|DCN23 & DCN24|
Why can’t I communicate with the digital crossover?
First of all you have to check if the wires to the USB pads are correctly connected. Often D+ and D – have to be changed because they are switched in
a connector like the Neutrik NAUSB chassis adaptor. In this case you’ll get a pop-up window like this
USB Device Not Recognized. Remember to disconnect the cable to the PC before switching the white and green wire.
NOTE: We recommend to use USB-cable of maximum 5m otherwise you might get communication problems and the pop-up window might also pop-up.
How do I install the driver for the USB-interface?
The USB-interface is actually an onboard USB to COM Port (RS-232) adaptor and the circuit is made by FTDIchip.com.
The driver for this device can be downloaded here FTDI driver (Windows OS) or at the manufactures web page
- also drivers for Mac. If you place the driver file on the desktop, it’s easy to find and to point out to the installation wizard.
Is it possible to change the assigned COM-port number?
Yes – you go to the Device Manager (see how above) and open the properties by right click Properties or double clicking the device. Choose the Port
settings tab – open the Advanced… – change the COM Port Number
to the desired number – look out for conflict, if another device has been assigned the same COM Port number.
The processing power of your filter is given in number of biquads. What can a biquad do?
One biquad can do either a PEQ, Notch Filter, 1.order High-Pass Shelving Filter, 1.order Low-Pass Shelving Filter, 2.order High-Pass Filter, 2.order Low-Pass Filter
or one All-Pass. E.g. DCN23 could do 4.order High-Pass filter + 4.order Low-Pass filter + one Notch filter + 11 x PEQ in one channel equal 16 biquads. Try it out for
your self: XOW.zip. You can see how many free biquads is left for extra processing in each channel just above the Driver Box.
Is it possible to supply 2 x DCN23 digital crossovers from one PSU DCN II?
NO - The PSU DCN II has more that enough power for one DCN23 and the onboard control circuitry is also adequate for one relay board,
but will be overloaded if 2 x DCN23 or 2 x relay boards are attached. PSU DCN II is simply designed to power "only" one DCN23.
How do I connect a RCA / phone plug to the balanced input of the digital crossover?
If you want to use a single-ended signal RCA / chinch connector, because your preamp has this connector type – you simply short the inverting input
(pad labelled 3) of balanced input of digital crossover to the AGND pad (analogue ground – labelled 1). The inner core connects to non inverting input
(pad labelled 2) and the screen wire connects to the AGND. RCA connected to balanced input
How is the balanced input connected to the XLR connector?
The input pads of channel A and B is simply labelled 1(AGND), 2(non-inverted signal) and 3(inverted signal) which correspond to the number on the XLR connector.
XLR connected to balanced DCN input
How do I make a RCA / chinch to XLR cable?
If you got a single-ended RCA / chinch output of your pre-amplifier you still have the possibility to exploit the performance of the balanced input of our
digital crossovers. You could make an adaptor cable with RCA connector in one end of a microphone cable (2 conductors + shield) and a XLR connector at the
other, especially if the cable is longer than 5m. I call this kind of cable “pseudo balanced”, because you still get the benefits of the balanced input
without a real balanced output. To enhance the performance a bit more you could add a physical small resistor (value 100R) and fit it in the RCA connector.
The resistor does the same as the output impedance of the pre-amplifier. The noise introduced on the cable will be balanced out at the input stage of the
balanced input. Connect like this: RCA inner connector - red conductor – XLR pin 2 (hot), RCA shield – resistor (100R) or short – white conductor –
XLR pin 3 (cold), RCA shield – wire shield – XLR pin 1 (neutral). RCA to XLR cable
Can I use my "old" +/-15V power supply from my current analogue active crossover?
Yes - maybe - no – depends highly on the “old” power supply. It has to be able to provide the total current of Vdd, Vcc and +Vs at least 300mA from
the positive rail and 80mA from the negative rail. It shall be able to cope with uneven loads or you have to make circuitry that loads the negative rail
the same as the positive rail – balanced load supply. You’ll have to ad regulation for the Vdd (3,3V) and Vcc (5,0V). You need some kind of muting to
protect the amplifier from DC bumps at power on and off.
Can I use the digital crossover with switching amplifiers - Class D?
Yes – (maybe - no - depends...). We haven’t encountered any problems this far and don’t expect any problems. If you were to build a system with a Class D
amplifier/s and you will have problems with interfering noise from the Class D amplifier I really recommend reconsidering the use of this particular amplifier
– it is probably so noisy that it should be banned…
Will a SMPS power supply for amplifiers affect the performance of the digital crossover?
