Product Review - Sharp One-Bit Digital System:

 DX-SX1 Stereo SACD player and SM-SX1 Integrated Amplifier - February, 2002

John Kotches.

I remember covering my first trade show with Secrets, namely CEDIA 2000, where I felt like like a child given the keys to a toy store, and hearing my parents say, Go play!"  It was a bit overwhelming, but there were a few products that really piqued my interest, and I requested review samples.  A year came and went, as did CES 2001 and CEDIA 2001.  Finally, a review sample of the last of the products came into my home for me to try out.

It was that rarest of rare beasts, a digital output of the DSD bitstream, coupled with a digital amplifier that can handle the bitstream directly input to the amplifier.  In other words, from the CD to the speakers, it is all digital, no analog. l be looking at a series of digital amplifiers over the next several months, and this is the first of the lot.

What's in the shiny silver packages?

The SM-SX1 is a low profile integrated digital amplifier, with a modest 50 wpc output into either 8 or 4 Ohm speaker loads.  It (and the companion SACD unit) ships in a matte silver finish with a mirrored, beveled faceplate.   I liked the reflective faceplates so much, I took the photos in my back yard, so the trees would show up.

The bottom of the unit has five spiked feet, two in front and three in the back which are used as both a stable base and as an isolation mechanism between the amplifier and the surface on which it is placed, or to couple it to a matching component from the family of products.  During operation, with the DX-SX1 placed atop it, and ventilation just to the sides, the amplifier became only slightly warm to the touch, indicating it is a high efficiency product with little energy wasted. In fact, this is serendipity for digital amplifiers. They sound great, and use most of the electricity that they draw, for the sound.

Although the SM-SX1 is a high tech digital amplifier product, it doesn't come with a remote control, probably because the line is still experimental.  A series of buttons on the faceplate gives you access to the array of inputs.  The far left portion of the front panel includes the power switch, as well as the input selections, SACD, Digital 1, Digital 2, Analog 1, and Analog 2.  The large button on the right hand side is the volume control.  

The back panel comes with a relatively standard complement of inputs. The analog complement from left to right are line-level analog preamplifier outputs, variable level line outputs, and two analog stereo inputs.  Next up is the 13-pin DIN connector labeled 1-bit, which is used for DSD-SACD digital input.  This is Sharp's proprietary interface, and no other digital format can be input and decoded here.  A single coaxial (S/PDIF) digital input and two optical (TOSLink) inputs complete line level input options.  A pair of gold plated five-way speaker binding posts are included, as well as a detachable IEC (AC) power cord.

Although there are three PCM inputs, the coaxial and one of the TOSLink inputs are shared as selection "Digital 1" on the front panel, and the SM-SX1 will automatically choose whichever interface has an active signal.  If both are active, the coaxial input is selected.  The second digital input is TOSLink only.  Although the S/PDIF and TOSLink interfaces are physically capable of transferring PCM up to 24bit/96kHz in stereo, the digital inputs will only accept a Redbook CD input, which is 16bit/44.1kHz.  No other signal will be decoded.   I verified this with both a DVD player with 24bit/96kHz output capability, and the Perpetual Technologies PT-1As digital output. 

The digital CD input then gets converted directly to DSD, via a  4x Delta-Sigma encoder, which conveniently outputs a 2.8224 mHz DSD bitstream.  This is then handed over to the switching amplifier as would the digital input of an SACD player.   Perhaps a future edition of the digital stage will be able accept a wider variety of sampling rates.  To do so would require a different approach, and with your indulgence I'll give you a guess on how this could be accomplished.  

