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Stepped Attenuator & legendary G.E.C CV 2523 tube

The stepped Attenuator is an alternative to the usual potentiometer controlling the volume. The difference is that the potentiometer uses a track of a resistive material like carbon or plastic, where a stepped attenuator uses a mechanical switch combined with traditional resistors.  A metal film transistor should be less noisy than the resistive material in a potentiometer and hence the improvement sound quality. The other benefit is that the balance between the channels should be absolutely perfect. That’s the theory at least.   There are different types of stepped attenuators…

Bottlehead Crack and Speedball review

The Bottlehead Crack OTL tube amplifier is widely praised  for it’s smooth, but neutral and detailed sound. If you own a pair of Sennheiser HD600, HD650 or even the HD800 flagship model, this is what many will recommend you to buy. This is especially true if you ask the question on the Head-Fi forums. Coming from the very neutral and lovely Objective2 amplifier, I wished for something more dynamic, more alive, simply with more feelings to the sound. Don’t get me wrong, I love the O2 and ODAC combo more than…

Speedball Upgrade

When I ordered my Bottlehead Crack kit, I also ordered the Speedball upgrade right away. Everybody that tried it, including reviews, said it was a night and day difference from the default Crack setup, and that you basically had to upgrade it. So of course I wanted to hear that for myself. Bottlehead recommends building the default Crack and make sure it works properly before moving on to the Speedball upgrade, so this is why I have done so.

Oculus Rift – Back to the future

  In the late 80s and early 90s, virtual reality was one of the most promising upcoming new technologies. There was a promise of amazing experiences in exhilarating virtual worlds, and consumers were more than ready for adventures that would blur the border between game and reality. Even the film industry was interested in the idea, which led to cult classics such as The Lawnmower Man and Johnny Mnemonic.

Soldering the components

The Bottlehead Crack is not made on a printed circuit board like modern amplifiers. Instead all the parts are mounted and soldered on terminal strips and connected with solid core wires between the components. If done properly with good soldering skills and quality wires, this is a very good way of making circuits for amplifiers. It’s also a way of using three dimensions, instead of the two dimensions you are often restricted to with circuit boards. Another obvious advantage is more space between components, wires and interconnects, causing less interference…

Objective2 Headphone Amplifier and ODAC

O2 or Objective2 is an open source headphone amplifier designed by the brilliant and shy engineer  NwAvGuy.  His purpose was to design an objective sounding headphone amplifier at relative low cost, that could compare to the most expensive neutral headphone amplifier made. He also made sure to make a design with the lowest possible input impedance, hence making it a good fit for any set of headphones, regardless of impedance. He claimed that nobody would be able to hear the difference in a blind test, compared to any neutral sounding headphone amplifier,…

KODA^2 – Optimizing the prototype

The KODA^2 – Optimizing the prototype   Since I made the prototype – I have done some optimizing of the design. It still looks the same on the outsize – but inside has been optimized with the correct sized bass port and 20% less material in overall. This makes them lighter and gives them just the right bass port directly from the laser cutting process. I feel that the weight of the KODA^1 is their only real downside and the new optimized design should issue this and make them below…