What is the benefit of very expensive DACs?

[LL21]

I see a lot of designers chasing new technologies, such as DSD, MQA and new digital filter technologies. They want the latest Saber chip in their new DAC. They believe that they will ultimately achieve performance by doing this, as well as checking some boxes that many consumers want.

I, on the other hand, spend most of my time optimizing the D/A technology I choose because it's the novel circuits and careful implementation that ultimately delivers the analog sound, not new technologies IME. Older D/A chips can sound amazing. Novel features also provide Trade Secrets that are difficult to copy (particularly by the Chinese).

Any designer can select the newest DAC technology. It's difficult to distinguish your products doing only this. Designing novel circuits and using optimum implementation is not something in the "cook-books" or datasheets either. A lot of experience and know-how is required.

The fact is that it requires one to wear a lot of hats to do an excellent DAC design:

digital design
analog design
grounding and shielding
transmission-line effects and termination
circuit board layout and stackup
power delivery/decoupling
power supply
passive parts selection
voltage regulator design
firmware design
S/W driver design
chassis/mechanical design

I would guess that 0% of DAC designers are experts in all of these critical areas. That is why I contract with other experts in some areas for their design expertise or license their technology. I licensed for instance; Paul Hynes regulator technology that I use in all of my products. I know which areas I am weak in, or those that are not worth my time getting up to speed on. I think it is important for a designer to know his limitations.

Steve N.
Empirical Audio

Another great post...thanks for taking the time!

 

[Pb Blimp]

What is the benefit of very expensive DAC´s?

I find they help reduce capital gains and dividend income when I do my taxes.

 

[Legolas]

I see a lot of designers chasing new technologies, such as DSD, MQA and new digital filter technologies. They want the latest Saber chip in their new DAC. They believe that they will ultimately achieve performance by doing this, as well as checking some boxes that many consumers want.

I, on the other hand, spend most of my time optimizing the D/A technology I choose because it's the novel circuits and careful implementation that ultimately delivers the analog sound, not new technologies IME. Older D/A chips can sound amazing. Novel features also provide Trade Secrets that are difficult to copy (particularly by the Chinese).

Any designer can select the newest DAC technology. It's difficult to distinguish your products doing only this. Designing novel circuits and using optimum implementation is not something in the "cook-books" or datasheets either. A lot of experience and know-how is required.

The fact is that it requires one to wear a lot of hats to do an excellent DAC design:

digital design
analog design
grounding and shielding
transmission-line effects and termination
circuit board layout and stackup
power delivery/decoupling
power supply
passive parts selection
voltage regulator design
firmware design
S/W driver design
chassis/mechanical design

I would guess that 0% of DAC designers are experts in all of these critical areas. That is why I contract with other experts in some areas for their design expertise or license their technology. I licensed for instance; Paul Hynes regulator technology that I use in all of my products. I know which areas I am weak in, or those that are not worth my time getting up to speed on. I think it is important for a designer to know his limitations.

Steve N.
Empirical Audio

Agree with your post, but many manufacturers who make good pre-amplifiers can and do make good DACs. If we take the expertise in pre-amplifier design out of your list, we are left with only 3 or 4 points.

I am not sure I agree with your DS points. You said in another post you found most of the problems in sound quality is the digital filter. If you did a ladder DAC with no up sampling, why not built it sans filter, so as straight through as possible? Seems to sound better to me.... Unless the market demands chasing the numbers?

 

[Empirical Audio]

Agree with your post, but many manufacturers who make good pre-amplifiers can and do make good DACs. If we take the expertise in pre-amplifier design out of your list, we are left with only 3 or 4 points.

I am not sure I agree with your DS points. You said in another post you found most of the problems in sound quality is the digital filter. If you did a ladder DAC with no up sampling, why not built it sans filter, so as straight through as possible? Seems to sound better to me.... Unless the market demands chasing the numbers?

Actually, jitter is #1 followed by digital filter.

I think I may have designed my last DAC. I have one now that is world-class, so I just want to add input modules, including an Ethernet interface that supports ROON. I already have a great DLNA Ethernet interface.

I also have plans to do a fully balanced-only headamp using my DAC output stage technology. Too many things to do before I finally retire, if I ever retire.....

Steve N.
Empirical Audio

 

[opus112]

The downside to discretes is the real-estate they take. A bad result of this is that power delivery to discrete stages is difficult and never as optimum as a chip.

