Review: Berkeley Audio Alpha USB

amirm

Banned
Apr 2, 2010
15,813
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Seattle, WA
OK, at long last, here is my review of the Berkeley Audio Design Alpha USB adapter. For people not familiar with this class product, this is a box that acts an external sound card. Its input is USB which means it nicely works with desktops and notebooks. The output is digital audio. In this case, the box supports both S/PDIF in the form of Coax BNC connector and AES/EBU which is a balanced audio output using XLR connections. You would connect this device to your favorite DAC, bringing it to the modern age of PC based music servers.



The other key differentiator here is the asynchronous interface to the PC. Instead of extracting its output clock from USB bus with its inherent instability, the machine turns the PC/Mac into a data pump, reading pure data with no sense of timing. The audio samples are stored in memory and then “clocked” out using a precision, custom oscillator (and other goodies they don’t let me talk about :) ). In addition, there is electrical isolation between the PC and digital audio outputs eliminating ground loops and noise from being transmitted through to the DAC.



The reason we do all of this is that when it is all said and done, we need a clean clock signal and power supply to convert our digital audio samples to analog. Better hygiene upstream goes a long way toward improving the performance of DACs. Paradoxically, even high-end DACs benefit from better interfaces. The only time I have seen no benefit was in a low end processor.

The Berkeley is a rather small box but it is big enough to have a power supply built in which is nice. And just heavy enough to support the cables connecting to it. In some way I wish it was the size of a normal Audio equipment (e.g. the Alpha DAC).

With that introduction, let’s get into what it sounds like. But first, a couple of important notes:

Note 1: This is a purely subjective review. It is entirely possible that my conclusions are wrong. Certainly the power of placebo is far higher than the small differences I hear. In my short testing, and the way these devices work, it is hard to set up the type of objective tests I like to have to reduce the effects of bias.

Note 2: My company carries the Berkeley audio products and in previous life, I acquired Pacific Microsonics/HDCD which was founded by the same people behind this product.

My test set up was the following:
1. Desktop PC with an SSD boot drive. Music on hard disk. Played using Windows Media Player. Control panel set to 24-bit, 44.1Khz for all devices for CD material. I find that 24-bit setting eliminates a lot if issues with Windows audio pipeline as the dither added is below the 16-bit audio samples.

For 24-bit material, I had 96 KHz samples I had saved from old days of Audio DVDs (not to be mistaken with DVD-A) which lacked encryption and hence were easy to rip. I set the control panel for all devices to 24-bit/96Khz to assure no resampling.

2. I had three connections on hand: Toslink out of the PC motherboard. Audiophilleo2 Asynch USB adapter (the one without the display). And Berkeley Alpha USB adapter. The latter connected using generic/random USB cables.

3. The DAC was my old friend, the Mark Levinson No360S. This is nice unit in that it has every kind of input. This allowed me to hook up the Audiophilleo using BNC connection, the Alpha with AES/EBU and the optical using that input.

4. The output of the ML DAC went into another old standby, a Rotel pre-amp. This gave me analog volume control so that I could set the volume control to max for all devices and player to 100%.

5. The output of the Rotel drove my NHT monitor speakers and sub. This is my home workstation setup which is where I was testing tonight. At some point I will also test in the office with the ML amplifiers, Revel speakers and Berkeley DAC.

Switching between connections involved having the sound control panel open and making the device I wanted to hear the default while WMP was playing and then switching the input on the DAC. This meant a 3-4 second gap. Pretty annoying and likely reduced my ability to here differences by a good bit. It also made the testing long and tedious.

This presented a good scenario. If all works as in the theory, the toslink should be the lowest performing, followed by Audiphilleo and then the Berkeley. Well, that is not how it went. At least not initially.

I played track after track. And while the toslink would often end last, in most tracks the Audiophilleo beat the Berkeley. I went through a ton of material and I would either hear little to no difference between devices or the Audiophilleo would win. I even ripped out the audio system and put in my Stax headphone system and still no cigar.

