DAC Attack ~ Need some Schooling

Holydoc

Ok guys (and gals) bear with me while I ask some basic questions.

CDs, DVDs, MP3, etc. are media that store data in digital format. In order for the digital format to be heard, it is converted to analog using a device called a Digital-to-Analog Converter (DAC).

I am ok so far correct?

Now the DAC can be located in either the source (i.e., the DVD player, CD player, etc) or the pre-amp/receiver driving the speakers. The way you determine which DAC is to be used to convert the stored data is by how you transfer the data to the pre-amp/receiver. If you transfer the data via coax or optical (i.e. digital), the pre-amp/receiver will take the data and do the conversion via its DAC. If you transfer the data via RCA cables (i.e. analog) then the source uses its DAC to convert the data and the pre-amp/receiver are just passed through.

Is this correct?

So, if you connect your DVD, CD, etc. via a digital cable to your pre-amp/receiver, it should not matter whether you have a $10 source or a $10,000 source since the receiver is doing the conversion via its DAC. However if you are passing the data via an analog cable, then extra money should be spent on the source since it is using its own DAC.

Yell at me when I am wrong here...

So how do you determine how good a DAC you have in your pre-amp/receiver so that you make a wise decision on how to hook up your components? How do you tell how good the DAC is in your source/transport so that you know which one to purchase?

Wouldn't it be best to spend the money up front on the pre-amp/receiver to get the best DAC possible so that you could save money on the source/transport purchases?

hmm...maybe I should of went to bed at 1:30am rather than babbling.

danger boy

I usually do an A-B test.. and which ever hook up sounds better. that's the one i use. whether it be digital or analog connection. Both are worth trying out. you could be suprised by a Left and Right analog hook up. It might just sound better than a digital one.

tonyb

danger boy wrote:

I usually do an A-B test.. and which ever hook up sounds better. that's the one i use. whether it be digital or analog connection. Both are worth trying out. you could be suprised by a Left and Right analog hook up. It might just sound better than a digital one.

AGREED!! However,a transport needs to be good quality also.Jitter and other
things play a role in the end result.A stand alone out board DAC is optimal but we all can not go that route.Bottom line is always buy the best source
componant you can afford along your upgrade path.:)

Ricardo

Holydoc wrote:

Now the DAC can be located in either the source (i.e., the DVD player, CD player, etc) or the pre-amp/receiver driving the speakers. The way you determine which DAC is to be used to convert the stored data is by how you transfer the data to the pre-amp/receiver. If you transfer the data via coax or optical (i.e. digital), the pre-amp/receiver will take the data and do the conversion via its DAC. If you transfer the data via RCA cables (i.e. analog) then the source uses its DAC to convert the data and the pre-amp/receiver are just passed through.

Is this correct?

Yes....with only one comment; in many AVR's you must assign the digital input in the setup; if you don't you won't hear anything (or hear sound from analog connections if you have both).

I agree also that you should test both and see what sounds better for you, this is, for you existing components; if you are buying and want to know where to spend more, I would buy a better source and use it's DAC.

steveinaz

Yes.

Yes.

No. If audio were only so easy, because the "bits is bits" argument, while logical, doesn't pan out in real life. Transports have electronics in them as well, even though they are only transferring a digital signal. The circuit design, power supply, clocking accuracy, etc can all have an effect on the signal. I will say that you probably won't need to spend as much money on a transport if you're running a good external DAC, but you should still get a good quality transport.

I just did a comparison with a Denon DVD-2910 DVD Player ($699) and a CEC CD Player ($600) used as transports; the CEC was clearly a better CD transport. Most likely due to lower jitter and better digital output section.

PolkThug

steveinaz wrote:

; the CEC was clearly a better CD transport. Most likely due to lower jitter and better digital output section.

Except jitter isn't caused by the transport, I think you even posted an article about this a few months ago.

steveinaz

Sure it is:

http://www.stereophile.com/reference/368/

Holydoc

So there are no specs supplied to the buyer that allows them to know what DAC is being used in a transport or receiver?

So I cannot read the Specs of ComponentA's DAC and compare it to ComponentB's DAC? I only know which one will do a better job by listening to it? Uggh!

It seems I was on the right track to being able to select the best components at the most fair price without having to hunt and guess. For instance if I knew that DACxyz always sounded better than DACabc, then I could spend my money wisely knowing that I would always try to buy components with DACxyz.

This is upsetting. I know logically that there are probably not that many companies that actually make DACs. They would then take those DACs and sell them to the different stereo, cd, DVD, etc manufactorers to put in their boards. Would be nice to know which company's DAC went into which company's system. Would make my upgrade path that much easier!

steveinaz

A quick quote from the article:

"It is commonly believed that transport jitter is rejected by the input receiver and not passed to the recovered clock. Unfortunately, that's true only above a certain frequency, called the "jitter attenuation cutoff frequency." Below this cutoff frequency, the input receiver and PLL simply pass the incoming jitter to the recovered clock. The popular Crystal CS8412 chip has a jitter attenuation cutoff frequency of 25kHz, meaning that the device is transparent to transport jitter below 25kHz. (This specification is clearly stated in the CS8412's data sheet [downloadable as a PDF file---Ed.].) The input receiver essentially acts as a low-pass filter to jitter. Note that jitter energy with a frequency between DC and 40kHz produces audible degradation.

