PC As Active Crossover

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What are you trying to implement a crossover to do? If it's for subwoofer and mains, I'd recommend Foobar2000 and foo_subwoofer. I've been using the subwoofer component for a week or so now and have to say I'm getting the best integration between sub and mains I've ever had. Plus it works with ASIO so everything is bit perfect to the sound card, after processing of course. I'm using a Xonar Essence ST sound card for left & right and an HDAV H6 card for sub out. I'm feeding three subwoofers out of three channels on the HDAV card.
 
Another cheap (?) option...

I've yet to do this but I have the hardware :)

Use a cheap PC "TV Box" that has built-in HDMI out. For example, the Pipo X8 or X9, either well < $200. Run this to most any home theater receiver that has 5.1 or 7.1 out. Use J River Media Center ($50) as your player and/or signal processing. You may run into problems with (for example) the Sherwood Newcaste R-722 (or R-772 I forget) :confused: can only drive a 6 ohm or higher load. So this might be an issue if you have a 4 ohm driver. I bought my Sherwood (used) at around $150. I defy anyone here to spec a cheaper Windows PC, active crossover DSP solution, everything but the speakers, for < $400 :D
 
I've yet to do this but I have the hardware :)

Use a cheap PC "TV Box" that has built-in HDMI out. For example, the Pipo X8 or X9, either well < $200. Run this to most any home theater receiver that has 5.1 or 7.1 out. Use J River Media Center ($50) as your player and/or signal processing. You may run into problems with (for example) the Sherwood Newcaste R-722 (or R-772 I forget) :confused: can only drive a 6 ohm or higher load. So this might be an issue if you have a 4 ohm driver. I bought my Sherwood (used) at around $150. I defy anyone here to spec a cheaper Windows PC, active crossover DSP solution, everything but the speakers, for < $400 :D

you said windows so i dont have an answer but i bought a dedicated pc used on craigslist for $80, then an m-audio delta 44 for $40.

i installed debian 8 jessie and brutefir on it and used rephase create the filters. total cost for two channels two way active $120 !!! :)


now Im running 3x 3 way active and two subs so I needed more outputs so I went a little bit higher end.

same pc, used digirme 9636 $60, 2x used rme adi-8 or nuendo 8 i/o $600

total cost $740 I have 16 inputs/16 outputs for some serious active crossover work.

plug for REPHASE filters. rephase will create IIR AND FIR filters. its creates linear AND minimum phase filters, and it will output .txt for direct input into brutefir.

it could not be simpler.
 
I have tried a few of the budget-pro-audio-targeted multi-channel audio interfaces over the years, including Behringer DCX2496, Rane RPM26x, Presonus Firepod. I found the SQ of all of them to be lacking for audiophile use.

Commercial multi-channel DACs of audiophile quality were too expensive, and DIY solutions were either not fully baked or had technical problems like jitter. Then I found this multichannel USB>I2S adapter with the new XMOS2 controller and excellent clocks, and matching ESS 2016 multichannel DAC kit. I bought them but not assembled it yet. The DAC comes with opamps and parts to make SE outputs. But the PCB exposes the balanced DAC outputs for I/V or balanced out.

2 years ago I wrote to diyinhk to ask if they had plans for something like this. They said nobody would buy it, no demand. I don't know how long it will remain available since it is not featured on their front page anymore, but it's still available. I had very good experience with previous stereo version of diyinhk USB>I2S adapter.

As bodzio said before, FIR filters (Acourate, Bodzio, Audiolense, RePhase, etc) allow linear phase crossovers. The natural lifelike sound of flat phase xo is worth the effort and complexity, imo. FIR also allows room correction. JRiver can do convolution for FIR filters. I like JRiver's 64 bit dsp engine and the 64 bit multi-channel volume control, with wifi remote options and active development.
 
If you use a VST engine, there are lot of linear phase possibilities. It can be a pain to set-up, but it works. I like the GUI and realtime changes over a .txt from RePhase (I have tried RePhase also).

Right now I use IIR, but plan to go FIR in the future. 200$ for a used Fujitsu Esprimo Q900 with DVD silent and with enough processing power for demanding use. I'm using my Asus Xonar u7 right now, and can't complaint. It sounds good, and its silent. The native Asio driver is not good. I doesn't seem to have advanced set-up, so I can't use this driver with my VSThost. But asio4all works well with this card, so no problems.
 
If you use a VST engine, there are lot of linear phase possibilities. It can be a pain to set-up, but it works. I like the GUI and realtime changes over a .txt from RePhase (I have tried RePhase also).

Right now I use IIR, but plan to go FIR in the future. 200$ for a used Fujitsu Esprimo Q900 with DVD silent and with enough processing power for demanding use. I'm using my Asus Xonar u7 right now, and can't complaint. It sounds good, and its silent. The native Asio driver is not good. I doesn't seem to have advanced set-up, so I can't use this driver with my VSThost. But asio4all works well with this card, so no problems.

Hi. couple of quicke questions.


Does this have to have a monitor and keyboard connected to start it? Or cab you set it up to begin processing automatically?

Also, what is the latency through the system? Ie, say you have a zero latency iir filter, how much additional latency does the vst/asio introduce?

Thanks
 
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Also, what is the latency through the system? Ie, say you have a zero latency iir filter, how much additional latency does the vst/asio introduce?

Thanks

ASIO is a low latency driver which allows to use as low as 32 samples buffers (if the CPU is good enough). (on Windows, common playback latency is around 50ms and input latency something similar). 32 samples @ 44.1kHz means less than 1ms latency.
Latency for a VST effect is few samples long.

Total latency depends on audio interface. IIRC, there still are few tools available for to measure this but you have to find those.
 
Hi. couple of quicke questions.


