Desktop DAC with a cheap ES9038-board…

Last year I mentioned that I had bought a cheap ES9038 DAC-board and now that’s starting to come together. This will be used as a controller to feed a pair of active monitors on my desk (that’s the “need” I mentioned in the original post) where it will save me a box as I currently have a separate USB DAC and passive pre). To make the box a bit more versatile (and to use some of that empty space inside…) I am thinking about including a Raspberry Pi Zero W in the box and connecting it to the I2S-input of the DAC plus add a potentiometer for volume control (digital on the DAC via an onboard uC). The ES9038Q2M DAC is asynchronous with its own clock so perfect for use with the RPi and this combination would give a Volumio-based source with two additional digital inputs and a volume control. That means that can be connected directly to a power amplifier input or active speakers – perfect for the desktop or a second system!.

The slightly unusual power arrangement with 5V input to a DC-DC converter is to support this setup. It will allow the RPi to be powered on constantly while the DAC power can then be switched on and off. I bought an early (”first generation”) of the ES9038 board with a slightly different power setup than the current version and crucially no DC input connector that I did not need (of course the newer versions of the DAC board can be used as well). Check the diyaudio-thread for the board for loads more examples of how people have been hacking this by the way – some of them are close to unrecognisable.

The original idea was basically to allow the power source to be a cheap 2A USB-charger, but reality seems to have thrown a spanner in the works here – none of the chargers I have tried will actually let the DC-converter start properly because of the high inrush-current it draws. Using a slightly more beefy 5V supply fixes the problem though, so the concept is more or less intact anyway 😀

Part of what drew me to this DAC-board originally were the on-board connectors, but as I couldn’t find any mechanical drawings having to make the back panel by hand seemed a bit of a risk. Using my own measurements and the datasheets of the connectors I managed to trace it out and with judicious use of paper printouts from Frontpanel Express to check the dimensions against the physical board it actually fits well for a first time attempts – although this is definitely an occasion where I would wish for a 3D-printer or a laser cutter to make prototypes before betting my money on ordering “the real thing” from Schaeffer/FPX (they are becoming quite expensive I think).

Soundwise this seems quite close to the other ESS-based DACs that I have tried. I am not sure that is such a good thing to be honest, but I am prepared to compromise a little bit on my desk where convenience is important and the differences aren’t night and day anyway 🙂

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Small thing – big difference

I don’t normally write (much) about the commercial gear that I buy, but for once I’ll make an exception.

I’ve actually owned both the previous versions of the Audioquest Dragonfly (DF) USB DACs but sold them after a relatively short time because I did not really need them anyway. Thanks to an ad on a local classifieds page I now find myself as the owner of the third generation DF as well – the Dragonfly Red. Apart from the new looks – which I really like – the new series of DFs also have the benefit of much lower power consumption, meaning they can be used with mobile devices.

I therefore tried hooking up the DF to both my iPhone and iPad. To be honest I wasn’t expecting that much, but it really does make a significant difference to the sound quality. The downside is of course that your phone becomes quite a bit less portable with a couple of extra dongles and adapters hanging off it, but the benefit in sound quality seems worth it. I wouldn’t use it every day, but if I really had to travel light then using the DF would save me packing and carrying a separate music player which could be very handy.

Photo of the device and a “real” red Dragonfly as well for comparison 😉 (that picture was taken by yours truly in Hong Kong – coincidentally exactly two years ago today)

Mini-stack (part 1)

Not exactly the most challenging builds ever undertaken, but still…

More or less since I originally built my passive preamps I have wanted to build more components in the same form factor. Here is the beginning of a “mini-stack”, namely a USB DAC and a passive pre, which should then be supplemented later by (at least) a power amp in the same small chassis (a GX143 from modushop.biz, so 124x40x73mm). That isn’t ready yet, but I do have a few ideas for what to do 😀 As for what is ready:

The passive pre is based on a Noble 10k pot that I happened to have lying around – not much more to say about that really 🙂

The DAC is based on an “off-shelf” module from ebay. It uses the SA9023 USB receiver/ES9023 DAC chipset so that it can accept up to 24/96 input signals. The module is powered from the USB connection. It is possible (and possibly recommended) to use an external supply instead, but since the preamp is passive I wanted to keep the design “cordless” except for the USB. Obviously that won’t work for the power amp… My only little piece of hacking here was to wire an “USB on” LED on the front panel instead of relying on the on-board SMD one.

The ES9023 DAC chip from ESStech is a highly respected performer and used in quite a few designs such as the AudioQuest DragonFly (albeit there with a more complicated/advanced USB front-end) and quite a few others. It is voltage output with a built-in charge pump to avoid capacitors in the signal path and it is actually capable of driving headphones directly, so the 10k load here isn’t really an issue.

The sound quality of the board is quite a bit ahead of the older PCM27xx-based designs as well. The sound from this little combo is actually quite good and the fact that no external power suppliers are required makes it a bit more interesting.

My idea for the power amp is to use a class D chip powered from an off-board switching supply. I have looked at both the TPA311x and the TDA749x chips but I am still exploring options here so nothing definite yet…let’s see what happens 🙂

Work in progress….

It’s been a while since I have posted here, but real life is still getting in the way of my build time. At the moment this means I am mostly starting up new projects, because for some strange reason I can always find time to start new projects – even when time to finish the old ones is nowhere in sight 😀

I have been shopping a little at diyinhk.com recently and bought several DAC boards and power supplies, so one a few DACs are in the cards for sure 🙂 Also, one or two gainclones might make an appearance as well at some point. One reason for this is that I rediscovered some pictures of the Audiosector “Patek” amp a couple of weeks ago, so guess who has been scouring ebay etc. for reasonably-priced copper bars lately? 😉

Lastly, the Borbely and the Le Monstre front/rear panels have arrived and I am pretty happy with those, so now I am just waiting for my transformer order and a free weekend and then at least that should be sorted out.

However, I have to say that even with not much new going on there are still plenty of people that find their way here. The blog was at 15k page views in the beginning of January and it is now over 21k views total – I can’t complain about that, so thanks a lot for stopping by 😀