Monthly Archives: September 2020

Nooelec Nano 2+ Software Defined Radio

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One side-benefit of unpacking after a move is getting reacquainted with old electronic gear, in this case, a Drake R8 shortwave receiver. HF is definitely alive, but it whet my appetite for more listening, more action.

Rather than pull out the old Radio Shack 2006PRO — another old acquaintance — I decided to give software defined radio (SDR) a try.

Like everything else electronic, VLSI digital signal processing revolutionized radio design. Smart folks realized that the RTL2832U chipset could be repurposed into a wideband SDR receiver. The RTL2832U chipset was originally designed as a DVB-T TV tuner and repurposing it is a spiffy hack!

Even better, the RTL2832U SDR is dirt cheap. Why spring for a $300 ICOM when you can buy a dongle for about $25USD? There are “high end” solutions such as the Airspy R2 ($169USD) or SDRPlay RSPdx ($199USD).
The Airspy HF+ Discovery extends coverage to HF (0.5kHz to 31MHz) for $169USD. Mid-range solutions include the Airspy Mini SDR ($99USD) and SDRPlay RSP1A ($109USD) among others. If you’re interested in adding HF, the Nooelec Ham It Up up-converter ($65USD) is an option.

Cheapskate that I am, I believe in the low-end theory — how much can I do with the least amount of money. 🙂 Thus, I chose the Nooelec NESDR Nano 2+ for $24. The original Nooelec Nano had a reputation for running hot. The Nano 2+ mitigates heat dissipation; the newer Nano 3 ($30) has a metal case/heatsink.

nooelect Nano 2+ Software Defined Radio

I went cheap. Yes, the Nano 2+ gets warm to the touch, but not to the level of concern. An x86 running full tilt is HOT — not the Nano 2+. It doesn’t run much hotter than my vintage Datong AD270 active antenna.

For software, I installed SDR#. The “sharp” comes from C#, the implementation language. There are many good getting started guides on-line. I especially like:

There are several more software options out there like CubicSDR. I chose SDR# because it has a number of useful plug-ins including a frequency manager/scanner.

The Nano 2+ is the size of a USB flash drive. The low-cost Adafruit dongle is similar, but it’s out of stock. The Nano 2+ is a nice replacement. The Nano 2+ is bundled with a tiny magnetic-mount telescoping antenna which is good enough for VHF/UHF. I placed the mag-mount on a small electrical junction box cover which provides a more stable base.

FM broadcast via SDR# and Nooelec Nano 2+ software defined radio

Follow the on-line guides! RTL SDR is quite mature for “hobby” software. I tuned in FM broadcast literally within minutes.

Based on this short experience, I splurged for an RTL-SDR Blog V3 receiver and antenna bundle ($35USD). The V3 has a metal enclosure and enables HF reception through direct sampling. The bundle includes a dipole antenna with a variety of mounting options. I believe that the innards of the dipole antenna can be adapted for HF, but decided to buy a Nooelec Balun One Nine V2 ($15), too. The balun can be used as an unun in order to match impedance with a long-wire antenna.

I also recommend a set of antenna adapters. The Nooelec Nano 2+ uses an MCX antenna connector and the V3 uses an SMA connector. So, if you want to mix and match components, be prepared with adapters.

HF for $35? I can’t vouch for receiver sensitivity, etc. at this point, not having received the V3. The potential, however, is amazing. If you’re good with just VHF and UHF, then give the Nooelec Nano 2+ a try.

Copyright © 2020 Paul J. Drongowski

Review: Roland Micro Cube GX for keyboard

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You’ll find plenty of rave on-line reviews for the Roland Micro Cube GX — the go-to battery-powered practice amp for guitar.You won’t find a review covering the Micro Cube GX as a portable keyboard practice amp — until now.