Super Bit Mapping Direct is Sony's method for outputting multiple data rates from the DSD bitstream.  Getting to 16/44.1 can be accomplished as a direct operation, although it is actually accomplished identically to other sampling rates.  First, the 2.8224 mHz DSD bitstream is oversampled 5x, yielding a bitstream with a datarate of 14.112 mHz.  Then the bitstream is divided up into segments correlating to the timespan of the PCM sample - 147 bits exist in the timeslice so more than enough data exists for mapping.  Finally, the aggregate voltage is summed algorithmically and a PCM comparable value is determined and stored.   Voila, you have now mapped DSD into a 24bit/96K PCM datastream.  If the process could be reversed, the higher data rate could be accommodated.  A 24bit/192K bitstream could be handled provided oversampling is 10x DSD. In plain English, future digital receivers would be able to take any digital input, whether it is from conventional CDs (16/44.1), or from 24/96 DVD-A, 24/192, SACD, perhaps even from DD and DTS, and convert them to high resolution DSD before sending them to the digital power amplifiers. The result would be very efficient, and very high quality audio, even in mass market products.

Analog inputs are passed through an Analog/Digital Converter (ADC), which samples the input with a 1-bit Delta-Sigma modulator running at DSD's sampling rate and depth, outputting the 2.8224 mHz DSD bitstream which is passed directly to the digital switching amplifier.

I covered the technical details to the amplifier section in a technical sidebar to JJ's review of the SM-SX100 amplifier.   

What's behind door number two?

The DX-SX1 SACD player is a stereo-only unit (no surround).  It is finished with the same styling as the companion amplifier described above.  

The DX-SX1 front panel has the power switch on the left of the beveled face plate, and the LED display centered on the faceplate.  In addition, the usual compliment of CD transport controls and a headphone output are included.  SACD and CD text are not displayed, but all the usual other CD indicators and information are present.

The back panel is fairly busy, with (from left to right in the photo) the following outputs: Digital 1-bit output for SACD/DSD, variable and fixed line level outputs, TOSLink and Coaxial S/PDIF outputs, and an IEC connector for a detachable power cord.   

The transport mechanism itself is a bit noisier than I would like but not loud.  Hopefully Sharp will work on quieting the mechanism in future players.

The remote control is finished in matching matte silver (plastic).  It can best be described as adequately functional with buttons close to the same size.  This and the fact that the control isn't backlit would mean poor marks on the usability portion of our increasingly famous benchmarks.   Thankfully, the grouping of buttons is logical.  Additionally, I found that its usable range was relatively small, but about half an hour with ProntoEdit and I had this remote control fully configured on my now aging universal remote.

Going digital (and analog) . . . yeah baby!

I did a lot of listening to this combo with CD and analog inputs, getting a feel for its ability to handle legacy formats that will be with us for many years.   At times, I used the Onkyo DV-S939 to feed an analog signal, while at other times, I used the companion DX-SX1 stereo SACD players analog outputs, and occasionally, I fed the digital output of the DX-SX1 directly to the amplifier.  Try as I might, I could hear no difference between the three connection options into the SM-SX1 for Redbook CD.

I started off with a hard to find incarnation of the Dave Brubeck Quartet, the album is Tritonis, and the track was "Like Someone in Love".  This track features the tenor sax of Jerry Bergonzi. Here we have him in strong form, demonstrating technical prowess.  There are moments of subtone, and some really cool false fingering effects throughout his extended cadenza to close the song.  You get a very distinctive tonal quality out of a saxophone when you use false fingerings to produce certain notes on the horn, and these "stick out" in exactly the way he desired.  In addition, his use of the altissimo register and his "strained" timbre is evident throughout.  Notes fly furiously, while never losing their groove.  Sadly, the electric bass sounds terrible, but this is the recording, not the electronics in use.  Level matched comparisons vs. the analog input yielded no sonic differences to my ears.

The Manhattan Transfer's Mecca for Moderns has a number of interesting tracks, but my favorite is probably "A Nightingale Sang in Berkeley Square".  One thing brought to the forefront is the use of reverberation in the recording to give a sense of spaciousness.  The Sharp combo tends to make me acutely aware of the amount of reverb in use - not a shortcoming of the gear at all, it's presenting the material very factually.  When I first started using an external DAC combo I became aware of this characteristic as well.  On a more positive note, I gained a renewed respect for Janis Siegel and Alan Paul, who get to sing the interior harmonies of this A Capella rendering.  Interior harmony parts are tough - some of the intervals can be brutal, and you get to sing most of the dissonances in the harmonic structure.   Also brought out were the unison breathing of the four vocalists, and in some respects it's as though one person was singing the four part harmony.

