Mechanically-tuned portable DSP radios: a shootout

Three of the five contenders: The Degen DE32, Degen DE321 and Tecsun R-2010D (Click to enlarge)

Three of the five contenders: The Degen DE32, Degen DE321 and Tecsun R-2010D (Click to enlarge)

Following is my premiere shortwave radio column for the January 2014 issue of The Spectrum Monitor digital magazine.  It takes the form of a review–or “shoot-out,” if you will–of a few select mechanically-tuned DSP radios I’ve tested over the years.

While I’m a big fan of print publications, digital publications like TSM offer me flexibility that I can’t get in traditional print: namely, shorter time to publication (thus more up-to-date information) and especially, the ability to embed links and audio as I do here on The SWLing Post. In this case, I’m able to include audio clips which the reader can utilize to compare the radios firsthand (embedded here, as well).

Note: This being my first contribution to a brand new magazine, I thought it would be fitting to begin by explaining why I still believe in shortwave radio…I mean, how could I resist? I guess I’ll always be a shortwave evangelist at heart.

Hope you enjoy.


First:  why I still believe in shortwave

SP600Dial3While I’ve been blogging about shortwave for several years now, I simply can’t tell you how many times I’ve received an email asking doubtfully, “This seems like a fun hobby, but isn’t shortwave radio dead?”

My response?  No way!  Here’s why.

I once had the truly good fortune to be interviewed by Gareth Mitchell, host of the BBC World Service technology program Click. For once, I made a point of listening to this interview that featured me––always a bit embarrassing––but after all, this was the BBC World Service!

But Gareth’s lead-in to our segment about my shortwave radio-based charity, Ears To Our World (ETOW), truly surprised me:  our non-profit, he said, “distributes portable battery powered devices that can stream audio in real time, all via an intuitive touch interface.”

Wow…how true.  And since that interview, this is exactly how I see shortwave radio, too: not as a forgotten relic of the past century, but as a medium at home in the future with a unique, highly accessible, and yet global reach.  Shortwave radio, after all, requires no apps, no subscriptions, and no mobile phone or Internet connection to deliver information worldwide at the speed of light.

All you need––in short––is a radio.

Shortwave lives!

This column exists to prove to the doubtful that shortwave radio––indeed, radio in general––is not only alive and well, but loud and clear in urban as well as rural settings the world over.   Here, you’ll find in-depth articles that reflect the changing state of shortwave radio:  the technologies, the techniques, and the vast array of content currently available across the shortwave radio spectrum. Best yet, because SWLing (shortwave listening) is what you make of it, you can be part of it:  share your input, so that I can cover (and uncover) shortwave topics you wish to discuss.

So I begin this first column with a little comparison––a shootout––between five newly-popular analog DSP radios.  Let’s find out who’s left standing.

The contenders

We’ll be pitting five models against each other here: the Degen DE321, the Degen DE32, the Tecsun R-2010D, the Kchibo KK9803 and the ShouYu SY-X5. With the exception of the ShouYu SY-X5, all of these manufacturers have in the past produced at least one portable with truly notable performance (the Degen DE1102, 1103, Kchibo D96L and an array of Tecsuns, including the PL 310, 380, 390, 600 and 660).

Moreover––so that you can hear the difference for yourself!––I’ve included linked audio clips for each model. They were all tuned to the same frequency, same broadcast and within seconds of one another.

But first, what is a DSP radio? And why do we need them?

The Silicon Labs DSP chip found in many of these radios.

The Silicon Labs DSP chip found in many of these radios.

Mechanically-tuned DSP

Radio is no longer just your granddad’s medium.  Several years ago, the digital signal processing chip manufacturer, Silicon Labs (SiLabs), altered the entire radio landscape with one little chip. Indeed, most new digital shortwave/AM/FM radios on the market use a SiLabs (or other manufacturer’s) DSP chip as the centerpiece of their receiver architecture.

Using a DSP chip in a fully digital radio makes sense: after all, you have a digital display, digital buttons, and digital encoder. But using a digital chip with a traditional analog display––a mechanically-tuned DSP radio––does that make sense?

