that these signals remain switched on during the congu­ration process.
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Reset button:
The Reset button is used to reset all the adjustments made in the software. Pressing this button also resynchronizes the connection between the device and the software.
Important information:
If you accidentally press the Reset button while adjusting the DSP without having saved your se­tup, you will loose all your data.
Save button:
Use the Save button to save an adjusted setup to a specied location on your PC. Clicking on the Save button opens a window which allows you to select the location and give the setup a le name. All setups are automatically given the le extension .afp. The .afp les contain all the PC-
Tool software settings and may only be opened using this software.
The Save button is also used to save the DSP settings as a micro SD card le. To use this func­tion, the amplier/processor must be connected to the computer and all the specic settings al-
ready adjusted (the settings must be saved using the “Store DSP” button). Then right-click on the
Save button. A window will now open which allows you to select the location. On conrmation, the program generates a micro SD card le with the le extension .ac1. This process can take up to a
minute!
This le can then be simply installed via the micro SD card slot on any of the devices of the same
type without the need for the device to be connected to the computer.
Please note: It is then no longer possible to open, and therefore amend, the .ac1 le. We therefore strongly recommend saving the settings as .afp les.
Important information:
Saving the settings as an .afp le does not save them in the actual amplier. Please use the “Store
DSP” button for this.
It is not possible to install the .afp les directly in the amplier/processor via the micro SD card
slot, the PC-Tool must be used instead.
Store DSP button:
The Store DSP button is used to permanently transfer the settings you made in the PC software to
the amplier’s/processor’s internal memory. The amplier then accesses this setup in its memory each time it is switched on. The .afp le is also always saved in the amplier/processor and loaded
from the device when the software opens. Nevertheless, we still recommend that you also always
manually save the .afp le on your computer.
Operating controls
Main navigation menu
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Please note: The PP50 DSP memory is only able to manage a single setup generated using this
software.
The C-DSP/P-DSP memory is able to manage two different setups. These can be
selected via the software.
Selecting the setups A–D:
The PC-Tool software allows the direct comparison of a maximum of four different setups using the “Setup A” to “Setup D” buttons. First, load a previously adjusted setup into the selected memory by clicking with the right hand mouse button on the respective box under “Setup A, ..., D”. This opens
a window in which you can retrieve the corresponding .afp le from a chosen location. A setup is
automatically active and audible as soon as it is loaded.
Important information: The volume is temporarily reduced when switching between the various setups in order to avoid any potential temporary static noise when modifying the parameters.
Channel routing - the “Congure Inputs/Outputs” button
This button is used to switch to the channel routing overview in which you can congure any of the
inputs and outputs. This allows you to assign names to each of the individual channels, to add up input signals and allocate a specic input signal to each output. To protect the connected louds­peaker, you are also able to load suitable automatic default settings for each of your settings for each channel, which may, of course, be amended as required.
Please note: The channel routing overview may only be found in the PC-Tool user interface of our standalone processors. The PP50 DSP does not have this function.
Congure DSP button:
This button is used to return to the main PC-Tool page from the channel routing user interface.
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Selecting channels for adjustment:
Select the channel you want to adjust. To do so, simply click on the respective box with the left mouse button. The active channel is indicated by the red LED (top front left in the example). The software allows each channel to be adjusted separately. In spite of this, it often makes sense
to link the two front channels, or the two rear channels, for example, and therefore adjust them
simultaneously. This is particularly recommended for the high- and low-pass lters since having
different values for the right and left channels should be avoided. Even with the equalizer, a sepa­rate adjustment of channels only makes sense if sound optimization is only required for a single listening position. Simply insert a tick by the channels you want to adjust simultaneously (in the example above, the two front channels)
Important information:
When linking two channels, the adjustments made previously to one channel are not automatically transferred to the other channel. Only those adjustments made after the link has been created are then applied in an identical manner to the linked channels. Therefore, please consider whether two or more channels should be adjusted simultaneously before making any adjustments.