 In short, I found the combination to be an outstanding pair for CD reproduction.

It's a 1-bit world!

This is the part that everyone will find the most interesting.  How does the 1-bit combo do on SACD?  As much as I'd like to write it's the most fabulous thing I've ever heard in my life, I can't.  It's quite good, and in some respects great.  Let's start with what it does right, and we'll get around to where I found things could be improved.  I listened to all the cited recordings on both my main speakers and also on the mains of a 5.1 setup.

I picked an "oldie but goody", The Duke Ellington Orchestra's magnificent disc Blues In Orbit.  One of the many great compositions from the stable of Ellingtonia is "In a Mello Tone".  The recently resurrected Mobile Fidelity Sound Labs released this as their first SACD title prior to their initial shutdown.   I heard the stacatto 5-note phrase played with delicate touch, and the rhythm section adds to the mix after the first four bars.  Harry Carney chimes in on the repeat of this tunes "A" section, and  continues solo for the "B" or bridge of the tune.  Finally, we return to the "A" section with an inverted harmonization (which means baritone sax playing lead over the sax section).  Fabulous trumpeter Ray Nance takes a plunger muted solo, and there are tons of microdynamics here that are the results of his moving the plunger nearly constantly while playing.  I was very impressed with the 1-bit combination's ability to play back at low to moderate levels capturing the essence of this 40 year old recording very nicely on my reference speakers

One thing that sucks as a reviewer is that we inevitably end up purchasing a new recording or two or three during a review cycle.  This time, it was James Taylor's Hourglass.  This is a "pure-DSD" recording, and is multi-channel.  Remember that with SACD, stereo mixes are required, and multi-channel mixes are optional. I could only listen to this one in stereo, because that is the limitation of this particular SACD player.  The opening track "Line 'em Up" starts off with JT singing "I remember Richard Nixon back in '74" and his voice seems to come out of nowhere, from a dead silent background.   The synthesizers and JJ Johnson's bass ring out into the room, and I was surprised by the amount of control this little amplifier was capable of producing.   Jimmy Johnson uses a 5-string bass, which means the bottom of the instrument is around the 30 Hz mark as opposed to the 40 Hz mark for a traditional 4-string bass.   Jimmy isn't afraid to use that 5th string, and I found myself really captivated by the clarity in this recording.   The background vocalists (Valerie Carter, Kate Markowitz, David Lazley, and Arnold McCuller) do a fabulous job behind JT, with a nice mixing technique of spreading the vocalists behind the lead spanning from left of center to right of center.  No vocalist is hard panned to any speaker, which gives a nice spread across the interior soundstage.   I was extremely captivated by the percussive aspects of JT's plucked strings. 

Billy Joel's The Stranger also made it into my collection during this review, and I particularly dig the biggest hit from this disc, "Just the Way You Are" for the work of the great alto player Phil Woods (a guest soloist).  I remember being a high school saxophone player trying to learn the licks Phil was playing, but I never did get down every note in some of his double time runs! This isn't the greatest recording out there - it has hiss (not an inordinate amount for its era) - nor is it the most "high brow" selection in my collection of music, but I don't care.  I like the tunes, and the band has an innate groove that makes it a worthwhile listen to me.  Liberty Devito is a very good drummer, and I could feel him subtly kicking the bass drum and keeping the rhythm of this tune flowing, without overwhelming the action.  Again I was very pleased with the clarity that the Sharp combo delivered to my reference speakers.  