Does this have to have a monitor and keyboard connected to start it? Or cab you set it up to begin processing automatically?


Thanks

Just tell windows to launch Hifi Cable (routing driver) and VSThost and telle VSThost to run the engine on launch. The it works directly withoun any keyboard, mouse and monitor. But I also use the PC as a music centre.

Every audio internally from any program and any input from outside (Mu turntable) are routed via Hifi Cable to the VSTengine, and asio4all routes everything to the 7.1 soundcard. I really like that I can see on a monitor what I'm doing, and I like the analyzer that monitor in realtime: I can see if anything is clipping and I can monitor phase between stereo-channels. And I can see what the crossover plugin is doing.

I still use Holmimpulse and a measurement microphone. So you still need to do a lot of work to get everything right, but the tweeking is so easy. I can just insert a point in the eq curve, and drag with mouse to alter gain, bandwith etc in realtime.
 
Right now I use EasyQ. It's not a dedicated crossover - but it has LP and HP filters build in.

Next I will try Filtrate LE - this is linear phase eq, also with LP and HP built in.

I have tried ReaFIR also (linear phase), but it did som strange things, so for now I don't use it.

Thuneau have a dedicated loudspeaker crossover (but not free - and I like free stuff), and also Rs-met have a crossover but not dedicated to loudspeaker, and I find it to be too simple.

You can also use RePhase to generate a crossover and eq. This can be loaded to a VSTconvolver - but there is no realtime GUI for this.
 
ASIO is a low latency driver which allows to use as low as 32 samples buffers (if the CPU is good enough). (on Windows, common playback latency is around 50ms and input latency something similar). 32 samples @ 44.1kHz means less than 1ms latency.
Latency for a VST effect is few samples long.

Total latency depends on audio interface. IIRC, there still are few tools available for to measure this but you have to find those.

Hi, I need some clarification. on a windows machine is 50ms the normal system latency when doing crossover functions, or 32 samples.. 50ms is a non starter but 32 samples is quite good. Right now the best i can do using brutefir is 32 samples but only with a short filter.

Just tell windows to launch Hifi Cable (routing driver) and VSThost and telle VSThost to run the engine on launch. The it works directly withoun any keyboard, mouse and monitor. But I also use the PC as a music centre.

Every audio internally from any program and any input from outside (Mu turntable) are routed via Hifi Cable to the VSTengine, and asio4all routes everything to the 7.1 soundcard. I really like that I can see on a monitor what I'm doing, and I like the analyzer that monitor in realtime: I can see if anything is clipping and I can monitor phase between stereo-channels. And I can see what the crossover plugin is doing.

I still use Holmimpulse and a measurement microphone. So you still need to do a lot of work to get everything right, but the tweeking is so easy. I can just insert a point in the eq curve, and drag with mouse to alter gain, bandwith etc in realtime.

Ok, I got it . thanks. it has the advantage that you can do eq in real time. once i set my crossovers and eq and drc, I rarely have to touch the machine so that wouldnt be a plus for me. I also dont like having a computer monitor in the "screening room" so I wouldnt use it anyhow.

one thing I would miss if I went to the pc is the 12 second load time of the linux os :) my pc takes at least 2 minutes before its useful
 
Hi, I need some clarification. on a windows machine is 50ms the normal system latency when doing crossover functions, or 32 samples.. 50ms is a non starter but 32 samples is quite good. Right now the best i can do using brutefir is 32 samples but only with a short filter.
...

I noticed earlier that my reply might cause confusion but as post editing option is here available only for a short time I couldn't improve my reply.

So, what I meant was that without ASIO or other kernel-mode drivers (WDM/KS or WASAPI Exclusive) you have about 50ms latency even in audio playback (and total latency is more when signal goes through AD --> DA path ).

Long FIR filter needs plenty of CPU power which usually prevents to use of short audio I/O buffers. With IIR filters you don't have this problem. Have you tried digital LR4 filters for your software based crossover setup ( 4-th order Linkwitz-Riley (LR4) HP and LP filters )?
 
hi, thanks for the clarification. i can get 32 samples system delay in brutefir with filters lower than 2048 taps. im using 8192 and i get 128 samples system delay(not counting the delay through filter itself) so its not too bad.

i AM actually currently running lr4 filters in iir. the filter delay is zero and when i use fir i can set the impulse center to 5% the length of the filter to still get acceptably low delay.
 
Avoid this combination:

If you need Windows audio here is a anti-recommendation. I do not like to trash products, but I have had nothing but bad luck (pops, clicks, stutters) using the WDM feature of J. River Media Center with my hardware. I have done limited testing but when I get identical symptoms on a 32-bit Win10 netbook and on a 64-bit Win7 with 4 GB RAM "better" PC, it is time to blame the software and hardware mix and not Windows itself. Here are the offenders:

J. River Media Center's WDM feature (to capture audio from non JRMC apps).

MiniDSP's USBStreamer (required for ADAT mode -- currently 6 channels for active EQ.)

Yes, I am using the latest software and driver versions.

The above system works flawlessly, but only for audio playback from within JRMC. Any use of the WDM results in pops/clicks/skips ranging from the annoying (a few per minute) to making an app useless (REW measurements.)

I am "stuck" with JRMC for the time being, since I need it for active EQ and x-over duty.

I would like to avoid having to buy new hardware since costs escalate rapidly and there is no guarantee of better performance, absent a "field test."

My biggest problem will be how to do reliable tests with REW. Unfortunately it is clear that JRMC WDM is not a viable choice.

I admire both companies that make the above products. The problem is simply that they do not play well together. And now recess is over :D
At some point it is not worth f- er mucking :blush: with all the settings and such in a vain hope of getting perfect response. Time to research non snap crackle pop alternatives. Suggestions?
 
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