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Pulseaudio Crossover Rack - multi-way crossover design & implementation with linux
Pulseaudio Crossover Rack - multi-way crossover design & implementation with linux
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Old 27th November 2018, 10:54 AM   #21
Tfive is offline Tfive  Germany
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I just released version 1.5 with a small bugfix that prevented the realtime parametrization of SubsampleDelay from working correctly.
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Old 27th November 2018, 02:40 PM   #22
tthorsten is offline tthorsten  Germany
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will there be an DRC Digital Room Corretion implementen like in Accourate - or in the MINIDSP Projekt with FIR filters ?
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Old 27th November 2018, 03:00 PM   #23
Tfive is offline Tfive  Germany
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Quote:
Originally Posted by tthorsten View Post
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?
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Old 27th November 2018, 11:43 PM   #24
DRONE7 is offline DRONE7  New Zealand
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Quote:
Originally Posted by Tfive View Post
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.
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Old 28th November 2018, 10:03 AM   #25
Tfive is offline Tfive  Germany
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Originally Posted by DRONE7 View Post
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
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Old 28th November 2018, 07:00 PM   #26
DRONE7 is offline DRONE7  New Zealand
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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
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Old 28th November 2018, 07:15 PM   #27
Tfive is offline Tfive  Germany
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Originally Posted by DRONE7 View Post
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.
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Old 29th November 2018, 11:28 AM   #28
Tfive is offline Tfive  Germany
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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.
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Old 29th November 2018, 08:20 PM   #29
Tfive is offline Tfive  Germany
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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.
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Old 2nd December 2018, 06:10 PM   #30
Tfive is offline Tfive  Germany
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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!
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