EK-DZ ILDA to ADAT Converter

[james]

All of that is fine. I haven't said anything about the utility of your new device.

All I've said is that once you have some waves on your hard drive (however they got there) there are some things you can do with them that are totally within the wheel-house of the LaserBoy technology and application.

The LaserBoy DAC is for playback.

The LaserBoy App is for on-screen display and conversion to ILDA files.

The LaserBoy DAC spec and construction technology is free and open.

The LaserBoy application is free and open source.

A wave is a wave is a wave...

James.

[swamidog]

got mine and dz went above and beyond helping me get it set up and working properly.

i pumped some lsx abstracts into it and the resulting wave file is *beautiful*.

thank you dz!

[JohnYayas]

First, I think it is very cool that the ILDA to ADAT converter was created. I joined this board because I was interested in laser shows from the technical point of view so I like seeing new technology created by users. Awesome!

I believe you saw a difference in quality between the sound card DAC and Layla but saying that the sound card DAC is inferior isn't fair. It may be inferior to the Layla in terms of latency, supported bit rates, and stability, but it has been demonstrated that the signals are fine for what we're doing. Also, I have used just about every USB DAC out there, including Pangolin products, and I don't see any quality differences. Especially not in terms of brightness. Admittedly, I don't have a Layla so I can't compare the two but one thing that seems obvious is that if there was a problem with signal quality, the very first place you would see it would be in the shape of the ILDA test pattern, not in color. More than likely, the color outputs were adjusted correctly on the sound card DAC and you weren't getting full 5V, as James suggested. However, I know you're both smart people (DZ/swami) so I'm open to being proven wrong.

[swamidog]

don't get me wrong, the output from the sound card dac wasn't bad. the biggest difference that came to mind was the smoothness of the color fades and transitions from the layla.

if you make it to selem, maybe we could sit down with james and dz and do some real tests. i have nothing invested in one being better than the other. it was just a thing i noticed.

First, I think it is very cool that the ILDA to ADAT converter was created. I joined this board because I was interested in laser shows from the technical point of view so I like seeing new technology created by users. Awesome!

I believe you saw a difference in quality between the sound card DAC and Layla but saying that the sound card DAC is inferior isn't fair. It may be inferior to the Layla in terms of latency, supported bit rates, and stability, but it has been demonstrated that the signals are fine for what we're doing. Also, I have used just about every USB DAC out there, including Pangolin products, and I don't see any quality differences. Especially not in terms of brightness. Admittedly, I don't have a Layla so I can't compare the two but one thing that seems obvious is that if there was a problem with signal quality, the very first place you would see it would be in the shape of the ILDA test pattern, not in color. More than likely, the color outputs were adjusted correctly on the sound card DAC and you weren't getting full 5V, as James suggested. However, I know you're both smart people (DZ/swami) so I'm open to being proven wrong.

[james]

Let's be reasonable about this. As I said, I have an echo Layla. I even contacted the mfg and they sent me scemos of the thing and told me exactly what caps to jump. The nice thing about the Layla is that it supports +4dBV outs (and -10dBV). With the +4dBV you don't need any external correction amps. The output is already centered around zero volts even after the caps are shorted and the voltage swing is enough to drive a laser projector directly. All you need to do is make a cable that adapts 1/4 inch phone plugs to a DB25 connector. That's very nice.

Apart from that, I did not notice anything so outstanding that I was discouraged in any way from using a little USB device.

The color linearity issue must be a matter of tweaking the peak voltages of the color channels to exactly +5.00V. There is no other explaination. A 16 bit linear DAC is....... well..... LINEAR! If your peak voltage is out of whack, you will either not get fully saturated colors or you will clip the top range of linearity. Either way your colors will look weird.

What about the guy who has a new super thin laptop like a Mac book with no PCMCIA slot and a small portable RGB laser projector? What is he supposed to do?

Rather than dumping on the USB DAC, you might consider it to be an obvious supplement to your new device.

And being able to convert waves made with your device to ILDA frames and files for free is also pretty serendipitous.

James.