Linking channels:
Channel selection
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Channel routing - conguring inputs and outputs
The C-DSP/P-DSP allows input channels to be freely allocated to the output channels. To perform
this allocation, click on the “Congure Inputs/Outputs” box in the DSP PC-Tool main menu once
the software starts. This will then present you with the following input mask:
Naming inputs:
On the left hand side of this mask you can allocate a name to each of the input channels (C-DSP: “A-H” and P-DSP: “A-F) to give you the best possible overview. Make the transfer using the right and left mouse buttons.
Not used (input is muted)
Front L Fullrange
Front L Tweeter
Front L Midrange
Front L Woofer
Front R Fullrange
Front R Tweeter
Front R Midrange
Front R Midwoofer
Rear L Fullrange
Rear L Tweeter
Rear L Midwoofer
Rear R Fullrange
Rear R Tweeter
Rear R Midwoofer
Center Full
Center Tweeter
Center Midwoofer
Subwoofer
The following names may be allocated to the input channels:
Please note:
This setting does not affect the functionality. It is merely used as an overview and helps you to better differentiate between the channels.
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Naming outputs:
Just as with the inputs, you are also able to allocate names to the outputs “A-H” on the right hand side of the input mask. They are selected using the right or left mouse button.
In this case, however, the selected conguration does immediately affect the default settings of the high-pass and low-pass lters in the DSP main menu. This
therefore prevents, for example, a tweeter connected to output A accidentally being assigned a broad band signal which may damage it. Any unused output channels should ideally be muted (“Not_used”):
Default settings of individual channel types:
Output channels Default high-pass Default low-pass
Not used Channel output muted Front L Fullrange - ­Front L Tweeter 3000 Hz, 12 dB, Butterworth ­Front L Midrange 500 Hz, 12 dB, Butterworth 3000 Hz, 12 dB, Butterworth Front L Woofer - 3000 Hz, 12 dB, Butterworth Front R Fullrange - ­Front R Tweeter 3000 Hz, 12 dB, Butterworth ­Front R Midrange 500 Hz, 12 dB, Butterworth 3000 Hz, 12 dB, Butterworth Front R Woofer - 3000 Hz, 12 dB, Butterworth Center Fullrange 200 Hz, 12 dB, Butterworth ­Center Tweeter 3000 Hz, 12 dB, Butterworth ­Center Woofer - 3000 Hz, 12 dB, Butterworth Rear L Fullrange - ­Rear L Tweeter 3000 Hz, 12 dB, Butterworth ­Rear L Midrange 500 Hz, 12 dB, Butterworth 3000 Hz, 12 dB, Butterworth Rear L Woofer - 3000 Hz, 12 dB, Butterworth Rear R Fullrange - ­Rear R Tweeter 3000 Hz, 12 dB, Butterworth ­Rear R Midrange 500 Hz, 12 dB, Butterworth 3000 Hz, 12 dB, Butterworth Rear R Woofer - 3000 Hz, 12 dB, Butterworth Rear Fill 200 Hz, 12 dB, Butterworth ­Subwoofer 1 - 80 Hz. 24 dB, Butterworth Subwoofer 2 - 80 Hz. 24 dB, Butterworth
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Please note:
These default settings may, of course, be modied in the DSP main menu. They are only used to
protect the connected loudspeaker and are not recommendations for correct settings!
Allocating inputs to outputs:
In the center of the input mask, you can allocate any of the input signals to each of the eight out­puts A-H. You can also use either the right or left mouse button to make this selection:
Important information:
In order to reach the maximum level on each output, it is important that each of the output
channels always (!) equals the sum of four input signals. If you only select one input signal
per output, the maximum possible output level is reduced by about 12 dB.
General information about the input/output conguration:
You do not have to use all the P-DSP inputs. It is entirely possible to generate all eight output channels from only two input channels.
We recommend setting all unused inputs and outputs to “Not_used”.
Each output channel should always equal the sum of four input signals. This means that all elds required for the sum signal must be completed, even if they are always lled with the same signal. If this is not the case, there will be a signicant drop in output.
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The following examples are provided as way of clarication:
a) If, for example, Output A “Front L Full” is allocated to Input A “Front L Full”,
then please select “Front Full L” in all four entry elds.
CORRECT:
INCORRECT:
b) If, for example, a sum signal is generated for the subwoofer from four channels front and rear, the following setting is useful:
c) If, for example, a front-center signal is generated from the two front channels, the following setting is useful:
d) If you are only using the optical digital inputs, for example, the following setting would be
suitable for a multiple channel conguration with a central loudspeaker and subwoofer:
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This section makes it possible to congure almost any type of high-pass and low-pass lter for the
selected channel. When doing so, the following parameters are adjusted separately: crossover
frequency, lter characteristics, slope and the Q-factor.
The functions of the individual parameters are described below.
Crossover frequency (Frequency)
Use the slide control to select the required crossover frequency for the high-pass or
low-pass lter.
PP50 DSP: It is possible to adjust the front and rear channels in 1/6-octave increments from 20
Hz to 20,480 Hz. The subwoofer channel high-pass may be adjusted between 20 Hz and 100 Hz and the low-pass from 20 Hz to 150 Hz in increments of 1 Hz.
P-DSP: It is possible to adjust the full-range channels in 1/12-octave increments between 20
Hz and 20,480 Hz. The high-pass may be adjusted between 20 Hz and100 Hz and the low-pass between 20 Hz and 150 Hz in increments of 1Hz.
C-DSP: It is possible to adjust the full-range channels in 1/24-octave increments between 20
Hz and 20,480 Hz. The high-pass may be adjusted between 20 Hz and100 Hz and the low-pass between 20 Hz and 150 Hz in increments of 1Hz.
Filter characteristics (characteristics)
There are four different lter characteristics available for selection and the option setting your own high-pass and low-pass lter using “Self-Dene”. The table presents an overview of the typical pro­perties of the different lter characteristics:
Butterworth
Regular impulse behavior
Sharp transition from the passband to the stopband
3 dB gain in the crossover frequency band
The most popular characteristics, suitable for almost all applications
Bessel
Very good impulse behavior
Very gradual transition from the passband to the stopband
Requires loudspeakers that also have a smooth frequency response outside the functional
range
Less than 1 dB gain in the crossover frequency
High- and low-pass lter settings
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Only practical in combination with very high quality loudspeaker systems; not recommended for subwoofers
Linkwitz
Very good impulse behavior
No steep transition from the passband to the stopband
No gain at the crossover frequency
Only useful in combination with very high quality loudspeaker systems; not particularly recom-
mended for subwoofers
Chebyshev
Very sharp transition from the passband to the stopband
Poor impulse behavior
Frequency response exhibits waviness (1 dB “ripple”)
Only recommended as a low-pass for subwoofer or as a high-pass as required for tweeters
which are operated near to their resonance frequency
Self-Dene
• Only available as a 12 dB lter, with adjustable lter values
• Useful as a high-pass lter in so-called “ltered bass reex systems”, whereby the crossover frequency usually corresponds to the tuning frequency of the bass reex tunnel
Examples of the different lter characteristics are presented for a 1000 Hz high- and low-pass lter
with a slope of 24 dB.
Fig. 1: Filter characteristics of the high-pass
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Fig. 2:
Low-pass lter characteristics
Slope
Use this slide control to adjust the slope of the lter in 6 dB increments from “0 dB” per octave (lter not active) to a maximum of “-42 dB” per octave on the C-DSP and a maximum of 30 dB per octave on the P-DSP (= lter with very steep slope). The effect of the slope on the frequency cha­racteristics of a lter is illustrated below using the example of a 1000 Hz high- and low-pass (with
Butterworth characteristic):
Fig. 3: Effect of slope on the high-pass
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The value you select for the slope depends heavily on the type of application. The following points may aid your decision:
• The steeper the slope, the worse the lter impulse behavior.
• The preferred level for the subwoofer channel low-pass lter is “-24 dB”.
