Sangean HDT-1 Review

[rbrucecarter5]

I found this over at fmtunerinfo.com. These guys know a thing or two about tuners!

http://users.tns.net/~bb/hdt-1.htm

 

[SUPERCASTER]

So Sangean stopped providing (analog?) AM stereo reception on the HDT-1 tuner.

 

[Chuck]

Thanks for posting that. I think it is particularly interesting that this tuner handles adjacent channel interference very well. If you could only lock out the HD function, it might have quite a few applications past just listening to HD.

 

[hipporadio]

The analog FM performance appears to behave in a fashion very similar to the criticized BA HD receptor... Highly selective (especially at +/- 200kHz), but rather unimpressive sensitivity—If surmised by noting the aggressive “blending threshold” and progressive high-cut filtering at much higher than typical RF levels. While the 13.6 dBf 50db mono quieting seems impressive—you must consider that measurement occurs WELL AFTER this tuner begins aggressively rolling off highs and attenuating the overall audio output by 10db (a linear reduction of over 3x). This behavior reminds me of a late-80s GM Delco car radio. FM analog distortion is very impressive considering the high adjacent-channel selectivity, but appears to rise rapidly at modulation “spikes” until a sluggish adaptive I.F. bandwidth increase kicks in.

The analog AM audio performance is impressive—well beyond typical. The AM audio distortion specs are among the best I have seen, but I’m disturbed by the rapid low-end roll-off. It appears that we get a rare high-frequency “mid-fi” performer only to be marred by wimpy bass response. WHY can’t we have our cake and eat it too I ask? The use of a synchronous detector is a very welcome surprise. Did you notice the reviewer’s lack of addressing the AM sensitivity performance though ???

I do NOT care for “stereo blend” and especially “high-cut” that cannot be user-defeated, nor could I tolerate the lack of stereo/mono and HD-auto/non-HD reception mode selection. Given HD reception problems, I cannot imagine a more imperative need for the latter. Interesting that the BA HD Receptor fails to include one also.

The reviewer’s observations in regard to HD audio “quality” on AM refutes the alleged “IBOC audio advantage”. With the low bitrate/artifact-ridden codecs used—so much for “AM that sounds like FM”, and NO RATIONAL REASON to employ IBOC on the AM band!

So here’s the Sangean HDT-1 scorecard as I decode this review:

Mediocre analog FM
Very good digital FM
Very good analog AM
Disappointing digital AM

...Seems to mirror the theme and opinion of many on this board as we speculate the results of and fallout from IBOC on the AM and FM bands.

 

[hipporadio]

So Sangean stopped providing (analog?) AM stereo reception on the HDT-1 tuner.

SUPERCASTER... Since the review was conduced for an FM forum—I suspect they never gave it a thought. I’m going to take an uninformed (but semi-logical) swing at the ball, and suspect that the HDT-1 may indeed provide C-QUAM AM-stereo output.

There is one somewhat-peculiar performance aspect in its AM section that may indicate this. Consider the very-prominent low frequency roll-off in an otherwise commendable AM audio output... Nothing new among low-class AM radios—but NOT the typical M.O. for Sangean AM receivers. On the surface—that seems rather strange until you consider the 25Hz C-QUAM pilot certainly required to trigger the C-QUAM capabilities which may be part of the instruction set in the digital demod. The DSP may be simply configured to low-filter all AM to guard against any residing tone being transferred to the sub-woofer in a substantial home system.

The only C-QUAM via HD AM radio example I have heard is the WNMB AM-stereo audio from the Accurian posted on the net. It also features a prominent bass roll-off—very similar to that described in the HDT-1 review.

‘Just a guess... I suppose we won’t know for sure until a brave soul buys one and gives us the word!

 

[audiophile.]

For the record, I know for fact that the two of us that bought the Accurian on black Friday, neither one recieves C-quam AM stereo under real world conditions with plenty of signal.