[swamidog]

like i said, i have nothing invested in this. We can run some compares at SELEM if you want. i'm just reporting what was observed.

there are "paper specs" and there are "real world specs". i would not expect a hacked 30$ usb sound card to have the same characteristics as professional recording gear. nor would i expect a 5mp cell phone camera to have the same quality as a 5mp dslr.

(shrug)

Let's be reasonable about this. As I said, I have an echo Layla. I even contacted the mfg and they sent me scemos of the thing and told me exactly what caps to jump. The nice thing about the Layla is that it supports +4dBV outs (and -10dBV). With the +4dBV you don't need any external correction amps. The output is already centered around zero volts even after the caps are shorted and the voltage swing is enough to drive a laser projector directly. All you need to do is make a cable that adapts 1/4 inch phone plugs to a DB25 connector. That's very nice.

Apart from that, I did not notice anything so outstanding that I was discouraged in any way from using a little USB device.

The color linearity issue must be a matter of tweaking the peak voltages of the color channels to exactly +5.00V. There is no other explaination. A 16 bit linear DAC is....... well..... LINEAR! If your peak voltage is out of whack, you will either not get fully saturated colors or you will clip the top range of linearity. Either way your colors will look weird.

What about the guy who has a new super thin laptop like a Mac book with no PCMCIA slot and a small portable RGB laser projector? What is he supposed to do?

Rather than dumping on the USB DAC, you might consider it to be an obvious supplement to your new device.

And being able to convert waves made with your device to ILDA frames and files for free is also pretty serendipitous.

James.

[james]

8 channels of 16-bit linear PCM digital audio DAC at 48KHz.

Essentially the same output as a black face ADAT; bit for bit compatible.

BTW, it hasn't even been mentioned that there are a hand-full of really nice internal PCI sound cards that can do the same 8 channels of 48KHz 16-bit DAC, with either C-Media or VIA chips on them. They need to be modified in exactly the same way as the USB device. They also need the LB Correction Amp to make them compatible with the ILDA output port standard.

James.

[DZ]

James, I can't light pipe into a sound card dac for recording, so really, why are we arguing about this in a converter thread? At SELEM, side by side there was a noticeable difference between the two outputs. If you are coming to SELEM this year perhaps we can recreate the test and account for different variables and see if one or the other is indeed superior, or if they are the same. Either way, for the purpose of this thread it's a useless conversation. ADAT optical is needed to record a show, be it an actual ADAT, a Layla or something else. If you already have a Layla to do the recording, what's so wrong with using it for output as well? And another thing, I've discussed this with you at length in the past. Even when you asked me to do a board layout for the sound card dac I told you that you should consider adding differential, it only costs an op-amp and a few resistors. Yet you were so set on single ended. I don't think you can find a set of scanners these days that don't have a diff receiver, why not take advantage of it? The Layla's that I've modified have a db-25 on the back with differential X/Y, clamped RGB and several controls on the front...

[james]

Size. Cost. Availability. Portability. Complexity.

If you have analog signals and your device converts them to LightPipe, what would be the purpose of converting that right back into analog?

I thought the whole point was to capture them as waves files and free them from those bulky outdated devices.

You can put a lot of waves on a 2TB external USB drive.

My scanner amps are single ended in. If the connection from the DAC to the scanners is only a 25 foot or less DB25 extension cable, who cares?

Some people have put the USB sound card and correction amp inside the laser projector case. All they need is a laptop, a USB cable and a laser projector.

My board turned out great and the people who have it and use it love it.

It is single ended through all and also has clamped color channels.

James.

[DZ]

FIne, James, you win. Can you move on now?

Size. Cost. Availability. Portability.

If you have analog signals and your device converts them to LightPipe, what would be the purpose of converting that right back into analog?

I thought the whole point was to capture them as waves files.

You can put a lot of waves on a 2TB external USB drive.

My scanner amps are single ended in. If the connection from the DAC to the scanners is only a 25 foot or less DB25 extension cable, who cares?

My board turned out great and the people who have it and use it love it.

It is single ended through all and also has clamped color channels.

James.