How much can a computer do?

Here is a better comparison of different crossovers:

The graphs below show 2 square waves the red one is unprocessed and the green one goes through a crossover.
The crossover point is 250 Hz and the square wave is 250 Hz.

As you can see in A. the standard 6db Butterworth shows excellent phase response. This design is simple (fewest components) and most speaker manufactures use it.

As we move up in crossover order (6=1, 12=2, 18=3, etc..) shown in B. and C. the separation of lows and highs gets better but the phase response suffers.

The Waves LinEQ (D.) is better but not perfect..

The Sheinkin 18db is bit strange but has very good phase response.

F. Uses a 'real-time' convolver. This is very cool because room response curves can be included and compensated for at the same time.



The good, bad and Latency:
PH = phase response
LR = Low/High separation
L = Latency

A. Excellent PH, poor LH, L=0
B. Fain PH, good LH, L=0
C. Poor PH, better LH, L=0
D. Good PH, better LH, L=2679
E. Excellent PH, better LH, L=0 but amplitude problem (not sure what this is)
F. Excellent PH, Excellent LH, L=65536

To be honest I'm not sure how to qualify B. and C. in PH. Is one really better than the other? I guess you could say B. is slightly smother.

Latency is a problem (see D. and F.) if you are trying to sync with a movie or other channels.
If everything is delayed together there is no problem other than a small delay between pressing play and hearing music.

All of these plug-ins are free except D.

Tested using VA-Visual Analyser 4.0. (freeware http://www.hitsquad.com/smm/cat/OSCILLOSCOPES/)

Hey Scott, Kudos man, that's a way cool setup.

As one of the few on the board who really can Grok what you'd done, I have give you props dude :bowdown:

It is something I always considered doing (although for me, I'd have used an old Dual G5 MacPro as the host).
But adding further complexity to my system made ME pause

Scott, linear phase response in the xovers is critical. But as you note, the delay (latency) is a killer.

That’s why I really dig the new Denon AVP preamp, it does all this stuff internally. Even the hundreds of room EQ filter points are all FIR based, which are much more phase neutral than typical IIR one found in other EQ’s.
But the secret sauce in the AVP, is that because it integrates a VDP (based on the Realta T2 HQV processor), it can delay video proportionately with the audio (or vice versa when there is much video processing), and can keep everything in synch.

Work wonderfully. And for $7.5K it’s a bargain in my book.

But it’s not as DIY as the route you’ve taken. Which I must say, is pretty good.

Now you need to do a multi-point measurement of your room, take the averages and do a room correction impulse response for the convolver to process as well.

It’s never done

PS- I think we lost a few of the others with the TLA’s and tech

Thanks Jonathan I knew you would get a kick out of it.

Yes, latency is big problem. Actually that is one of the more easily solved problems inside ffdshow. But having said that the real problem of computer based media systems starts to become more visible namely codec’s. Up until fairly recently playing media from inside Vista (x64) Media Center was difficult if not impossible. The latest codec’s go a long way towards making it “easy”. This however is putting it mildly. Getting a computer setup to the point where it can be used like an “appliance” is not a trivial task. In some ways it’s an all or nothing proposition.

It can be relatively painless to store music and stream it bit perfect to external processor, but when video gets added to the mix it gets much more complicated. Especially when you start looking at all the different video/audio formats in all the different containers like MKV for example.

For someone like me or you (with a computer background) it is an attainable goal. For the average person it’s probably going to be too painful to attempt.

Thanks again for the kind words,
Scott

JonFo said:

...I really dig the new Denon AVP preamp, it does all this stuff internally. Even the hundreds of room EQ filter points are all FIR based, which are much more phase neutral than typical IIR one found in other EQ’s. ...

Click to expand...

I wanted to ask you about that. I think that pre uses Audyssey Laboratories ARC System which is now available as plug in: http://www.ikmultimedia.com/arc/ What do you think of it? Does it do XO as well as EQ? Is it possible to get the averaged room measurement out (so I can convolve it with my XO)?

Now you need to do a multi-point measurement of your room, take the averages and do a room correction impulse response for the convolver to process as well.

Click to expand...

I've been looking into Audiolense:
http://www.juicehifi.com/index.html

Once I get everything working I'll post an update...

ScottGardner said:

I wanted to ask you about that. I think that pre uses Audyssey Laboratories ARC System which is now available as plug in

What do you think of it? Does it do XO as well as EQ? Is it possible to get the averaged room measurement out (so I can convolve it with my XO)?

Click to expand...

Scott, that really cool news to hear that someone licensed Audyssey for a DAW plug-in. It seems to be 2ch only though, is that going to work for you?

The Pre uses MultEQ XT, and I upgrade to the MultEQ XT-Pro (including calibrated mic and the PC based Software that computes many more points based on many more measurements (up to 32).

The preamp uses the data from the measurements to establish certain crossover points (which I can then override). But primarily, it's used for the room correction on all active channels (up to 12).

I've yet to try and extract the individual impulses for the saved measurements file my Pro version does. I've been curious to look at the impulses in ETF/R+D.

But you could still extract a convolution target form an averaged set of impulses using Audiolense or another measurement software (like R+D).

ScottGardner said:

I've been looking into Audiolense:
http://www.juicehifi.com/index.htmlView attachment 8464

Once I get everything working I'll post an update...

Click to expand...

Very interested to see what you think of Audiolense vs your DAW+plug-ins.

Like Audyssey, they are using FIR filters, so phase should be good.

I feel like I barely have time to tweak my current system, which is complex, but simpler than before. But nothing compared to what you’re doing, my god, that must be a major time-sink

JonFo said:

Very interested to see what you think of Audiolense vs your DAW+plug-ins.

Click to expand...

Unfortunately it only creates the convolvable curve I still have to use a plug-in to convolve it via convolverVST. Jeesh if I had to say that out loud I would have just convolved my tongue.

I feel like I barely have time to tweak my current system, which is complex, but simpler than before. But nothing compared to what you’re doing, my god, that must be a major time-sink

Click to expand...

It is but hey thats what hobbies are for. Actually I can tweak it while I listen to it. All the "wiring" is virtual so I can change it around in real-time and get immediate feedback to determine how it sounds. I fact I'm listening to now while I type this.

Wow!

Hi Scott,

I'm back after a period of hard work and a newborn baby!

I'm impressed about your system! Do you confirm that the only hardware (pc excluded) before you amplifiers is the rme? Are you using their PCI card?

This puts down the basis of a potentially unlimited system, features speaking.... hey, I'll not get asleep tonight..

Ciao!

Paolo

pidigi said:

Hi Scott,

I'm back after a period of hard work and a newborn baby!

I'm impressed about your system! Do you confirm that the only hardware (pc excluded) before you amplifiers is the rme?

Click to expand...

Yes that is correct

Are you using their PCI card?

Click to expand...

Yes

This puts down the basis of a potentially unlimited system, features speaking.... hey, I'll not get asleep tonight..

Ciao!

Paolo

Click to expand...

It is practically limitless and I have made a few changes:

I am now using Acourate to generate crossovers and driver linearization filters.


I run seven convolve engines with 64 bit double precision filters.


Inside Plogue Bidule:


Scott

I almost forgot I have abandoned Windows Media center in favor of J River media center. JMC supports ASIO and, because it fully supports external codecs, has no problems with DRM.

Here are a couple of pictures:

Audio:

Video: