UPDATE: Tutuorial has been updated with a complete wiring diagram and detailed tuning instructions from DrLava himself!

EDIT: drlava is presently sold out of full correction amp kits, but you can still buy bare boards from him. If you want a full kit, assembled or unassembled, you can get them from 300EVIL here: http://www.photonlexicon.com/forums/...696#post139696 These kits are a tad more expensive, but they include a very good 12V dc-dc converter (results in a larger scanned image) and a built in DB-25 connector. I highly recommend them. Wiring the 300EVIL amp is actually a bit easier than the drlava amp kits since the DB-25 output connector is already installed. All you need to do when using these is wire the connections between the soundcard and the amp.

I've tried to include everything necessary for construction of a soundcard DAC here in this tutorial. Many thanks to Drlava for his help and input. Hopefully someone finds this useful! Also, special thanks to Dean Hammonds for the original correction amp design.

This system is typically used with either Spaghetti (which I highly recommend) or LFI Player show software. These are available online for download:

Spaghetti: www.hingednewt.com

LFI laser player: https://sourceforge.net/projects/lfiplayer3d/

This tutorial assumes you already are familiar with soldering electronic components and very basic electronic theory and are comfortable building DIY kits. It also assumes you are aware of how to set up and install drivers for a computer USB sound card.

The most commonly used sound card for this setup is this cmedia sound card card from DX. (the correction amp can be purchased here or here) The only other tutorial that talks about a sound card DAC on this forum uses the previous revision of this card. The most recent revision has slightly different connections, since it is an 8 channel card as opposed to 6 channels for the previous revision. Due to issues with buggy Vista drivers, I don't recommend using this sound card with any OS other than Windows XP 32bit or Linux. Any other sound card can be used as long as you feel comfortable finding the proper channel output capacitors to connect to on whatever card you might use.

For the DAC setup, we'll only be using the first 6 channels. You'll end up with the correction amp outputs connected to your laser modulation (up to three for RGB) and your galvo amps (to control X,Y movement).

The connections must be made on the positive side of each output capacitor so that we get a DC signal (you can see exactly where to connect in the closeup photo below).

In the following image, on the sound card, the connection points are as follows:

Blue wire = L Front channel
White wire = R Front
Yellow wire = L Rear
Red wire = R Rear
Black wire = Center
Orange Wire = Subwoofer




On the correction amp board there is a row of input pins. The first two pins are labeled 5V and Ground, and the last pin is also labeled Ground. Both these ground connections must be connected to ground for the correction amp to work. The middle G is a redundant ground pin on the correction amp, so it needs no connection. On the USB sound card board are some solder points right behind the USB connector that can be used to supply power to the correction amp.
The power connections to the correction amp are as follows:

Red wire = 5V (pad furthest to the left)
White and Black wires = Gnd. (both pads furthest to the right)

The connections can be seen in this image:



The defaults in Spaghetti are as follows:

Soundcard channels | Scanner function | Soundcard Pin in Picture Below (looking from left to right.. you can also see my channel labels written on the card)

Left | X galvo | 1
Right | Y galvo | 2
Left Rear | Red Laser Modulation | 3
Right Rear | Green Modulation | 4
Center | Blue Modulation | 5
Subwoofer | Intensity (not used with spaghetti) | 6



Here's a complete wiring diagram:


You have to go into the settings for the sound card (which you access through the little white and blue icon in the system tray in the case of this specific card) and set it to 6ch. By default it is set to stereo 2ch, which will not work. 2ch does not allow for your modulation channels, and using the DAC in 2ch mode will make it impossible to tune.

__________________________________________________ _____________
NEW!!

Here's tuning instructions direct from drlava himself:

Tuning the sound card DAC correction amp:

Tuning the amp is simpler than it looks. There are 6 channels, but only two adjustments per channel, and each channel is adjusted the same way. Tuning only needs to be done once after construction of the audio card DAC.

First, a note of caution: Never plug in or unplug the USB sound card while your projector is on and connected to the DAC. Doing so will cause the sound card DAC to produce out-of-spec voltages that may cause dangerous beams to shoot out of your projector.

Tuning the sound card DAC. Needed: multimeter, small flathead screwdriver, max.wav, wires.

