My DIY Audio Scope so far (will update)

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barfle

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Actually buried somewhere in the forums within, oh, the couple of years was a project that did that. It was technically successful but aesthetically mediocre. The difference being that a CRT phosphor has a measurable decay time; the time it takes for a spot to fade out after the spot has moved elsewhere. That makes the CRT version much smoother & easier to interpret the display. Discussion was made on how to add artificial decay time to the software project & it fizzled out at that point.


Now if you want something that is 2 ch but is so powerful it has been known to cause Royal Houses of Europe to crumble. The Atari MusicVision:


Yes I have one. I've never hooked it up to my 8' screen for fear of causing cerebral hemorrhage.
I have one also. I modified mine so it outputs composite video instead of CH3 RF. Interestingly, it fills my 1080 screen, but I never figured out why. Great fun with disco and its heavy bass line. 😀
 

doity

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I have one also. I modified mine so it outputs composite video instead of CH3 RF. Interestingly, it fills my 1080 screen, but I never figured out why. Great fun with disco and its heavy bass line. 😀

Would love to see it since I missed that long, lost post. I have seen some digital oscilloscopes online for computer audio but was not impressed. Ain’t nothing like the real thing baby!
 

Wurly1

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Really cool I've watched the video more than once. I like the "4" in the middle & I don't think the widescreen display is a problem at all. Did you say this uses 6" LED display? That's pretty big you can see that from across the room. I am also curious what music and decode format did you use for the YT video?

About a hundred years ago I built something similar but smaller. Actually it was part of a quadraphonic input/output control center:
View attachment 53599

You can see the rectangular display window where the LED meters went. I had to go to a machine shop to get the hole cut out. I don't have the skills or tools to make it look professional. Like in your project the 'tronics is sometimes the easy part, making an enclosure that looks good & suits your purposes is the hard part.

Here's the little LED board that sat inside the tinted window:
View attachment 53600

Notice that the LED modules on the left side are inverted. They were red/green with green being at the center. The board behind was just the input buffer board with multi-turn trimpots so I could calibrate the level detection precisely. Of course it is very rectangular to fit the window. Doing it today (which you're kinda getting me revved up to do) I would do the layout more as you have done.
Those LED modules were sold seperately at Radio-Shack in the end of the 70's.
 

Soundfield

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That’s really interesting Doity, and quite a co-incidence – I was toying with a design for a similar thing a few months back! I was inspired by those pseudo ‘scope displays that Pioneer put on their quad receivers. Like Sonik said, there are loads of VU boards available either as built modules or as DIY kits you can use for this sort of thing. I used a kit as it was then easier to change the mulitcoloured LEDS to normally fitted to such things to large square green LEDS more suited to mimicking a scope:

modified VU pcb.JPG


I tried a couple out as shown here with a stereo signal where I’m also experimenting with making a scope style graticule:

LED Level Indicator on test.JPG


The next stage was to make another two boards and arrange all four in a suitable housing (this was a modified deep picture frame, shown here without the graticule and glass):

quad vu display frame.JPG


But then, as so often happens (!) I lost interest and moved on to another project so it’s not gone any further. I might get back to it but the real reason I haven’t got much enthusiasm for it now is that it’s not a proper vector-scope display and so doesn’t tell you anything about what’s going on in positional terms between the four cardinal points. You also need to take phase into account to do that of course. So I am thinking about doing this as an addressable x-y array of LEDS. Whether this one gets any further than the prototype stage is, given my track record, problematic!!
 

Sonik Wiz

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not my area of expertise, not even near it but I wonder if this is a way in?

I see the actual scope portion is not cheap
Yuppers if you just google USB oscilloscope you'll find a wide range both in features & price, kit or assembled, and some that have their own phone size screens built in. It is important to choose one that show Lissajous tracings where both the X & Y axis can be controlled by the input. Since this simulates a CRT scope where the deflection plates are vertical & horizontal you would also need a rotational matrix at the front end to convert the 4 ch signals to work with this.
 

