Ben's Blog

At about one o’clock today, I was invited to go to Tramlines. I hadn’t been planning to go, but thought it would be fun, so rushed off into town. I just got in in time, I think. It was pretty full.

I don’t really know much about music festivals, or live music in general, but I do know that it was amazing, even if I’m not going to recover my hearing for weeks! The picture above is of a rubbish band that no one liked, hence me stopping to take a photo.

We went down to stand up for the last few bands before we left: some Australian lady, One Night Only and Playground Mafia. It was awesome fun, until the last song: the crowd was incredibly jostly and pretty violent at some points: I felt like I was going to be swept off my feet at some points, and that’s a weird feeling when you’re my size…

All in all it was an amazing afternoon though, so thanks to Anita for inviting me! :D. I was also amused to find out that I ended up getting a lift home with someone whose brother I’ve played DnD with in the past, but didn’t realised this until I got home… We skilfully missed the last bus.

As you may know from my last post, I have managed to destroy my primary flash drive by accidentally crushing it under a chair leg. However, there were things on that flash drive that I didn’t want to lose, so I set about attempting to extract whatever I could. I cracked open the casing, downloaded the USB specification and got to work.

This was initially an extension cable for use with the flash drive: in the end it served a much more useful service.

I eventually managed to get all of the wires soldered onto the right contacts…

…and was rewarded with a blinky light when I plugged it in!

With some money I had from Christmas, I decided that I wanted to upgrade my audio setup a bit. Somewhere in a previous post I mentioned that I’d bought a pair of Audio Technica ATH-AD700, which are my primary headphones, although I’d really like a pair of Sennheiser HD650s…

The first thing I needed was a DAC, as these headphones don’t really need an amplifier. A DAC is a Digital to Analogue Converter, which takes the digital signals from your music library on your computer, however they’re encoded (I’ve started re-ripping in flac :D). It then converts these into an analogue signal using some technical wizardry to make a nice analogue signal that can then be amplified for your headphones or speakers to play.

I was originally just looking at some high-end ‘audiophile’ (I hate that word…) sound cards, but they were all a bit boring. I wanted an external solution, and the most cost-effective and fun way to do this would be to build my own. This doesn’t mean I was going to read up on digital circuitry to design one, oh no! There are some members of Hi-Fi forums that design these devices in their spare time, and publish the schematics for free on the internet, often selling a circuit board to go with it.

I settled on the Gamma 1 from AMB Audio, a fairly small but well reviewed DAC. I ordered the parts, and a couple of weeks later everything had arrived, including two parcels from America, one of which incurred some interesting customs charges. That, however, is another story.

Building this DAC involved a fair amount of surface mount soldering (SMT) work. This is the first time I’d done it, but it went very well considering the incredibly small size of the chips and that it worked the first time I plugged it in. SMT soldering is where the legs of the device don’t go through the circuit board, they sit on top. This and that the fact that SMDs are generally much smaller than their through hole equivalents makes soldering them with conventional irons quite tricky, but you can still do it. If you interested, Curious Inventor has an excellent video on the subject.

With no further ado, here are some pictures of the assembly in all its gory detail:

The mess that I laughingly call my ‘workspace’. Spot the oboe? Those are the trick to soldering quickly and accurately.

The first IC soldered.

A few more.

Adding some resistors to the mix.

Showing the 3.5mm output, which can handily also drive headphones. I still want to build a proper amplifier though… Also pictured is the illuminated input select switch: it glows red when powered on and switches to green when music is playing. Finally, you can see the ‘audio grade’ output capacitors which came in at a whopping >£1 each.

The IC originally pictured, now surround with capacitors, resistor networks, transformers and all sorts of magic.

This shows the tiny size of some of the parts: the chip in the foreground (in the centre, not off to the left) easily fits on my little finger nail. That’s the tip of a normal biro for some size comparison. I still don’t know how I managed to solder that…

The Gamma 1 in in all its glory. The circuit board is about the size of two credit cards next to each other.

I’m listening to Dire Straits right now, with it sitting on my desk, a USB cable in one end and my headphones in the other. I haven’t heard any other proper Hi-Fi equipment, but I can certainly say that it sounds good. VERY good.

I’ve ordered a case for it to live in: the brilliantly named ‘Box B2-080BK’ which will arrive (hopefully) on Tuesday, so I can case it up properly. I’ll drill the needed holes using the drill press at school.

I really enjoyed building this, and now want MOAR! I have a little list of things I’d like to build:

• An AMB Mini3: a portable, battery powered headphone amplifier
• A CKKIII headphone amplifier: a proper, mains powered beast
• A Sennheiser HD650, reterminated to two XLR plugs for balanced listening. Not exactly a build, but meh.
• A Twisted Pear Opus balanced DAC, which is a step up from my Gamma 1 and also balanced
• An AMB β22: The ultimate headphone amp. This might be a way off… It should be an awesome project though.

So there we are, that should keep me busy for a while amongst my other hobbies.