 

[SUPERCASTER]

Hippo said:

The analog FM performance appears to behave in a fashion very similar to the criticized BA HD receptor... Highly selective (especially at +/- 200kHz), but rather unimpressive sensitivity—If surmised by noting the aggressive “blending threshold” and progressive high-cut filtering at much higher than typical RF levels. While the 13.6 dBf 50db mono quieting seems impressive—you must consider that measurement occurs WELL AFTER this tuner begins aggressively rolling off highs and attenuating the overall audio output by 10db (a linear reduction of over 3x).

That explains why some people hear an improvement when the radio switches to HD from analog. It is caused by a (deliberate?) defect in the analog FM section of the HD receiver.
AM HD works much the same. Cut the station's transmitted AM analog fidelity in half, add some HD digital buzz, and hiss, narrow the radio's analog bandpass much more then usual, and it sounds like a miracle when the radio switches to HD.
No miracle with HD at all, just slight of hand, trickery.

 

[R.F. Burns]

For the record, I know for fact that the two of us that bought the Accurian on black Friday, neither one recieves C-quam AM stereo under real world conditions with plenty of signal.

I own the Sangean HDT-1. It is far and away the most sensitive FM tuner I have ever owned (and my amp/pre amp is a mac MA-6100. My system consists of some pretty good equipment) I can say that the radio does to C-Quam, but the signal needed to activate the C-Quam detector must be much higher than what it took to say make my Sony AM stereoradios to open up. The FM section is remarkably sensitive and selective. I am able to hear a station that is 150 or so miles away and betwen two local first adjacents. I can hear stations on this radio which are unlistenable on my Sansui Tuner. There are two stations in particular that stand out. One is running 8 watts from about 25 miles away and I get a nearly noise free signal from them and the other is running 11 watts from about 40 miles away. My Sangean was purchased in December. Whether you like HD or hate it, it's a great radio with many excellent features.

 

[Mike Walker]

The Sangean, as with the Accurian (apparently made by Sangean) is heavily weighted toward allowing NO NOISE through with analog. That's not a "defect". The dual techniques of hf rolloff with decreasing strength and/or stereo blend with decreasing strength are features that have been engineered into various fm tuners (usually expensive ones) for many years. However, past component tuners let you defeat these features. So should Sangean! But with a good outdoor antenna, even in a remote area like where I live, keeping signal levels above the "collapse to mono" or "close down the high end" threshold should be no problem.

And it's fascinating that these tuners, which have been described by some as "cheap junk" incorporate synchronous detection! Pretty damn cool. The rolloff on the bass end of the AM bothers me. This is freaking stupid, but lots of manufacturers do this. Fortunately it's within a range that can be equalized back to pretty darn flat with a graphic eq. That's why God invented equalizers in fhe first place!

 

[hipporadio]

The Sangean [HDT-1}is heavily weighted toward allowing NO NOISE through with analog. That's not a "defect". The dual techniques of hf rolloff with decreasing strength and/or stereo blend with decreasing strength are features that have been engineered into various fm tuners (usually expensive ones) for many years. However, past component tuners let you defeat these features....

AGREED, Mike—but the guys over at FmTunerInfo scrutinized the VERY HIGH RF level threshold at which all this auto-activity kicked in. IIRC the blending begins at 45dBf while the S/N is still at 60dB—the hi-cut soon follows. At 42dBf signal input—separation is down to a mere 10dB! While an “FM geek” may not appreciate this form of auto-pilot (I would simply switch the tuner to mono)—consider casual listeners in the marketplace... They wouldn’t bother messing with “mpx blend”, “high-cut”, and even “mpx mode” switches. Sangean probably figures they would appreciate a design that would hold on to a usable signal right down to the very last dBf unit. My chief concern is the ramping down of the AUDIO OUTPUT during this process. Imagine a weak signal being selected and the appropriate amplifier volume being set by the listener. What happens if that signal increases during the listening session? Does that poor fella loose his speakers?

