Tuesday, November 11, 2008

Audio Analogue to Digital Converter AD2496

Currently I ran out of a couple of important and difficult to get parts.

The bad news is:
No complete AD2496 kits are available, neither now, nor in future, but:
The good news is:
I am preparing the successor of the AD2496. Its name is AD24QS ("Quad Speed"), because it will be capable of 10 different sample rates up to 192 kHz.
Also, its sibling, the 24 bits, 192 kHz DAC DA24QS is coming up.

The latest circuit diagram of the AD2496 is shown here. All modifacations I intended and described in the article about the prototype have been implemented. Additionally I introduced two current compensated chokes for higher EMV immunity. Not that I experienced them to be necessary, but I know about the extreme requirements of the relevant regulations. And this design is meant to be professional.

from www.beis.de May '06: I also found out that the TOTX141 has to be replaced by a TOTX179P because the TOTX141 is a 3.3 V type (which does actually not prevent it from working in all my units). Except its operating voltage of 5 V the TOTX179P is fully compatible. Also, the discontinued CS8405A is replaced by the fully compatible CS8406.

I rearranged the DIP-switches so that the 4 relevant ones are on the leftmost side. The others are for experimental use and not meant to be populated in an actual device.

For my units I used an SG206 case from the (German) company Fischer Elektronik. Front panel, case and board are directly fixed to each other using the element 5.60.422 from the (German) company Ettinger, available at B├╝rklin. You need not necessarily use the case I used. The board can easily be built into other cases. For this case I provided a detailed dimensional drawing, either as a GIF file or as a PDF file.

You will see there how the board is fixed within the SG206 and how it can alternatively be fixed directly to other front panels. Of course you may also use four stand-offs, pillars or distance tubes to fix the board on the bottom of your case. The drilling positions can be found in the dimensional drawing, too.

The front panel is manufactured by Schaeffer AG (in Europe) and is available in the US from Front Panel Express, LLC, too. You need the design file for the front panel, then you just have to send it to the manufacturer and you'll get a perfectly milled and engraved front panel, as the photos show. You may also modify the design file with the front panel design software "Front Panel Designer" German or English (it's free and very convenient) so that it fits to other cases of your choice. As the back panel only contains two simple 10 mm holes and maybe the markings "L" and "R" I forwent to prepare a design file for that, but it is simple to modify the front panel design file to obtain the corresponding file for the back panel.