WinXP directly driving two 4-way active speakers

[steph_tsf]

Since a few years I'm using an old WinXP SP3 computer dating back from 2007 as infotainment center in my living room, HDMI connected to a big TV screen, and DVI-connected to a desktop-sized screen. I'm using it everyday for surfing on internet, read and write emails, watch videos on YouTube, listen to music using Winamp and watch movie (in stereo, not in 5.1) using MPC-HC, which is a decent movie player bundled with the K-Lite Codec Pack bundle.

What makes this setup so special, is that it always runs an .exe compiled by Flowstone, what's regarding the sound. This way, my old WinXP computer embeds a stereo 4-way crossover. Each speaker driver gets individually filtered by a combination of IIR Biquad filters, FIR filter, and delay. For each speaker driver, the FIR filter gets automatically setup using a realtime dual-channel FFT analyzer, realtime gain/phase comparator (comparison with the target gain/phase), realtime inverse FFT computation delivering the required filter impulse response, which indeed describes the required FIR coefficients. This way one single FIR filter inherently combines the speaker linearization function, and the speaker filtering function defined by the crossover goals.
This is done by Speaker Lab, another Flowstone application I completed a few months ago.
You can see it here : viewtopic.php?f=3&t=1607

The 7.1 audio system outputs eight audio channels. Four channels go to the left speaker. Four channels go to the right speaker. You thus need four stereo power amplifiers. For a medium-sized living room I would recommend four BTL Class AB TA8254-based stereo power amplifiers designed for car audio and motorcycle audio (Lepy LP-V3s). They need a 12 Volt DC power supply. There are 12 Volt 60 Watt switching power supplies available nowadays. One 12 Volt 60 Watt power supply can power two stereo amps. You thus need two 12 Volt 60 Watt switching power supplies. Regarding the Lepy LP-V3s, in case you have electronics skills, you can bypass the JRC4558 Opamp, tone controls, and volume control. The TA8254 maximum tolerable supply voltage is 18 Volt when not hot. Knowing the reservoir cap is a 2,200µF/16V, the power supply should never exceed 15 Volt. You may double or triple the capacitance, soldering more 2,200µF/16V capacitors in parallel. Make sure they exhibit a low ESR (equivalent series resistance), and can withstand a 105°C temperature. In case you want to extract the maximum power from the TA8254, you may go for a 15 Volt 70 Watt power supply. Possibly the Lepy LP-V3s are cheap alternatives of the LePai LP-V3, presented as audiophile-grade BTL Class AB TDA8566-based stereo power amplifiers (I have not these). Finally, remember to put back enough silicon grease on the power amplifier IC when re-assembling those little amplifiers. As soon as they overheat, they shut down as a matter of protection.

Be very careful, when dealing with multiway active speakers.
Never connect or disconnect a jack or a cinch while a power amplifier is still on.
Always remove the power supply from the amplifiers, before connecting or disconnecting any jack or cinch.
If you fail to observing the rule, you run the risk of damaging the speaker driver that's connected on the power amplifier, the one you moved the jack or the cinch.
When dealing with multiway active speakers, the power amplifier volume pots need to stay fully open. Any glitch coming into the power amplifier can thus be fatal for the speaker driver.

Here are the steps required for setting up the system, what's regarding software.
Actually this is a memo for myself.
Without it, each time I try installing the whole thing, I miss something.

