A how to for a PC XO.

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#661
durwood said:


I need to be able to make adjustments while I am listening in the car. Theories and usual ideal crossover/filtering design just don't work in the car. A lot is trial and error adjusting.



I agree. RED and I currently use an outboard processor doing capable of 4-way crossover, 31-bad/parametric EQ and Time Delay. The unit is an "Alpine PXA-H701" which accepts optical SPDIF IN. But what we would like to try to do is eliminate the Alpine PXA-H701 and use the computer to control sound processing. I would settle for an outboard DAC as long as it is controlled in some way by the computer, hopefully in real-time.

Would a 1Ghz embedded processor mini-itx board be powerful enough to do such a task?

Do you know of an external DAC/external soundcard or PCI software solution? The end result must be 8-10 channels of analog output.

The goal is to fully integrate a computer in the car and have it do what high-end car audio electronics can do without any car aduio processors, just computer based processing.
Click to expand...

Seems like you are trying to achieve exactly the same thing as I am.
I want my carputer to be a 3-way crossover, EQ and do 8 channel time correction...
The only thing I don't have yet is the right software.

My Carputer:
Pentium M 1,6 GHz
512 MB RAM
2 GB Compact Flash (for windows xp)
100 GB 2,5" SATA disk
Pioneer DVD-RW
Griffin Powermate
7" touchscreen
M-Audio Firewire 410 (has 8 good analog outputs)

The processing power should be more than enough to run this real-time. Pentium M can't be compared to the weak EPIA.
I know it's possible to use ACXO in foobar2000, but these filters should be running in the background.
Isn't there any software designed for this purpose?

If it isn't possible to make this work I'll have to go with the PXA-H701.
 
#665
its a pentium M tho.. faster clock for clock i belive.

anyways, Shiobi, thanks for this great effort!

iv been doing this with Kx drivers and my soundblaster 2 for a while now, but i get some new stuff soon that requires some uppgrades in the active EQ department, and il be sure to have good need of your exencive effort in this thread 🙂

-Marius
 
#666
Red GTi VR6 said:
a 1.6?

wow, if the 4000+ was brought to it's knees, I would worry about a 1.6....BUT if it was enough, that would be awesome!
Click to expand...


Yes, a Pentium M 1,6 compares to a P4 3,4 GHz...
In addition the Pentium M can be overclocked to over 2 GHz if it's needed.
Remember it has 2MB L2 cache and 533 MHz FSB 😉
 
#667
M-Audio Firewire 410 (has 8 good analog outputs)

The processing power should be more than enough to run this real-time. Pentium M can't be compared to the weak EPIA.
I know it's possible to use ACXO in foobar2000, but these filters should be running in the background.
Isn't there any software designed for this purpose?
Click to expand...

I had my eye on the M-audio Firewire 410. How is it in your opinion? I am looking for a step up form the creative labs products.

I was also looking at the Terratec Aureon 7.1 FireWire.

Join us over here too at http://www.mp3car.com/vbulletin/showthread.php?t=88359

Any studio experts that specialize in near-field listening are welcome to help us out too. 🙂
 
#669
durwood said:


I had my eye on the M-audio Firewire 410. How is it in your opinion? I am looking for a step up form the creative labs products.

I was also looking at the Terratec Aureon 7.1 FireWire.

Join us over here too at http://www.mp3car.com/vbulletin/showthread.php?t=88359

Any studio experts that specialize in near-field listening are welcome to help us out too. 🙂
Click to expand...


I haven't had too much time to listen to it yet, but it's great!
Only drawback at the moment is that my carputer doesn't have Firewire...
I've used it on my laptop a bit, but only with two channels.
Sound quality is very good, a lot better than the analog outputs on my Audigy. No noise 🙂
Pretty handy with the phantom power for my Behringer ECM8000 measuring mic. That way I can use my laptop and eventually carputer as an RTA.
 
#673
interesting bob_bsme, hadent thought of that.

Thuneau's Allocator looked interesting, and i belive foobar allows for manipulating suround channels into active crossover use..
you may not need more than foobar itself to make that work perhaps?

i recall seing the addon in the dsp section, on a screenshot once.
may work.
 
#674
Your typical sound card with SPDIF output can not assign its multiple output streams to a single AC3 stream. That's what's needed for a receiver to decode the single SPDIF signal and assign its individual streams to the amps. Besides, AC3 encoding is lossy- comparable to MP3 at 192kbs. If you were listening to lossy source files to begin with you would hurt the sound even more than it was originally by lossy encoding it again. There are Dolby Dital Live and DTS Connect sound cards that perform the encoding in real time on some sound cards. The Dolby Digital Live data rate is 448 kbit/s for 5.1 channels. The DTS is up to 1.5Mbit/sec on DVD's, but I believe the sound cards with DTS Connect use the more lossy spec of 754kbs.

