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Old 8th July 2011, 07:37 AM   #1
matsj is offline matsj  Sweden
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Default Computer based 4 way x-over ?

To my new speakers i need a 4 way x-over and i want it computer based. So i bought an computer and putted 2 Lynx two B soundcards inside it. But now i don't know how to get it to work. All people i have talked with says that it won't work with 2 soundcards.

Is there a way to go with these or buy something else ?

Mats
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Old 18th October 2011, 05:24 AM   #2
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matsj,

I do not wish to sound disparaging, but people really must decide what they are trying to do before spending the best part of 2k on hardware and hoping it will just work.

That said, I do not know who told you that multiple Lynx sound cards will not work together, because they patently will. Read the Lynx manual to find out how to set up the cards correctly. Once this is done, they will appear and behave as a single, large, sound card.

Beyond that, you're sort've on your own. You really cannot switch on a computer with some sound cards in it and just expect it to be a crossover. It will require special software (search around the forums, there are several examples or, if you know enough DSP, you can write your own). I have done this in the past with a single Lynx TWO-B card on Windows and can tell you for certain that it works great. But in the end it requires a lot of work, time and know-how. From the wording of your post I do not expect this is the correct way for you to get a working system.

If you really want digital crossovers I would recommend something like the Behringer DCX2496 or, given that you have a big budget, one of the DEQX units (there are lots of posts on here about both)
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Old 18th October 2011, 07:40 AM   #3
matsj is offline matsj  Sweden
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I have talked with Lynx and it will work. Im avare off that i need a "program" and im looking at; DSP Crossover for PC. Frequency Allocator. . So im not "stupid". If you dont try something we will be standing on the same spot all life.
One problem is to find people that can help you.

Ill work on this in winter, when time is available.

mats
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Old 18th October 2011, 10:38 AM   #4
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I've done what you want using Windows XP, Winamp, VAC, Synthmaker, ASIO4ALL and any multichannel sound card. It was more than one year ago.

Winamp gets used as audio player.

VAC intercepts the Windows audio stream and converts it into a ASIO audio stream. You need to pay for VAC, otherwise you get the demo version injecting an intermittent "peep" in the audio.

Synthmaker allows you to create your own DSP through a .osm file. Synthmaker reads thus the ASIO audio as stereo input. The crossover kernel I designed through the .osm file was a Lipshitz-Vanderkooy delay compensated, with a 4th order Bessel as lowpass. This is a complementary crossover outputting very small relative phase shifts in the transition bands, and outputting a perfect flat reconstructed phase. Such crossover got published at the AES long time ago, before the digital era. It never went commercially used because it requires a delay line (not a phase shifter approximation), unobtainable in analog technology.

ASIO4ALL provides an ASIO interface and a software driver for transforming any multichannel sound cards (including the ubiquous Realtek HDaudio that you find on most computer motherboards), into an ASIO peripheral.

If you want more quality you can opt for an external multichannel soundcard. Personally, I had success with the motherboard Realtek HDaudio, the Trust 5.1 USB, and the Sweex 7.1 USB.

Today, it could be that some new Synthmaker version could enable more simplicity like directly exploiting the Windows stream at the input, converting it into an ASIO stream, instead of relying on VAC as pre-processor. I have not tried this. By the way, I think that the new Synthmaker version still needs ASIO at the output, for accessing the 6 or 8 audio channels.

Some people tell me that I need to look at Foobar2000 1.1.8 as music player, as it can be "bit-exact" controlled like when using 2496 audio files, without any internal sample rate conversion, then drive the multichannel audio card in "bit exact" 2496 mode, and possibly design as cherry on the pie, a digital crossover plugin using x86 SSE2 instructions and 64-bit math.

As hobbyists, one could use a WinXP-Atom netbook, or assemble a miniaturized fanless WinXP-Atom PC. The issue is the Windows licence.

The obvious future would be a Foobar audio player for Android, running on a 7 inch 800 MHz ARM tablet, about 129 USD today and 99 USD sooner than you may think. Provided that the USB connector of the ARM tablet can communicate with a 5.1 or 7.1 USB audio card. That's another story ... Quite encouraging is the fact that Foobar is already dealing with Android. There is a Foobar Android app, for controlling Foobar using your smartphone. I guess your Windows PC is getting Foobar commands through WiFi.

I looked to the THUNEAU.COM "frequency allocator". This is an interesting VST application. They had a good idea trying to pre-compensate the phase deviations. Did they pre-compensate the phase of all drivers individually, or do they apply a global phase pre-compensation ? By the way, I think they currently don't propose crossovers topologies like the Lipshitz-Vanderkooy "delay compensated", exhibiting minimum relative phase shifts in the transition bands. Would be nice if they add the Lipshitz-Vanderkooy "delay compensated" crossover as "textbook crossover". Would be nice also to include a measurement modality (using a mike) for generating the .frd files instead of importing them from some external software, and for measuring the resulting overall gain and phase response.

Cheers
Steph

Last edited by steph_tsf; 18th October 2011 at 10:47 AM.
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Old 19th October 2011, 05:20 AM   #5
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matsj

I am sorry, I did not mean to imply I thought you were stupid. But, I thought you had not taken the time to read the information that is already abundant and freely available on the forum in this area. It is considered bad etiquette to ask people to hold your hand through things which are already discussed at length in other places - and this is what your post sounded like to me. But, if you have specific questions about why something won't work, that is of course why we are all here.

What is your specific application? Is this a dedicated crossover computer or a desktop machine which also does crossovers? Be aware that Lynx do not provide drivers for Linux, and while they offer some unofficially through 4Front Technologies, they do not support them (I had so much trouble getting them to work that I've had to ditch Lynx cards in favour of RME). steph_tsf gives some good sounding options for Windows-based software.
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Old 19th October 2011, 06:48 AM   #6
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I'm attaching a few files to get you started with Synthmaker, just in case.
Use IIR_Lab v1.00 for calculating the IIR coefficents. See post #12 in IIR_Lab : a design help for digital audio filters

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Old 19th October 2011, 07:25 AM   #7
matsj is offline matsj  Sweden
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Wingfeather: No problem, im just trying to make something that some other says dont work.

My computer will be music library, Pre-amp, x-over. Im using windows in it.

mats
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