USB Audio DAC mod + LaserBoy Correction Amp

[ElektroFreak]

I'm using a New Star Lasers >150mW module w/TTL blanking (it's a green-only system). It has worked perfectly so far with my DMX board and most of the time with spaghetti. I got a PM over on LPF from carmangary just a minute ago in which he stated that in spaghetti the ILDA test pattern must be viewed with blanking optimizations off in order to see the circle properly, otherwise it will always appear to be a horseshoe-shaped curve, so I imagine it has something to do with spaghetti's blanking optimization. Without optimization, all of my frames including the ILDA test look wonky so hopefully at least the circle will look right.

In truth, with blanking optimization the system works pretty much awesome, except for three or four of my frames which don't come out right (this may be because of problems with the frames themselves, or it may be that the frames don't like the blanking optimization.

I have noticed that when you enable blanking optimization in spaghetti it causes the scan rate to decrease slightly (due to the extra passes used to force the blanking to be more precise, I'm guessing). I understand why blanking optimization is necessary (due to the mechanical delay between the signal reaching the galvo and the time it takes the galvo to move), but is there a way to tune the system so that blanking optimization is not necessary, or would it be too big of a pain to be justified?

[DPSS]

Hi ElektroFreak,

I think I have the same problem as you. I haven't done extensive testing concerning the matter because up to now I've been triying to correct my scan angle problem, but I did realise the cicle problem you mention while displaying the ILDA test pattern. I also have problems displaying any circles, when playing the circle.wav file generated with laserboy I get a bit of a wobbly round shape and if I play back shows in spaghetti small circles appear distorted. I mean the starting and finishing points of the circle dont meet up, the latter shoots towards the outside of the circle displaying something like this:



I'm also using a pair of SP20's but my laser is an Aixiz 15mw green module.

Domingo.

[ElektroFreak]

That does sound like the same problem. Are you using the blanking optimization feature in spaghetti? I believe that the problem is caused by these blanking optimizations that are included in spaghetti, and so my fix is to only use frames that I know look good. I'd say easily 85-90% of my frames look just fine, so it's not a real limitation for me. I just want to make sure that it's not due to errors on my part.

[DPSS]

I've tried disabling the optimization and, when displaying the ilda test pattern, it does make a difference. I have to lower scan speed to arround 12000 in spaghetti to get the circle more or less correctly inside the square, but I am scanning at about a 30 degree angle, so I supose it's about correct forthe SP20's. Still, the pattern doesn't look completely right.
While playing shows in Spaghetti, blanking optimization doesn't seem to make any difference at all. I've tried playing arround with the settings but circles still appear as in my previous pic.
I feel the same way as you, I just want to make sure it's not something I'm doing wrong. If it's a problem with the USB DAC we'll just have to live with it. I mean, I supose we have to be reasonable, we are using a homemade DAC which cost just over 40 € to build, so we can't expect it to work like a Pangolin LD2000.
This >SHOW< is the one I'm referring to when I mention the distorted circles in shows played with spaghetti, give it a try and let me know if the circles at the beginning are displayed correctly for you.

Domingo.

[drlava]

I'm working on adding a little something to the EzAudDac driver that may help this..
can you take a photo of the distorted circle (from a show, not the test file) so I can be sure?

[DPSS]

That sounds promising, please let me know how it turns out. Here goes that photo:



It's from one of the circles at the beginning of the show I mention in my last post.

Domingo.

[ElektroFreak]

That circle looks about like mine does. I'm at work and can't take a picture presently, so I'm glad DPSS could do it. I can't wait to see the results..

[drlava]

Ok, try downloading the driver again and replace the driver that is in the drivers folder of spaghetti. Open the downloaded EzAudDac.ini and copy the BlankDelay 3 lines to the same location in the EzAudDac.ini file in the spaghetti drivers folder. The open the ILDA test frame in spaghetti with optimization off and you can tune the Blank Delay number up and down till the blanking tests at the top look the best.
This should help with the circle tail, but it won't help make the circle end where it started, that's a tuning issue.

[ElektroFreak]

carmangary: If you're out there and happen to see this, check your email. I sent you information about another bug I found in spaghetti..

@DrLava: I'll try that updated driver once I get my spaghetti issues sorted. Right now I can't use it at all.

[DPSS]

Ok, try downloading the driver again and replace the driver that is in the drivers folder of spaghetti. Open the downloaded EzAudDac.ini and copy the BlankDelay 3 lines to the same location in the EzAudDac.ini file in the spaghetti drivers folder. The open the ILDA test frame in spaghetti with optimization off and you can tune the Blank Delay number up and down till the blanking tests at the top look the best.
This should help with the circle tail, but it won't help make the circle end where it started, that's a tuning issue.

Ok, I've tried the new driver and played arround with the BlankDelay setting in it and what I've found is that, the higher the number, the better the blanking test lines in the ilda pattern look, although far from perfect. But, when I play the show with the circles in it, they still seem to have the same tail and, on one or two of the circles, you can seee part of the line the scanners trace just before they get to the starting point of the circle.

Domingo.