Standard values for the crossover between the woofer and the tweeter in fully active systems
lie around “-12 dB”.
If the woofer exhibits considerable lack of clarity in the frequency response slightly above the set crossover frequency, it may be useful to select a steep slope (e.g. -24 dB per octave) for
the low-pass lter.
A small 19 mm tweeter operated in a fully active system at up to 3000 Hz also requires a stee-
per slope (-18 dB to -24 dB) to avoid overloading the woofer and causing a considerable distor­tion factor.
• In most instances, a high-pass lter for a woofer or subwoofer is sufciently dimensioned with
“-12 dB” and is only necessary when small loudspeaker systems are used.
A lower slope steepness of just “-6 dB” in fully active systems is to be used with caution, par­ticularly with tweeters, and are only useful in combination with a suitably selected crossover frequency.
Important information:
• If you have selected the “Linkwitz” lter characteristics, you are only able to set the values to
“-12 dB” and “-24 dB”.
• The “Self-Dene” characteristics always has a slope of -12 dB per octave.
Fig. 4: Effect of slope on the low-pass
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Q-factor (Q-Factor)
This slide control is only active if you select the “Self-Dene” characteristics. The slope for this characteristics setting is xed at -12 dB and there is the option of adjusting the Q-factor of the
high- or low-pass between 0.5 and 2.0 in increments of 0.1. The Q-factor effect is illustrated below
using the example of a high- and low-pass lter with a crossover frequency of 1000 Hz.
Fig. 5: Q-factor effect for the high-pass
Fig. 6: Q-factor effect for the low-pass
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Important information about the PP50 DSP:
If you are using the PP50 DSP with the PP 7E or PP 7S subwoofers,
please adjust the subwoofer channel high-pass lter settings as follows:
Crossover frequency: 49 Hz
• Characteristics: Self-Dene
Q-Factor: 1.5
High- and low-pass lter bypass function
Use the bypass button to completely bridge the effect of a high- or low-pass lter with a single push of a button to obtain a simple acoustic comparison “with and without lter”.
Important information:
In fully active systems, do not simply bypass the tweeter high-pass lter. Without any frequency crossover, irreparable damage may be caused even at low volumes! Bridging a low-pass lter, on
the other hand, is generally uncritical and will not result in any damage to the loudspeaker.
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Adjusting the output level
The output level of each of the channels may be adjusted using the “Output level” slide control. This increments depend on the governor setting. The “–10” to “+5 dB” band has increments of 1 dB, the “–30 dB” to “-10 dB” band increments of 2 dB and that below “–30 dB” has increments of 6 dB. The exact value is also indicated on the scale next to the slide control and as an absolute value above the slide control.
When adjusting the slide control, values greater than “0 dB” must be avoided, otherwise there is
a risk of overloading the amplier signal processor. Ensure that the red area of the level indicator
is never visible at any volume. This may possibly occur if you have used the full boost of “+6 dB” in an equalizer frequency band, for example. The red bar in the level indicator is a clear sign that the signal processor is overloaded, which may cause a dramatic and sudden rise in the distortion
factor. In contrast to an analog amplier, which overloads slowly, the digital amplier stages are
comparably very “intolerant”. Digital overmodulation sounds extremely uncomfortable and may quickly damage the connected loudspeaker (tweeter). It is therefore preferable to set the quietest channel to “0 dB” and adjust all other channels downwards accordingly until the volume balance meets your requirements.
Muting an output channel (“Mute”)
The mute button is used to mute the output of a channel. Clicking on this function again takes the channel off mute.
Bypassing the equalizer and the time alignment (“Bypass”)
Activating the “Bypass” button on the left next to the Output Level slide control bypasses
the graphic 1/3 octave equalizer, the parametric lter, the ne-EQ functions and the time alignment
settings. The “Bypass” may be removed by clicking on the function for a second time.
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Adjusting the phasing and time alignment
Time alignment overview page (“Overview”)
So that you don’t have to constantly switch backwards and forwards between the individual chan­nels when adjusting the time alignment and phase, you can use the Overview button to display all the channel values simultaneously. This presents you with the following display:
Use the “Back to DSP Menu” button located in the top left hand corner to return to the previous display.