A second source of word-clock jitter is the input receiver's intrinsic jitter. Input receivers vary greatly in their intrinsic jitter, from 40 picoseconds in the UltraAnalog AES 20 input receiver, 200ps for the Crystal CS8412, up to 5000ps (5ns) in the Yamaha YM3623 chip. (The Yamaha receiver's jitter can be reduced with a few circuit tricks.)

We can quickly see that the sonically degrading word-clock jitter in a digital processor is influenced by several variables:

1) the transport's jitter;
2) S/PDIF or AES/EBU interface-induced jitter (the digital interconnect);
3) how well the digital processor's input receiver rejects transport and interface jitter;
4) the input receiver's intrinsic jitter; and
5) how well the clock is recovered and handled inside the digital processor."

steveinaz

Holydoc wrote:

So there are no specs supplied to the buyer that allows them to know what DAC is being used in a transport or receiver?

So I cannot read the Specs of ComponentA's DAC and compare it to ComponentB's DAC? I only know which one will do a better job by listening to it? Uggh!

Your equipments' manual doesn't say what type of DAC's are used?

Holydoc

steveinaz wrote:

Your equipments' manual doesn't say what type of DAC's are used?

Been looking at everything from Outlaw pre-amps, mine, and the Denons manuals. All I ever see is:

• 192 kHz 24-bit DAC’s for all channels

That does not tell me anything. That is just it capabilities and not the type of DAC.

***** Update: I found the specs for the Outlaw one in the user's manual AD1852.

steveinaz

well, the other thing to consider is that it's not just the DAC's used, but more importantly it's implementation.

Get your read on...this stuff is far too complex for me to try to **** my way through. But as recommended, your ears don't lie; listening is the easiest way to determine wether your transport or receiver has a better sounding D/A section.

Holydoc

steveinaz wrote:

well, the other thing to consider is that it's not just the DAC's used, but more importantly it's implementation.

I agree it is not just the DAC. However if you know one DAC does a better job than another, then you can eliminate some of the millions of different brands to listen to.

:cool:

steveinaz

It can be very confusing and complicated. Here's an example:

My Denon DVD-2910 sounds better using it's internal DAC's than it does when running thru my $1000 ext DAC...why? I suspect it's a combination of 2 things; 1) the Denon's digital output section is not very good; 2) The Benchmark DAC is acting like a "microscope" and showing every little flaw in the Denon's output. When the denon's lower resolution DAC's/analog section are used, the flaws are less noticable. I had the same outcome with my Polk XM tuner--it sounds better using its internal DAC's and analog section because they are lower resolution and also hide flaws. Higher resolution requires better sources.

Digital camera's are a good analogy; take a 5 megapixel camera and a 2 megapixel. If you print standard size photos from both, they'll look nearly identical---BUT, enlarge the photos, and it's a whole different story.

It's the biggest paradox in audio---the better your equipment gets, the better it has to be.

mldennison

I agree it is not just the DAC. However if you know one DAC does a better job than another, then you can eliminate some of the millions of different brands to listen to.

but is it ever really that cut and dry? if it is just another component in the system then different people are going to think different things about it, some might like dacA better and some might like dacB better.

steveinaz

Yep, listener preference will always be a factor, as it should be.

heiney9

There are so many things in the design and implementation of a well regarded DAC section. The chipset is one very small part. The key things you are getting with a stand alone DAC unit. Should contain dual da chips one for each channel, to me this is a must have. Complete isolation of one channel from the other. Seperate discrete power supplies for the analog and digital sections, along with discrete power supplies for the input and output sections which ideally should be class A. My Adcom has the input and output section transformer coupled rather than capacitor coupled, which tends to be better and more expensive. Few to no opamps in the circuit. No IC chips what so ever anywhere.

In my experience it's impossible to make a great sounding DAC section in an AVR. There's just too much going on in the reciever to do it properly. I'm a huge advocate of seperate stand alone Dac's. They don't fit everyone's situation or wallet.

This is just scratching the surface. Lot's of discussion has been done in the past by myself and others, use the search function if you haven't as it may turn up lots of interesting info.

H9

Holydoc

heiney9 wrote:

This is just scratching the surface. Lot's of discussion has been done in the past by myself and others, use the search function if you haven't as it may turn up lots of interesting info.

H9

Oh my of the reading I have been doing on this messageboard. Yes, I definitely used the search function and enjoyed all the reviews. I was just making sure that I had my thoughts in order.

I really do appreciate everyone's patience with me on these kind of questions. Slowly, I think I am getting a better grasp on what makes a system tick. Not that my system is anything to brag about yet, but it will be as I mature a bit with my knowledge of what to purchase.

heiney9

Holydoc wrote:

Oh my of the reading I have been doing on this messageboard. Yes, I definitely used the search function and enjoyed all the reviews. I was just making sure that I had my thoughts in order.

I really do appreciate everyone's patience with me on these kind of questions. Slowly, I think I am getting a better grasp on what makes a system tick. Not that my system is anything to brag about yet, but it will be as I mature a bit with my knowledge of what to purchase.

Just remember it really is a journey and it's impossible to learn it ALL at one time. Just keep plugging away and keep an open mind and you will have fun. Some things will work out really well and others won't. I've been in this hobby the better part of 25 years and still learn new things now and then.

H9

steveinaz

...just don't forget to enjoy the music, first and foremost. You can analyze this stuff to death, but in the end, trust your ears. In this hobby, you get what you pay for, there's rarely a shortcut, and "true" giant killers are few and far between.