Bryston BDA-1 External DAC

List Price $1,995

by

Ken Wong

This is a rather unusal review for Stereomojo in that it is not a world's first exclusive. This Bryston DAC has been reviewed by others, but the main reason it appears here is because we received a large number of emails asking us to review it. The same was true with the Benchmark DAC's among many others. I guess people just wanted our opinion. I also guess it does pay to write to us if you have review requests.


I haven’t been much of a digivore of late. I gave up on CDs back in the mid 90’s when upgrades were too frequent and costly to keep up. My last digital set up was a Theta Data Basic Transport and Theta Data Basic II DAC. During that time I had a Linn LP12 turntable. Linn had introduced the Lingo, Cirkus and Linto upgrades which slaked my musical appetite for years to come until the Keel upgrade became too costly. Today my analog front end is completely overhauled, but I digress.


Fast forward to today. My analog front end is based on a TW Acustic Raven One and we have digital downloads available to play back on computers. After listening a bit to a few modern DACs, I found that my evaluation software was lacking in resolution. HDTracks recently announced a free 24/96 Sampler. It was the 4th track Misery by Dave’s True Story that got me hooked. I downloaded the album Unauthorized by Dave’s True Story Chesky Records 2002, a quirky clever retro swing album with contemporary subject matter that the band members aptly describe as beat lounge. The sense of the acoustic space is well captured which I felt was sorely lacking with mid-90’s recordings as I recall. A friend suggested that I try the FIM K2 recordings. I normally don’t like Asian instrumental audiophile recordings but the resolution, bandwidth and soundstaging on the This Is K2 HD Sound! FIM Label CFIM78 was absolutely incredible.

 

Feature Set


• Dual 192K/24Bit Crystal DAC’s
• Independent dual power supplies
• Discrete Class A analog output stage
• Oversampling
• Synchronous upsampling (176.4K/192K)
• Selectable upsampling feature
• Independent analog and digital signal paths
• Inputs: USB (1), COAX (2), OPTICAL (2), AES-EBU (1) BNC (2)
• 32, 44.1, 48, 88.2, 96, 176, 192K sampling
• 16-24Bit PCM, 16Bit 32K-48K USB
• Fully differential balanced XLR and unbalanced RCA stereo outputs
• Transformer-coupled SPDIF and AES EBU digital inputs
• SPDIF COAX bypass loop output
• RS-232 software upgrade
• Optional remote control
• Remote 12-volt trigger
• Compatible with CD drives, sound cards, computers, music servers
• Cosmetically matches Bryston C-Series BP26/MPS2/BCD-1

According to Bryston, their DAC chip has some unique features. “The Bryston DAC chip we use is a hybrid multi-bit delta sigma DAC (digital to analogue converter) device. Before the digital data reaches the delta-sigma modulator, it is run through an 8x over-sampling process and digital interpolation filter. Due to the inherent over-sampling process of a delta- sigma modulator architecture, the overall interpolation ratio of the device is 128 times. Over-sampling and up-sampling have some great benefits when implemented correctly.


There is a significant diff erence between up-sampling and oversampling. Over-sampling is when the samples are repeated (2x, 4x, 8x, etc.) to create a new sampling frequency. The new samples are then generally run through an interpolation filter to create a more analog-like waveform.


Up-sampling usually refers to a mathematical process in which the new sample rate is not a multiple of the old sample rate, and the numbers have to be calculated in real-time. This is what is happening when a sample rate converter chip is in an up-convert mode. So in the BP-26 DA, if a 44.1 kHz signal is present: we up-sample to 96kHz (with the Sample Rate Converter) and then the DAC will internally 8x over-sample that signal. The great benefit of both of these methods is that it relaxes the requirements of the analog filter after the DAC. This is important because it allows designers to implement higher cutoff frequencies with slower roll-offs, which results in a phase linear circuit in the audio band.
The up-sampling method, when implemented correctly, also has the side effect of jitter reduction, since the output clock is usually asynchronous from the input clock. Another thing to note is that if the over-sampling or up-sampling processes are implemented poorly, they can actually introduce jitter. This is usually a result of poor power supply implementation.


So, in the Bryston DAC, each stage in the digital chain (input receiver > sample rate converter > digital audio converter) is independently regulated to prevent any interactions and to provide rock solid power supplies for any up-sampling/oversampling process”.


Like many designers today, Bryston recognizes that AC noise is a big problem with audio gear and perhaps no more problematic than in digital systems where electronic signals are miniscule and are easily susceptible to noise. When that tiny signal gets amplified, so does the noise, so it has to be minimized. Both the digital and analog power supplies are heavily filtered and isolated to keep noise where it belongs – on the other side of the back panel.

According to the company, each unit is hand built and tested.

What I found to be truly compelling features were Jitter Reduction circuitry, Upsampling on the fly, and the discrete Class A analog output stage. The two independent DAC chip’s used in the BDA-1 are the Crystal CS-4398.