Agreed about real-estate, though that's become much less of an issue with SMT. Because discretes offer so many more degrees of freedom than do ICs, it turns out its possible to engineer the discrete circuit to draw a more-or-less stable current under all signal conditions. Then the difficulty of power delivery is hugely reduced. Its a case of 'pick your poison' - my chosen one is to rely less on having top-notch regs, power delivery networks and decoupling by making the active circuitry more PSU-agnostic.

 

[LL21]

Agreed about real-estate, though that's become much less of an issue with SMT. Because discretes offer so many more degrees of freedom than do ICs, it turns out its possible to engineer the discrete circuit to draw a more-or-less stable current under all signal conditions. Then the difficulty of power delivery is hugely reduced. Its a case of 'pick your poison' - my chosen one is to rely less on having top-notch regs, power delivery networks and decoupling by making the active circuitry more PSU-agnostic.

What is SMT?

 

[opus112]

What is SMT?

Surface mount technology. Its a boon to have transistors nowadays in SOT-23 and sometimes even smaller packages. Not a boon when power dissipation is an issue (then having small packages is a downright pain) but for most line-level circuits the smaller sizes mean much lower parasitics (inductances of wires/traces are a significant issue).

 

[LL21]

Surface mount technology. Its a boon to have transistors nowadays in SOT-23 and sometimes even smaller packages. Not a boon when power dissipation is an issue (then having small packages is a downright pain) but for most line-level circuits the smaller sizes mean much lower parasitics (inductances of wires/traces are a significant issue).

That is what i thought...but i could not understand how SMT alleviates the requirement for high quality PSU? Sorry for being ignorant!

 

[opus112]

SMT doesn't directly alleviate the requirement for the very highest quality PSU. But indirectly it does because the small sizes of circuits possible through use of SMT mean we no longer need huge board areas to implement discrete circuits. Its the discrete circuits which allow the possibility to design more PSU-agnostic circuits, not SMT itself. SMT renders PSU-agnostic discrete circuits economically attractive.

 

[LL21]

SMT doesn't directly alleviate the requirement for the very highest quality PSU. But indirectly it does because the small sizes of circuits possible through use of SMT mean we no longer need huge board areas to implement discrete circuits. Its the discrete circuits which allow the possibility to design more PSU-agnostic circuits, not SMT itself. SMT renders PSU-agnostic discrete circuits economically attractive.

Got it...thanks! Do you think in an 'all out assault on high end' you would still use heroic PSUs with your design? Or do they matter that little in such a design that even in all-out assault, it would not matter? I am thinking of Aries Cerat which has 3 million microFarads of capacitance...for its DAC!!!

 

[opus112]

Its a very interesting question to consider Lloyd and I have to confess that at this stage I don't know the answer. This is because I've not been aiming at the 'all out assault on the high-end', rather I've been going along with the principles of 'Disruptive Innovation' as set out by Clayton Christensen in his book 'The Innovator's Dilemma'. Which is start at the bottom end and then slowly work upwards powered by customer demand - so I've been designing cheap, cheap, cheap. Then, assuming that 'cheap' gets a market foothold I'll be in a position to answer your excellent question.

 

[LL21]

Its a very interesting question to consider Lloyd and I have to confess that at this stage I don't know the answer. This is because I've not been aiming at the 'all out assault on the high-end', rather I've been going along with the principles of 'Disruptive Innovation' as set out by Clayton Christensen in his book 'The Innovator's Dilemma'. Which is start at the bottom end and then slowly work upwards powered by customer demand - so I've been designing cheap, cheap, cheap. Then, assuming that 'cheap' gets a market foothold I'll be in a position to answer your excellent question.

Much appreciated!

 

[opus112]

Another confession I feel important to make is that concerns for portable DACs and amps have driven my requirement for PSU-agnostic circuits. Its simply not possible to fit heroic high-end PSUs into hand-held and battery powered kit, but I still would like to achieve the high-end sound.

Here's a prototype portable DAC taking shape - it still needs decoupling caps and I've not added these yet as they're the most bulky parts even with an optimized discrete circuit, as here. The DAC chips here are stacked 5 high in the foreground to the right. The power supply is behind.

