basic question that bothers me

[susdujcrd]

First let me introduce myself. I'm David and I've been a reader of this wonderful site for quite a while, learned a lot from each article and review. I now wish to gain further knowledge using these informative forums and I'm sure I'll have a pleasent stay.

 

I've noticed most people here use professional soundcard, like Lynx AES16, to connect to their DAC. I understand AES/EBU is considered the best method of digital transfer however if the digital-analog conversion is done in the DAC wouldn't a simple card will suffice for delivering the bits using toslink/coax? what is the advantage of using

soundcards that can be gret DAC's themselves just for using them as a transport? Is there a hidden purpose that eludes my mind?

 

[The Computer Audiophile]

Hi David - That's a common question. A few things come to mind when I think about why I prefer the Lynx AES16 cards.

 

1. The Lynx AES16 supports all sample rates I need. Many cards do not support 24/88.2 and 24/176.4. They support 24/96 and 24/192 but I need the other rates as well.

 

2. The Lynx allows external word clock input.

 

3. The Lynx has really low jitter specs.

 

4. The Lynx supports dual wire AES that is required by some DACs I use.

 

 

[susdujcrd]

Thanks Chris for clearing that. I can understand how the added functionallity and bit rate support outweighs the price.

 

[earflappin]

Welcome to CA David and great question. I'll give you my perspective and I'm sure others will chime in as well. In no particular order....

 

- one can buy lots of different sound cards. Some have on board DAC and ADC capabilities, while others, like the Lynx AES16, just provide digital I/O. Given the noisy environment of a computer platform I would think the best sound quality is achieved with an outboard DAC. Most PC/Mac platforms will provide toslink and coax as standard outputs, as well as USB and firewire. If you want AES/EBU you need a sound card.

 

- once one decides to go with an outboard DAC the optimal interface for that DAC will vary. In some cases it will be firewire (e.g. ULN-8/Model 4), in others it will be USB and for others it will be AES/EBU. From a pure technical standpoint, many would argue that a properly designed async USB or firewire interface is superior to AES/EBU, toslink or coax. However, the final sound quality one realizes out of the DAC is a function of how the entire system has been designed - i.e. interface, processing, power supplies, etc.. For example, I could drop a Ferrari engine into a Mustang, but that wouldn't necessary improve the car's performance if every other aspect of the car has not been designed for that engine.

 

- Up until recently, AES/EBU, toslink and coax have been the defacto digital audio interfaces. However, USB and firewire digital interfaces have emerged in the past several years and USB in particular is becoming more common. Personally, I believe it will become the new defacto standard. For it to deliver optimal sound quality from the DAC, however, will require the designers to implement it properly.

 

- If you have a DAC that only accepts AES/EBU, coax and toslink inputs, it's been my experience, that without using a reclocking device in between the computer and the DAC, AES/EBU tends to produce the better sound quality. But again, this will depend on how well the DAC designer has engineered the various inputs. It is very tough to generalize in this area as there will always be exceptions. One has to ask the DAC manufacturer and/or experiment.

 

- I have a Berkeley Alpha DAC and the AES/EBU interface provides the best sound quality compared to toslink or coax. So I got a Lynx AES16 card for my silent PC server. However, subsequently, I discovered that noise and jitter from the Lynx card degrades sound quality....so....to deal with this I need to use a device in between my PC and the DAC to isolate the electrical noise and, if one want the very best sound quality, to reclock the signal. Why, well the Lynx card is designed to a price point and as good as it is, it does not provide the nth word in noise isolation and clocking. This to me, this is the weakness of AES/EBU and why USB/firewire will replace it as the defacto standard. Who wants to spend $700 for a Lynx card and then another $1-2K for a noise isolator/reclocker? I know I don't.

 

Bottom line, my advice would be to select the outboard DAC you want to build your system around based on the features you need/want and budget. Ask the manufacturer what is the best interface to use and then implement that in your computer server. Ideally, your DAC of choice will be at its best using a USB or firewire interface and you can skip having to get a sound card, noise isolator/reclocker, etc.

 

For those of us with existing investments in DAC's with only AES/EBU, toslink and coax inputs there are products on the market which will convert USB and firewire to these standards while providing noise isolation and reclocking.

 

I think my response should be clear as mud by now....time for a glass of wine....I hope it helps at least further your understanding a bit as to why there is so much discussion on this topic.

 

 

 

[susdujcrd]

earflapin, your elaborate explanation was enjoyable to read. It helped me get things into perspective. I already have my USB DAC which plays me the music the way I want to hear it, the motive behind this topic is purely educational.

 

I agree that USB is now gaining momentum throughout the industry and is becoming more common. However it is quite frustrating that a lot of companies that market DAC's that are considered high end, don't release dedicated USB drivers for their gear. Spending endless man hours on research and fine tuning a DAC should at the very least be backed up with an appropriate software. Sending the customers to an audio settings tweaking journey is just not right.

 

[earflappin]

Thanks for your comment and I agree with you entirely! I think the issue is that most of these high end DAC companies are small and since USB interfaces are new to them it has taken them a lot of time and money to integrate the USB interface into their designs. So you have learning curve issues, etc. Plus I am sure there are subtle issues to deal with on the PC/Mac side as well given how USB standards have evolved.

 

Berkeley by the way, deliberately did not elect to offer a USB interface on their Alpha DAC as they felt adding such circuitry would add noise and degrade sound quality. So their approach is to offer a second box that will do USB/AES conversion.

 

Ahh...that's what makes a good market for consumers....lots of choices. What USB DAC do you use and did you audition many DAC's before deciding on it?

 

[Suteetat]

Do you have any more information on Berkeley outboard USB/AES converter? I have been thinking of getting Weiss NT202 but if Berkeley is planning something similar, I might wait awhile and see what they have to offer.

 

[susdujcrd]

I own an Abrahamsen V6 DAC, it is a company founded by previous owner of Electrocompaniet. My system is lightyears from being audiophile level but it is still a pleasure to listen to.

 

[earflappin]

Berkeley hasn't made a formal statement, but here's what I know based on talking with them.

 

They plan to release their USB/AES converter mid this year. It will be async USB to AES and provide noise isolation. I presume, by am not sure, that it will support sample rates up to 192khz. Nothing yet on pricing that I'm aware of.

 

BTW, the new Antelope Zodiac Plus DAC should be shipping in March/April and it will provide USB and AES inputs with AES and SPDIF dejittered and reclocked outputs, as well as an integral DAC at a price of approx $2500. I'm going to try that with my Berkeley. Should be interesting.