Thursday, January 17, 2008

Sangean HDT-1X Offers Upgrades

Sangean released the HDT-1 component-style HD Radio receiver to the delight of radio engineers. Many of us had been waiting for a radio we could put in our racks to replace a homebrew car receiver (or similar jury-rigged solution) for our in-house monitoring. The HDT-1 filled that need, and then some, with its stylish design, intuitive controls and large display. Even so, the HDT-1 wasn’t entirely perfect, and Sangean has released an updated version, the HDT-1X, that adds a few nifty features while maintaining the same performance of the original.

Quickly recapping the original and new units, the radio is a component-style tuner. It will easily fit in any 2RU space, although it needs a rack shelf. The front panel controls include a large power button, a numeric keypad for presents or direct entry of a frequency, and three rocker switches for incremental tuning, seek tuning, and seek tuning for HD stations only. There’s also a “band” button to cycle through two sets of FM presets and two sets of AM presents, and an “info” button to cycle through various functions on the display.

The rear panel has an AC power connection, a coaxial FM antenna jack, a twin-lead AM antenna jack, two unbalanced analog RCA audio outputs, and a new addition: an optical digital audio output, also unbalanced. A remote control that duplicates most of the front panel’s controls is also included.

I mentioned the optical digital output, that’s one of the main upgrades in the HDT-1X. Its consumer, not professional, but I imagine you could easily convert the optical TOSlink to balanced AES or whatever format you need. However, in comparing the optical output to the analog, the optical sounds slightly “brighter”, with more high-end treble. It’s possible this is a by-product of my amplifier, but this tended to make over-compressed audio sound more “crunchy”, especially on our local HD-AM stations.

The display is fairly large, 2.75 inches wide and 1.5 inches tall. It can be cycled through showing the time, a graphical EQ, artist/title in large, call letters, and frequency + call letters + artist/title. It can also show “SSI” which presumably means “signal strength indicator”. I’m not sure how useful this meter is, since it seems to vary wildly for no apparent reason. Of course, perceived signal strength does tend to do that. Still, it can be handy to fine-tune your antenna’s orientation.

Another bonus in the HDT-1X’s display is the addition of a stereo indicator. A quick scan of the dial revealed all HD signals from FM stations are in stereo…even stations obviously broadcasting mono content. However, on the AM side I noticed news/talker WBZ 1030 was choosing to transmit their HD signal in mono. It’s been long-suspected that the Sangean HD tuners also decode the old C-QUAM AM Stereo, and listening to the sole Boston source of AM Stereo confirmed it; the stereo icon appeared about 15 seconds after I tuned to WJIB 740.

One oddity carried over from the HDT-1 is that where some other HD Radios show some combination of station information, or artist/title, the Sangean will only show call letters. I have a suspicion that Sangean is actually displaying it “correctly” but other radios might using a more aesthetically sensible method.

A Well-Received Upgrade?

In the end, this is ultimately just a radio – so how good reception does it get? I’d say "Pretty good." It’s not the most sensitive tuner I’ve ever owned, but even in Boston’s packed radio dial, it tuned in most stations that I expected it to. Interestingly, some stations that had pretty poor analog reception…and low numbers on the SSI…would still successfully switch to HD. To compare it to the original HDT-1, I split the stock FM dipole antenna into both my HDT-1 and the HDT-1X, and found that they both seemed to have the same sensitivity. Similarly, the stock AM loops in about the same location yielded comparably sensitivity (and SSI numbers) for both radios.

One thing I couldn’t test was reception of HD3 channels and/or multicasts using the Expanded Bandwidth transmission. Unfortunately nobody in Boston is using either as of this writing. However, HD2 multicasts, when present, came in just fine whenever the HD1 channel successfully buffered.

Sangean seems to want to appeal to radio engineers, and the proof is in the HDT-1X’s signal diagnostics and control. The original HDT-1 had several interesting signal diagnostics, such as Bit Error Rate, carrier-to-noise ratio, FUSE Bit Check, (HD) Transmission Mode, and station ID. But the –1X adds some very broadcaster-friendly tricks: force-analog only, force audio to digital-on-left / analog-on-right (for time-synchronization purposes), and force mono vs. stereo (only in analog mode). Worth noting: even in analog-only mode, the display still shows HD PSD information, and not RBDS, if IBOC carriers are present.

And proving that Sangean really aims to please, even certain whining reviewers of other HD Radios (Directed Electronics DHHD1000 Tabletop HD Radio) :-) they even added a bright/dim control to the backlight! And the backlight shuts off when you power off the unit – yay!

So is the HDT-1X every engineer’s dream? Well, not quite. When the radio loses AC power, it defaults to "off" when power comes back. And if the radio loses the HD signal, it switches back to main analog audio after a minute or so; which could be problematic if you’re using it as a multicast channel’s monitor. I spoke to Sangean a bit about this and there’s talk of a branching a true “broadcasters’ radio” model off from the base HDT-1 design. Such a unit would cost more, but would have all the “professional” features like balanced outputs and even more signal diagnostics.


With the HDT-1X, Sangean has taken a pretty good “prosumer” tuner and made it even better for broadcasters. Could it be more sensitive? I suppose, but it’s hardly “deaf”. Could it have a few more features? Perhaps, but the ones it does have are nice. For the price, these downsides are easily outweighed by the improvements: a digital output to preserve the all-digital chain, and the added analog/digital and forced analog controls are very useful. The stereo indicator rounds out a great package of improvements. If you’ve been desiring a house monitor for HD that won’t break the bank and looks slick, the HDT-1X might be just the ticket.

Handy digital/analog audio tools.
Reasonably priced.
Large display / Easy-to-use controls.
Good manual / documentation.

No professional audio outputs.
Not ideal for silence-sense monitoring.

PRICE: $249 (MSRP)


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