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The Open Source Scan Converter continues to turn heads in the gaming community, having only recently picked up another accolade from Eurogamer.de. One thing the unit does lack, however, is support for audio over HDMI. There were several reasons why this was omitted from the design. First and foremost it was to keep the cost of the unit down. Modern TVs are designed to be as flat as possible and that usually means compromising on the sound. Because of this, many users have external speakers powered by amplifiers or home theatre receivers and so have no need of digital audio output from their OSSC units. Of course, that doesn’t apply to everyone and given that some modern TVs only accept audio via HDMI, the problem turns from being a mere inconvenience to a potential deal breaker for a number of people. The problem is made worse by the fact that the readily available digital audio integrators are often expensive and of a poor standard (such as the one we reviewed here). Clearly, a more elegant solution was required.
Thanks to friendly hardware genius Borti, it’s now possible to add a digital audio integrator directly into your Open Source Scan Converter. The board is pictured above and fits neatly within the OSSCs case, with no protruding wires or connectors. For hardware experts, the gerber files and assembly instructions are available on Github here, allowing you to construct your own board if you’re so inclined. For the less experienced, we will be selling both DIY boards and providing a fitting service in the near future, once we get the first batch from the manufacturers. To fit the board yourself, you must disassemble your OSSC, cut a number of connections on the board and then solder the boards plated half holes to pads on the OSSCs motherboard. Once this is done, there are six wires to connect and the process is complete. Unlike earlier revisions of the mod, there’s no need to lift any pins/legs from the OSSCs FPGA chips, making the installation considerably easier. You will still need a fine-tipped soldering iron and a steady hand as soldering the plated half-holes to the board is fairly intricate.
With the OSSC audio board installed, make sure you flash your OSSC with the new audio capable firmware, then simply route any analogue audio to the OSSCs SCART input socket and the audio board will instantly encode it to digital audio and inject it into the DVI/HDMI output. The required audio-enabled firmware adds an extra menu with a couple of options. There’s the option to output at either 48khz or 96khz (this made little discernable difference in our tests) and the option to swap the left and right audio channels (this option is included since a number of early revision OSSC units had a hardware fault that caused the audio channels to be reversed).
Sound quality is nothing short of excellent. The board adds no noise whatsoever as far as we were able to tell, meaning if you use high quality SCART cables then any audio buzz should be minimal or non-existent. Compatibility is also very good, having tested the audio upgrade on a range of home theatre receivers, televisions and video processors, we’ve yet to encounter any compatibility problems.
If you use the component video or VGA/D-Sub15 connectors on the OSSC then you might be wondering how to feed in audio when using those inputs. When using any input, the audio board stays active and will process any audio fed in via the SCART socket, so it’s simply a matter of feeding in the audio through your SCART switching matrix. Most SCART switches can accommodate this just fine and there are breakout adapters that can be used (finally, a use for those old composite video to SCART adapters that used to come with consoles a decade or so ago). Certain automatic SCART switches may not detect a signal if you try to route audio only, so keep that in mind when planning the cabling. Should you need to use it, the existing 3.5mm audio output connector on the OSSC still works, allowing you to hook up headphones or an alternative set of speakers if desired. Connecting anything to the 3.5mm jack does not disable the digital audio board. Update – several readers pointed out that it’s also possible to feed in audio via the 3.5mm headphone jack. To do this, simply connect an audio source and make sure there’s no audio being fed in via SCART. Unfortunately, if you have a SCART cable connected to AV1 (even if there’s no signal coming down it), the audio fed in via the 3.5mm connector becomes very quiet.
The OSSC audio board add-on is a neat and convenient solution. While it won’t be essential for many users, it’s very convenient, especially if you ever visit friends or relatives and want to take an OSSC plus a retro console to use on their TV. The drawback of course is the cost. Final pricing hasn’t been confirmed yet, given the current volatile nature of the pound, but the price is expected to be around £24 inc VAT for the DIY kit and £50 inc VAT for the board and installation. At that price, the cost of an OSSC is pushing closer into Framemeister territory, which makes the decision over which device is best for you a little harder. Nevertheless, this is easily the most elegant and convenient way to add digital audio output to your OSSC.