- install the SWEEX SC016 8-channel USB-audio attachment using the Windows XP driver that's supplied by SWEEX
- such install adds an icon at the right bottom side of the screen - it's labelled "USB Multi-Channel Audio Device"
- click the "USB Multi-Channel Audio Device" icon for configuring the SWEEX SC016 in 8 channels (by default it comes configured in 2 channels only)
- install VAC and make sure it is licenced (otherwise it periodically generates a noise)
- install ASIO4ALL, remembering to configure it later on, in "advanced mode"
- open the Windows Sound Control Panel
- go in the "Audio" tab and select "Virtual Cable 1" for the Default Audio Play and "Virtual Cable 1" for the Default Audio Record
- go in the "Sounds" tab and select "no sounds" - this will ease Windows job (no more beeps to process and mix)
- launch Flowstone and add the ASIO-in component and the ASIO-out component on a new, blank schematic
- ASIO4ALL should wake up, the ASIO4ALL icon should appear at the right bottom side of the screen - it's labelled "ASIO4ALL v2 - Flowstone"
- for configuring ASIO4ALL in advanced mode, click the ASIO4ALL icon in the tray, the ASIO4ALL configuration windows pops up, and for accessing the advanced settings you need to click the "tool" icon on the bottom right corner
- look the "+" symbol preceding each device in the WDM Device List : AMD High Definition Audio Device (that's the HDMI on the motherboard), Realtek High Definition Audio (those are the audio jacks on the motherboard), Virtual Audio Cable, and USB Multi-Channel Audio Device (this is the SWEEX SC016).
- only "Virtual Audio Cable" and "USB Multi-Channel Audio Device" must be active
- click the "+" in front of "Virtual Audio Cable" - over there, only the "In" should be active
- click the "+" in front of "USB Multi-Channel Audio Device" - over there, only the "Out" should be active
- go back to Flowstone, and make sure that the ASIO-in and the ASIO-out modules are activated - in the schematic, you may need to click on the "ASIO4ALL v2" labels for getting them blue instead of grey
- blue labels over there mean that Flowstone has properly detected the installation and the configuration parameters of the SWEEX SC016, VAC and ASIO4ALL
- regarding ASIO-in, make sure the ports are labelled "Virtual Cable 1.1" to "Virtual Cable 1.8" - actually we will only use Virtual Cable 1.1 port and Virtual Cable 1.2 port
- regarding ASIO-out, make sure the ports are labelled "Audio Device 1" to "Audio Device 8" - we will use them all for a stereo 4-channel crossover
- of course, the crossover should sit between ASIO-in and ASIO-out
- any kind of crossover can now be designed : IIR Biquad filters based, FIR filters based, adding delays, subtractive schemes also, etc.
- thanks to Flowstone graphical programming, this is a matter of minutes instead of weeks or months

I won't go in the details regarding the crossover, as this is living matter, depending on personal skills and preferences.
- Some want a digital crossover imitating the analog Linkwitz-Riley.
- Some want the gain curves of the analog Linkwitz-Riley, without the phase distortion.
- Some want sharper curves than the Linkwitz-Riley, and symmetric, and no phase distortion.
- Some want delay-compensated Bessel-lowpass-based subtractive schemes.
- Some want the Baekgaard crossover basing on the 2nd-order state-variable-filter . Actually, this is a 3-way crossover, the simplest crossover, however exhibiting a 180 phase shift between the woofer and the tweeter.
- Some want to hook a subwoofer, adding the subwoofer phase shift to the midbass-high medium satellite for avoiding relative phase shifts.
- Some want to try bidirectional (inherently phase linear) IIR filters
- Some want to try Almost Linear-Phase Polyphase IIR filters
- Some want to try Berchin's FDLS method for designing arbitrary magnitude and phase filters using IIR filters
- Some want to try "frequency warped" filters, using a relatively short convolver having its delay cells replaced by allpass (phase shifter) cells

All what's above, Flowstone can do it, the way you want it.
Just ask Flowstone to generate the .exe, when you are happy about your schematic.
Put such .exe in the "Start" list in Windows, so it automatically executes after each boot.

Flowstone is also able to export using the VST modality.
You may thus distribute your preferred crossover as a VST.
This way you enter the PRO-AUDIO market.

[steph_tsf]

The schematic made under Flowstone relies on the ASIO-in module, reading the stereo audio coming from all Windows applications, thanks to VAC Cable 1 (port 1.1 and port 1.2).
The schematic made under Flowstone also relies on the ASIO-out module, writing the 8-channel audio going to the SWEEX SC016 8-channel USB-audio operating under ASIO4ALL.

We ask Flowstone to create a stand-alone .exe - do not specify "full screen", do not specify "Launch on completion", specify "Start audio on launch"

We close Flowstone.

We launch the crossover .exe compiled by Flowstone.
The crossover GUI pops-up, as a small window. We can thus modify the settings at will.
When the GUI consists of more than a few potentiometers, the GUI size gets bigger, and the GUI window comes equipped with a minimize button.

Let's check if all audio coming from Windows gets trapped by the Virtual Audio Cable, feeding the .exe compiled by Flowstone. We'll test YouTube, MPC-HC (this is a movie player that's bundled with the K-Lite Codec Pack) and Winamp.

Opening a Chrome window, viewing a YouTube video.
Nothing to configure. Each time YouTube plays a video, the sound of that video gets automatically processed by the crossover. Great !

Launch MPC-HC, watching a movie.
Nothing to configure. Each time MPC-HC plays a movie, the sound of that movie gets automatically processed by the crossover. Great !

