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Six DAC Comparison

I am in the middle of comparing the sound of six different DACs in my system. I own them all (I know weird) but one of them is still within a trial/return timeframe.

Not to share specific comparisons today, but a couple of observations so far are that first, they all definitely sound different from each other. On one hand, they all sound pretty good and play what is fed to them without significant flaws but on the other hand there are definite sonic differences that make it easy to understand how a person might like the sound of some of them while not liking others.

Second, raises the observation that most of them must be doing something to shape the sound in the manner the designer intended since one of the DACs, a Benchmark DAC3 HGA, was described by John Atkinson of Stereophile as providing "state-of-the-art measured performance." In the review, JA closed the measurements section by writing, "All I can say is "Wow!" I have also owned the Tambaqui (not in my current comparison), which also measured well ("The Mola Mola Tambaqui offers state-of-the-digital-art measured performance." - JA). The Benchmark reminds me sonically of the Tambaqui, both of which are excellent sounding DACs.

My point is that if the Benchmark is providing "state-of-the-art measured performance," then one could reasonably presume that the other five DACs, which sound different from the Benchmark, do not share similar ’state-of-the-art" measurements and are doing something to subtly or not so subtly alter the sound. Whether a person likes what they hear is a different issue.

mitch2
stuartk
2,764 posts
 

@vthokie83 

QUESTION: My Jay's CDT2MKIII has an OCXO. How does such a transport affect DAC clocking ?

fuzzbutt17's avatar
fuzzbutt17
74 posts
 

@ brbrock

Sorry it took me so long to respond...I don't go on forums every day.

LC = choke + capacitor

CLC = capacitor + choke + capacitor

In a CLC they use smaller chokes than in an LC power supply.

Most power supplies in audio gear are just C (only capacitors) and have no chokes at all.

LC is better than CLC and CLC is better than just C power supplies. 

As for tube DACs...

Let me start by saying that the DACs I designed up until 2013 were all tube DACs.

I found that tube stages are inherently noisy (usually <95dB SNR) and putting a tube stage inside of a DAC chassis tends to lower the performance. 

Keep in mind that DAC chips all contain solid-state op amps inside of them making DACs inherently a solid-state component.

If you were to reproduce a DAC chip with 100% tubes the DAC would likely be the size of a microwave oven and would have to cost several times as much. 

Don't get me wrong: I love tubes.

Tubes add what I like to call "attractive distortion." 

I just prefer to add a little "attractive distortion" to my system with a tube preamp and/or amplifier because I can always upgrade my preamp or amp as opposed to the often less than optimal noisy colored tube stage built into most DACs. 

Why am I saying that tube stages inherently have coloration and distortion?

Aside from the individual sonic characteristics of each specific brand and type of tube, all tube stages require an output transformer or capacitor between the tube and the output. Yes, even the so-called LTA Aero with their "ZOTL" output stage has circuitry between the tube and the output jack...it is in no way "direct-coupled."

OK...yes...there are actual OTL tube stages (such as Atma Sphere Audio) but they require BANKS of tubes.  

Transformers, capacitors, and exotic output stages all add a character and color to the music as well as degrade the purity of the music. 

Less is more.

That's why the DACs I've designed since 2013 are direct-coupled with nothing but a single Vishay "Nude" resistor between the amplification stage and the output.

On the positive side, a significant percentage of the better tube DACs do have LC or CLC power supplies which is likely why people find they have better timing and timbre than solid-state DACs most of which don't have chokes in their power supplies.  

vthokie83
847 posts
 

stuartk

The Jay's CD transports do have an excellent OCXO clockl, their transports are excellent in my experience. The Jay's CD transports have 4 different connections: RCA unbalanced SPDIF, BNC unbalanced SPDIF, AES/EBU balanced connections, and of course I2S.

In all of those connections, the digital data and the clock are sent by the transport; and the DAC will use the transport's clock data.

Using the unbalanced RCA/BNC SPDIF connections, the Jay's will transmit the digital data and the clock packed together, in an unbalanced format, and the DAC will then unpack the data and clock, convert back to I2S, and then perform the digital to analog conversion. Some higher end DACs may have the ability to regenerate the clock signal.

The AES/EBU connection will transport the data and clock together, in a balanced format (balanced will do a better job of ensuring the data arrives correctly). That said, the DAC will still unpack the data and clock, convert to I2S, and then convert the digital data to analog.

The I2S connection will transport the data and clock separately, so no need for the DAC to unpack it from the data, and no need to convert to I2S for the DAC, and then the DAC will convert the digital data to analog.

In my opinion (and through some experience), I would use the I2S connection if possible, the AES/EBU if I2S is not available, and the SDIF connections as a last option. 

stuartk
2,764 posts
 

@vthokie83 

Thank you for explaining.

If the clock in a dac is, for example, a Femto, wouldn't it be advantageous to utilize the Jay's connections that bundle the digital data and clock together in order to utilize the Jay's superior clock?

vthokie83
847 posts
 

Yes it would, you'd want to keep the oven controlled crystal oscillator in the Jay's transport as the master clock

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