Of jitter, Bryston has this to say: “Jitter is a mistiming of data being moved from point A to point B in any synchronous digital system. Think of jitter as individual ticks on a clock—however each tick is not occurring at exact one-second intervals. Some are slightly less than a second and some are slightly longer, and they average out so that no actual time is being gained or lost over a large number of seconds. Jitter is the difference between the shortest and the longest second, and in digital audio systems this specification is usually measured in nanoseconds. Both the frequency and the jitter characteristics of the system’s digital clock will affect the accuracy of reproduction. The frequency, if not accurate, can cause the pitch and speed of the music to change, and in some systems cause drop-outs if there is no data available.

Listening

Redbook CD playback was done with my trusty 15+ year old Theta Data Basic Transport y through Canare coaxial cable via S/PDIF. High Resolution downloads were played on my Windows Intel based pc. I used cMP, Foobar 2000 with a 12 foot Toslink cable from the next room with my high tech hole through the baseboard into my listening room connection. Contrary to what many listeners think, I am able to get superior sound quality with a pc than with a transport. Many listeners agree that Toslink adds more jitter and that coax tends to introduce RFI into the signal. Here is where I found Bryston’s Jitter Reduction to be highly effective. I could hear no discernable difference when playing back CDs through the transport via coax and the pc via Toslink a true testament to the jitter reduction scheme. I wasn’t able to test the USB port however. From my understanding the BDA-1 supports synchronous USB 1.1 which means only 48 kHz support. This may be an issue with laptop music servers.

In most cases I found the upsampling to add a greater perception of depth to the sound staging but in some cases it robbed the music of dynamics and texture. The on the fly upsampling button allows you to quickly compare and experience what’s best for that recording. Importantly, most upsampling DACs do just that – upsample - with no ability to listen to the CD at normal Redbook 16/44.1. The Bryston allows you to do that to hear exactly what the upsampling is doing to the original. A very convenient feature.

For comparison I had a Benchmark DAC-1 with a recent build date of November 2008. We have reviewed both the DAC 1 and the Dac/Pre - publisher. The BDA-1 had a sonic signature very close to the DAC-1. Both DACs have a very similar bell like purity of tone and a similiar powerful bass propulsion moving the tune forward. Both companies have an enviable reputation and loyal customer following. The Bryston’s soundstage had a more recessed presentation, the Benchmark, more ballsy, immediate and rock and roll friendly. But the Bryston adds just a touch more detail and warmth giving the music a gentler more relaxed feel. Not that the Bryston doesn’t rock, but it would rather caress than try and shock you.

For sentimental reasons, I pulled out Hell Freezes Over by The Eagles Geffen GESSD 24725. The Benchmark gives a more immediate hit. Center stage, tightly packed front row. The Bryston, a little recessed, wider, deeper soundstage, sort of a waving of cigarette lighters in the air feel. More bass slam with the Benchmark, more treble detail and warmth with the Bryston. Keep in mind that I didn’t have a USB connection to try. I suspect that the Benchmark would excel with their asynchronous USB implementation.

For hi-rez, I played back Unauthorized by Dave’s True Story. The wealth of treble detail and touch of warmth made the recording more intimate in the dark with your date rather than up front and personal with the band.

I suspect that the discrete class A analog output stage has a lot to do with the warmth and detail of the sound. By design, class A amplification eliminates notch distortion at the zero cross over point since the circuit is switched on all the time. This should result in increased low level accuracy and could also add a touch of warmth to the tonal balance. This is not necessarily a bad thing with digital. This was very apparent with female voice. Track 8 Heart of Glass by Youn Sun Nah envelopes you like a warm blanket.

One of the things I find lacking in digital playback is the ability to recreate the soundstage in the rear corners . Good quality vinyl playback is able to do this in spades. On redbook playback, the BDA-1 was able to do this as well as any DAC I have heard of late. Track 16 Canon in D of This is K2 Sound! Is a clear example of just how deep the recording space is rendered.

Tonally, the precise bell-like clarity was very apparent with Canon in D track 8 of This is K2 Sound! by The All Star Ensemble. The overtones of the bells shimmered in space in this interpretation of the Pachelbel standard. A similar effect was experienced with track 5 Touch by Christopher Hardy, this time in a cavernous acoustic space.

One important note; Bryston is famous for their 20 year warranty on the amplifiers. That is not the case with this product; the warranty is 5 years – still above the norm of high-end products and way better than the 30 or 90 days you get with midfi stuff.

So what do you get for your $1995? Clear pure tonal accuracy. Highly detailed treble. A large recessed soundstage which fills the rear corners. 8 digital inputs. Upsampling on the fly. Exceptional jitter reduction. And a touch of warmth that a well executed discrete class A output stage can deliver. In this price range, it is a must audition for those looking to upgrade their existing digital player whether it be a stand alone CD player or computer based.

Bryston, LTD.
677 Neal Drive
Petersborough, Ontario, Canada
K9J 7Y4
(705) 742-5325
www.bryston.com

Stereomojo Music Reviews CD's Jazz/Pop/Rock

 

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