Yes – (maybe - no - depends...). We haven’t encountered any problems this far and don’t expect any problems. If you were to build a system with a SMPS
and you will have problems with interfering noise from the Power Supply I really recommend reconsidering the use of this particular Power Supply – it is
probably so noisy that it should be banned…
Can I build a stereo satellite loudspeaker system with mono sub with a single DCN23 digital crossover?
Yes – you can build a 2.1 system, because DCN23 has two independent input channels A and B. These two channels can be processed by the 3 DSP channels and
outputted through two dual channel Digital Analogue Converters. One DAC converts the first two DSP channels and the second converts the third DSP channel.
The third DSP channel is outputted as non inverting and inverting from this second DAC – this way you can easily bridge two amplifier modules for higher bass power
capability. The signal for this third DSP channel is a mix of the two input channels (A+B/2). It’s presumed that the satellite speakers have full-range drivers or
have passive crossovers for drivers.
Does DCN23 have a DC-blocking capacitor at the output?
No - DCN23 do not have any DC blocking capacitors as our amplifier modules have it at their input. It is highly recommended to have a DC-blocking at the input
of the attached power amplifier to prevent the amplifier from either putting out DC or going into protection mode. If capacitors were placed both at DCN23
output and at the input of the amplifier you would get more group delay and a higher High-Pass frequency.
How do I optimize for best performance in the DA converter?
To obtain the best resolution in the DA converter you have to adjust the input sensitivity of the attached power amplifier at full power to the full voltage
swing of the filter. E.g. DCN23 has a maximum of 12Vpp at the output and if the attached power amplifier has a higher sensitivity for full power out than
12Vpp you can place two resistors at the input of the amplifier like this: R3 & R4
How do I optimize for best performance in the AD converter?
To obtain the best resolution in the AD conversion you might think that it “only” to ensure that you get as close as possible to the maximum input - e.g. 4Vpp
for DCN23. But no – you have to make sure that when the DA converter reaches it maximum voltage swing = maximum binary value (0dB) in the digital domain the AD
converter should also reach is maximum binary value. Now you see that it has nothing to do with 4Vpp and then again it has. When you input a signal of 4Vpp you
will have 0dB at the AD converter in the digital domain – so you have to make sure that 0dB in is 0dB out in the digital domain. Where do you do that? In the
software – you will have to make the setup so that its overall gain is 0dB for the channel that has to have the highest gain and the others –xdB. Download an
Example for the XOverWizard and see how.
Why do I get distorted sound using your digital filters?
In general you don’t get distorted sound only occasional at higher volume. Then you’re simply over the top – which means that you input stronger signals that
4Vpp at the input of the filter. Options to solve the problem – don’t play this loud or optimizing the filter setup can give a bit more head room or get some
drivers with higher sensitivity or don’t try to make the drivers do something that they are not capable of or get higher powered amplifier or live with the
fact that you don’t have a PA system.
Explanation to the optimization of filter option: This could be that you try to extend the bas response of a small mid-bass woofer to a point where you gain
the low part of the response with a low shelving filter or PEQ of +10dB and by doing this you simply loose the gain in head room limited in X max or in the
power capability of the amplifier. Sometime you can get away with this little trick by adding a steep high-pass filter type Butterworth 48dB/oct. or 96dB/oct.
at an appropriate frequency to save the woofer for break down etc.
I repeat – Why do I get heavily distorted sound using your digital filters?
You are using the filter direct coupled to a source and you regulate the volume after the filter - by doing so you consequently get a distorted sound because
you overload the DA converters in the digital domain, which means that you try to output signal levels with higher values than 24 bits. Or you are consequently
are overloading the AD converter with input signals higher than the 4Vpp maximum. If you overload the AD converter you simply turn down the output signal or
insert an attenuation made of two resistors. In the first case of DA converter overload you are not obeying rule of 0dB gain or less in the digital domain.
In the software – you will have to make the setup so that its overall gain is 0dB for the channel that has to have the highest gain and the others –xdB.
Download an Example for the XOverWizard and see how.
Can I implement a Linkwitz transform in your digital crossover?
Yes - Linkwitz transform is simply two PEQ placed in a manor so that you get extended flatter bass response in a closed box to a lower frequency. The first
PEQ boost the bass 12-15 dB at a very low frequency and the second PEQ levels out the peak that comes from the first PEQ to flatten the response. BUT instead
I do recommend measuring the system to see what is really needed for a much more accurate flat extended bass response.