1) plug in the sound card DAC, open the control panel for the sound card and set it to 6 channel mode.
2) Set the wav and output volume to max, mute all others, and confirm no 'effects' are on, and each speaker gain is set to 0dB.
3) In the windows 'Sounds and Audio devices' control panel, 3rd tab, verify your sound card DAC is the default device.
4) while no audio is playing, connect your multimeter in volts mode between the output G and output channel 1. Adjust the channel 1 Offset pot with your screwdriver until the meter reads 0 volts.
5) repeat step 4 for all 6 channels.
6) play max.wav in windows media player, repeat on, volume all the way up. Measure the voltage between output G and output channel 1 and adjust the channel 1 Gain pot till your multimeter reads either +5V or -5V (adjust to whichever it is closest to)
7) repeat adjustment in step 6 for all 6 channels while max.wav is playing
8) stop windows media player, and exit. Go back to windows 'Sounds and Audio Devices' control panel, 3rd tab. Set the default playback device back to your normal audio card.

That is all the hardware adjustment that needs to be done. Later I can write about setting up Laseroids with EzAudDac and the sound card DAC.
Happy lasing!

If you have trouble playing max.wav, download and install the AC3 decoder here. (thanks to MISTERWILLING for pointing this out) The AC3 decoder is not free, but should work long enough to accomplish the tuning. If it's not sufficient, You could probably also use klcodec pack.

There have been reported issues with the supplied cmedia sound card drivers. If you experience issues with jumbled output from the DAC, make sure you are using this driver: CMEDIA AUDIO DRIVER

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The soundcard DAC comes with a +-9V DC-DC converter. This will limit the scan angle that is possible with the DAC. I highly recommend replacing the DC-DC converter with one that supplies +-12-15VDC such as this: 580-NKA0512SC This is a drop in replacement for the correction amp board which will vastly improve the scan angle.

Here's the complete setup:


Here's a diagram of how the PC, DAC, and scanner get connected:

To maintain the ILDA standard in your system, you'll need to install a DB-25 connector on the DAC to connect the DAC to the scanner. Here's the pinout for ILDA DB-25 connectors:


Here's some video of the completed DAC in action:





Anyone with questions can PM me or email me at faze4djs@yahoo.com.

Thanks for the write up. Very informative. So the outputs for the RGB on the correction amp go straight to the FlexMod's? And the other two go to the Galvo Amps? Do they all share the same common ground?

Chuck

So does this new sound card offer any improvements in scan quality, or just the addition of 2 extra channels?

That's correct. The outputs each have a ground connection pin, but I believe they do all share the same ground source.

@Mario: From what I can tell, they only offer two new channels, but I'd be a bad person to ask about that since this is my first sound card DAC. I have nothing to compare it to. I noticed there were some revisions to the sound card board compared to the instructions I found elsewhere on this forum, so I thought a fresh writeup was in order.

Right. They just offer 2 new more channels which could be used for whatever you want. One cool thing that it could be used for is to create a single wav file with both audio and laser date in it. You could then play it using media player and you would get both sound and a laser show out of the single file. That's pretty cool. Other options are to use the extra channels for a 4th or 5th laser, to drive a DMX or TTL output board, or anything you can think of.

great writeup! i planned to build a sDAC in summer, now its everythin in this thread

@Gary: has it to be wav? have you ever tried lossy/not lossy compressed 7.1 formats, like AC3 or multichannel FLAC? i imagine how it would rock to have it all on a DTS coded DVD-A that you drop in a standalone Surround Decoder and there will be Laser!

A lossy compression would not work since it would remove points from your image. It would be an interesting experiment to see what the resulting image looks like, though.

A lossless compression like FLAC or APE would be as good as wave.

But, you really don't have to deal with sound files at all if you use something like DrLavas driver that makes a sound card look basically like any other laser DAC and will let you use it with various laser show software, including mine.

Thanks for the writeup elektrofreak. I still got to order the parts myself, but this tutorial really puts a load off and makes it seems easy to get working. I'm not sure exactly how I'll tune the channels, but I'll figure something out.

Thanks again

When you say "DrLavas driver" you mean the correction amp board, correct? Or does he have something else available that I should know about??

Whoops, I was wrong

In this case im sure he means the Dr's modded easylase.dll

^That's what I thought he was talking about, but I didn't know much about that until I did some research into it last night. Looks quite handy.