SiLabs and a growing number of radio manufacturers and retailers believe the answer is a resounding “yes.” In truth, there are concrete benefits to making this addition; among them:

  • Decreasing production cost of radios by as much as 80%
  • Decreasing R&D costs of new radios dramatically
  • Digital signal processing with the simplicity of analog radio design
  • Reduced power consumption when compared with digital display radios
  • An avenue to make radios more affordable––especially to listeners living in poverty, such as those in developing world settings, who make up a large subgroup of listeners

When I first learned about the implementation of a DSP chip with a mechanically-tuned radio in 2010, I felt like it might be “the” way to make quality receiver performance available and accessible to many.  Now, four years later, several manufacturers have produced mechanically-tuned DSP shortwave radios.  All are available from sellers at a price of under $40 USD. Not bad…

Common review points for mechanically-tuned DSP radios

I’ve now reviewed enough mechanically-tuned DSP-based radios that I’m beginning to note performance commonalities that can only be attributed to the design of the DSP chipset itself, regardless of how these are implemented in each model. So, before the shooting starts, let’s take a quick look at some common review points of the contenders.

Tuning: not quite an analog radio…

I’ve got to begin with the most obvious common review point: namely, tuning.

For those of us accustomed to analog tuning, the DSP/analog combination is, well, completely different and a little quirky. Tuning a traditional analog radio is a fluid process which allows for a certain amount of play; you need not be precisely on a frequency to hear a station, and often you hear a station fade as another pops into the band pass. But when tuning analog DSP, you hear stations and static pass by in comparatively coarse 5 kHz chunks. Especially in radios with tiny analog frequency dials, it makes tuning feel somewhat “sticky” or finicky, and ironically, rather imprecise. You feel like you’re skipping over stations while band-scanning.  And for those accustomed to digital tuning, instead of using buttons to tune in these 5 kHz increments, you’re using a tuning wheel, with no customary “step” response.  Not what you would expect from either digital or analog radio.

But of course, you can locate your station with this method.  It takes a little practice––and a measure of patience––but you’ll adjust to this different method of tuning.  Note that much of this awkwardness may disappear if SiLabs produces a chip with more precise tuning increments, such as 1 kHz steps with decreased muting.

Automatic Gain Control

In all the models I’ve tested so far, the Auto Gain Control (AGC) is a little too overactive when listening to weak AM/SW stations. This results in a “pumping” sound and serious listening fatigue when set on weaker stations. However, on strong stations, all models perform quite well.

Conformity

Since all of these radios are based on the same chip family from SiLabs, you can expect eight shortwave bands: two FM bands, one AM (medium wave) band, and eight shortwave bands. The frequency ranges available to the manufacturer in all bands are identical.

FM

FM performance on each of these radios is above average, and the coverage quite wide––from 64 MHz to 108 MHZ in two FM bands. If you like listening to FM radio, you’ll be pleased with any of these inexpensive models.

And now for some action!

Now, we’ll pit these five radios against each other in an listener’s challenge that will leave the losers in the dust…and the winners clear.

Degen-DE321

The Degen DE321 – Current retail:  $21.00 USD

The DE321 was the first analog DSP shortwave radio on the market. The DE321 is small, slim, über-simple, and fits nicely in the hand. The analog tuning dial takes up more than half of the front face of the radio––a good thing, as the larger the dial, the easier the tuning. Performance-wise, the DE321 holds its own in this crowd; it’s quite reasonable in both sensitivity and selectivity. The DE321 is the most bare-bones radio among the five described here.

Degen-DE32

The Degen DE32 – Current retail: $27.00 USD

The DE32 is the smallest radio of the five. Unlike the DE321, the DE32 is not “just” a radio; it also sports a simple MP3 audio player and a small white LED flashlight. The DE32 has a small built-in speaker which delivers tinny and rather cheap audio, but is okay for a single listener, and fine for spoken-word broadcasts. Audio fidelity is greatly improved with headphones. Performance-wise, the DE321 is slightly better than the DE32 on shortwave.

Tecsun-R2010D

The Tecsun R-2010D – Current retail: $39.00 USD

When I first held the R-2010D, I initially assumed I had found the holy grail among analog/DSP radios:  while the R-2010D is the largest of the five radios, measuring nearly equivalent to my Sony ICF-SW7600GR (not a pocket-sized portable like the others) it nonetheless has a beautiful large analog display (a major plus!), an amply-sized speaker for great portable audio, and a fluid tuning mechanism. To top it off, the R-2010D has a small digital frequency display so that you can verify your frequency. The R-2010D’s AGC circuit handles strong stations well, but clips on weak stations. But the promising R-2010D has one major flaw: terrible selectivity. Indeed, the selectivity is so sloppy, that you will not be able to delineate two strong signals spaced 10 kHz apart from each other.