Here’s a quick rundown (from the Roland site):

  • Compact guitar amp with a 5 inch (12cm) custom-designed speaker
  • 3 Watt rated output power
  • Eight COSM amp tones, including the ultra-heavy EXTREME amp
  • Eight DSP effects, including HEAVY OCTAVE and dedicated DELAY/REVERB with spring emulation
  • MEMORY function for saving favorite amp and effects settings
  • i-CUBE LINK jack provides audio interfacing with Apple’s iPhone, iPad, and iPod touch
  • Free CUBE JAM app for iOS
  • Chromatic tuner built in
  • Runs on battery power (6xAA) or supplied AC adapter; carrying strap included
  • 6 pounds (2.7kg)

I haven’t tried the Roland CUBE JAM application yet, so I’ll be concentrating on the amplifier itself. The included 3.5mm cable is the usual 4 conductor affair although it’s rather short. Roland also includes the AC adapter.

I’ve been searching for a good portable, battery-powered keyboard rig for quite some time. On the keyboard side, the line-up includes Yamaha Reface YC, Yamaha SHS-500 Sonogenic and Korg MicroKorg XL+. Although the YC and Sonogenic have built-in speakers, their sound quality is decidedly inadequate and poor quality. The MicroKorg XL+ doesn’t have built-in speakers. All three keyboards have mini-keys and are battery-powered.

To this point, I’ve been using a JBL Charge 2 Bluetooth speaker.The JBL has solid bass, but its output volume is easily overwhelmed during living room jams. It’s been a good side-kick, but I found myself wanting.

Roland Micro Cube GX and Yamaha SHS-500 Sonogenic

So, the latest addition is the Roland Micro Cube GX. Without comments from fellow keyboard players, buying the GX was a risk. Guitar amps are notoriously voiced for electric (or acoustic) guitar tone. Like the GX, you’ll typically find amp and cabinet simulators that help a guitar player chase their “tone.” The GX, however, includes a “MIC” amp type in addition to the usual 3.5mm stereo AUX input. Fortunately, my intuition was correct and the “MIC” setting does not add too much coloration.

Of course, there is some compromise in sound quality. The amp puts out 3W max through a 5 inch speaker (no coaxial or separate tweeter). Needless to say, you don’t hear much high frequency “air.” The GX cabinet does have a forward-facing bass port, producing acceptable bass even with B-3 organ. No, you will not go full Keith Emerson or Jon Lord with this set-up. 🙂 I first tested the GX with Yamaha MODX and found the B-3 to be acceptable.

Volume-wise, yes, you can get loud — too loud for your bedroom or ear-health. Bass heavy sounds can get buzzy. For clean acoustic instruments, I recommend the “MIC” amp setting. The reverb is pleasant enough and adds depth to my normally dry live patches. The delay is a nice alternative to the reverb ranging from reverb-like echo to explicit (non-tempo synch’ed) repeats.

I find the Sonogenic/Micro Cube GX combination to be the most fun. The SHS-500 has DSP effects, but they are rather tentative, as if Yamaha is afraid to offend anyone. That’s where the GX makes a good companion for the Sonogenic. Feel free to dial in the Jazz Chorus amp with the jazz guitar patch or a British stack with electric guitar. Or, try any of the modulation effects on the Sonogenic’s electric piano. Working with the GX is a far more intuitive and rewarding experience than the built-in Sonogenic DSP effects. You can cover Steely Dan EP to Clapton with this rig!

I have to call out the Heavy Octave and Spring reverb effects. You’ll find them at the right-most position of the modulation (EFX) and delay/reverb knobs, respectively. You can think of them as “going up to eleven.” The spring reverb is decent and you can throw the Heavy Octave onto just about anything to thicken up the sound.

Overall build quality is good. The Micro Cube GX feels solid. A metal grill protects the speaker. The knobs have a pleasant resistance and don’t feel cheap. The only not-so-robust feature is the battery compartment and its cover. As long as you avoid heavy abuse, you should be OK.

For the money, $160USD, it’s a decent sounding, inexpensive package. Given the physical cabinet, output power and speaker size, one should adjust expectations. However, if you’re a keyboardist and need a light, portable, battery-powered amp, the Roland Micro Cube GX is worth a try.

Copyright © 2020 Paul J. Drongowski