And it's fascinating that these tuners, which have been described by some as "cheap junk" incorporate synchronous detection! Pretty damn cool.

YES IT IS—and very commendable. No more straining your eyes to search for the few Sony portables that offer the benefits of that feature. The sync-detect is this tuner obviously contributes to its impressive distortion specs (in analog of course). Humorously, I-Com incorporates this feature into their IC-R75 table-top receiver—BUT the synchronous detection feature is A.W.O.L.—it is nearly un-functional without a very expensive third-party upgrade!

The low-frequency roll-off is unfortunate and has me scratching my head, but it CAN be augmented externally.

You know that I’ve taken a poster here to the woodshed several times over his characterization of Sangean as “cheap junk”. I own FOUR Sangean radios (and have had my paws on a few others)—they are EXCEPTIONAL... Only the ATS-909 seems to be a bit out-of-line in its price/performance ratio (but it is NOT an unworthy product and can be modified into a “monster”).

An irony here is that HD capability finally motivated Sangean to offer a home component tuner that provides exemplary analog AM audio performance. An even bigger irony is its full disclosure of the pathetic audio provided by IBOC AM HD... Do we need ANY further examples to indicate how fruitless its deployment on the AM band is?

 

[Chuck]

My chief concern is the ramping down of the AUDIO OUTPUT during this process. Imagine a weak signal being selected and the appropriate amplifier volume being set by the listener. What happens if that signal increases during the listening session? Does that poor fella loose his speakers?

I'm beginning to think that is a fairly common phenomenon with today's radios, but I don't see the logic in it. My new GM-Bose car radio seems to do that as well. It's been driving me nuts.

As many of you know, I manage an LPFM station that uses two translators. As I drive away from one station and switch to another frequency, the more distant (weaker) station will be considerably lower volume that the stronger station when I make the switch. This is despite the fact that they all broadcast the same program material and each transmitter has been calibrated using the same Inovonics modulation monitor. Any difference in actual level at the transmitter sites is very slight, well below the threshold of audibility.

Perhaps the people who design radios think you won't be as bothered by a potentially noisy or weak signal if you turn down the volume. That's probably true, but I'd rather make that decision for my self, rather than have the radio do it.

None-the-less, the Sangean HDT-1 looks to me like it might be a “keeper” even if you never use its HD capabilities.

 

[hipporadio]

I own the Sangean HDT-1.

This may explain what brings you to this fun place in cyber-space! I truly hope you will remain with us after removing a little sand from your face. There ARE “passions” here, and I believe Tom Wells summed up much of the rationale very well in is post on the “Harris” thread (Reply #54). Yes, this CAN be a “playpen” at times—and a month passed before I fully figured out how to properly manipulate the “quote” function here. I generally prefer technical discussions, but occasionally enjoy some frolic and “comic relief” also

Mr. Burns... To understand the idiosyncrasies of this site fully—allow me to offer two quotes:

The first from the late/great Hunter S. Thompason:

“The radio business is a cruel and shallow money pit... A long plastic hallway where good men die like dogs... And there's also a negative side.”

And this from a recent post in a different location on an unrelated topic here at R-I:

“This room is just a reflection of the reality of the business today. It's no worse, just a little more candid. It's harder to backstab, politic, lie, cheat, and steal here, so there's a tendency to speak more freely to make up for the absence of those usual techniques.”

No back to our regularly-scheduled program...

It is far and away the most sensitive FM tuner I have ever owned... The FM section is remarkably sensitive and selective. I am able to hear a station that is 150 or so miles away and between two local first adjacents. I can hear stations on this radio which are unlistenable on my Sansui Tuner...

No doubt, this is to date possibly the BEST HD RADIO offering—and THE FIRST to appear in a home component format. While I can emphatically give a “thumbs up” to many products from Sangean—I have been MUCH less-than-impressed with the HD radios I have researched and actually used (e.g. the Boston Acoustics HD-version of the Receptor)—and I am not alone in that summation.

