Sound card DAC tutorial

[ElektroFreak]

did you try a driver reinstall?

 

[Benm]

There are two ways around getting output from the desired soundcard:

you can configure it as the default sound card in windows, then start up LFI. This will work, but play any sounds through the galvo set. I've noticed some sounds like the 'bing!' error sound coming out of the galvo's doing that. As far as i know it wont damage them, but it isnt convenient either.

The other way is to select the usb soundcard in the .ini files, which is a process of trial and error. The enumeration of sound devices isn't always all that logical, so its a matter of trying different numbers until it comes out of your usb soundcard instead of somewhere else

 

[ElektroFreak]

I was a little confused by the fact that he's not getting sound out of the card when he checks it in the card's tray utility..

 

[Grix]

Yes, that's the problem. I can see the visualisation bars move showing that there should be sound, but nothing when I plug in the headset, or the laser.

 

[Benm]

That's odd indeed. The sound card could be broken, or its still a driver problem, hard to tell. If you have another computer at hand, i'd install the driver from the first post of this thread and try the soundcard on that.

 

[Grix]

Ok, suddenly it worked again.. These sound cards sure are unpredictable.. :undecided:

 

[ElektroFreak]

Chinese drivers can be unpredictable, but I've never really had many issues with mine. You might consider getting another of the same card in case there's something wrong with that one.

Also, there is another sound card that has been used frequently with the sound card DAC, but I haven't used it myself so experimentation will be necessary.. I will buy one soon to figure out and add to the tutorial: 7.1-Channel 3D USB 2.0 External Sound Box w/Digital Output USBG-SOUND-71 LOW PRICE $22.50

 

[Benm]

I suppose it will be very comparable too the DX soundcard, just a matter of finding the DC output points - which can't be that hard, just look for the caps tracing back from the output jacks.

I'd reckon the approach is generic for all usb sound cards - they output the signal from the dac with about 1/2 supply voltage bias. I would be surprised to see any the correction amp circuitry doesn't work on. The only important thing is that they output the signal unmodified, without any audio enhancements and such. Luckily those can usually be disabled from the driver / control software.

 

[HIMNL9]

Sooorry ..... can't resist ..... :evil: :evil: :evil:

:crackup: :crackup: :crackup: :crackup: :crackup: :crackup: :crackup:


Ok, back to serious part ..... does this mean that the internal features of this soundcard are programmable from the user ? ..... if yes, it's strange, this usually require a full dsp, and i've seen similar features only on high-end professional devices ..... or maybe are programmable only preferences ? ..... the automated translation that they posted is really confused, imho ..... :thinking:

 

[Benm]

Maybe that comes from the CM6206 chip datasheet - it doesnt look like the box has any sort of connector for programming.

I think the buttons on the box will just manipulate the driver on the pc, just like those on scanners and such do. I might be wrong there though, things like volume controls or effects could be done in the actual soundcard, which wouldn't be convenient for a laser DAC.

 

[ElektroFreak]

Sooorry ..... can't resist ..... :evil: :evil: :evil:

:crackup: :crackup: :crackup: :crackup: :crackup: :crackup: :crackup:


Ok, back to serious part ..... does this mean that the internal features of this soundcard are programmable from the user ? ..... if yes, it's strange, this usually require a full dsp, and i've seen similar features only on high-end professional devices ..... or maybe are programmable only preferences ? ..... the automated translation that they posted is really confused, imho ..... :thinking:

Here's a link to c-media's website which contains some info about the cm6206 chip specifically:
C-Media Electronics, Inc.

 

[HIMNL9]

Thanks EF ..... in the meantime i've also found the complete datasheet of the chip, and it report also the schematic principle and a lot of details about internal registers, but i think it need to be a programmer for understand completely them, and i'm mainly a hardware technician, more than a programmer ..... but, for the few that i can understand from it, seem that all those registers controls the functions, not the characteristics or quality of the signals (except maybe the ones that controls the DACs) ..... ah, well .....

 

[spanqee]

so i got my "modified" 6 ch usb soundcard from midwest lasers and plug it in to find my scanners are still putting out jibberish when i can get it to drive the scanners at all. the test pattern (the only recognizable image i could get it to project) in spaghetti (lfi was totally unresponsive) has blanked areas that travel all around the design? now i find that i need another component called the "correction amp". ok... i kin find 1 of those eventually.

:thinking: but im going through the steps outlined in 1st post and opening the .wav file provided in the link just to confirm all 6 channels work using headphones to listen for a sound(groovy trak btw, a real toe tapper) : front L and front R ok- white noise, volume of both channels change appropriately when i move volume slider, but rear R and rear L behave unexpectedly as i move the volume slider in media player to max. the sound goes from one channel to the next and fades completely out when the slider reaches max volume.(the only way to get full volume on both channels is to park it precisely in the middle)and the same with the jack for center and bass. is this normal or is there something seriously wrong with the mods or the soundcard itself? :thinking: the only mod i can see that was done to the soundcard would be some new caps next to the output jacks, where im gathering i would connect the leads to the correction amp.
oh yeah 15kpps scanners if that matters.

HHHEEEELLLLPP! i got 12 days to figure this out.(we got a memorial day gig that , properly executed , will allow us to fire the boss/owner of our outfit) the best tech support i could get from the seller was to "just play with it and figure it out" for myself.:tsk:
thanx
stvn

 

[Benm]

I've placed a schematic for a working correction amp on page 2 of this thread.

Obviously you need to have a working soundcard to get it all to work. Make sure to get the drivers installed as detailed in the opening post. You should be able to verify output using headphones, different projected images will result in different sounds. Also, the blanking signal sounds different from the x/y control signals.

The only 'modification' i did to the soundcard is connect before the output capacitors. The first post in this thread has very clear images that show which points you need to solder onto.

 

[spanqee]

ok (plz try not to laugh)so im able to get the blanking to work. connected output to TTL leads (youre gonna love this) BY LICKING MY FINGER AND HOLDING THE CONNECTIONS TO BOTH LEADS SIMULTANEOUSLY!!!!!:yabbmad:
THE (oops) the output measures quite short of the required 5v described in this tutorial and elsewhere. needless to say ive already boxed it up and its going back to the seller FIRST thing monday ... C.O.D.
im sooo cheezed off right now, not because i was sold something unfit for the purpose it was sold for but because i screwed around with it for a week before i found out, so the chances of getting something that will work in time for the all important gig are slim to nil!:scowl::scowl::scowl:
DAMMIT!!! "oh just plug it in and itll work" he says. BS!
ok i feel a lil better , thanx for all the helpful info


and speaking of helpful, there a guy on the PL forum wrote a sweet little ild file browser/viewer. theres a couple bugs but still very functional... you know youve wanted something just like this.

 

[spanqee]

admins plz feel free to delete these posts as i have duplicated the questions here in a more accessible, less stickied thread