Gaz38

How do DACs differ?

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Super Wammer

....of course we are assuming the transport is delivering a bit perfect output and this is transmitted via the link to the DAC in equally bit perfect condition 

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3 minutes ago, PuritéAudio said:

That isn’t my experience, all a transport can do is deliver bit perfect data to the dac, perhaps if the DAC is extremely poorly designed it might be susceptible?

Keiht

Well next time you're in Devon Keith, come and have a listen and you might be surprised.

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I've owned 5 different DACs and they all sound different, subtle but enough to notice even with my knackered ears. I've never been able to tell any difference between transports or different digital carriers.

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6 minutes ago, MF 1000 said:

....of course we are assuming the transport is delivering a bit perfect output and this is transmitted via the link to the DAC in equally bit perfect condition 

Why would we simply assume that though.

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Super Wammer
Posted (edited)

It's what Keith (purite) quoted 

in my experience transports and interconnects both deliver less than perfect digital signals to DACs

Edited by MF 1000
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Posted (edited)

A fantastic...now less than fantastic track by Nils Lofgren...'Keith Don't Go'....comes to my mind at this late hour. Here....it should be 'Keith Please DO Go'.....added by Eric Clapton's 'Further on up the road' (further than that!)....with a touch of Yazz 'The only way is up'.....baby.....!

Edited by Mad4it

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2 hours ago, Gaz38 said:

Does anybody recall a multi thousand dollar American cdp that contained a cheap Phillips (I think) dvd player inside a fancy box? 

I can't remember the make but it got great reviews

Maybe you're thinking of the time Lexicon stuck an entire Oppo player, chassis and all, inside a bling box and charged a hefty fee for the effort.

https://www.audioholics.com/blu-ray-and-dvd-player-reviews/lexicon-bd-30-blu-ray-oppo-clone/oppo-inside-lexicon-outside-1

  • Haha 1

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3 minutes ago, mansr said:

Maybe you're thinking of the time Lexicon stuck an entire Oppo player, chassis and all, inside a bling box and charged a hefty fee for the effort.

https://www.audioholics.com/blu-ray-and-dvd-player-reviews/lexicon-bd-30-blu-ray-oppo-clone/oppo-inside-lexicon-outside-1

Seem to remember Goldmund doing exactly the same. Brand loyalty and marketing has a lot to answer for.

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Super Wammer
2 hours ago, Gaz38 said:

Does anybody recall a multi thousand dollar American cdp that contained a cheap Phillips (I think) dvd player inside a fancy box? 

I can't remember the make but it got great reviews

Was it a Theta?

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Super Wammer

I believe the Flash will be doing a little DAC demo so if your at Kegworth drop in to his room and check out the music. Not sure what Keith is bringing himself but I am going to lend him an old Denafrips DAC which I quite like the sound of .

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Super Wammer
6 hours ago, bencat said:

.......... Not sure what Keith is bringing himself but I am going to lend him an old Denafrips DAC which I quite like the sound of .

I'll be running my Lector setup ...the Trichord Pulsar will be in the bring & buy sale but could be demoed by a potential purchaser 

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Charles Hansen (Ayre) wrote this at CA:

.

Just about everything affect the sound of an audio product, but when it comes to DACs, I would rank (in order or sonic importance the general categories as follows:

1) The analog circuitry - 99.9% of all DACs are designed by digital engineers who don't know enough about analog. They just follow the app note. The specs on the op-amps are fabulous and digital engineers are inherently seduced by the beauty of the math story. There are minor differences in the sound quality between various op-amps, but it's kind of like the difference between a Duncan-Heinz cake mix and a Betty Crocker cake mix. 99.8% of the op-amps are used a current-to-voltage converters with the inverting input operating as a virtual ground. This is probably the worst way to use an op-amp as the input signal will cause the internal circuitry to go into slewing-limited distortion. http://www.edn.com/electronics-blogs/anablog/4311648/Op-amp-myths-ndash-by-Barrie-Gilbert

With discrete circuitry, the only limit is your imagination. You are free to adjust the topology of the circuit, the brands of the parts, the active devices, the bias current in each stage - anything you can think of. Think of this as going to a world-class patisserie in Paris and seeing all the different things that can be made.

