HifiZine
The enthusiast's audio webzine

The Audio-GD NFB-7 DAC

Digital is a strange thing in the audio world, and the topic of many heated conversations between anyone with a pair of ears and an interest in audio reproduction. Simplistically, as a digital information stream is just a string of ones and zeros, many an electrical engineer and audiophile alike will tell you that ones and zeros are always bit-perfect, and that a stream of information is exactly the same on both ends of the audio equipment chain. This is true in theory, but I also cannot discount my ears and the fact that I can hear differences in digital equipment. Having studied science in college and having a very scientific mind, I follow the science and technology involved with audio equipment and electrical circuits, but I also cannot neglect the unimaginable complexity of hearing and the human ear.

The Audio-GD (Audio Global Delivery) NFB-7 Digital Analog Converter piqued my interest as a DAC because it uses the Sabre32 ES9018 chip. (The “NFB” in the name stands for “no feedback,” referring to the circuit topology of the analog output stages.) This is one of the newer DAC chips on the market, and has been receiving good reviews in a number of different pieces of equipment. Obviously, sound quality is the most important aspect of audio reproduction for me, and I was interested to see how this piece of equipment sorted out those ones and zeros.

Audio-GD is relatively new to the audio world, but has a well-studied mind at the helm of their ship, with all components being designed and developed under the leadership of Mr. He Qinghua (Kingwa). Audio-GD has created a number of products in their years, including DACs, headphone amps, integrated amps, monoblock amps, preamps, CD players, and most recently a USB digital interface. As impressive of a product line-up as that list is, what is even more impressive is that Kingwa and his crew hand-build every unit to order, followed by 100 hours of testing and burn-in before the unit gets shipped. Now that is commitment to quality.

Audio-GD products utilize a technology that they call ACSS (Audio-GD Current Signal System), which is Audio-GD’s system for transmitting audio signals. This concept, first seen in 1966, has been used for many years, and since 2006, Audio-GD has evolved the technology to include all audio signals in their systems, from the digital source to the power amplifier. If craftsmanship and innovation are on your list as key ingredients for an audio company, Audio-GD may be up your alley.

When I unpacked the NFB-7 DAC, I was amazed by how heavy it was. I have owned and reviewed a number of DACs in the past, and none was larger or heavier than the Audio-GD. At 17″ x 17″ x 4″ and 35 lbs, the NFB-7 is neither small nor light. It looks the part as a serious piece of audio equipment, yet with a fairly simple yet functional look. The front of the unit has just three items: the power button, input selection knob, and the input readout display. The rear of the unit has a standard IEC power connector, XLR, BNC/RCA, RCA, and TOSLINK digital inputs, and XLR, RCA, and ACSS analog outputs.

Under the hood, the DAC is very nicely appointed and laid out, with three R-Core transformers to power everything, and separate digital input and right/left analog output boards loaded with parts with names such as Vishay, DALE, WIMA, NOVER, WBT, Solen, Toshiba, and Hitachi. Not only does Audio-GD use quality parts, but all parts are matched, including transistors.

Now you may ask yourself, “Why do you need a DAC and circuit using the tiny Sabre32 chip to be so big, when I’ve seen DACs that use the same chip one-quarter of the physical size?” After all, everyone prefers smaller electronics, and saving space is good – sometimes it is just not obvious what the designer is trying to accomplish. The reality of electronics life is that, while new DAC chips are very small, many of them – including the Sabre32 – require large and elaborate circuits to maximize the aural benefits of the chip. Can a smaller circuit be designed? Always. But as with all hifi equipment, it’s not the size that counts, but how it sounds.

After running though all the usual preliminary tests to ensure that the NFB-7 DAC was working correctly, I turned on some pink noise and let it burn in for a while. I do not have a hard and fast rule when it comes to burn-in times, as every piece of equipment varies, but my base burn-in time is usually 100 hours. After the allotted time had passed, I sat down to listen to my trusty system through the digital lens of the NFB-7.

Popping on Retrospective by Rebecca Pidgeon, the first thing that I noticed was the increased clarity of space over the Matrix mini-i. Whether it was the Sabre32 chip or the surrounding circuits that were kissing my ears, I loved the clarity and detail that flowed so easily out of the NFB-7. Starting off her album with “Spanish Harlem,” it was very easy to hear the echo of the recording studio, as well as the distant maracas that accompany her half-way through the song. Every instrument and voice sounded live and fleshy, with plenty of air and distance between the entire company. Switching to “Texas Rangers,” the body and clarity of her voice and the recording was reinforced. Rebecca’s lone voice with the pluck of a country guitar produced a perfect combination that conveyed the emotion of her story.

