Many decades ago, Sony has a big reputation in audio and video system. A guy like me who live in 90's know really well how expensive and premium Sony really was. The good sounding Sony is not without any reason; they make their reputation in audio quality far beyond any competitor was think about it. It is proven when on my hand right now, I have Sony DAS-702 ES, the first DAC built by Sony in 1985. Yes, at that era where CD hits the market, replacing the vinyl records, everyone starts to aware about this new audio technology.
Imagine where this CD technology just penetrates the market, Sony was not satisfed with the DAC built-in the most of CD player, so they start making a separate DAC unit. Especially for the marked with ES logo that have the meaning Elevated Standard, or above the standard, built by cost-no-object in the Sony engineering division.
Let's take a look!
I have this unit in the pristine condition; I can consider this is just like a new unit. Consider the size and weight of this DAC unit alone is big enough with more than 10 kilos, I can assume that whoever owned this unit before has been handle it like his child. Maybe if it is me, I would do the same way.
This DAC cost US$1.500 in 1985 which when I recalculate with online inflation calculator, I get US$4.700 in 2026. Honestly speaking, this cost is still making sense and fair enough. We know many manufacturers put much more high price tags, but I still doubt quality and sound performance.
Back to this DAC unit, it built by all aluminum casing. The material is thick and heavy chassis that damped the electronic vibration to reduce the noise. Not the mechanical noise, but the noise that capture by the components and effecting the sound quality. We know that this weight is now applied to all high-end audio electronic as well.
Since this DAC was built in the first era of digital audio, so I can only see two selectable SPDIF input via coaxial RCA plugs. No USB, no optical Toslink, no any others digital input available. This is also making sense since at that era, the only wide available digital input is this SPDIF and it was also developed by SONY and Philips.
For me, SPDIF is the only digital purist signal outperforming optical Toslink and USB. Except I2s which more direct and not widely available for consumer market yet until now. Thankfully my audio ecosystem was built by this SPDIF digital input with all my music collection in CDs are transferred to WAV files.
When looking deeper into this DAC unit, I amazed on how this 40 plus year unit design still looking fantastic and far from outdated. The design is everlasting and the function is simply for sound quality.
No gimmick at all.
At the front facia, from the left side to the right side, this DAC unit has power switch by a push button and a 6.35 mm headphone jack is available at the bottom of this power switch. This allows you to connect the headphones directly to this DAC unit.
The front center display is basic large square LED indicator that shows the digital input present, indicate by on-air logo. The next to it is the sampling frequency detected which only at 32 kHz, 44.1 kHz and 48 kHz. This DAC unit is stereo 16-bit, so in-line with said sampling frequency that can be process with this DAC.
The far right there are two rotary knobs, on above is the 2-position digital input selector which selected from digital input-1 or digital input-2. Bellow that switch is a volume control for headphone output level.
I always curious about what inside this unit. So, I open up by removing all the hex-screws on top of this unit. Again, the top cover is thick aluminum plate and it damped with rubber material. This for sure to reduce chassis vibration that they believe effecting to the sound quality.
Inside this DAC unit is full of high-quality components. The first things that I notice is the big toroidal transformer. This to provide high current and clean power supply the DAC components. Remember that all DAC requires clean power supply, and Sony was starting this by put this giant toroidal transformer at the first placed.
Going to the PCB inside the chassis, the main PCB in the center is the DAC circuitry. The half size of it is for the regulated power supply circuitry. Many big capacitors seen inside, all of them are Elna Cerafine, the capacitor manufacture that specialized in high-quality capacitor for music.
The half of the others main PCB is for the analog section which also takes a lot of spaces. In this DAC unit, the converter and buffer was configure by few op-amps. This is a common configuration for DAC when using op-amps as transimpedance for IV converter, LPF and buffer stages. This to assure for the voltage compliance for the DAC IC is within zero ohm, where this condition is ideal for the DAC IC itself.
The DAC itself took small portion in the PCB. The DAC ICs is 2x PCM53, placed on top of the PCB.
The PCM53 is 16-bit DAC, manufactured by Burr-brown, long before the Texas Instrument acquisition. This PCM53 DAC is only accepting parallel signal input, meaning each of the bit are feed independently by serial to parallel IC converter. This method is really old which far from newer vintage multibit DAC that accepting a simple serial input.
The components layout is placed neatly, symmetrically and aligned for both channels.
At the far right is where the digital input is process to feed to the PCM53 DAC is covered with metal, this for protecting the digital components inside from the noise that coming from other DAC section such as power supply and analog stages.
I am not sure if you are noticing the components use in this DAC, especially for the resistors are high-quality resistors that are not widely available in the market. I think they are made special for Sony high-end product like this DAC unit. If you look more closely, almost all components use in this unit are high quality as well.
The PCM53 DAC IC is an old technology DAC.
This is the brief.
It is 16 bit DAC, which I always said that this is more than enough to listen to the music in high resolution. But this old DAC technology is use parallel digital input (which I was mentioned earlier), it is more complicated to adding additional stages outside the DAC ICs for the conversion from the serial data input to comply to the parallel DAC bits input.
PCM53 DAC IC also use sample-and-hold circuitry at the analog output. This to avoid deglitching noise which is occurs when the data changed from one music track to another. This circuitry just like a muting circuit to hold the DAC until is settled before pass the data correctly. By using this sample-and-hold circuitry, the audio output from this DAC is free from any high frequency noise coming from the digital section. Since this circuity use relay component, so in every track change, there always mechanical relay clicks sound heard from the unit.
Today DAC didn't use this sample-and-hold circuitry anymore. It is starting from PCM56 DAC and above.
Now I want to know is how well the sound of this Sony DAS-702 ES in my audio system.
Remember this DAC unit is parts of the high-end audio that came in 1985 to pursuit best possible sound quality, and Sony didn't make any mistake at all when they offer this DAC into the market.
I am amazed on how fluid the music!
The sound of these early R-2R multi-bit DACs is just like having a "flesh and blood" realism, a deep three-dimensional soundstage, and a punchy, organic bass. The organic bass is not only deep, but if I heard the string bass played in the music, it likes the sound of the attack of the strings presenting real. The start and finish from every music instrument that have attack and bass presenting deep and direct.
This DAC can capture every music detail without any harsh and overly transparency. The detail is more in the mid-range, in the vocals where the singers and the instruments plays. This is without a feeling for any dark presentation or dull. This DAC is very open and holographic presentation without ear fatigue when listen for hours.
This DAC is an absolute legend in audio history—it was the world’s very first standalone consumer DAC that released in 1985 but with the sound that still the best until now. I will assure this DAC will never win for the measurement contest, but for the best sound quality for human to hear, it is the best DAC that I've ever heard!
Disclaimer: Any statement and photos in this article are not allowed to copy or publish without written permission from the writer. Any injury or loss from following tips in this article is not under writer responsibility.
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