ShouYu SY-X5

The ShouYu SY-X5 – Current retail:  $27.00 USD

The SY-X5 surprised me: what makes this model stand out is the fact that it can be powered by either a rechargeable slim battery pack (found in the DE32) or three standard AA batteries.  It also has a built-in MP3 player that, like the Degen DE32, uses a standard microSD card for media storage. Unlike the DE32, the SY-X5 has a bright red LED display that helps in navigating MP3 files. The SY-X5 also has surprisingly good audio from its built-in speaker, rivaling the much larger Tecsun R-2010D. The negative here? Though the SY-X5 has a fluid tuning mechanism, it is prone to drifting when trying to adjust the analog tuning needle to frequency.

IMG_0823The Kchibo KK9803 – Current retail:  $16.00 USD

When I first wrote this review, I didn’t even include the KK9803. Why? Because, frankly, it’s one of the worst performing radios I’ve ever owned, and I would strongly discourage you from even considering it. My primary criticism of this radio is that the tuning is barely functional:  the shortwave band segments are far too close to one another on the dial, hence the digital tuning steps are too narrowly-spaced to offer any sort of tuning accuracy whatsoever. Barely moving the tuning wheel, one may pass over even a strong station…undetectably. The only hint of the station’s existence may be an occasional quick blip or audio buzz. I must confess that the experience of band-scanning (tuning) this radio offers is the worst I’ve ever known in any radio. Don’t buy it. In our shootout, it’s bitten the dust before it even aims, because let’s face it:  this radio just can’t.

Audio comparisons

Click on each radio model to hear a short comparison audio clips. Note that I added an audio sample of the Tecsun PL-660 to the weak signal DX examples as a benchmark.

The Tecsun R-2010D (left) has the best audio from its large internal speaker, the Degen DE32, on the other hand, produces "tinny" audio via its speaker.

The Tecsun R-2010D (left) produces excellent audio from its large internal speaker. The Degen DE32 (right) produces “tinny” audio via its tiny built in speaker.

Local AM Comparison (1350 AM)
Degen DE321
Degen DE32
ShouYu SY-X5
Tecsun R-2010D

Weak Signal Shortwave Comparison (KBS 9,805 kHz)
Degen DE321
Degen DE32
ShouYu SY-X5
Tecsun R-2010D

Tecsun PL-660 (AM and Sync)

Strong Signal Shortwave Comparison (WINB 9,265 kHz)

Degen DE321
Degen DE32
ShouYu SY-X5
Tecsun R-2010D

The Winners

All of these radios share similar qualities.  After all, they’re brothers of a sort, built around the same family of DSP chips. If you’ve read the summaries above, then you won’t be disappointed by any of these that follow–especially at this modest price point. Still, I reach for different radios based on their strengths, and to help you choose, here’s a “best of” list:

Most versatile: ShouYu SY-X5

Best Audio: Tecsun R-2010D and ShouYu SY-X5

Best sensitivity: Tecsun R-2010D

Best value: Degen DE321

Best overall?

The ShouYu SY-X5

The ShouYu SY-X5

If I had to choose just one of these radios, it might just be the ShouYu SY-X5. It offers the most value and versatility for the performance. I think its audio is brilliant for a pocket radio, and I love the fact it has an LED display to help me navigate through the MP3 files loaded on my microSD card. However, as with any of these low-cost contenders, don’t expect to try any weak-signal DXing with the SY-X5.

By the way, if the Tecsun R-2010D simply had better selectivity and weak signal gain control, it would win this contest, hands down. In fact, I actually sent feedback to Tecsun engineering regarding the R-2010D selectivity shortcoming in the hope that they’ll fix this problem in future production runs.  You might do the same.

In conclusion, mechanically-tuned DSP portables may not pack DXer-grade performance, but they are priced so that everyone can afford to experiment. And for your buck, that’s pretty good radio bang!


This article was previously published in The Spectrum Monitor.