I was almost going to come and report everything as such and then I realized something. I had used an audio cable for AES/EBU connection. I swapped that out with an AES/EBU cable and I was taken back by the difference it made. It completely reversed the roles of the Audiophilleo and Berkeley with the latter always sounding better when there was a difference.

Reason for the difference in performance is that the asynch interface cleans up the PC interface but you are still stuck with this ill designed interface on the output, even in its pro version. Waveform distortion caused by cable mismatch impedance results in increased jitter feeding the DAC.

What did I hear? First, on many tracks nothing. As I mentioned, on a lot of material the difference is either not there or if it is, it is too small to rely on it existing in such an ad-hoc test. Where it did surface, it was predictable. The high frequencies were slightly cleaner. And ambiance and decay more pronounced which impacts the perceived soundstage of music/instruments. I hate to use this word but I can’t think of any other to way that the overall experience was more “analog like” in the sense of it sounding more pleasant.

I found the difference easiest to hear on my audiophile A-DVD 24-bit, 96 Khz tracks. Perhaps due to higher sampling rate, jitter reduction matters more. Or else, these are just better recordings so the difference is easier to hear.

For the objectivists in the crowd, the difference was never night and day. All three interfaces were dynamic, and were enjoyable to listen. The Berkeley and Audiophilleo simply added a bit more fidelity on top. It is like putting some pepper on a good stake :).

My general opinion is that these devices improve the performance of any DAC you already have, even if it is a low end one in an AVR. They perform a nice function of providing a digital audio interface for your PC. They cost a few dollars, but in the grand business of high-end audio, they are a reasonable way to tweak your system.

So if you have the cash, by all means go with the Berkeley. It retails for $1,895. The Audiophilleo2 I tested goes for $579. The Audiophilleo1 which has a nice little jitter simulator and such, costs $949.
 

Orb

New Member
Sep 8, 2010
3,010
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Thanks Amir,
definitely an interesting product and maybe one day they will decide to develop the product for markets such as the UK, bah :)

Cheers
Orb
 

amirm

Banned
Apr 2, 2010
15,813
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0
Seattle, WA
Thanks Orb. Their DAC had a version for EU. I assume this one does too. For now, this thing uses very little power so an outboard transformer should provide the right voltage and be good to go if you want to import it from here.
 

microstrip

VIP/Donor
May 30, 2010
20,702
4,590
1,840
Portugal
Thanks Orb. Their DAC had a version for EU. I assume this one does too. For now, this thing uses very little power so an outboard transformer should provide the right voltage and be good to go if you want to import it from here.

Unless they have recently certified the DAC to get the CE label, it is not possible to get it in EU. I tried to get one some time ago and the only way was getting it from Switzerland. But is is a dangerous process - if anytime you have to ship it for service or upgrade it can be seized by customs.
As far as I can see your unit also does not have the letters CE in the back.

Anyway many thanks for the review - can you tell us what were the XLR audio and digital cables yo used in the test?
 

amirm

Banned
Apr 2, 2010
15,813
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0
Seattle, WA
The XLR audio cables are the ones I got for my Audio Precision analyzer. They are thin gauge wires so nothing fancy at all. The unbalanced cables from DAC to pre-amp were Transparent MusicLink Plus.

The Audiophilleo was direct connected to the DAC's BNC input with a coupler so no cable there. I don't recall the brand and origins of the AES/EBU cable for the Berkeley ouput. It is a thick gauge coax cable.

All USB cables were random ones I had on hand.
 

Tam Lin

Well-Known Member
Mar 20, 2011
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Looks like a typical 'audiophile' product fitted with components of dubious value but look 'techie' to appeal to know-nothing audio snobs. Does anyone else see the problem?
 

amirm

Banned
Apr 2, 2010
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Seattle, WA
Looks like a typical 'audiophile' product fitted with components of dubious value but look 'techie' to appeal to know-nothing audio snobs. Does anyone else see the problem?
I hope the "know nothing" excludes present company :). Just in case not :) :), what do you think is dubious about this approach?
 

