New AKGs are in…

It’s been a while since I last added to my already sizeable (and frankly unnecessary) collection of headphones, but now was the time.

Although new models come on the market regularly, the one “top of the line” model that I really wanted to get was the AKG K812. Up until a few months ago they have been very expensive and were only sold at RRP, but as they have started appearing at discounted prices I’ve renewed my interest. Although I’ve been eyeing them for a while now, it wasn’t until last week the stars finally aligned (or at least the combination of bank balance and foreign exchange rates 🙂 ) and I could finally press the “buy” button.

When it came on the market some of the first reviews of the K812 mentioned harsh treble, but on the few occasions I’ve demoed them it didn’t sound particularly harsh to me. To be on the safe side I’ve bought one of the later-model “Made in Slovakia” ones, mainly on an assumption that any treble issues might have been teething problems in the first production runs of the original “Made in Austria” series.

I’m quite a big fan of the AKG house sound – and I have been since I first bought the K501 model when it was “flavour of the month” on head-fi a little over 15 years ago (yes, time flies…). I also own the K701, K550, K495NC and a few others and just as I expected my initial impressions of the K812 are that they are “more of the same” but better. As is the case with most other large AKG models (at least for me) the K812s are very, very comfortable once properly adjusted and I think I can wear them for a long time before they start being uncomfotable. For someone who wears glasses, this is definitely not a given when you buy a high-end headphone.

Obviously this purchase impacts the audio-related budget for my next big trip (in a couple of weeks) a little bit, but that’s ok – I’m sure it’ll be worth it once I get to spend a bit more time with these new AKGs 😀


Panda Headphone Amp

Another half-arsed half-finished project… 😀

This is a HA-1 mk2 headphone amp, also known as the “Panda” amp. I bought the kit a few years ago when this amp was FOtM (“flavour of the month” – or as some would say “fad of the month” :D), but of course I don’t really need any more headamps and so it was just lying in my box of “may need at some point” unassembled kits. However, I few weeks ago I was cleaning looking through said box and found it again, and since I felt like soldering something that day I started working on it.

Unlike most “cheap” kits, this actually comes with decent components. I replaced a few components for cosmetic reasons and bought new main caps because the ones provided did look a bit worn, but other than that everything is what was provided. The amp is an all-discrete design with JFET input stage and a BJT output stage, so I had to do some matching to the input FETs, but other than that it is a straightforward build. Initial impression is that the sound is very good, but one of the reasons for the hype around this amp originally was that it is supposedly very good with AKGs and so I need to dig out my K501s and K701s to try that as well (they’re in another box..) 🙂

Now, I am still counting on the upcoming x-mas break to give me some time to finish some builds, but it’s unlikely that this will be one of them. When I started putting the board together I just wanted to do some soldering, but I didn’t have a case design in mind then. I still don’t to be honest, and since I’ve used 35mm tall heat sinks and capacitors the board is now too big to fit into a 1U modushop case – grr!

Maybe it is time to head to ebay for some “inspiration” instead then? 🙂

A well-balanced sound…

Inspired by a recent thread on a Danish headphone forum, I finally summoned up the courage to do something I have been planning for a while, namely to convert my AKG K701 headphones to balanced drive. Balanced drive in theory provides double the voltage swing and four times the output power of normal single-ended drive. In the case of fairly power-hungry headphones like the AKGs that should translate into better sound, especially in the bass. Obviously, the real benefit is that it provides a perfect excuse to build another headphone amp or two 😀

Normally converting headphones to balanced drive means replacing the stock cable, but converting the AKGs is quite easy since the stock cable is four-conductor and so already provides for split return signals. The only effort is therefore to chop off the old TRS plug and solder on a 4-pole XLR instead. I used a Neutrik NC4-MXX and I managed to find a grey boot for it to make it look a bit closer to the original look.

Reusing the stock cable also meant that I could reuse the original plug to build a balanced to single ended adapter to ensure the headphones can still be driven by unbalanced amps. Visually I admit it isn’t the most elegant solution in use, but it works without issues 🙂

If you have a pair of K701s and want to try the mod, here is the head-fi thread that describes the connections in the stock cable.

Headphones with a couple of extra connectors on :D

Headphones with a couple of extra connectors on 😀