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Old 20th August 2019, 09:18 PM   #701
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by ishizeno View Post
Okay, but you're talking about VREF then, which will be fed by the Jung/Didden Super Regulator, not by the LT3045/LT3094 LDOs directly. So, how would the DAC output bias be affected by the LDOs with respect to PSRR?

Adding the synoptic again for references purposes.
That was an example, not the only possible one.

It could refer to a discrete output stage, too. In some cases even opamps don't sound so good with LDOs.

It might even pass through the Jung regulator to some extent, don't know until I listen and compare it to the linear +15v version.
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Old 20th August 2019, 09:27 PM   #702
ishizeno is offline ishizeno
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Originally Posted by Markw4 View Post
That was an example, not the only possible one.

It could refer to a discrete output stage, too. In some cases even opamps don't sound so good with LDOs.

It might even pass through the Jung regulator to some extent, don't know until I listen and compare it to the linear +15v version.
Oh sure, but then again, I have some constraints that I cannot escape:

- my power source is USB (whether I like it or not).
- the DAC brick can't be larger than 4.5" × 1.5", and ideally 3" × 1.5".

And with these constraints, I have to live with the fact that my power source is switched, and that I do not have a lot of room to put things like transformers. But as you wrote, with enough time and efforts, there should be a way to make it work, and I make it my goal to find it, one way or another.

These constraints are really important for me. Without any constraints, there can't be any creativity.

Last edited by ishizeno; 20th August 2019 at 09:29 PM.
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Old 20th August 2019, 09:27 PM   #703
ishizeno is offline ishizeno
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Default Fidelice

Rupert Neve (one of my all-time heroes) just released a new DAC powered by an AKM chip (probably not the AK4499EQ). He also put out a preamp and a headphone amp. Really cool!
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Old 20th August 2019, 09:37 PM   #704
ishizeno is offline ishizeno
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Default Improvement to Power Supply Architecture

Here is a new refinement of the power supply architecture.

This time, the +15 V line that we need for VREF is totally decoupled from the rest of the power supply system, with a dedicated LTM8045. Doing so, it should reduce the temperature of the regulator, and avoid some level of cross-feeding. With that change, the architecture feels really balanced. Overkill maybe, but balanced.

Also, the more I am reading the documentation for the LTM8045 and LTM8049, the safer the µModule form factor makes me feel (Chris had a great point there). In order to better understand this, one might look at this manual for the DC2244A evaluation board of the LMT8049. Figure 7 on page 6 shows the Radiated EMI CISPR25- Class 5 Peak Limit, which is never crossed, no matter which frequency is being used. If we ever try to get the DAC brick certified, this would certainly help.

Note: This sheet analyzes all the regulators we are planning to use for this power supply system (both boards).
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Last edited by ishizeno; 20th August 2019 at 09:44 PM.
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Old 20th August 2019, 09:40 PM   #705
Markw4 is offline Markw4  United States
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Originally Posted by ishizeno View Post
Rupert Neve (one of my all-time heroes) just released a new DAC powered by an AKM chip...
POWERING
Operating Mains Voltage: 100-240VAC, 50/60 Hz
AC Power Consumption: 45W Max
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Old 20th August 2019, 09:41 PM   #706
Markw4 is offline Markw4  United States
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Originally Posted by ishizeno View Post
Without any constraints, there can't be any creativity.
Any particular constraint on sound quality, or okay if you could have gotten better sound quality from AK4497?
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Old 20th August 2019, 09:42 PM   #707
Markw4 is offline Markw4  United States
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USB C should be fine. Just ship a powered USB C hub with it that uses wall power.
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Old 20th August 2019, 09:46 PM   #708
ishizeno is offline ishizeno
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Originally Posted by Markw4 View Post
Any particular constraint on sound quality, or okay if you could have gotten better sound quality from AK4497?
Ah! That is a great question.

Yes, I want it to sound as good as possible within the set of self-imposed constraints, and if it were to sound better with AK4497, I would downgrade to that chip. But someone will have to build an AK4497-powered DAC brick with the same constraints while I work on the AK4499 version, because I remain convinced that we can make it sound better.
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Old 20th August 2019, 09:48 PM   #709
ishizeno is offline ishizeno
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Originally Posted by Markw4 View Post
USB C should be fine. Just ship a powered USB C hub with it that uses wall power.
I just deleted the part of my previous post that wrote about USB-C, because I realized that USB-C gives us up to 3A at 5V, which is massive already (Cf. Wikipedia). For the type of applications that we have, we probably do not need more than that, and there is no point making the system more complex than it already is.
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Old 20th August 2019, 09:52 PM   #710
ishizeno is offline ishizeno
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Default Going with Linear

Unless there is any major objection, I'll go with this list of regulators for a first set of prototype power supplies, because they're all made by Linear, and they're perfectly matched with each other. Also, in my opinion, Linear produces the very best documentations and evaluation boards, with highly detailed explanations of the PCB layout, super cool Jedi tricks like Kelvin connections, and affordable evaluation boards for all their components (at least all the ones that I care about).
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