Steve Williams

Site Founder, Site Owner, Administrator
I hope the "know nothing" excludes present company :). Just in case not :) :), what do you think is dubious about this approach?


I agree as we already are seeing threads regarding PD's USB-x as well as many other bridges on this website alone
 

Tam Lin

Well-Known Member
Mar 20, 2011
91
31
923
I hope the "know nothing" excludes present company :). Just in case not :) :), what do you think is dubious about this approach?
Didn’t you notice the **** floating in the punch bowl? That’s a 50-ohm BNC on the back of the box. The S/PDIF spec calls for an electrical connection with a 75-ohm impedance. That spec can only be met when the cable and connectors are all 75-ohms. A 50-ohm BNC is electrically equivalent to a RCA jack.

Why would a company like Berkeley Audio do such a thing? Perhaps they’re ignorant of basic component engineering. If so, I wonder how many more ***** are inside the box. Perhaps they intentionally choose a 50-ohm BNC to save money (50-ohm BNCs are less expensive) and are counting on their customers not knowing difference. How many audiophiles think BNCs are superior to RCAs for digital audio applications? I suspect a DAC or other digital audio box with BNCs can command a higher price than one with RCAs.

Either the electrical and mechanical properties of an S/PDIF connection make a difference to the sound or they don’t. Either use the proper connector, a 75-ohm BNC, or use the most common connector, a RCA jack. For S/PDIF, a 50-ohm BNC is neither proper nor common.
 

RBFC

WBF Founding Member
Apr 20, 2010
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Albuquerque, NM
www.fightingconcepts.com
Let's please be cordial in our posting. You can say the same thing in two different ways. One way, nobody wants to read any more from you. The other way, an obviously knowledgeable post is appreciated and causes forum readers to pay attention to what you have to say. Doesn't seem to be much of a choice, considering you're spending the time writing the posts!

Lee
 

Steve Williams

Site Founder, Site Owner, Administrator
Didn’t you notice the **** floating in the punch bowl? That’s a 50-ohm BNC on the back of the box. The S/PDIF spec calls for an electrical connection with a 75-ohm impedance. That spec can only be met when the cable and connectors are all 75-ohms. A 50-ohm BNC is electrically equivalent to a RCA jack.

Why would a company like Berkeley Audio do such a thing? Perhaps they’re ignorant of basic component engineering. If so, I wonder how many more ***** are inside the box. Perhaps they intentionally choose a 50-ohm BNC to save money (50-ohm BNCs are less expensive) and are counting on their customers not knowing difference. How many audiophiles think BNCs are superior to RCAs for digital audio applications? I suspect a DAC or other digital audio box with BNCs can command a higher price than one with RCAs.

Either the electrical and mechanical properties of an S/PDIF connection make a difference to the sound or they don’t. Either use the proper connector, a 75-ohm BNC, or use the most common connector, a RCA jack. For S/PDIF, a 50-ohm BNC is neither proper nor common.

Let's please be cordial in our posting. You can say the same thing in two different ways. One way, nobody wants to read any more from you. The other way, an obviously knowledgeable post is appreciated and causes forum readers to pay attention to what you have to say. Doesn't seem to be much of a choice, considering you're spending the time writing the posts!

Lee

I'll go one further and tell Tam that his manner of posting is somewhat inflammatory and I have laundered his post
 

amirm

Banned
Apr 2, 2010
15,813
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Seattle, WA
Didn’t you notice the **** floating in the punch bowl? That’s a 50-ohm BNC on the back of the box. The S/PDIF spec calls for an electrical connection with a 75-ohm impedance. That spec can only be met when the cable and connectors are all 75-ohms. A 50-ohm BNC is electrically equivalent to a RCA jack.
The Bomar BNC connector used on Berkeley is indeed 75 ohm. 50 Ohm version has much thicker insulation. Here is a picture that shows the inside pin for a similar part (can't find a picture that shows the center pin otherwise): http://www.alliedelec.com/search/productdetail.aspx?SKU=2022009



And part description: "CONNECTOR, RF COAXIAL, DUAL BNC RIGHT ANGLE PCB JACK, METAL, 75 OHM"

To be sure, I just checked with Berkeley folks and they confirmed the same.