In regards to the HDT-1... All I can do is attempt to read, scrutinize, and arrive at some conclusion minus personal experience. That’s what makes your visit here productive.

I’m sure the FM HD provided by the HDT-1 will satisfy those early-adopters who want to embrace the technology. My question still stands: Will the typical 24-year-old postpone his desire to own the latest iPod upgrade and shell out $200 for HD from this tuner? A single pair of underwear remaining clean for a full week is a more realistic proposition!

I can say that the radio does to C-Quam, but the signal needed to activate the C-Quam detector must be much higher than what it took to say make my Sony AM stereoradios to open up.

C-QUAM AM-stereo form the IBOC-endowed digital demod is not far-fetched, and it has been widely reported. I recently captured (and saved to .wav format) playback from a website where 900AM WNMB (which offers a music format via C-QUAM) had posted a demo of such from Radio Shack’s Accurian HD radio. The only music included was the Mamas & Papas’ “I Saw Here Again” (produced in 1966, and far from creative excellence at presenting a stereo soundstage). The demodulated audio was NOT compelling... Nearly NO content over about 2.5k [YUCK]... And I was not convinced that it’s even “real” (hard left/right) stereo. I’m wondering if it’s merely an interesting “image” created by a confused DSP. It sounds like a low-bandwidth version of synthesized stereo from the infamous Orban box of the 1980s used by early-adopters of the stereo television technology. So... Does HD radio REALLY offer genuine Motorola C-QUAM capability?

Whether you like HD or hate it, it's a great radio with many excellent features.

Everything considered... ONE unforgivable design flaw would make the purchase of the HDT-1 a “no can do” with me. I cannot tolerate an illogical lack ofthe option to defeat the HD reception mode—especially when one considers its superlative analog AM audio quality. I cannot imagine wanting to endure IBOC’s low-quality artifact-ridden codec when the analog alternative is MUCH BETTER!

 

[rbrucecarter5]

If you can post that recording of "I Saw Her Again" - I can compare it with the original stereo version on vinyl to see if the separation is really there. As far as production value - I find some of the stereo tricks people pulled when it was first in vogue very creative and interesting. In this case, it is an excellent song to really check stereo separation.

Funny that an AM C-Quam oldies station can manage to play it in stereo, when our local oldies station can only play a (YUK) mono version of the song. Sort of takes the fun out of it. They do that to a couple of other classics like "Fun Fun Fun" by the Beach Boys.

 

[Mike Walker]

Hipporadio asks "An irony here is that HD capability finally motivated Sangean to offer a home component tuner that provides exemplary analog AM audio performance. An even bigger irony is its full disclosure of the pathetic audio provided by IBOC AM HD... Do we need ANY further examples to indicate how fruitless its deployment on the AM band is?"

None. Give us CLEAN AUDIO! Hell, FM HD would perhaps be useless as well, IF manufacturers had actually been researching how to improve fm reception through the years. The last great tuner to really attack fm noise was the Carver TX11b, with the ridiculously named "Asymmetrical Charge Coupled Decoder", or whatever the f they called the damn thing. It was an ingenius design that just about eliminated noise and distortion on ANALOG fm, while preserving separation!

(Then there was Carver's "Magnetic Field Amplifier"...whose amplification circuitry had nothing whatsoever to do with any freakin' magnetic field! Who wants to "amplify" a magnetic field, anyhow? I'd rather you amplify my audio!)

 

[hipporadio]

The last great tuner to really attack fm noise was the Carver TX11b, with the ridiculously named "Asymmetrical Charge Coupled Decoder", or whatever the f they called the damn thing. It was an ingenius design that just about eliminated noise and distortion on ANALOG fm, while preserving separation!

Ever heard the terms “technical tradeoff”, “no free lunch”, and “you can’t fool mother nature”—the Imperial Margarine commercial spiced that one up nicely. Setting aside the temptation to remind iBiquity of those, let me comment on Carver’s infamous ACCD in the TX11b... I own one, and can tell you from personal experience the benefits of that design carried a healthy tradeoff.