I was originally a little worried by the disclaimer on the NFB-7 page:

The DAC NFB-7 has extremely high fidelity; its sound signature is neutral. It can show you how good or how bad a recording is. If you are looking for a DAC which can always deliver quite warm or tube sound, the NFB-7 is maybe not your cup of tea; maybe the NFB-8 will be better. If you use the NFB-7 with a low-grade amp, you can’t experience the performance of NFB-7 and it maybe a waste of money.

I was not worried however that I did not have a sufficiently high-enough fidelity amplifier, but that the neutral signature and transparency of the DAC might be a little too much of a good thing with similarly-voiced horn speakers. However, and to my joy, I was wrong – the NFB-7 provided even more clarity and detail though my horns than I had previously heard on the system!

The other great attribute of the Audio-GD NFB-7 is its ability to impart texture to recordings. Switching over to the album Ella and Louis, I was not only overcome with detail as I had been before, but the texture of both of their voices on this recording stood out so much more than it had with Rebecca Pidgeon. As “Cheek to Cheek” played through, it not only seems like Louis was sitting on my component stand, but I felt like I could reach out and tap the snare drum behind him. And by the time Ella threw her voice into the song, the sound was smooth and silky with a nicely brassy trumpet backing her up.

As I slumped back into the couch, I realized that this listening session was just about perfect. Between the great level of detail present in the music, to the body of all the instruments and singers, the NFB-7 bested the Matrix mini-i DAC in leaps and bounds. Its sound in its entirety was refined, precise, and intentional – but also natural enough to make you believe you weren’t listening to a calculator. The ability of a DAC to turn ones and zeros into music still impresses me – not only does each sound different, but they present the music differently. But I would warn anyone looking for a digital upgrade that, even though the DAC is a digital device, not all of them have the ability to present life and realism like the NFB-7 does.

Upon almost completing this article, I learned from Kingwa that the NFB-7 and all of their Sabre32-based DACs had been discontinued. When asked why, he stated that it was lack of interest in that particular chip, coupled with them being swamped by production of their ever-popular DACs and headphone amps based on the Texas Instruments and Wolfson chips. Being such a great DAC, there was a single tear in my eye with this news, but Kingwa assured me that with enough interest, they would bring back the Sabre32-based DACs at the will of the people. This news brings me to believe that not only is Audio-GD keyed into what their customers want, but that they are always adjusting their products to produce the best audio equipment they can.

What started as ones and zeros from my source, ended as sublime sound in my ears. The Audio-GD NFB-7 transforms your digital source into an incredibly detailed and balanced music signal. Audio-GD was right when they warned on their website: “DAC NFB-7 has extremely high fidelity; its sound signature is neutral. It can show you how good or how bad a recording is.” Being a detail hound, I thrive on extreme detail and neutrality in musical presentation, and this Sabre32-based DAC does that very well.

Great sound quality is one thing, but it does not stand alone without great build quality, good component selection, and great customer service. Having never worked with Audio-GD or listened to their products previously, I was initially a little hesitant, as they are newer to the industry and have a limited number of reviews. However, I was extremely impressed with Kingwa and all of the Audio-GD staff, and their knowledge of the products as well as their prompt customer service.

Associated Equipment

• PC Music Server
• Virtue Audio Nirvana USB Cable
• Musiland 01USD USB Transport
• DH Labs D-75 Digital Coax
• Matrix mini-i Balanced DAC
• Transparent Audio MusicLink Plus RCA
• Custom KingRex T20U+PSU Amplifier
• Custom Shuguang Treasure S300MK Amplifier
• DH Labs Q-10 Signature Speaker Cable
• Klipsch Forte speakers with Jantzen Crossover and Crites Tweeters
• Monster HTS2500 Power Center

Specifications

• Maximum resolution and sample rate: 32Bit/192kHz
• Digital inputs: XLR, BNC, RCA, Toslink
• Analog outputs: XLR, RCA, ASCC
• Power : 110v 60Hz via IEC connector
• Dimensions: 17″ W x 17″ D x 4″ H
• Weight: 35 lbs
• MSRP: $1350

Manufacturer’s website

• http://www.audio-gd.com/