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-   -   Pulseaudio Crossover Rack - multi-way crossover design & implementation with linux (https://www.diyaudio.com/forums/pc-based/330273-pulseaudio-crossover-rack-multi-crossover-design-implementation-linux.html)

Tfive 27th November 2018 10:54 AM

I just released version 1.5 with a small bugfix that prevented the realtime parametrization of SubsampleDelay from working correctly.

tthorsten 27th November 2018 02:40 PM

will there be an DRC Digital Room Corretion implementen like in Accourate - or in the MINIDSP Projekt with FIR filters ?

Tfive 27th November 2018 03:00 PM

Quote:

Originally Posted by tthorsten (https://www.diyaudio.com/forums/pc-based/330273-pulseaudio-crossover-rack-multi-crossover-design-implementation-linux-post5614572.html#post5614572)
will there be an DRC Digital Room Corretion implementen like in Accourate - or in the MINIDSP Projekt with FIR filters ?

Somebody already asked this question via PM. What exactly do you need for this? It would probably be relatively easy to add a FIR convolver plugin where impulse responses could be configured by loading some kind of PCM impulse response file (WAV or similar). Would this be enough for your needs?

DRONE7 27th November 2018 11:43 PM

Quote:

Originally Posted by Tfive (https://www.diyaudio.com/forums/pc-based/330273-pulseaudio-crossover-rack-multi-crossover-design-implementation-linux-post5614218.html#post5614218)
Does that mean you'r listening to a speaker crossed over py PaXoverRack? If so, you're definitely first, man. :) My SCS4s are still lurking in the basement and I will have to build a 6 channel amp first to get my setup going...

If you want you can take a picture of your test setup and I will post it on the homepage as first ever system running on PaXoverRack ;)

I'm still testing..... I've always been an Alsa user so Pulseaudio is a bit of a learning curve... The usb card I am using has no controls in Alsa but is configured correctly by pulseaudio..(Sound Blaster X-Fi Surround 5.1 Pro)

Finally found why I was getting all sorts of thumps and pops, why the card turned off when music stopped playing and why I was constantly having to redo the config as it defaulted to internal speakers after resuming from suspend....

TLP.... damn laptop power-saving....grrr..

Edited /etc/default/tlp and changed enable from 1 to 0

Card stays on now and suspend/resume works fine.

My basic testing is with small powered speakers (such as for use with ipod or mp3 player) as the satellites and a small home theatre powered sub for the mono woofer. So, yes a system running on PaXoverRack though a most meagre and basic one just for trying all the features.

Next the workshop big system using Kef satellites with Quad amp and a Monitor Audio sub (Silver W-12 | Subwoofer | Monitor Audio)

Once that's running I'll post some pix.

Tfive 28th November 2018 10:03 AM

Quote:

Originally Posted by DRONE7 (https://www.diyaudio.com/forums/pc-based/330273-pulseaudio-crossover-rack-multi-crossover-design-implementation-linux-post5615165.html#post5615165)
Finally found why I was getting all sorts of thumps and pops, why the card turned off when music stopped playing and why I was constantly having to redo the config as it defaulted to internal speakers after resuming from suspend....

TLP.... damn laptop power-saving....grrr..

Edited /etc/default/tlp and changed enable from 1 to 0

Card stays on now and suspend/resume works fine.

Never heard of TLP. It seems interesting though, maybe i will try it for my laptop as well. From what i read you can disable the audio power saving feature separately. On the other hand, never change a running system

DRONE7 28th November 2018 07:00 PM

The audio powersaving I think only supports Intel HDA, AC97.
I tried that first but no joy so just took the blunderbuss option and turned tlp off.

Thinking further it probably is the tlp usb auto-suspend that is playing havoc with the soundcard.
When I have a moment I will turn tlp on and disable the auto-suspend for the usb souncard and see if that works.

Question...any chance of a third-order filter 18db/octave for the Xover-rack ?

cheers,
bob

Tfive 28th November 2018 07:15 PM

Quote:

Originally Posted by DRONE7 (https://www.diyaudio.com/forums/pc-based/330273-pulseaudio-crossover-rack-multi-crossover-design-implementation-linux-post5615929.html#post5615929)
Question...any chance of a third-order filter 18db/octave for the Xover-rack ?

cheers,
bob

I guess you're talking about 3rd order Butterworth? Implementing filters is relatively easy, so by the time i find out how to calculate biquad coefficients for them (I'm still a DSP noob) this should be no problem.

Tfive 29th November 2018 11:28 AM

After some reading I have to admit that there is a design mistake I made in the LR-2 low/highpass filters. these are not LR-2 characteristic as announced but effectively are second order Butterworth filters with -3dB gain at the crossover frequency and not -6dB as they should have. LR-4 filters are two 2nd order Butterworth filters in series and are thus implemented correctly. I will correct these mistakes in the next release and I will also add 2nd and 3rd order Butterworth filters to the mix.

Tfive 29th November 2018 08:20 PM

Update: 1.7 was released together with ladspa-t5-plugins 1.3 which fixes the wrong filter characteristics of the LR-2 filters. 2nd order and 3rd order butterworth filters will likely come tomorrow, the code base of the ladspa plugins has been reworked and cleaned up big time in preparation for these.

Tfive 2nd December 2018 06:10 PM

Another update: I'm struggling hard to find a formula to calculate the IIR filter coefficients for a third order Butterworth filter. Anybody here who can help with this?

I'm searching for something like:
Code:

    def _coeffsBA(f, samplerate):
        """ return 12db/oct high pass biquad coeffs for given frequency """
        w0 = 2 * pi * f / samplerate
        alpha = sin(w0) / 2 / 0.7071067811865476 # Butterworth characteristic, Q = 0.707...
        cs = cos(w0)
        norm = 1 / (1 + alpha)
        b0 = (1 + cs) / 2 * norm
        b1 = -1.0 * (1 + cs) * norm
        b2 = b0
        a1 = -2 * cs * norm
        a2 = (1 - alpha) * norm
        return (b0, b1, b2), (1, a1, a2)

In the meantime I'm trying my luck with some DSP literatur but my head is already aching like hell! :xeye: :faint:


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