Sonik Wiz

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That’s really interesting Doity, and quite a co-incidence – I was toying with a design for a similar thing a few months back! I was inspired by those pseudo ‘scope displays that Pioneer put on their quad receivers. Like Sonik said, there are loads of VU boards available either as built modules or as DIY kits you can use for this sort of thing. I used a kit as it was then easier to change the mulitcoloured LEDS to normally fitted to such things to large square green LEDS more suited to mimicking a scope:

View attachment 53985

I tried a couple out as shown here with a stereo signal where I’m also experimenting with making a scope style graticule:

View attachment 53986

The next stage was to make another two boards and arrange all four in a suitable housing (this was a modified deep picture frame, shown here without the graticule and glass):

View attachment 53987

But then, as so often happens (!) I lost interest and moved on to another project so it’s not gone any further. I might get back to it but the real reason I haven’t got much enthusiasm for it now is that it’s not a proper vector-scope display and so doesn’t tell you anything about what’s going on in positional terms between the four cardinal points. You also need to take phase into account to do that of course. So I am thinking about doing this as an addressable x-y array of LEDS. Whether this one gets any further than the prototype stage is, given my track record, problematic!!
I really like that. Good 'ol Velleman kits! I think it would be worth persuing it looks like your almost done. CRT quad scopes are better for showing non-coherent sound than LED meters but LED VU meters are more readable if you are looking closer at amplitude levels. Hey! It's a VU meter!
 

doity

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That’s really interesting Doity, and quite a co-incidence – I was toying with a design for a similar thing a few months back! I was inspired by those pseudo ‘scope displays that Pioneer put on their quad receivers. Like Sonik said, there are loads of VU boards available either as built modules or as DIY kits you can use for this sort of thing. I used a kit as it was then easier to change the mulitcoloured LEDS to normally fitted to such things to large square green LEDS more suited to mimicking a scope:

But then, as so often happens (!) I lost interest and moved on to another project so it’s not gone any further. I might get back to it but the real reason I haven’t got much enthusiasm for it now is that it’s not a proper vector-scope display and so doesn’t tell you anything about what’s going on in positional terms between the four cardinal points. You also need to take phase into account to do that of course. So I am thinking about doing this as an addressable x-y array of LEDS. Whether this one gets any further than the prototype stage is, given my track record, problematic!!
Wow, I love that design. Very ingenious. Well I had no illusions that my ‘scope’ was nothing more than just a way to see that all channels are working and to look at some flashing lights in the meantime. And truthfully most people that used these things probably just wanted some cool lights to groove out on or some similar 1970’s jargon 🙂

I hope that you can finish the project and let us see the results. I love the picture frame idea. I was thinking of duplicating the grid on the Pioneer scopes by copying and magnifying the image and possibly having a nylon decal(?) done up that would at least look like the real deal but gave up on that idea.

I do have one of those Radio Shack LED power meters that hook up to the speaker connection that are true meters in the sense of measuring wattage. Maybe I will hook up mine to the remote speaker connection and see if I can run all simultaneously? Never enough flashing lights 👍
 

doity

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But wait......there’s more! I mentioned earlier that I wanted to replicate the grid of the Pioneer receivers with the fake scopes but gave up on that idea. So I decided to buy some pinstripe tape and do ‘something’. I eventually decided to try and replicate the look of the Marantz 4400 scope.

The markings mean absolutely nothing, but hey it looks like they do so that is all that counts right? 🙂

I am officially done now as there is no way to improve on it in it’s current form.
 

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Sonik Wiz

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But wait......there’s more! I mentioned earlier that I wanted to replicate the grid of the Pioneer receivers with the fake scopes but gave up on that idea. So I decided to buy some pinstripe tape and do ‘something’. I eventually decided to try and replicate the look of the Marantz 4400 scope.

The markings mean absolutely nothing, but hey it looks like they do so that is all that counts right? 🙂

I am officially done now as there is no way to improve on it in it’s current form.
Looks good! You must have a very steady hand to apply that tape so perfectly.
 
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