Windows XP and extreme DSP

[bill]

Hi, I am new here. I have not read much here yet but from what I have seen I doubt my current approach will fit in well. Regardless, I am very interested in opinions and suggestions for my audio system.

 

My audio room is a hateful thing with mountainous frequency response, something like + or minus 15 db. My options were to treat every square inch of the room with acoustic treatments (mostly bass traps) or eq the response flat at a single spot. Since I only listen from one spot and I had been using the computer as transport for several years now the obvious choice is eq for now and a better room for the future.

 

Then I had to decide on internal or external eq. Software or hardware. Since I also needed (wanted) a nice crossover as well, my top choices were the behringer dcx (hardware), a pro style 8 channel xo with 4 bands of parametric eq per leg and other goodies for about $300 (+ xlr to rca custom cables for input and output) OR the thuneau pc xo (software) with also features 8 channels, also with 4+ bands of parametric eq for $60 (add $150 or so for the phase perfect version - thuneau.com). I chose the software option.

 

It took a couple of weeks at least to learn the audio routing procedures to get it all working clean with no dropouts or digital noise. I still get random pops and clicks but I am still working it out. The current setup uses a dedicated server pc with integrated sound and video that does NOTHING but play sound and video. 2.5 gig processor, 1 gig ram, windows xp. All sound is routed the software crossover and 6 channels of filtered audio are realized at the three 3.4 mil jacks. Here is the path.

 

First, ASIO4ALL is installed to allow the crossover to accept the inputs. All windows audio output is routed to cable 1 in a program called virtual audio cable (basically just internal software patchcords) and from there into the software crossover. DSP is applied, then the audio is sent via cable 2 (virtual audio cable) to audiorepeater (bundled with virtual audio cable), which as far as I can tell is just a way to insert working buffer, since dropouts and digital noise occur regardless of the ASIO4ALL buffer settings if used without virtual audio cable and audiorepeater. Between these two buffers, latency can still be set low enough for use with video. Cable 2 sends the (up to 8 channels of filtered) output to the integrated sound card, and then out to the individual speakers. Unfortunately this approach does not allow external dacs to be used, so the soundcard output is as good as it gets.

 

At that point, I followed this guide http://www.imageevent.com/cics (item #3, the art of building computer transports) to trim windows down a bit and make the computer a more audio friendly environment. It is a nice guide but does not specifically tell you WHY it wants you to make some of these changes.

 

Next up I measured the speakers in room from the listening spot with Room EQ Wizard and ARTA, 2 wonderful and free programs. Used SPLTracer (also free) to make individual .frd files for each pair of speakers and for each sub, all in room from the listening spot. Then imported the .frd files into the xo program and easily eq (kind of) flat.

 

I know that people that call themselves audiophiles do not like dsp much, even tone controls on amps can make an oldskool audiofool cringe. At the same time, they do not seem to mind listening in nasty rooms like mine with + or - 15 db range and minimal (if any) treatment. I am certainly not an audiophile but I am not stupid. The difference a flat(ish) frequency response makes is more dramatic than any component upgrade I can imagine (unless maybe your speakers are actually broken and do not make sound). This approach actually makes my combination of nasty room and very uncomplimentary speakers sound VERY enjoyable.

 

So I have 2 questions.

 

1. What do you think about extreme dsp. (My question mark key does not work)

2. Are there any difinitive guides like the one I posted that go way indepth into cutting windows down to the bone but explaining it along the way so I know what I am doing with each change.

 

And I guess while I am at it...

 

3. Do you know of any good preferably ASIO soundcards with full duplex capability. Cheap is a HUGE bonus. ASIO is not completely necessary but preferred. Must output at least 8 channels.

 

 

 

[Steelman]

"Cable 2 sends the (up to 8 channels of filtered) output to the integrated sound card, and then out to the individual speakers. Unfortunately this approach does not allow external dacs to be used, so the soundcard output is as good as it gets."

