Using ILDA DACs with CRTs (Oscilloscopes, etc.)

[allenwp]

Is a page found searching for high speed DAC of any relevance?

Example:
https://www.digikey.ca/en/product-hi...igh-speed-dacs

Thanks, Greg! Yeah, I think I might need to go down this route. My hope was that I could use something with a stable and simple API/SDK that I could simply plug into a USB port on my computer, similar to my ASIO DAC (and also similar to ILDA DAcs, I presume)... But something custom might be necessary here. Let me know if custom USB DACs is the sort of thing anyone here has experience making and they want to help out 😅

Cheers,
Allen

[mixedgas]

Try a 600 ohm load resistor at the end of your cable. My P-26 does not have that issue.



Steve

[allenwp]

Try a 600 ohm load resistor at the end of your cable. My P-26 does not have that issue.

Thanks, Steve, I’ll give that a shot.

…what issue(s), specifically, does your PreSonus Studio 26c not have?

[dchammonds]

All that to say, this is the sort of hardware behaviour I fight against with my current DAC. At first I thought it might be some other piece of equipment or combination in the chain that was causing difficulty, but... I think I just need a DAC that isn't designed for audio...

The output filtering is definitely more aggressive on 1-2, it's like looking at a totally different DAC pair than 3-4. Then there's that 93uSec shift between the two pairs- I've seen multiplexing DACs that have small time shifts between channels, but such shifts are only a fraction of a sample period.


Just for curiosity- can you switch your XY control to 3-4 and blanking on 1 or 2 (or vice versa)? It would be interesting to see what difference it makes in your application.

Dean

[dchammonds]

Thanks, Greg! Yeah, I think I might need to go down this route. My hope was that I could use something with a stable and simple API/SDK that I could simply plug into a USB port on my computer, similar to my ASIO DAC (and also similar to ILDA DAcs, I presume)... But something custom might be necessary here. Let me know if custom USB DACs is the sort of thing anyone here has experience making and they want to help out 😅

Cheers,
Allen

Grix is on this forum, he's the creator of the Helios DAC. Perhaps he could come up with a higher sample rate version of his product. I've been meaning to ask about that myself.

Dean

[allenwp]

Just for curiosity- can you switch your XY control to 3-4 and blanking on 1 or 2 (or vice versa)? It would be interesting to see what difference it makes in your application.

I actually did this back when I was just starting out and got my first oscilloscope with a Z-input

https://allenwp.com/blog/2020/04/28/...us-studio-26c/

[dchammonds]

I actually did this back when I was just starting out and got my first oscilloscope with a Z-input

https://allenwp.com/blog/2020/04/28/...us-studio-26c/

Now I see, 1-2 and 3-4 are entirely different circuits. It's like two different models of stereo DACs poorly linked together.
Back in the day, it was common to tie identical PCI stereo sound cards together with a clock bus to form a multitrack recorder.

[mixedgas]

The audio device IS the reconstruction filter. School of the Internet, [SOI] doesn't teach that. Fact of the matter is, there are two schools of audio design thought plus the build it exactly like the example on the data sheet types.

School one, Perfect reproduction.

School two: Musicians like distortion and noise, Give them their so called "sound".

School two has the finances.

So asking a device to be 24 bit perfect and have 86 Khz of bandwidth is quite a stretch. Read up on DAC chip specs, interpolation is allowed in audio DACs, has been for a long time.

SOI doesn't teach about transfer functions and reconstruction filtering as that makes the brain hurt for many of its customers.

STEVE