Resources

Click on the radio model to read full reviews of each radio on the SWLing Post–I’ve also provided links to eBay:

A review of the Degen DE32 shortwave radio: compared with the DE321 and Tecsun PL-380

The Degen DE32 (Click to enlarge)

The Degen DE32 (Click to enlarge)

The Degen DE32 is one of the latest DSP-based analog radios to hit the market. In the past, I have reviewed two others: the Degen DE321 and the Kchibo KK-9803. Tecsun had announced a version of their own–the Tecsun R-2010–which I had eagerly anticipated, but I now believe it’s been dropped from their future offerings. [Update: Not true–the Tecsun has been released as the R-2010D, see review].

I purchased my Degen DE32 from this China-based seller on eBay. To my knowledge, eBay is the only place the DE32 can be purchased, at time of posting. As with the other radios mentioned above, my expectations were quite low for this little radio.  After all, at $27 US (shipped), you can’t expect top-notch performance characteristics.

IMG_5886

The DE32 un-boxed (Click to enlarge)

The DE32 comes with a carry strap, USB cable, a carry pouch, slim rechargeable battery, and operating instructions in Chinese. It does not come with a USB wall adapter (you’ll have to plug it into a USB port on your PC or other USB wall charger) and it does not come with a Micro SD card (for digital audio playback).

Audio

The DE32 has a small built-in speaker. The sound is a bit tinny, but is actually better than I expected from a speaker of this size. It makes for comfortable listening at close range–especially of spoken-word broadcasts. Happily, plugging in a good set of earphones helps audio fidelity tremendously.  This is the only way I would listen to music on the DE32 for an extended period of time. On FM, in fact, audio via earphones is surprisingly good (again, for a $27 radio–check out the audio sample below).

(Click to enlarge)

(Click to enlarge)

Performance

The DE32 covers three radio bands: medium wave (AM), FM and shortwave (5.6-22 MHz). Performance between bands varies greatly. The best band, by far, is FM. Again, no surprise here, as the DE321 and KK-9803 performed quite well on FM.

Here’s a 20+ minute audio sample of a local classic rock radio station I recorded, 95.7FM The Ride:

From my home, I can pick up my benchmark distant NPR station quite easily if I hold the radio in my hand. If I place the radio in a window sill, its performance degrades somewhat and contains more static as the extra grounding (from holding the radio) made a positive difference. The audio, though, is still perfectly intelligible. Local FM stations come in quite clear and fidelity (through headphones) is excellent.

The Degen DE321 (left) and DE32 (right)

The Degen DE321 (left) and DE32 (right)

I found that strong local medium wave (AM) stations sound quite good on the DE32–better than its cousin, the DE321, by a small margin.

While traveling over the holidays in December, I recorded extended samples of local station (630AM WAIZ) with both the DE32 and the DE321. You can listen to audio samples below, but first it’s important to note that I recorded these (and the FM sample above) with my Zoom H2N digital audio recorder, with radios at a comparable volume and via an audio patch cord.

Note that these recordings represent what each radio sounds like via headphones, not their internal speakers.

This is WAIZ on the Degen DE32:

Compared with WAIZ on the Degen DE321:

(Click to enlarge)

(Click to enlarge)

You’ll note that the DE32 sounds a little fuller than the DE321, but reception is nearly identical on this local strong medium wave (AM) station. I also found that the DE32 was quite effective at nulling out local RFI (electrical noises) on medium wave. At the beginning of the recordings, above, you’ll hear the static increase and fade as I null out the noise by turning the body of the radio. The DE321 couldn’t null out the local noise quite as effectively as the DE32.

For medium wave DXing, though, you’re better off finding a different ultralight radio. The AGC simply can’t handle marginal signals. Indeed, the same AGC problems plague the shortwave bands as well. DXing would be very unpleasant as the AGC circuit simply can’t cope with weak signals or fading.  All in all, as with medium wave, shortwave radio reception is fine for most strong signals.

Tecsun PL-380: What a difference an extra $23 makes

On shortwave, I decided to also compare the DE32 ($27) to the Tecsun PL-380 ($50). I tuned to a Radio Australia broadcast on 11,945 kHz. The comparison between these three portables is interesting:

First, the Degen DE32:

Now, the DE321:

Both the DE32 and DE321 struggled to receive the Radio Australia signal. In fact, if you really wanted to hear those broadcasts and had to listen on either radio for 30+ minutes  it would be frustrating and fatiguing. Notice, however, the difference when listening to the same broadcast with the Tecsun PL-380:

The Tecsun PL-380 receives circles around the DE32 and DE321 on shortwave and medium wave

The Tecsun PL-380 receives circles around the DE32 and DE321 on shortwave and medium wave (Click to enlarge)

There’s no comparison, really. In other words, you can hear it. The PL-380 has a lower noise floor, a fuller sound and no AGC problems as with the DE32 and DE321.  Hence the reason I always take the PL-380 while travelling–and as a back-up if I plan to record a broadcast on-the-go.

