Jürgen Grau sent me new photos of his latest creation - this is a hybrid tube phono preamplifier. It is sold as a kit and should take about an hour to assemble.
Good news, the USB powered Magic Eye Winker from NixieKits.eu is finished! It is based on the same dimensions as the tube board from the Magic Eye VU-Meter (50 mm diameter) this gadget does only one thing: "Winking".
It is powered via USB * and all 6V heater tubes can be fitted. Solder bridges on the bottom side will connect the signals according to the socket needed for the tube.
These tubes can be fitted:
EM80 / EM81 / EM84 / PM84 / EM85 / EM87 / EM800 / EAM86 / 6BR5 / 6DA5 / 6E2 / 6E3P / 4FG6 / 6FG6 / 6DH7 / 6HU6
* it can also be powered from an external battery pack up to 18V, so it is possible to fit tubes with different heater voltages like the UM80 with 19V for example
Want to know more? Ask Jürgen in the forums.
This little device comes to us from NixieKits.eu. It is a dual triode headphone amplifier from based on surplus Russian military tubes. This is a largely subjective review but I’ll do my best to stay as factual as possible.
Each new gadget from NixieKits.eu has a more refined enclosure than the previous and this is no exception. The device is made out of (what appears to be) laser cut acrylic and has a very solid feel. The panels are slotted and fit together nicely and give the entire device a solid feel.
These images are from NixieKits.eu. The top graph shows the total harmonic distortion, the middle diagram shows the output voltage with different loads and the final diagram shows the output of a 100 kHz square wave @ 500mV.
Black (no load), 150 ohm (cyan), 23 ohm (green)
As far as testing the device, I performed 12 distinct tests. The sample songs were ripped from a CD and stored in a lossless format and then loaded on to the three test devices.
The source devices used were an iPod (2010 160GB), an iPhone 4s, and a MacBook Pro (early 2011) with a Behringer F Control FCA202 DAC. The headphones used for testing were the original iPhone earbuds and a Sennheiser 5xx series open headphone.
The scale below ranges from -5 to +5 and is in subjective units. Higher is better and lower is worse. The scale is centered on 0 given (iPod, no amp, ear buds). This combination I believe covers the larges portion of the population and so a number higher than this (0) sounds better. A number below this sounds worse.
The results are not too surprising. The best combination is the laptop with the headphone amp with the Sennheisers. However, in EVERY CASE, the headphone amp helped by at least one subjective unit. In my opinion, if you already have a nice set of headphones, you will probably benefit more from this device.
To begin, I left this device disconnected and plugged in my headphones. I let it warm up and turned it up all of the way. The result: silence. This is fantastic. Not even my home stereo amplifier has complete silence when I turn it up all of the way.
To test distortion, I played a techno song with a deep and loud baseline. I compared how it sounded coming directly from my computer versus from the amplifier and the difference was notable. The song was clearer at louder volumes using the amplifier than it was without. I played with a few other demo songs that Jürgen sent me and the results were similar.
On the quiet end, it doesn’t add any noise. On the loud end, it doesn’t distort or clip the waveform like a transistor-based amplifier does.
As far as the “warm” sound of a tube amplifier it is there. If, like me, you only grew up using more modern designs, it may sound foreign at first. It is not very pronounced but if you know that it is there, you can hear it. For things like an acoustic guitar, I really like the results. For piano solos, things sound a little muted but not in any bad. This is completely subjective and depends on your preferences. I can say, however, that since I received this device, I have not disconnected it from my system!
Jürgen shared this color coded photo of the original design on the bread board versus the final product. It's quite an evolution!
About €110 for a complete kit, excluding tube
Back in the old days, when technology mysterious and needed to "warm up" before you could use it, there was a little green thing on the front of radio that told you how strong the signal was. These were "magic eyes", and they fell out of fashion, because they are hard to drive and there were much easier ways of achieving the same result. LED killed everything.
If you look around on eBay for "magic eyes", you'll find a fair umber of results, but only very few of them are full solutions.You're going to have to deal with the heater voltage, the driver voltage and mounting the tube yourself. That's no good.
Mr. Nixie has put together a kit for most Noval (9-pin socket) magic eye tubes, which takes care of the voltages needed to drive the tube, and has an automatic input gain adjustment, so you can just fit the tube in, connect it up to a supply and a signal, and you are ready to go!
If you fit an EM83 tube, (which is a stereo tube), you'll get a stereo display. Nice!