Fortunately, that mode was selectable—and I usually chose “OFF”! Indeed it DID dramatically reduce multiplex noise... It also TOTALLY rearranged the stereo perspective and soundstage, and introduced artifacts that resembled multipath interference (when none was present in the signal to begin with). ACCD was basically a magician-conducted dynamic stereo-blend. In the late 80s, It’s tires were flattened by a three-to-one margin in the audio review community.

 

[hipporadio]

If you can post that recording of "I Saw Her Again" - I can compare it with the original stereo version on vinyl to see if the separation is really there.

The link to the WNMB C-QUAM stereo audio via the RS HD Accurian was posted here in an earlier thread which was moved by the “mod”—and several of the posts have vanished. The aircheck was converted to a streaming mp3 which I captured a month or so back and saved in a stereo 44.1 kHz 16-bit .wav format so as to not reduce the already unimpressive quality any further. That makes it impossible to re-stream... And let me assure you—it wouldn’t be worth it. The audio is unimpressive. If that’s all the better rendering of AM stereo a radio can muster, Motorola should put the “squash” on it in the interest of upholding their legacy!

I have three M&P CDs which feature “I Saw Her Again” (it’s one of my favorites). As you noted—it’s in mono on the early “Best of” collection. Later remasters corrected “issues” in many of their titles such as the infamous out-of-phase “Creeque Alley” where the vocals disappeared in mono sum. My later two CDs (“Best of—Millenium Collection” and the “All the Leaves are Brown” compilation) feature our target song in TRUE STEREO. I compared the WNMB file to the stereo track on Millenium in my studio. The presiding judges were my ears and an audio analyzer set to display “difference” material.

The WNMB aircheck presents a surround-effect, but NOT “hard” left/right separation. My CD copy of this song features Mama Cass Elliot’s vocal “hard left” (appropriate wouldn’t you say)—NOT SO on the WNMB sample. Understand that we have no darn idea what WNMB’s source is for the song—it may be “synthesized stereo”, so in fairness, we can’t make a definitive charge based on this sample only. Suffice to conclude, IF their copy IS the post-1999 remaster—the HD Accurian IS NOT properly decoding C-QUAM AM stereo.

 

[rbrucecarter5]

If that’s all the better rendering of AM stereo a radio can muster, Motorola should put the “squash” on it in the interest of upholding their legacy!

I have three M&P CDs which feature “I Saw Her Again” (it’s one of my favorites). As you noted—it’s in mono on the early “Best of” collection. Later remasters corrected “issues” in many of their titles such as the infamous out-of-phase “Creeque Alley” where the vocals disappeared in mono sum. My later two CDs (“Best of—Millenium Collection” and the “All the Leaves are Brown” compilation) feature our target song in TRUE STEREO. I compared the WNMB file to the stereo track on Millenium in my studio. The presiding judges were my ears and an audio analyzer set to display “difference” material.

AM stereo sound was supurb when done correctly. Dare say better than FM stereo in many instances. The technology really worked - unlike Ibiquity which manages high bit rate streaming quality at best.

As for hard left vs. "real" stereo imaging - I find the old hard left / hard right tecnique a pleasing contrast to the plethora of "correct stereo imaging" records today that all sound alike. No doubt it was created for the old left channel on AM, right channel on FM method of broadcasting stereo.

 

[Mike Walker]

I just found on Napster (the legal one!) four different stereo versions of "I saw her again"...from the album "Gold", from "20th Century Masters, the Millennium Collection", from "Greatest Hits-The Mamas and the Papas", and from "All the leaves are brown, The Golden Collection". All imaged boy singers left, girl singers right. Interestingly enough, that's reversed from WNMB. Obviously WNMB's channels got "flipped" somewhere.