 

[Empirical Audio]

Agreed about real-estate, though that's become much less of an issue with SMT. Because discretes offer so many more degrees of freedom than do ICs, it turns out its possible to engineer the discrete circuit to draw a more-or-less stable current under all signal conditions. Then the difficulty of power delivery is hugely reduced. Its a case of 'pick your poison' - my chosen one is to rely less on having top-notch regs, power delivery networks and decoupling by making the active circuitry more PSU-agnostic.

SMT has its place and works decently for digital, but mostly I have found SMT discretes to be lacking in performance. Their "Q" is just too low to work very well for decoupling audio circuits.

Steve N.

 

[Empirical Audio]

Got it...thanks! Do you think in an 'all out assault on high end' you would still use heroic PSUs with your design? Or do they matter that little in such a design that even in all-out assault, it would not matter? I am thinking of Aries Cerat which has 3 million microFarads of capacitance...for its DAC!!!

I have designed with both LI batteries and Ultracaps before. Ultracaps work better than the average regulator, but a really fast responding regulator on an AC supply will outperform both LI batteries and Ultracaps. These discrete regulators are typically large and inefficient, so they create a lot of heat. Not so good for portable.

Steve N.
Empirical Audio

 

[Aries Cerat]

I have designed with both LI batteries and Ultracaps before. Ultracaps work better than the average regulator, but a really fast responding regulator on an AC supply will outperform both LI batteries and Ultracaps. These discrete regulators are typically large and inefficient, so they create a lot of heat. Not so good for portable.

Steve N.
Empirical Audio

I never liked batteries regardless of technology, also never liked the Ultracaps. Out top dacs use massive capacitor banks with esr down to single digits. Fed via extremely low dcr chokes. These feed the regulators.

 

[Empirical Audio]

I never liked batteries regardless of technology, also never liked the Ultracaps. Out top dacs use massive capacitor banks with esr down to single digits. Fed via extremely low dcr chokes. These feed the regulators.

Chokes are necessary for high-voltage, but I never use them for low voltage. They block di/dt and therefore reduce dynamics IME.

Regulators and proper decoupling is the key. Fast responding regulators with good input rejection and high-Q decoupling caps are the ticket.

Steve N.

 

[LL21]

I never liked batteries regardless of technology, also never liked the Ultracaps. Out top dacs use massive capacitor banks with esr down to single digits. Fed via extremely low dcr chokes. These feed the regulators.

Chokes are necessary for high-voltage, but I never use them for low voltage. They block di/dt and therefore reduce dynamics IME.

Regulators and proper decoupling is the key. Fast responding regulators with good input rejection and high-Q decoupling caps are the ticket.

Steve N.

On the one hand, i am lost in this...on the other hand, it is great to see educated digital designers having a technical discussion that we can watch/read and take notes. Thanks for taking the time.

Let me start with Aries Cerat...why NOT batteries? There is layman talk about 'dirt on the power grid'...and liking massive batteries to power systems (didn't Living Vox Olympia do this in Munich?) Hate to even ask the 'dumb question'...but isnt a capacitor essentially a storage unit for power (...a battery?)...where you have 'instant' access to power sitting in a massive storage tank waiting for transients/dynamic power to enable the system to have 'limitless power on tap' for transients/crescendos, etc?

In the most dumb'd-down language...how or why do you find that different than batteries? Thanks for answering (if you can stomach what is perhaps a very, very basic question).

 

[LL21]

I never liked batteries regardless of technology, also never liked the Ultracaps. Out top dacs use massive capacitor banks with esr down to single digits. Fed via extremely low dcr chokes. These feed the regulators.

Chokes are necessary for high-voltage, but I never use them for low voltage. They block di/dt and therefore reduce dynamics IME.

Regulators and proper decoupling is the key. Fast responding regulators with good input rejection and high-Q decoupling caps are the ticket.

Steve N.

So in the most basic of basic questions...is there a theoretical powersource/powersupply that just puts 'pure electrical juice' straight into the audio reproduction system without 'emi/rfi', blocked dynamics, chokes, filters, running out of juice, etc? Again, in theory? And then of course, the next question...if cost were no object, is theoretical possible to implement in reality?

 

[opus112]

SMT has its place and works decently for digital, but mostly I have found SMT discretes to be lacking in performance. Their "Q" is just too low to work very well for decoupling audio circuits.

Are you talking here about SMT electrolytics? If so I have found the same, very poor ESRs compared to through-hole equivalents.

I wasn't referring to passive components in my post, rather discrete semis.