Once you use the card in ASIO mode, I'm not sure that the encoding still works. It might- I have not tried it yet. But, AC3 has to be 48kHz, so if you are playing a CD you will have to resample to 48kHz first.

I have a motherboard with Dolby Digital Live chip on board and should give it a try.

The newer HDMI interface available on some receivers allows for uncompressed audio, but I don't know of any sound cards with HDMI output. A while back I saw a video card that also served as a sound card through the HDMI output. If there were ASIO drivers for it, it could be a very good solution for Allocator with a newer home theater receiver serving as a multi-channel amplifier.
But knowing the newest trend in protecting data from copying they will make it really hard to use in any other way than intended- that is playing DVD's.
 
#675
bob_bsme said:
Would it be possible to use Thuneau's Allocator Light with Console, a simple non-asio surround card with spdif output and a surround reciever?

I just want to try this out before spending a lot of money on a dedicated xo-pc/multiple amps 😱
Click to expand...

You'd be doing a lossy DTS or Dolby AC3 encoding. I've only heard of one off-brand sound card that would do DTS encoding. And Dolby AC3 tops out at 640 kbits with some receivers only supporting 384-512.

And with a 5.1 soundcard you might only get to use 5 channels which wouldn't allow you to do a 3-way crossover. I'd worry that the LFE .1 channel is somehow limited.
 
#676
I haven't had too much time to listen to it yet, but it's great!
Only drawback at the moment is that my carputer doesn't have Firewire...
I've used it on my laptop a bit, but only with two channels.
Sound quality is very good, a lot better than the analog outputs on my Audigy. No noise
Pretty handy with the phantom power for my Behringer ECM8000 measuring mic. That way I can use my laptop and eventually carputer as an RTA.
Click to expand...

I went a different route that was less expensive. I have to upgrade my carputer to handle Allocator, so I went the Pentium M route with a desktop board. I picked up an Audiotrak Prodigy Hifi. Sounds better than my Audigy cards. I am still having problems getting Winamp to send the audio through Allocator. The card has ASIO drivers, I have the ASIO output plugin for winamp, but no matter what I do I can't seem to get Allocator to intercept the sound before it exits the sound card. I seem to have some sort of routing issue. I ahve even tried using the console program and still no luck. Any suggestions?
 
#678
Console Question

Hi,

when i use art teknika console as stand-alone VST Host i can see all my channels in the output, and i can design my PCxo.

But how can i play any Music Files (wave) from the same computer over console?


When i use console as vst plugin in Winamp, i can play all my Music files over console, but - two channels ony!! - i do not see all my chanels of the audio card -and i can not use PCxo.

thanks for advice,

Ralf
 
#680
This forum is amazing!!! I have read some 20% of the posts, and will definitely read carefully all of them, but for now I would appreciate comments on the following.

I am planning for a home stereo (for now) installation with BruteFIR and, I guess, Acourate. Now I am in process of buying the speakers (maybe Mackie HR624 and M-Audio BX10s), and this is somewhat urgent as the search is tied to boxing week. I do not really have much experience with electronics and have no experience with DIY speakers, so I thought of the following solution to bypass the crossover:
- buy two identical monitors per each channel (L & R),
- in one of them, disconnect the woofer from its amplifier, in another,
disconnect the tweeter,
- put both monitors upside down, one on top of another, tweeter-monitor on top to keep "working" woofer and tweeter close.

IMHO, such setup would give the advantages of
- doing only small and recoverable "damage" to the monitors,
- preserving balanced input for all channels (2 tweeters, 2 woofers and 1 sub),
- keeping amplifiers designed to work with drivers,
- keeping overload protection built into monitors.

My questions:
- for the purpose of digital processing discussed in this forum, would this way of bypassing the crossovers be appropriate?
- if not, what are its flaws?
- should disconnected amplifiers be loaded with something? I was advised to load them with 100 Ohm / 2 W resistor, would it be OK?
- alternatively, if it is relatively easy to bypass internal crossover while keeping one monitor per channel, how can it be accomplished?
- how different would Mackie sound from, say, Behringers after applying digital correction? I guess difference between them would be shortened?

Thanks a million,
and merry Christmas!
Alex
 
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