On the shortwaves, as with medium wave, the DE32 is respectable when tuned to a strong signal. For comparison to the weaker signals above, here is a short recording of the DE32 tuned to Radio Havana Cuba:

Not too bad, really. Keep in mind, though, that in my part of North America, Radio Havana broadcasts are so strong that I can pick them up without even extending the whip antenna on most portables.

Conclusion:

The DE32 has a built-in LED flashlight (Click to enlarge)

The DE32 has a built-in LED flashlight (Click to enlarge)

I haven’t tested the digital audio playback on the DE32 yet, although I expect the audio to be pleasant enough.  Of course, it lacks a display to show any information about the audio you’re playing, but it would be great to load a few podcasts or audio books on.

In summary, I’ve tabulated the pros and cons below from the moment I took the DE32 out of the box, below. Note that these pros and cons take into account the $27 price level of this radio:

Pros:

  • Very portable and lightweight
  • With micro SD card, storage for hours of pre-recorded content (though not tested in this review)
  • Adequate shortwave coverage (5.6 to 22 MHz) (see con)
  • Good audio fidelity, via headphones, on strong stations, slightly better than the DE321
  • Above average FM reception
  • Great nulling ability on medium wave (AM)
  • Features a built-in LED light (see con)
  • Overall build quality seems to be acceptable
  • Standard analog volume control (not digitally incremented levels)
  • Red LED tune light (see con)

Cons:

  • Shortwave sensitivity and selectivity are poor
  • Shortwave coverage lacks the lower tropic bands
  • Bandwidth is not adjustable and too broad for crowded conditions
  • AGC (as with many DSP portables in this class) cannot deal with weaker DX stations
  • Medium wave (AM) imaging on the shortwave bands if strong local station present
  • Antenna slightly loose in antenna hole when fully extended
  • No battery level indicator
  • No back stand
  • Tinny sound from tiny built-in speaker
  • To operate LED flashlight, you must press a button continuously to keep illuminated and LED  bulb orientation does not help with reading display in dark (see pro)
  • No option for standard AA or AA batteries–only included li-ion rechargeable pack
  • LED tuning light only works with very strong stations (see pro)
Conclusion? Though slim, lightweight and inexpensive,  I wouldn't find the DE32 DSP radio/digital audio player a useful radio in my collection.

Conclusion? Though slim, lightweight and inexpensive, I wouldn’t find the DE32 DSP radio/digital audio player a useful radio in my collection.

If I were you, would I buy it?

If you’re looking for a very inexpensive MP3/Digital Audio player with AM/FM and shortwave, and your expectations are fairly low, the Degen DE32 is a reasonable $27 piece of kit. Especially if you only plan to use the FM band.

If the digital audio playback abilities are not important to you, I would go with the cheaper ($18 US) Degen DE321.

But if you really want performance on medium wave and shortwave, and you could care less about digital audio playback, spend the extra $23 ($50 total) and buy the Tecsun PL-380, instead.  As you can hear above, it’s a much, much better receiver.

The Degen DE32 combines analog styling with MP3 features

The Degen DE32

I just ordered the Degen DE32–a new addition to the Degen shortwave product line. The DE32 is unique in that it has a (nearly retro) analog radio dial for tuning across the FM/AM/Shortwave bands, yet features MP3 playback.

Details are a bit scarce, but I have to assume that this is an analog radio as I see no mention of DSP in the description. (Though building on the DE321’s DSP chip could make sense.) It appears that MP3 recordings can be played back from an SD card and/or potentially from internal memory. Since there’s no digital display, sorting through recordings will be similar to using the iPod shuffle.

At $27 US shipped from Hong Kong, it’s certainly affordable, and my expectations will be adjusted accordingly. Still, I’m eager to see what this little radio has to offer. Check back as I will publish a review soon–simply follow the tag: DE32.

Thanks, Michael, for bringing this little radio to my attention!