 

Did anyone ever find a way to send 8 channels of information out digitally (e.g. from the computer to a home theatre integrated DAC/Preamp/Amp)?

 

This would be a great and very inexpensive way to test some multi-channel equalization, try some active cross-overs, test new gear!!! I have been searching this issue for a while and this post seems to be 80% there.

 

Any suggestions would be welcomed!

 

S

 

[bill]

Did anyone ever find a way to send 8 channels of information out digitally (e.g. from the computer to a home theatre integrated DAC/Preamp/Amp)?

 

Sure it's actally pretty easy. I'm still using the same program from thuneau.com but finally realized that the software "fixes" just don't work, regardless of what they say on their forum. The only real way to make it work is to use a real asio soundcard. Then everything works great.

 

There are a multitude of asio soundcard options for under $200, many of them can handle 8 channels. I didn't really want to spend $200, so I just used an old card I had lying around. (Most Soundblaster Live! or Audigy cards will work fine if you use the kx drivers which include asio support - NOT the Soundblaster drivers - and these cards can be found used for $5 - $10 but mine only supports 6 channels.)

 

I've been living with this setup for a year now and absolutely could not give it up now. It's a bit tricky for the beginner to set up due to windows audio routing but once that's done it works and it works well with no problems. I spent a total of $60 on the program, the soundcard was free (previously used) and I've got a 3 way active xo with 4 (+2) bands of parametric eq per leg. With a better soundcard I could use the full 4 way (8 channels). Can't beat that price as far as I know. It's not a perfect program and it doesn't ever get updated but for what I need it works fine.

 

[Steelman]

Thanks Bill!

 

Just to outline my goals, which are certainly computer-audiophile based, although a bit different from those of typical posts here:

 

Experimenting with new speakers. I thought it would be a good exercise to try a bunch of crossover solutions via an inexpensive digital process, find the best options then build up a few dedicated crossover networks (maybe passive, maybe better quality active). So at this stage I am not too concerned about incredible sound quality, but rather minimizing cost, complexity and the amount of cables I need to run.

 

I had a few follow up questions for you or anyone else who wishes to chime in:

 

- Based on your description, it looks like you are using computer soundcard as the six channel DAC, so are taking six channels of ANALOG out of your PC box and sending them to an eight channel power amplifier and controlling volume from the PC (or taking the six ANALOG signals to a preamp to control volume, then to a poweramp.) Are either of these the case?

 

Questions:

 

1. Do you know of any sound cards that can take 8 digital channels out of a PC or Mac? I see there are all kinds of options for 7.1 (which is really two channel digital only in every case I have found - information for the surround channels just buried in the two channels I think).

 

1a. Any firewire or USB options?

 

1B. Where did you find the solution to route music player software to thuneau?

 

2. Will a hometheater receiver actually receive 8 different digital inputs simultaneously? It would be a great intro to use a hometheater receiver as a DAC, volume control and power amplifier.

 

3. Any thoughts on these options:

 

A. Windows XP ==>foobar2000==>thuneau software==>focsrite saffire pro 24 firewire card

==>some type 6 channel amplifier

==>mono subwoofer

 

B. Behringer DCX (maybe this is just easier; it only has six channels but I can integrate the sub later. It has no global analog volume control but I can use the digital from the PC for now I suppose)

 

Thanks!

 

S

 

[bill]

Sorry, I guess I didn't read your post carefully enough. I'm not sure how to get 8 channels out digitally. You are correct, my setup puts out analog to separate power amps. I don't see any need to send out digital if the dacs in the soundcard are good quality.

 

1b - Routing is all done through the soundcard drivers in my case, although with different soundcards there are several different ways to route everything. Even with my soundcard there are several different ways to route everything. The different options can get quite elaborate but as far as I know it's not possible to to do 8 channels digitally.

 

2 - Not that I know of, but I haven't really looked into it.

 

3 a,b - either option will work. The behringer dcx (as far as I can tell) is the hardware option, the thuneau program is the software option. They do pretty much the same thing and have very similar features.