# Help me decide if I really need a DAC?



## Guest (Aug 24, 2006)

Ah!! the audio bug might be biting again. My present 2 channel system consists of: A Conrad Johnson PV14L tube preamp, Van Alstine OmegaStar440EX amp, Consonance CD120 upsampling CD player, & AAD 2001 monitors. Now don't get me wrong, I really do like the way my system sounds, but it's just been buging me about this DAC issue. Do you think a DAC would benefit me & in what way? What are your experiences? What DAC's have you used & how did they perform? My budget is maxed out at $1800. Hopefully your info will allow me to make an educated decision.


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## Sonnie (Apr 11, 2006)

Well I am absolutely dumb when it comes to DAC's. Being an HT guy I figure I've never needed any outboard processing. I do remember doing some research on them years ago when they seem to be so popular, but I kinda thought they were a thing of the past.

I'm thinkin' we'll have some guys that can help you with this though.


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## JCD (Apr 20, 2006)

My response it going to be pretty similar to Sonnies. My personal opinion, based purely on hearsay and personal bias, is that just about any DAC from your $250 receiver to your over the top $55,000 exotic hand made DAC are going to sound the same. 

But, again, I don't have any first hand experience, just my own readings and prejudices. :devil: 

JCD


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## brucek (Apr 11, 2006)

> about any DAC from your $250 receiver to your over the top $55,000 exotic hand made DAC are going to sound the same.


Oh my... I will have to disagree with you on that... hehe addle: 

The differing available DACing methods (PLL, FIFO, Delta-Sigma, ladder, synchronous, asynchronous, etc) and qualities of DAC circuitry with regard to clocking and the newer asynchronous re-clocking, jitter time variance reduction, upsampling (asynchronous sample rate conversion), interpolation, oversampling, harmonic distortion (THD+N), etc, results in a huge disparity in sound qualities.

There are some exceptional DACs on the market for reasonable prices. 
I always seem to hear about the  Benchmark DAC1 at a good pricepoint, but have no experience with it.

Personally, I simply don't feel that you can beat the analog output of a quality CD player if you have a proper analog bypass or dedicated analog stereo system. All the issues associated with external DAC systems can be reduced to a single problem - jitter. Jitter is a time based error that occurs between the clock we use to get the data off the disk in a CD transport and the clock used in the DAC system. In the simple CD player we use the identical master clock for these two functions and so in this 'synchronous system' jitter isn't a concern. The master clock that is in charge of getting the data off the disk is also used by the CD players internal DAC...... 

Jitter isn't really a problem that is determined by how accurate you pull the data from a disc. In a stand alone CD player you use the same clock to get the data off the disk as you do to clock the oversampler, the D to A converter and the sample and hold circuit, etc. Now indeed, this clock is divided and multiplied to obtain the correct rate, but the fact is this 'synchronous' system is nearly jitter free. 

It doesn't matter how well you clock the data from the disc and assemble it into the correct format to transmit it out the SPDIF interface, you will have an embedded clock that must be re-created by various means to take care of the D to A process in another external circuit. Errors will be present in this re-created clock no matter what method is used unless you connect a second cable between the transport and DAC with the original clock. This would work beautifully, but correct me if I'm wrong, if you put all this in a single box, could we call it a CD player?

The player is the best possible situation, and in that regard, if the DAC and analog output circuitry of the player are well made (and there's the rub), then this situation will arguably beat the transport/DAC combo every time. You do require a good player though.

In the transport / DAC situation that exists when we use the digital output of a CD player, the responsibility for clocking the digital data from the CD player (whether PCM or AC-3 or DTS) is that of the SPDIF transmission format. The SPDIF format combines the data from the disk and the CD players clock using a method called biphase-mark encoding. The clock (in a conventional DAC) is then recovered by the sampling and DAC circuitry. 

This recovered clock is then used to clock the DAC. Unfortunately, since the timing of the bits for DAC clocking is determined by the zero-crossing point of the signal, then any distortions can introduce jitter. It's a very real problem - not to be underestimated. No amount of buffering and reclocking will solve the problem that the recovered clock has jitter and is 'asynchronous' with respect to the transports master clock. There will always be some jitter irregardless of the jitter reducers used.. 

This time-base error is up for debate whether it's audible or not though. Can you hear the effects of jitter - maybe. Personally, I think so, and there's lots of anecdotal data to support it. 

My suggestion is to get a good player and a good bypass or analog system.

brucek


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## JCD (Apr 20, 2006)

This is kind of cool.. I have to admit that my prejudices have kept me from even considering an external DAC in the past, so a lot of this is new (and interesting) to me as well.