Befaure launching Winamp, the Winamp output plugin needs to be selected and configured.
One can rely on the WaveOut plugin.
Options - Preferences - Plugins - Output - WaveOut v2.17 (d) - Configure - Peripheral "Virtual Cable 1"
Options - Preferences - Plugins - Output - WaveOut v2.17 (d) - Configure - Peripheral "Default Player".
Both should work, as "Default" got defined as "Virtual Cable 1" in the Windows Sounds Control Panel.
Another possibility is to rely on the DirectSound plugin instead of the WaveOut plugin.
Options - Preferences - Plugins - Output - DirectSound v2.64 (d) - Device tab - Select "Virtual Cable 1".
Options - Preferences - Plugins - Output - DirectSound v2.64 (d) - Device tab - Select "Default".
Both should work, as "Default" got defined as "Virtual Cable 1" in the Windows Sounds Control Panel.
Need to validate the choice, and restart Winamp for the changes taking effect.
Each time Winamp plays music, that music gets automatically processed by the crossover. Great !

I won't claim this is audiophile discipline. The WinXP audio format is 16-bit 44.1 kHz. The SWEEX SC016 is thus asked to operate at 44.1 kHz. As soon as the source audio is not 44.1 kHz (like from movies or from high quality vinyle rips), the Windows Mixer resamples to 44.1 kHz for mixing with the other sources. Because of the Windows Mixer staying just before ASIO, one cannot guarantee to be bit-exact. Well, I can live with that, after considering the outstanding usability / cost ratio delivered by a system working like this. Even if this is only 2.0 or 2.1 audio.

The next stage would consist on trying all this on Windows 8, for determining :
- if everything we are doing on WinXP SP3, is still possible on Win8
- what Win8 WASAPI can bring, possibly in exclusive mode
It would be interesting to start a new subject entitled "Win8 directly driving two 4-way active speakers".

[steph_tsf]

ASIO4ALL settings.
Those settings are not guaranteed to remain after a reboot.
Remember to verify them after each reboot.

[steph_tsf]

WINAMP WaveOut v2.17 (d) settings.
This way the WINAMP WaveOut output plugin sends the stereo audio to Virtual Cable 1.
It should also works when specifying "Default", knowing that "Default" got defined as "Virtual Cable 1" in the Windows Sounds Control Panel.

[steph_tsf]

Kind of .fsm that you can ask Flowstone to compile as Standalone .EXE

For safety, the Audio is disabled upon loading the .fsm.
Before enabling Audio, please reduce the audio volume to a safe level.
In case you have mikes connected on ASIO-in, and you are not sure about VAC, please disconnect the mikes for avoiding any Larsen risk.
Only enable audio when you are sure no Larsen car happen.

See attached file.

[steph_tsf]

WINAMP DirectSound v2.64 (d) settings.
The "Device" tab enables the WINAMP DirectSound output plugin to send the stereo audio to Virtual Cable 1.
It should also works when specifying "Default", knowing that "Default" got defined as "Virtual Cable 1" in the Windows Sounds Control Panel.

The WINAMP volume potentiometer is working well, independently of the other audio sources. This was not the case when the WaveOut output plugin was selected.

[steph_tsf]

Windows Sound Control Panel settings.

[stw]

Kind of .fsm that you can ask Flowstone to compile as Standalone .EXE
See attached file.

EDIT: [...] Removed warning of possible feedback after starting the initial upload [...]

[steph_tsf]

There are words in your posts like "feedback loops" and "unpredicatble behaviour". I'm pretty sure that you have noticed that the .fsm doesn't contain any such things, so why bothering with that in plain blood characters ? Can you please edit your post and make it less brutal, more specific, and less ambiguous.

You need to realize that we live in the real world, with computers being part of the real world. Flowstone is a software aiming at generating sound. You can not ignore this, because you have installed Flowstone. Why would you bother with Flowstone otherwise ? Curiosity kills the kat !

Thus, each time you load a .fsm into Flowstone, you are supposed to take all actions, on your side, for avoiding any potential damage. If you made the choice of using headphones so powerful they can damage your ears, or if you made the choice of using power amplifiers so powerful they can damage your speakers, you'll assume the consequences.

I remain open to any suggestion for making users and newcomers more aware about Flowstone (vast) capabilities. Perhaps you could post a text here, motivating newcomers for trying Flowstone. I fully trust Flowstone development team. As they permit saving a .fsm having the audio enabled, I'll use such facility . As they permit generating an .exe with the audio turned on, I'll use such facility. And you should too, for delivering a .fsm that's immediately usable. Unless it contains dangerous things like youd described above. We may thus agree.

[stw]

Imagine a setup where the Flowstone running PC has built in mircrophone and speakers (like mine).
Use your obvious indepth physical knowledge to imagine what happens if i open your schematic.

Reconsider your ignorant answer about who should take care about what.

My suggestion: Remove or edit your schematic so that you have point to say that you've taken care of things you demand from users trying your work. Should be easy enough!

And no... i won't edit my post until your upload resides unedited just to shelter others from making the same experience!

EDIT: Just to avoid misunderstandings. My post is no way meant to discredit your commendable intentions and workings!