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Old 4th January 2009, 03:19 PM   #101
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Quote:
Originally posted by MJL21193
I do like the idea of a stand alone unit, dedicated to this rather than a computer and sound card. I generally use my "lab" computer to run Speaker Workshop, so I need to change the cables and settings and it become too much of a headache to run RMAA.
What would be the overall cost Glen?

Well yes, I can think of a few reasons why, say, someone with an amateur interest in mixing/recording/producing may prefer a 1U rack case over another PC for monitoring purposes.

This 21-band unit is more of a toy designed and built for the fun of it more than anything.

The 60 band 1/6 octave unit with the much more accurate and selective filters will be a far more serious instrument though.

Jan; The monster amps are progressing slowly. I'm juggling multiple projects.

Cheers,
Glen
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Old 4th January 2009, 03:48 PM   #102
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Quote:
Originally posted by G.Kleinschmidt
[snip] I'm juggling multiple projects.

Cheers,
Glen

Sounds familiar...

Jan Didden
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Old 10th January 2009, 02:42 PM   #103
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Got the thing up and running in a 1U-rack case today. Still have to etch in install the final version of the digital PCB though. The prototype board version in currently in situ, insulated from the chassis with a bit of cardboard

Click the image to open in full size.


Have not begun the write-up on the circuit operation yet, but the diagram attached below that I just put together in MS Paint, along with the schematics on my website, should explain everything............


Cheers,
Glen
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Old 22nd January 2009, 01:04 PM   #104
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Quote:
Originally posted by janneman
I just looked at EZGPIB the other day. I have a Neutrik RT-1M I'm trying to talk (and listen) to over the GPIB. Multitone audio analyzer, should be fun to get it going.
But I have some hardware problems, looks like IRQ conflicts. All that legacy stuff is far from PnP!

Jan Didden

Edit: Sorry for OT. I'll shut up now...
Hi Janneman!

How do you proceed with RT-1M?

BR,
Milan
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Old 9th February 2009, 11:27 AM   #105
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All finished and working like a treat (except for the green power on indicator led bezel which I blew up by rewiring it without a series resistor )
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Old 9th February 2009, 11:34 AM   #106
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I've also updated my website with an 80% complete write up on how the thing works:

http://users.picknowl.com.au/~glenk/VGAASAMK1.HTM

Still have to add the powersupply and wiring schematics.

If I get the time this week I'm going to place an MOQ order for those 1/6 octave switched capacitor chips from MSI for the 60 band MKII analyser.

I'll update this thread with the initial evaluation results if anyone is interested.

Cheers,
Glen
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Old 9th February 2009, 11:39 AM   #107
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Default WOW.

Beautiful prototype.

Congratulations.
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Old 9th February 2009, 11:59 AM   #108
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Thanks!
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Old 25th March 2009, 10:59 AM   #109
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Time to resurrect this thread as, with that VGA Spectrum analyser intermission out of the way, I have finally gotten back to the fancy digital sampling swept frequency spectrum analyser project that I outlined in this threads opening post.

I have, however, scrapped all the previous design work and redesigned to a higher performance specification. As another project on the go I am essentially designing and building my own AP-functional audio analyser system, so I figured I might as well make a companion spectrum analyser of comparable sophistication. I intend to use this spectrum analyser primarily to examine the harmonic spectrum of the THD residual extracted by the audio analyser.

As originally intended, the spectrum analyser will still work as stand-alone unit, providing X/Y/(Z) outputs to drive and generate a display on a conventional analogue oscilloscope, but I have, however, redesigned the digital sampling recorder/motherboard with an RS232 / USB interface for computer control / display / storage as well (I have been looking for a good excuse to upgrade from MS Visual Basic to MS Visual C, and the graphical interface for this project will be a good excuse).

I have also radically revamped the design by increasing the display / recorder resolution (for the horizontal sweep as well as the vertical axis) to 12-bits. This has significantly increased the complexity of the unit.

Anyway, besides this (12-bit resolution and PC interface), the basic operation of this part of the analyser is the same as the previous version I described in post 27:

http://www.diyaudio.com/forums/showt...89#post1495589

For the new design I have scrapped the discrete low-resolution R/2R ladder DACís and replaced with high performance 12-bit IC DACís (AD9752ís).
The design is complete on paper and as was the case with the now completed VGA analyser build previously documented in this thread, with this more ambitious project it is now just a case of entering the schematics into CAD, laying out the PCBís, etching, loading, soldering and applying power.

Attached below is a quick teaser pic of how far I got this evening. This is the display module that will plug into the digital motherboard. It contains itís own little PIC uC (timing functions / sequencing), a pair of 12-bit DACís and is responsible for reading out the contents of the double-buffered display/record memory and generating the analogue signals for producing the analysers frequency domain display on an external analogue oscilloscope.

I hope to have the whole digital sampling/display section up an running over the Easter break.

Cheers,
Glen
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Old 25th March 2009, 12:00 PM   #110
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Quote:
Originally posted by G.Kleinschmidt
... (I have been looking for a good excuse to upgrade from MS Visual Basic to MS Visual C, and the graphical interface for this project will be a good excuse).
Hi Glen, this (free) library should help you out with your Visual C GUI programming efforts.


Ultimate Toolbox

Good luck.

argofanatic
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