8 channel Linux audio with active crossovers

Hi folks,

Based on soundcheck's excellent work on linux sound i've managed to get my open baffle speakers up and running. Crossover and equalisation as yet don't match the quality of what i have configured in windows but its a good start.

I've attached a screenshot. The setup consists of a
core 2 processor 2gig
audiotrak prodigy

ubuntu studio - realtime kernal
jack configured for realtime with eight channels and 1ms latency

patchage - installed by default by studio

calfjackhost with 4 fiters for high pass tweet, low pass woofers and band pass mids.

it sound reasonable but has quite a ways to go.

The biggest problem is the quality of the crossovers and as yet no equalisation.

Can anyone advise me on some decent plugins for linux?
 

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dwk123

Member
2002-02-06 4:51 pm
I hadn't seen the calf plugins before - looks somewhat interesting, but unusual in that they only support low-pass/high-pass filters. Since the math and implementation for all biquads is pretty much the same, it's odd that they didn't include parametric/shelving etc filters also.

I think most people using Linux tend to look at BruteFIR rather than using biquads. A more general/powerful approach, but it is definitely more work to get started.

There is a standard biquad ladspa plugin here LADSPA that you should be able to use with jack-rack or a similar ladspa host. Probably not graphical though.

A nice looking ladspa/lv2 plugin is here linuxDSP but it actually costs money. Not expensive, but unusual in the linux world.

One thing that may or may not be interesting is Reaper - this is a Windows based DAW product, but they list 'Wine' as a supported platform. Using WineASIO to patch directly into jack might be worth a look. I'm currently using Reaper under Windows and the included Parametric EQ seems to be pretty good.
Reaper is also commercial, but quite reasonable ($60 I think) and the built-in JS scripting environment is GREAT for prototyping dsp code.
 
Thanks dwk,

There are other filter available with calf and afaik they are modelled on the ladspa setup. I have found that the calf plugins can't be saved so that the setting are there upon restart.

I've tried wine and managed to get console running with some vst plugins but in reality i don't want any overhead.

I'm very surprised that linux isn't better supported by the pro audio brigade particularly when it comes to the likes of steinberg and the vst plugin standard, they support win and mac so why not linux?

Linux DSP looks like exactly what i need - ill have a good read.

I'm currently learning about FAUST -- Faust Server - a programming language designed specifically for DSP and parrallel stream processing using a C++ wrapper to design and build your own plugins. In theory i should be able to build a very small but functional realtime linux active crossover system.

I'd also like to find a way to run multiple identical card with an external clock and still utilise all the outputs - the idea being that i would have a small linux box running the active crossovers connected to my open baffles or to my surround system which can be fed with whatever digital source i want e.g. gaming machine or win pc.
 
Thanks dwk,

There are other filter available with calf and afaik they are modelled on the ladspa setup. I have found that the calf plugins can't be saved so that the setting are there upon restart.

I've tried wine and managed to get console running with some vst plugins but in reality i don't want any overhead.

I'm very surprised that linux isn't better supported by the pro audio brigade particularly when it comes to the likes of steinberg and the vst plugin standard, they support win and mac so why not linux?

Linux DSP looks like exactly what i need - ill have a good read.

I'm currently learning about FAUST -- Faust Server - a programming language designed specifically for DSP and parrallel stream processing using a C++ wrapper to design and build your own plugins. In theory i should be able to build a very small but functional realtime linux active crossover system.

I'd also like to find a way to run multiple identical card with an external clock and still utilise all the outputs - the idea being that i would have a small linux box running the active crossovers connected to my open baffles or to my surround system which can be fed with whatever digital source i want e.g. gaming machine or win pc.

erm, they support windows because its the most popular OS overall and they support mac because as opposed to the relatively low percentage overall, in pro audio it is considerably higher than 50%, last time i saw numbers it was well over 75%. pro audio doesnt use much vst on mac anymore though and hasnt for years, audio units and protools format plugins are most popular. cubase is a very small amount of studios, most use logic audio or protools. cubase is used more in schools and semipro people in general these days

linux on the other hand is vanishingly low, well under 10%, supporting a version, although a straight forward port from macos these days is not worth it
 
Last edited:

jazbo8

diyAudio Moderator Emeritus
2011-01-05 8:34 am
In Transient
How are you designing/implementing the crossovers? And what drivers are you using in your OB design?

Thanks,
Jaz

Hi folks,

Based on soundcheck's excellent work on linux sound i've managed to get my open baffle speakers up and running. Crossover and equalisation as yet don't match the quality of what i have configured in windows but its a good start.

I've attached a screenshot. The setup consists of a
core 2 processor 2gig
audiotrak prodigy

ubuntu studio - realtime kernal
jack configured for realtime with eight channels and 1ms latency

patchage - installed by default by studio

calfjackhost with 4 fiters for high pass tweet, low pass woofers and band pass mids.

it sound reasonable but has quite a ways to go.

The biggest problem is the quality of the crossovers and as yet no equalisation.

Can anyone advise me on some decent plugins for linux?