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.
Here is the latest version of the Nixiekits.eu magic eye VU meter -- it now supports stereo! Check out the forum link to learn more.
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.
Video Review:
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.
THD
Output Voltage
Black (no load), 150 ohm (cyan), 23 ohm (green)
Square waveform
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!
Here is an interesting gadget from Jürgen Grau. It is a VFD tube based sound pressure level meter. The tube is an IV-26 with seven large indicators stacked vertically. As the sound level rises so does the height of the indicator. The sound is sensed via a built in microphone placed on the base right in front of the tube.
The device displays the sound level in several ways. When you’re building the kit, you have the option to choose between a single dot and bar graph mode. In dot mode, only the top most position is illuminated. So, if the readout is 74 dBa, then only that position is illuminated. In bar graph mode, the dots below it are illuminated as well. Finally, the user can select between peak mode and average (RMS). All of these setting are achieved by setting a solder jumper on the PCB.
Jurgen took great efforts to make sure this device was accurate. The readout shows the sound level in both decibels (A Weighted for human hearing) and Sone. According to the website: “The microphone is matched to the sensitivity of human hearing and the OP amp based active multipole equalization, full wave precision rectifier and integration circuit ensure that the display is accurate.”
I want to call out the enclosure too. The footprint is nearly identical to the NixieTherm but don’t be fooled, this design has some big improvements. First, the scale has several bright warm-white LEDs. This makes the markings much easier to read in daylight and it even appears that the markings are slightly deeper to help with this as well. The scale now is slightly thicker and has more robust mounting hardware inside the base of the unit which adds to stability. While this isn’t a kid’s toy, it is a solid design.
So what do I think? Well, this is a great device. It is fun to watch and it does exactly what you expect it to. For 79 EUR, you can’t really go wrong with this. (It would probably make a great Christmas gift too....)
I know the last few updates have been about NixieKits.eu and this next device doesn't even have a display component - but it is cool, it is something that I would buy, and it is something that I think you'll like :) This is a headphone amplifier designed by Jürgen Grau. It is still a work in progress you can start to get an idea of what this will look like. For size comparison, It has the same footprint as the NixieTherm and Nixie SPL (70mm x 70mm).
I like this because I'm a bit of an audio nut. I own a nice pair of Sennheiser cans and a nice external firewire DAC for listening to music. I'm in the market for a headphone amplifier so this got my attention when he sent it to me. He is already working on an awesome VU meter so this new product makes sense.
To power the amp, you need a 12VDC 1A power supply and; the amp itself draws around 8VA. The 6N28B-V tubes are powered with a 34V anode voltage, created with a voltage trippler from the 12VDC. These tiny double triodes are from military surplus, have an ultra long life and are shock proof. They are specially designed to run with a low anode voltage (max. 50V). Thanks to the "star milling" socket soldering of these wired tubes is super easy. Output connector is a Neutrik 6.3mm stereo jack, inputs are RCA type.
The headphone amp should be for sale within a month so if you're looking for Christmas presents, this may be for you :)
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