Adjusting the phase
The phase position of each of the front and rear channels can be switched between 0 and 180 degrees. Regulation of the subwoofer channel phase is particularly sensitive and may be adjusted between 0 and 360 degrees in increments of 22.5 degrees. This makes it possible to acoustically adjust the subwoofer precisely to the front and rear channels.
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Adjusting the time alignment (“Time Alignment”)
It is only possible to achieve a clean natural response of the music if the time alignment is adjus­ted correctly. The program therefore allows sensitive adjustments in increments of 7 mm. The software provides two different ways of adjusting the time alignment:
• “Calculate Distance”: This mode requires the input of the distance between the loudspeaker and the ear of the listener. The program uses this to calculate the necessa ry time delay for each channel.
• “Calculate Delay”: This mode requires the direct input of the preferred time delay value if available.
The optimum setting is most easily calculated using the “Calculate Distance” mode as follows:
Use a tape measure to measure in centimeters the distance between the front left loudspeaker and your head in your sitting/listening position.
Adjust this value using the slide control.
Repeat these steps for each of the other channels.
The program uses these distances to calculate the required time delay for each of the channels
and displays these values accordingly in “msec”. This prevents a delay on the loudspeaker furthest from the listening position (usually the subwoofer channel), whereas the loudspeaker closest to the listener usually experiences a delay.
It is not necessary to measure/adjust the values as accurately as possible as they merely serve as initial values for the ne adjustment.
Now mute the rear channels and the subwoofer using the “Mute” function.
Select a piece of music which preferably consists of only a voice and no accompanying instru-
ments.
In small increments, adjust the time alignment of one of the front loudspeakers until you can hear the voice either directly from the front, or slightly from the right (1 o’clock position). It is
usually only necessary to regulate the time alignment by only a few centimeters to reach the desired result.
Now mute the front channels using the “Mute” function and reactivate the rear channels.
Listen to the same piece of music again and adjust the time alignment of the rear channels so that the voice can be heard from directly behind you, or slightly from the right (5 o’clock positi-
on).
Reactivate the front channels (keeping the subwoofer channel muted as before).
PP50 DSP: The PP50 DSP also has the option of using the “Additional Delta Delay Front/Rear”
slide control to shift the rear channels backwards until it is almost impossible to hear them or they no longer have any negative effect on the natural response of the front loudspeaker.
It is not usually necessary to adjust the time alignment of the subwoofer following the “tape measure method”. Setting the phase control is particularly effective in this respect.
This completes the adjustment of the time alignment.
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Important information:
The time alignment function may only be used to achieve optimum stereo reproduction for one listening position in the vehicle. However, spatial reproduction in the other positions is usually worse with time alignment!
Always switch on the time alignment before you adjust the frequency response with the equali­zer.
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Adjusting the equalizer
Graphic 1/3 octave equalizer
Each of the DSP channels has its own equalizer which affects the frequency response in high resolution 1/3-octave increments. The front and rear channels therefore have 30 slide controls for the bands between 25 Hz and 20 kHz. The subwoofer channel has 10 bands from 25 Hz to 200 Hz. The curve displayed above the slide control indicates the function of the equalizer. The frequency bands have been subdivided into 1/3 octave internals because this is particularly suited to human hearing and makes it easy to adjust the equalizer if the frequency response is also measured in the same 1/3 octave resolution (please also refer to the chapter “Measuring fre­quency responses”). Each band of the equalizer allows a maximum boost of “+6 dB” and a maximum cut of “-18 dB”. This asymmetrical design was chosen because boost levels of more than “+6 dB” are rarely required. Any stronger, narrow band frequency dips measured in the frequency response are usually due to signal cancellations caused by the phase shifts which may not be eliminated by the equalizer, even with greater boost levels. Expe­rience shows that attention should be paid to the elimination of excess gain in the frequency res­ponse when adjusting it. Hearing is considerably more sensitive to narrow band excess gain than to narrow band frequency dips. You can read more about adjusting the equalizer in the chapter entitled “Measuring frequency responses”.