There is one quote that I'd like to follow up on:


> Personally, I simply don't feel that you can beat the analog output of a quality CD player if you have a proper analog bypass or dedicated analog stereo system.


My original statement said something to the same effect as that -- well close at least. Exchange _CD _player for _Receiver _and I THINK we're saying the same thing. 

Also, I hope SteveCallas chimes in -- he did an A/B test with different components testing their respective DAC's on another forum (can't remember which). As I recall, he tested inexpensive recievers through reasonably priced separates with the end result that he thought there wasn't a "real" (bad word, can't think of a better one) difference between the units. I can't remember the details of the test (hence the reason I hope Steve chimes in), so we might not be talking apples to apples here.

In any case, great info and hopefully helpful for our fellow shackster pearsall001.

JCD


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## Phil M (Apr 19, 2006)

I don't know your CD player Phil, the only contribution I can make is when I added the Musical Fidelity X-DAC3 to a Sony 777ES (CD, SACD) player, and it made a significant improvement - more detail and tighter bass.

The Benchmark has good reviews, here's a link to a recent review:

http://www.stereophile.com/digitalsourcereviews/886/

I would try and get a DAC on demo for a few weeks before investing any $$$$$.


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## khellandros66 (Jun 7, 2006)

Take a look at the dCS Elgar and something like the Musical Fidelity, Dan Wrights mods etc. These are all pieces I have had the pleasure of experiencing and will say that I am more then impressed with any of the above.

~Bob


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## lcaillo (May 2, 2006)

What is it that accounts for the improvements in sound?


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## Pupton (Jul 15, 2006)

Wow, this is very interesting thread!



> Jitter is a time based error that occurs between the clock we use to get the data off the disk in a CD transport and the clock used in the DAC system.


Bruce, would the same logic apply with a DVD player to HT Processor? Would it make sense to have a DVD player with DD/DTS/etc processing built in? So the DVD player would do the conversion using it's internal clock, then run analog to a "HT pre"... just curious... and if so, does something like this exist?



Regards,

Mike


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## khellandros66 (Jun 7, 2006)

Monarchy Audio still sells/makes there Low Jitter Master Clock/Upsampler, which works with DVDs and CDs alike. 

~Bob


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## brucek (Apr 11, 2006)

> Would it make sense to have a DVD player with DD/DTS/etc processing built in?


Nope. The end-game effect of a timebase error is in minute distortions to the final analog signal. Timebase error of this nature is not severe enough to modify the *digital value *(bit errors) of the signal. Jitter is only a concern when listening to music - not explosions. 

brucek


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## Pupton (Jul 15, 2006)

Cool. Thanks for the feedback.


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## Guest (Sep 8, 2006)

I'm still on the fence on the DAC issue. I am using a Musical Fidelity A3.5 Int Amp and was using a Marantz DV9500 DVD/CD/SACD player double bi-wired AQ CV-4 DBS into a pair of Tannoy Saturn S10 towers. I was really happy with the sound. I came across a deal I couldn't pass up....Musical Fidelity X-DAC V.3, X-PSU V.3 power supply, X-10 V.3 tube buffer, AudioQuest Coral interconnects, AudioQuest Optilink 3, and AudioQuest power cord in brand new condition for $800....about a $2200 value.

I noticed a little difference, but not the "Ahh" difference I was hoping for. I bought a Sony DVD player as a transport and did a A/B comparison between the Marantz and the Sony and could tell no difference, so I sold the Marantz. 

I think (just my opinion) that the results from a DAC had to be kept in proportion to what kind of deck you were originally using, i.e coming from a nice transport deck like the Marantz 24/192 to a 3-pack Dac like I bought is not as noticable as if you started with a ****** cd player.

I'm still glad I bought the DAC 3-pack because I plan to build a music server out of a spare computer and using an external sound card into the DAC "should" make a big difference.

Anybody with experience building a music server......I could use some advise.

Mark


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## Otto (May 18, 2006)

Marks57 said:


> Anybody with experience building a music server......I could use some advise.
> Mark



Hi Mark,

I posted some info about my music server on the PC forum. You can check it out here.

Lemme know what you think.


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## dknightd (Sep 17, 2006)

My experience has been that an external DAC can make a difference. Sometimes good, sometimes bad. Usually small. You can try a benchmark dac1 for 30 days. For me it was worth buying (but I use a computer - mac g5 - as a transport, so YMMV). From what I've heard you have to go lots up in dollars spent to get a better source. Could be your CD player is better. Only one way to find out, that is try it for yourself.


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