Why would a company like Berkeley Audio do such a thing? Perhaps they’re ignorant of basic component engineering.
In an earlier post you said you were a software engineer. When did you acquire your hardware expertise enough to know from a slant and small picture of a connector that it is 50 ohm?:confused:

If so, I wonder how many more ***** are inside the box.
You don't need to wonder. And we certainly could do without the innuendo.

Perhaps they intentionally choose a 50-ohm BNC to save money (50-ohm BNCs are less expensive) and are counting on their customers not knowing difference.
Oh I am sure :(.

How many audiophiles think BNCs are superior to RCAs for digital audio applications? I suspect a DAC or other digital audio box with BNCs can command a higher price than one with RCAs.
We have had extensive discussions on this topic in this forum. So people reading this forum know the advantages. As to higher price, I don't think that would do that. Addition of AES/EBU does however and I was happy to see that on the Berkeley which I used for my testing.

Either the electrical and mechanical properties of an S/PDIF connection make a difference to the sound or they don’t. Either use the proper connector, a 75-ohm BNC, or use the most common connector, a RCA jack. For S/PDIF, a 50-ohm BNC is neither proper nor common.
So was this your sum total of objections here? A mistaken assumption about the impedance of the jack?
 

Orb

New Member
Sep 8, 2010
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Maybe Tam saw the BNC and assumed all BNC are 50-ohm *shrug*, no excuse for the way the post is constructed though.
And yeah I appreciate it can be 50 or 75-ohm, only way to know for sure is to test the interface (if one does not know the part - thanks for sharing the Berkeley component Amir), but seems to me doing even a quick check shows Berkeley used 75-ohm.

Just to add, a lot of established engineers feel (have stated on various forums) BNC is superior to RCA or that it is more ideal, so not sure what Tam is suggesting.
Cheers
Orb
 

amirm

Banned
Apr 2, 2010
15,813
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Seattle, WA
Thanks Orb :).

The Berkeley folks were kind enough to send me close ups of their connector and the 50 ohm version of the same:



As you can see the 50 ohm to the right has much thicker insulation as they typically do. And in an ironic twist, they tell me that the 50 ohm is actually more expensive from this manufacturer! So much for conspiracy theories on this front.

Probably more important is their responsiveness over the weekend to answer this question.
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
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Looks like a typical 'audiophile' product fitted with components of dubious value but look 'techie' to appeal to know-nothing audio snobs. Does anyone else see the problem?

?? I don't even know what the "problem" is so therefore I can't see it.
 

amirm

Banned
Apr 2, 2010
15,813
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0
Seattle, WA
50-ohm on the left, 75-ohm on the right.
I hope you didn't post that to say that all 75 ohm connectors lack insulation on the center pin. Plenty do. It is up to the manufacturer's material science engineers to achieve 75 ohm impedance. How they get there is up to them.

Here are more examples of 75 ohm BNC connectors with insulation:

Molex: http://parts.digikey.com/1/parts/360150-conn-jack-bnc-r-a-75-ohm-pcb-au-73101-0570.html


In the spec sheet: Impedance 75 Ohm

Amphenol: http://octopart.com/b6252hb-npp3g-75t-amphenol-3723600

From spec sheet: Impedance:75ohm

Not they typical BNC connector but similar use:


The picture you posted from audioasylum does not equate proof point that no other variations exist. You can only conclude that the 50 ohm version happens to have thicker insulation. I hope we both agree that you don't become an RF designer reading audio forum posts :). And by the same token, the little knowledge gained that way cannot be used to throw rocks at the other side, claiming they know too little!
 

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