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In addition the graphic 1/3 octave equalizer, the PP50 DSP also has one parametric lter for each channel which may be used to make even ner acoustic adjustments. This lter is intended exclu-
sively for compensating excess gain in the frequency response (range: 0 to -30 dB). This prevents any boosts and therefore eliminates any dips in the frequency response.
A parametric lter is typically used for the narrow band resonance of a door panel, for example,
which cannot be eliminated with the 1/3 octave equalizer. The center frequency of the parametric
lter may be precisely adjusted using the “Hz” slide control in 1/6-octave increments, and for the
subwoofer channel in 1/12-octave increments; the corresponding value is displayed above the slide control.
The following diagram illustrates their function:
PP50 DSP: Parametric lter
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The “Q” slide control is used to adjust the bandwidth of the frequency cut. A low Q-factor equates to a broad band reduction, while a high Q-value equates to a particularly narrow band cuts. The effect of the “Q” control is illustrated in the following diagram:
P-DSP: Graphic equalizer ne adjustment function
The FineEQ function is used to precisely adjust the 1/3 octave equalizer and provides a similar
function to the parametric lter of the PP50 DSP. The FineEQ function makes it possible to adjust
each of the 30 bands of each channel even more accurately. Therefore, both the center frequency
and the Q-factor of each band may be adjusted with great precision. To nely adjust the selected band, click with the mouse on the level control of the specic band. This should turn red. On the
right hand side in the “EQ Fine Setting” area, you can now adjust the center frequency of the band up and down. This adjustment is made in 1/12-octave increments. The quality (Q-factor) of each band may also be adjusted. The default value for each band is 4.3. In this respect, the P-DSP provides the option of adjusting a frequency cut or boost with a narrower band width. This function
mainly serves to eliminate specic individual problems in the frequency response.
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C-DSP: Graphic equalizer ne adjustment function
The C-DSP also has a ne adjustment function for each individual band in the 1/3 octave equali­zer. Its functionality is identical to that of the P-DSP, although the setting options are signicantly
more comprehensive. This makes it possible to adjust the central frequencies of each of the bands of the C-DSP by increments of 1/24 octaves which allows almost any frequency to be selected as required. The Q-factor setting also has an extended range of possible values. The adjustment ran­ge lies between 0.5 and 15, whereby the individual bands may be adjusted more broadly in com­parison to the P-DSP. This function therefore offers almost the same setting options as a purely parametric equalizer.
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To optimally adjust setting of the equalizer using the “HELIX DSP PC-Tool” it is absolutely neces­sary to be able to measure the frequency responses of the loudspeakers in your vehicle. Even absolute professionals are unable to make perfect adjustments using their hearing alone.
Thankfully, good measuring equipment is now affordable and is denitely worth the investment.
The following list of necessary components and software have been tested by us and judged to meet the operational requirements.
Behringer ECM8000 measuring microphone
T-BONE Micplug USB microphone USB interface with phantom power
Praxis measurement software from Liberty Instruments - free to download from www.libinst.
com/praxis_downloads.htm
A music CD containing a pink noise test signal
Measuring microphone
The Behringer ECM8000 is a very robust and linear measuring microphone with omnidirectional characteristics. In comparison to considerably more expensive microphones, it also provides per-
fectly sufcient results for this application. The supplied wind deector should not be used when taking measurements. It always requires a preamplier which supplies the microphone with the
necessary voltage (“phantom power”). There is therefore no need for a direct connection to a PC sound card.
Suitable preampliers
A microphone preamplier with phantom power is required for the measuring microphone to
function with the PC. This function can be performed by the T-Bone MICPLUG USB, for examp­le. It is simply attached to the measuring microphone and connected directly to the PC using the
(unfortunately very short) USB cable supplied. There is no need for a specic driver. If the USB
connecting cable is too short, we recommend using an additional XLR microphone cable to con­nect the microphone and the preamplier. When using the MICPLUG USB, ensure that the phan­tom power has been activated using the small button on the underside. This is easy to spot as the
transparent ring on the preamplier changes color from blue to red (this requires that it is already
connected to the PC).