Caution

I prefer planar (electrostatics, ribbons, etc.) loudspeakers, but I also have an inexpensive 5.1 speaker setup I used during the review cycle, and I switched back and forth between the two on several occasions.  This allowed me to get a feel for the Sharp combination's sonic characteristics with a couple of different loads.  Some planars (particularly the speakers from Apogee) can provide brutal loads to an amplifier.  The old Apogee Full Range and Scintilla both had a minimum impedance of under 1 Ohm - the amplifier is almost driving a dead short circuit.  My main speakers from Soundline Audio utilize a Bohlender-Graebener RD-50 ribbon driver, so from 250 Hz on up they have a nice flat impedance of approximately 4 Ohms for the majority of the frequency range.  The woofer (from Scanspeak) is about 6 Ohms below 250 Hz with a minimum impedance of 4 Ohms.  A well designed crossover with some impedance matching brings it closer to its rated impedance of 8 Ohms, which is very nice for this amplifier to drive.

My review 5.1 setup mains are a different story, with a nominal impedance of 8 Ohms and a minimum impedance of  3.2 Ohms at roughly 2 kHz.  It is not at all unusual to have an 8 Ohm rated speaker with an impedance drop at the tweeter's resonant frequency - and such is the case with the review speakers.  Why am I talking so much about speaker impedance?   Although I found that the SM-SX1 delivered excellent sound on my main speakers, which are tough loads, it is important to choose your speakers carefully with this amplifier. The fact that Sharp supplies an 8 Ohm/ 4 Ohm selector switch suggests they are concerned about the load too. So, if they are, you should be. I suspect that, at this experimental stage, the power supply is still pretty modest.  

I did hear a "cupped hands" kind of sound in certain situations. The recording that brought this home most conclusively was Carole King's Tapestry, and specifically "So Far Away", which is track 2 for those of you with this disc in your collection.  This recording isn't a model of clarity and even on my reference speakers it has some mild "cupped hands" syndrome.  On the review speakers this tendency was heightened dramatically.  So, like any reviewer would do, I connected the rig to my familiar setup, i.e., I ran the analog outputs of the Sharp SACD into my reference amplifier (Cinepro).  With my reference amplifier now driving the review speakers, the amount of "cupped hands" was greatly reduced, so the effect is a characteristic of the Sharp amplifier. Whether or not it occurs in all amp speaker combinations is a different question.

I went to Billy Joel's 52nd Street for another comparison track, "Zanzibar" which also includes a great flugelhorn solo from Freddie Hubbard - sure enough, even Freddie's flugelhorn was lacking some of the characteristic roundness and warmth that I'm accustomed to in my reference setup. We also have to keep in mind that perception of tonality depends on what you are used to listening to.

The basis for my comparison (at matched volume levels thanks to my Radio Shack SPL meter) was the Meitner Switchman and Cinepro amplifier combination driven from the analog outputs of the DX-SX1 player.  

Conclusion

Sharp isn't usually  tops on anyone's list of audiophile manufacturers because they have focused on the mass market.  But, just because their usual demographic is a substantially lower priced market segment doesn't mean they can't deliver a product with good to great performance.  Such is the case with the DX-SX1 SACD player and SM-SX1 Digital Integrated Amplifier.  

The SM-SX1 integrated amplifier seems to be picky about loads it likes to drive, and loads it doesn't like to drive.  I suspect there will be huge changes in the next generation of the Sharp digital products, based on what they have learned from the first ones.  The 1-bit amplifier technology is quite fascinating, and it'll be interesting to see how Sharp's lineup looks in another year or two as their mass market items move over to their 1-bit amplifier technology. My guess is that they will be dynamite.

I look forward to Sharp's 1-Bit Home Theater setup, sometime in 2002.  If improvements in digital audio technology follow Moore's Law,  we will see rapidly diminishing costs along with marked performance improvements at every price point. 

Digital technology is becoming a larger part of our systems, and with Sharp's 1-bit amplifier, the digital signal chain can be maintained all the way from the source to the speakers.  Unlike some earlier digital amplifiers, the digital amps I have experienced of late are solid contenders versus their comparably priced analog cousins.

- John Kotches - 

Associated Equipment used during review:

© Copyright 2002 Secrets of Home Theater & High Fidelity
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