Active crossover music player

  • aartsci2
Posted: Fri, 03/27/2009 - 02:17
I'm interested in setting up a music player that will give stereo 4-way crossover function. Each stereo channel would have a high frequency, mid-high, mid-low, and low frequency output. A separate amplifier is fed by each output (yes 8 amps in a stereo 4-way system). Further, the system would have adjustable delay in each frequency channel to adjust time alignment of the sound from each driver. I'm thinking this is something already done.......but where caaan I get it? I could help in the physics and math of putting this together....

Audiophile listening?

  • picothinker
  • 08/22/07
  • Thu, 04/02/2009 - 21:42
That is not my area of expertise at all, so I can't advise. I do know that 8 years is several generations in "electronics device years", and I'm sure a lot has changed. The 'load the CD into memory' part will take a little while, no matter how much ram you have. I think the bottleneck there will be the CD player, since you are effectively ripping it each time you put in a CD. Ardour has no filters on it's own anyway. There are tons of LADSPA plugins that Ardour will use, but I'm not familiar enough with what you want to do to know if that could work, or if suitable plugins exist. A much better performing way would be to rip your CDs to some lossless codec. You could play them from disk as desired and run it through your virtual crossover, or re-write some ripping/encoding software to split it up while it's being encoded. If you have thousands of CDs, that is a daunting job to start, I know, but hard drive space is very cheap. I have no suggestions for your phasing and timing questions. Good luck, it sounds like an interesting concept, just not one that I know much about or have need for.

This is my current

  • aartsci2
  • 03/27/09
  • Wed, 04/01/2009 - 16:17
This is my current system: CD player --> Nady 4-way stereo 24db/oct crossover --> 10 amplifiers --> 2 Vifa DG25AG-35 tweeters, 2 Vifa P13WH midrange, 2 Vifa M26 woofer, 2 Eclipse DVC12 subwoofers. (the subwoofers are dual coil so 2 amps each) This system was built after attending the CES and concurrent "The Show" in Las Vegas 2001. It sounded better than anything I listened to there. My ~$1500 vs their $5000-$40,000 systems. However, the cheap Nady crossover has developed hum and scratchy adjustment pots. It needs replacement. The design issue with a system as above is that the closely spaced crossover points can influence each other and in general there is a lot of phase shift and group delay with 24db/oct. Digital filtering is a solution. It is possible to separate frequencies with no phase shift. Software like Ardour do not have these zero phase shift filters implemented. One possible system is a bios rewrite such as is done in LinuxBIOS. This system could replace both the CD player and crossover. Possible system would be GiGAbyte 708G based motherboard with DualBios. If equipped with 8Gb of Ram the bios could boot, load the CD into memory, divide each channel into 4 frequency separated files and then play these files through the onboard sound. It would be much nicer though to have the flexibility of a complete system with data disk and personal computer functions.

In software?

  • picothinker
  • 08/22/07
  • Fri, 03/27/2009 - 05:01
Are you wanting to do this all in software? If you're going to need 8 amps, it would be pretty easy to add active crossovers, and just adjust them to be what you want. I don't know about the time aligning, however. Looking online real quick, it looks like you can get cheap mono 4-way crossovers for USD $49. Two of those, and you would be in business. Of course, getting the cheapest thing possible isn't always a good idea, but such things exist already (in hardware). Looking a little more, you can get a 4-way crossover[/url] for USD $174. http://tinyurl.com/c9kmey Sounds more like a listening room concept than music production, but you could set up 8 busses on Ardour to output to it.

dupe

  • picothinker
  • 08/22/07
  • Fri, 03/27/2009 - 05:02
dupe