2) The power supplies - 99.9% of all DACs use "3-pin" power supply regulators, which are pretty much op-amps connected to a series pass transistor. Everything in #1 applies here.

3) The master clock - jitter is a single number assigned to measure the phase noise of an oscillator over a fixed bandwidth. It is far more i important to know the spectral distribution of the timing variations and how they correlate to audible problems. 99.9% of all DACs use a strip-cut AT crystal in a Pierce gate oscillator circuit. It's pretty good for the money but the results will depend heavily on the implementation, particularly in the PCB layout and the power supplies (#2).

It's hard to rank the rest of these so I will give them a tie score.

4) The digital filter - 99.9% of all DACs use the digital filter built into the DAC chip. About a dozen companies know how to make a custom digital filter based on either FPGAs or DSP chips.

4) PCB layout - grounding and shielding, impedance-controlled traces, return currents, and return current paths are all critical. For a complex digital PCB, 8 layers is the minimum for good results.

4) The DAC chip - almost everything these days is delta sigma with a built-in digital filter. Differences between different chips is one of the less important aspects of D/A converter designs. Both ESS and AKM have some special tricks to reduce out-of-band noise, which can be helpful, but not dramatic.

4) Passive parts - the quality of these can make a large difference in overall performance, especially for analog. Not many digital engineers sit around listening to different brands of resistors to see what sounds best.

These are just a few of the things that make differences in the way that a DAC will sound.

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Super Dealer
1 hour ago, tuga said:

Charles Hansen (Ayre) wrote this at CA:

.

Just about everything affect the sound of an audio product, but when it comes to DACs, I would rank (in order or sonic importance the general categories as follows:

1) The analog circuitry - 99.9% of all DACs are designed by digital engineers who don't know enough about analog. They just follow the app note. The specs on the op-amps are fabulous and digital engineers are inherently seduced by the beauty of the math story. There are minor differences in the sound quality between various op-amps, but it's kind of like the difference between a Duncan-Heinz cake mix and a Betty Crocker cake mix. 99.8% of the op-amps are used a current-to-voltage converters with the inverting input operating as a virtual ground. This is probably the worst way to use an op-amp as the input signal will cause the internal circuitry to go into slewing-limited distortion. http://www.edn.com/electronics-blogs/anablog/4311648/Op-amp-myths-ndash-by-Barrie-Gilbert

With discrete circuitry, the only limit is your imagination. You are free to adjust the topology of the circuit, the brands of the parts, the active devices, the bias current in each stage - anything you can think of. Think of this as going to a world-class patisserie in Paris and seeing all the different things that can be made.

2) The power supplies - 99.9% of all DACs use "3-pin" power supply regulators, which are pretty much op-amps connected to a series pass transistor. Everything in #1 applies here.

3) The master clock - jitter is a single number assigned to measure the phase noise of an oscillator over a fixed bandwidth. It is far more i important to know the spectral distribution of the timing variations and how they correlate to audible problems. 99.9% of all DACs use a strip-cut AT crystal in a Pierce gate oscillator circuit. It's pretty good for the money but the results will depend heavily on the implementation, particularly in the PCB layout and the power supplies (#2).

It's hard to rank the rest of these so I will give them a tie score.

4) The digital filter - 99.9% of all DACs use the digital filter built into the DAC chip. About a dozen companies know how to make a custom digital filter based on either FPGAs or DSP chips.

4) PCB layout - grounding and shielding, impedance-controlled traces, return currents, and return current paths are all critical. For a complex digital PCB, 8 layers is the minimum for good results.

4) The DAC chip - almost everything these days is delta sigma with a built-in digital filter. Differences between different chips is one of the less important aspects of D/A converter designs. Both ESS and AKM have some special tricks to reduce out-of-band noise, which can be helpful, but not dramatic.

4) Passive parts - the quality of these can make a large difference in overall performance, especially for analog. Not many digital engineers sit around listening to different brands of resistors to see what sounds best.

These are just a few of the things that make differences in the way that a DAC will sound.

A extremely poor measuring Charles Hansen ‘Ayre’ design, 

https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-ayre-codex-dac-amp.7282/

Keith

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