Suitable measurement signals
So-called “pink noise” is used as a measurement test signal and must be reproduced by the car radio. This is the only means of ensuring that the equalization in many factory-installed radios (in this instance, the sound control which is not accessible to the user) is taken into consideration during the reading.
If you don’t have the CD with a “pink noise” test signal, you can download it from the Audiotec
Fischer website under “Downloads”, “Tools”. If you want to burn the track onto a CD, please use the “Rosa Rauschen.cda” le („Rosa Rau­schen“ is the German term for pink noise). If your car radio can also play music directly from a USB stick, select either the uncompressed WAV format “Rosa Rauschen.wav” or the MP3 format
Measuring frequency responses
Measuring equipment
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“Rosa Rauschen.mp3” and copy them to the USB memory. We recommend creating a CD of the test signal if possible.
Appropriate car radio settings for taking readings
To take readings it is important that your car radio is set up correctly. All sound controls should be set to either “linear” or the central position. Deactivate any existing loudness functions. The balan­ce and fade controllers must also be adjusted to the “central position”.
For measuring the frequency responses, we recommend the Praxis measurement software from Liberty Instruments. This is free to download from www.libinst.com/praxis_downloads.htm The software offers a considerably greater range of functions than is necessary for measuring fre-
quency responses. To simplify it, we have therefore created a conguration le which performs all the necessary software settings so that you can get on with the measurements. This conguration le is available on the Audiotec Fischer website under “PC-Tool”, “Downloads”. Download the “Pra­xis Setup ATF.ini” le and save it preferably in the same directory where you previously installed
the “Praxis” software (usually under C:\Programs\Praxis\). Also download the reference curve which you will use later to help you adjust the equalizer. This is also available on the Audiotec Fischer website under “PC-Tool”, “Downloads” (“Reference
frequency response curve Europe.px2”). This le must be saved in the same directory as the con­guration le. Now install the conguration le by starting the “Praxis” measurement software as follows:
“Cong” -> “Load Cong File” -> “Software specic”
Measurement software
1.
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2.
This opens a window in which you can select the directory where you previously saved the “Praxis
Setup ATF.ini” conguration le. Click with the mouse on “Open” to automatically load the conguration le, and “LOAD CONFIG”
will be temporarily displayed.
Now you need to adjust the microphone you are going to use to take the measurements:
“Setup” -> “D/A&A/D” -> “Dev”.
This naturally requires that you have already connected your measuring microphone to a USB port
on your PC via the preamplier.
“Praxis” is now ready for the frequency response reading.
3.
4.
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Ensure that you have correctly adjusted the time alignment using the HELIX DSP PC-Tool be­fore you start the measurement.
• Sit in the driver’s seat with the measuring microphone.
It is best to place your PC (Notebook/Netbook) on the passenger seat so that you can use it
easily. Ensure that the screen is not positioned directly in front of the loudspeaker on the pas­senger side as this can distort the readings.
Start the “pink noise” reproduction on your car radio. Set the volume to fully cover any ambient noise. Ideally, the vehicle will be in an enclosed garage while you are taking the measurements
so that trafc noise does not affect the readings, for example.
Begin by measuring the front loudspeaker system, i.e. initially mute the rear loudspeaker and
any connected subwoofer (e.g. using the HELIX DSP PC-Tool Mute function).
Hold the measuring microphone upright and gradually turn it to a horizontal position in a semi­circle between your left and right ears.
To start taking readings on your PC, press the F12 function key. “Praxis” will now start measu­ring for approximately 18 seconds.
You can then identify the determined frequency response together with the red reference curve on your PC.