Right, I am talking about the DLL he wrote that makes the soundcard appear to be an EasyLase DAC. It is a lot more convenient than having to create WAV files and play them through media player.

Bumpity Bump Bump

Important new info added to the tutorial.. see first post.

Bump!! SEE UPDATE IN FIRST POST

That's a great tutorial so far. Tuning up I think needs a bit more detail:

Tuning the sound card DAC correction amp:

Tuning the amp is simpler than it looks. There are 6 channels, but only two adjustments per channel, and each channel is adjusted the same way. Tuning only needs to be done once after construction of the audio card DAC.

First, a note of caution: Never plug in or unplug the USB sound card while your projector is on and connected to the DAC. Doing so will cause the sound card DAC to produce out-of-spec voltages that may cause dangerous beams to shoot out of your projector.

Tuning the sound card DAC. Needed: multimeter, small flathead screwdriver, max.wav, wires.

1) plug in the sound card DAC, open the control panel for the sound card and set it to 6 channel mode.
2) Set the wav and output volume to max, mute all others, and confirm no 'effects' are on, and each speaker gain is set to 0dB.
3) In the windows 'Sounds and Audio devices' control panel, 3rd tab, verify your sound card DAC is the default device.
4) while no audio is playing, connect your multimeter in volts mode between the output G and output channel 1. Adjust the channel 1 Offset pot with your screwdriver until the meter reads 0 volts.
5) repeat step 4 for all 6 channels.
6) play max.wav in windows media player, repeat on, volume all the way up. Measure the voltage between output G and output channel 1 and adjust the channel 1 Gain pot till your multimeter reads either +5V or -5V (adjust to whichever it is closest to)
7) repeat adjustment in step 6 for all 6 channels while max.wav is playing
8) stop windows media player, and exit. Go back to windows 'Sounds and Audio Devices' control panel, 3rd tab. Set the default playback device back to your normal audio card.

That is all the hardware adjustment that needs to be done. Later I can write about setting up Laseroids with EzAudDac and the sound card DAC.
Happy lasing!

Just a question... if i dont need ILDA suport right now, cant i just use two correction amp circuits and pass the other ones directly to the analog drivers, setting them instead to do 100% at whatever-volts-the-soundcard-output-is?

If you are using drivers that allow you full control over what their max voltage is, then yes. I still recommend using the correction amp for modulation since it provides th standard 5V if you ever want to use commercially made lasers..

*BUMP* The tutorial has been updated with detailed tuning instructions courtesy of DrLava!

I somehow missed this, but putting the tuning instructions in here is a good idea

That's the very reason why I compiled this tutorial (with drlava's input) here and on PL. It is more helpful and easy to find if all relevant information pertaining to the construction of a soundcard DAC can all be found in one thread.

Regarding Laserboy, it is a very capable program with no emphasis on user friendliness whatsoever. If you take the most capable program in the world and make it difficult to use, you rob it of some of it's universal appeal.. it becomes something that only advanced users or people willing to put forth the effort are able to use.. therefore I do not feel comfortable recommending it to new people as an easy-to-use program for creating laser shows when compared directly to the other software options. That's just honesty, though. I'm not one to bend the truth on account of a third party.. (To be fair, I haven't tried to use Laserboy in quite some time, so the more recent revisions may be easier to use..)

The bottom line is that people are free to use any or all of the available options in terms of software and hardware when building and using a soundcard DAC. There are many ways to build it, and several good software options for running it. This tutorial is only for constructing the most common version of the soundcard DAC using drlavas "laserboy" correction amp and a specific sound card based on the CM106 or CM6206 chips. It can be constructed in several other ways using ANY 5.1ch sound card and the proper op-amp buffer circuits if one has the inclination.

I will add links to Laserboy software download and forum..

when tuning the soundcard, i dont understand what the max.wav file is for. when i download it, and click play, a window pops up that says it encountered a problem while playing the file.

That isn't good. You should be able to play it even with a normal media player.

Anyway, the purpose of the file is to output a signal that you can use for calibration. I don't know what the output of it looks like but it is probably cycling between min and max so you would set your voltmeter on the outputs and then tweak the pots on the sound card DAC until you see the correct voltage on your voltmeter.

I was able to tune the correction amp even without the file. Is that okay?

Probably, the correction amp doesn't have even voltage to overdrive most galvos so as long as it isn't distorted and it is relatively centered it will be fine.