C-Quam AM stereo was great...I've SEEN measurements greater than 45db during proof of performance. But let's not give it more credit than is due, RBruceCarter. Frequency response for AM stereo extended only down to 50hz, due to the 25hz pilot tone. And "on top" few radios topped 8khz. Not only that, the nature of Quadrature modulation is that the greater the separation, the more distortion on mono radios. Hence "Compatible"...the "C" in C-Quam..."Compatible Quadrature Modulation" is what it stands for. Quadrature modulation, which in it's pure form is quite incompatible with distortion-free Amplitude modulation is made compatible by capping extreme separation at a point where going futther would result in horrendous distortion. Even so, AM at it's best was hard pressed to ever do more than 2 to 3 percent distortion at 100 percent modulation. That's true today even with modern transmitters (the exception perhaps being some of the digitally modulated ones from Harris which synthesize Amplitude modulation by switching fixed-amplitude amplifiers in and out of the circuit. And even great AM has no more than 60db s/n ratio across the street from the tower.

So let's not exaggerate. 50hz-8khz frequency response, 30-40db real-world separation, 2-3 percent distortion. Now that sounds like "high fidelity" compared to most AM, but in comparison to HD radio with 96db s/n ratio, 90+db separation, and distortion almost as low as the recording being played...now that's a different league. I have before posted files that were identical except that three were a straight cd rip (uncompressed), one had been processed by aac+.

Let's repeat that test, but a little differently. Say you can REALLY hear aac+ processing on a 96kbps HD broadcast? PROVE IT! Before are four files. All are uncompressed .wav. Two of them are straight cd rips from Working in a Coal Mine, cut 1 on Harry Connick Jr's new album "Oh My NOLA". One of them was encoded in AAC+ at 96kbps, then decoded back to uncompressed .wav. The other was encoded in AAC+ at 48kbps, then decoded back to uncompressed .wav (simulating an HD2 stream). Encoding was done with MediaCoder (I don't have aac+ on my workstation program...Adobe Audition).

If you really can tell such a huge degradation from aac+ coding on HD radio, PROVE IT! Tell me which two of these files are uncompressed cd rips, which one was compressed to aac+ at 96kbps, and which was compressed at 48kbps. If you don't get all four then you've proven one thing...you're only guessing! Science...what a concept!

http://www.theproductionroom.net/coal01.wav

http://www.theproductionroom.net/coal02.wav

http://www.theproductionroom.net/coal03.wav

http://www.theproductionroom.net/coal04.wav

 

[vsa]

Mike Walker wrote: "If you really can tell such a huge degradation from aac+ coding on HD radio, PROVE IT!"

I agree with you on this. Without even bothering to listen to the posted audio files, I already know that most people will be very hard-pressed to tell the difference between them.

It is very easy to bash iBiquity's HD radio system. It has lots of problems. Audio quality and the choice of audio codec at 48kbps and 96kbps is not one of them. IBiquity was right to dump its own (actually Lucent's) PAC codec in favor of licensing AAC+, just like XM did. For the life of me, I don't understand why Sirius uses PAC. Perhaps they are stuck with it and can't change now.

 

[SUPERCASTER]

Mike.
While we are at it, why not dump all the digital HD noise and just go with FMeXtra, which uses the AAC+ codec, you so highly recommend. There is no logical reason why there should necessarily be a digital duplicate of the analog FM audio, as required by the HD spec. Most people are perfectly satisfied with the analog FM range and fidelity they are now getting.
That leaves an excellent quality 64kbps aac+ digital stream with FMeXtra for the programming that would be on HD2 at a lower bitrate with iBiquiuty/HD radio.
Better digital for the new programming, excellent analog stereo for the main channel. No new rules changes, or expensive, power consuming, buzz creating, HD transmitters.
What a great deal!
Everyone benefits.
One we should all get behind FMeXtra, and drop HD Radio like a hot potato. Just consider HD Radio a nightmare, that is now over.
And best of all, FMeXtra battery powered portable "walkman" radios will soon be on the way.
FMeXtra:
http://www.radio-info.com/smf/index.php/topic,62340.0.html
www.dreinc.com