Now use the HELIX DSP-Tool equalizer to adjust the frequency response so that it matches
Frequency response readings
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the reference curve as closely as possible. This is an iterative process, whereby the equalizer
is rst adjusted before further measurements are taken. However, you will see that the desired
result is usually achieved after just a few attempts. Bear in mind that the “Praxis” measurement software is set up so that the frequency response is measured in the same 1/3 octave intervals with the same center frequencies you set in the HELIX DSP PC-Tool equalizer.
We recommend you “link” the two front channels so the right and left hand front channels can be adjusted simultaneously. Individually optimizing each channel is only recommended in rare
circumstances. Audiotec Fischer always adjusts the vehicle-specic setups of the left and right
hand channels in the PP50 DSP in an identical manner, thereby avoiding adjusting the chan­nels separately.
When adjusting the frequency response, avoid large boosts; large cuts pose no problems, however.
Do not attempt to balance out deep narrow band dips in the frequency response. Such dips are nearly always caused by out-of-phase signal cancellations and it is not possible to sufciently
compensate for them. The human ear does not usually perceive these signal cancellations as disturbances.
Strong narrow band gain in measured frequency responses should, on the other hand, be completely eliminated as the ear is very sensitive to this. If the graphic equalizer is insufcient for this function, please use the additional parametric lter (PP50 DSP) or the ne adjustment
function (C-DSP/P-DSP).
Once you have corrected the front channels, mute them and activate the rear channels (keep the subwoofer muted as before).
Now perform the measurement process as described in the same way for the rear loudspea­kers. There are different approaches, however:
• You also measure the rear loudspeakers from the driver’s seat. This method is only recommen­ded if the vehicle has just two seats, or if you usually only travel alone. The rear loudspeakers
usually sound very unpleasant in the rear seats if they have been optimized for the driver’s
seat.
Alternatively, in vehicles with four or more seats, sit in the middle in the rear to take the rea­dings for the rear loudspeakers and adjust the settings to achieve a pleasant sound in the rear
seats. Audiotec Fischer use this procedure to create the vehicle-specic setups for the PP50
DSP.
Now reactivate all the loudspeakers including the subwoofer and take another frequency res­ponse reading. The next step is to optimally adjust the subwoofer to the front/rear loudspea­kers. The equalizer should only be used as the last means of adjustment.
Following this adjustment, the PP50 DSP should have the optimum setup for your loudspeaker
system. Do not forget to save this conguration to your PC using the “Save” button and transfer it to the memory of the amplier using the “Store DSP” button.
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If you are using the PP50 DSP with the PP 7E or PP 7S subwoofers, please use the following settings for the subwoofer channel high-pass lter crossover frequency: 49 Hz characte­ristics: Self-Dene Q-factor: 1.5
• Begin with a suitable setting for the subwoofer channel low-pass lter. A good initial value in
this respect is a crossover frequency of 80 Hz with a slope of -24 dB and a Butterworth charac­teristics.
In many cases it is useful to relieve the front and rear loudspeakers from low frequencies using a high-pass lter. The following settings have proven to meet the operational requirements for the various loudspeaker sizes (LS): 6x9” or 20 cm LS: high-pass lter –12 dB, Butterworth, crossover frequency 40 Hz16.5 cm LS: high-pass lter –12 dB, Butterworth, cross­over frequency 50 Hz13 cm LS: high-pass lter –12 dB to –18 dB, Butterworth, crossover frequency 70 Hz 10 cm LS: high-pass lter -18 dB to –24 dB,
Butterworth, crossover frequency 80-100 Hz
Now set the phase control and the output level of the subwoofer channel so there is a harmo­nious balance between the front/rear channels and the subwoofer even without the help of the equalizer.
If it is not possible to achieve an even frequency response in the bass range using the settings given above, you can use the equalizer for further adjustments in the subwoofer channel.
Important information about the PP50 DSP
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Audiotec Fischer GmbH
Gewerbegebiet Lake II · Hünegräben 26 · 57392 Schmallenberg · Germany
Tel.: +49 (0) 2972 9788 0 · Fax: +49 (0) 2972 9788 88
E-mail: helix@audiotec-scher.com · Internet: www.audiotec-scher.com
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