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Thread: NOS DACs

  1. #61
    Join Date: Jan 2013

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    Quote Originally Posted by brian2957 View Post
    Yup , I bought Uniross rechargeable batteries and they made a marked difference to the SQ of the DAC .
    They probably are manufactured differently and therefore have a different set of characteristics. Check out the below.

    "Here is a good article about the pros and cons of Battery power, SMPS and LPS. It doesn't include tube regulated PS or SHUNT.

    Note: A version of this article was originally written and published on Larry Ho’s personal blog on December 1, 2014.
    There’s a common assumption that battery power supplies are much less noisy than switched-mode, or even linear, power supplies.

    I think the most likely reason that people make this assumption is because, they believe, pure DC power doesn’t have any AC noise on it. But let’s take a closer look at this and see if I can help you decide which method for powering your audio gear is best.

    The way a battery produces power
    Batteries produce and deliver power through a chemical reaction. Every type of battery will use a different chemical mixture to generate power. Lithium Ion and Sealed Lead Acid are two of the most popular (of the more than 150 types of) batteries. For your reference, Wikipedia has a nice long list of battery technologies here: http://en.wikipedia.org/wiki/List_of_battery_types

    As a battery drains, the amount of chemical compound available to produce electricity is reduced. That means there’s an exponential decay on the amount of power a battery can produce. So a battery with a 100% charge will have far more capability of producing fast transients than a battery that isn’t fully charged, especially if that charge is below 50% of its capacity. Depending on the battery’s manufacturing process and the stage of its life cycle, the problem of power delivery speed is compounded. This is the reason some people note that a new battery sounds better than an older battery.

    With this information, it behooves users to replace batteries often and keep them charged to capacity as much as possible. This, of course, means that larger budgets must be set aside for batteries as frequent charging leads to shorter battery life.

    Battery noise generation
    The assumption that batteries aren’t noisy is flawed because batteries have a substantial amount of high frequency ripple. Meaning that there’s a large amount of high frequency AC noise that rides on top of the DC output voltage. Different batteries using different chemical reactions will generate different types and frequencies of noise. And, as the chemical reaction changes as the battery drains, the spectrum of noise changes as well. Also, as discussed above, as the battery discharges, the output voltage and current destabilizes, causing a slower transient response.

    Ultimately, batteries provide a non-constant power source that produces a variable spectrum noise that users are trying to get rid of by switching to batteries in the first place.

    Introducing Noise as Batteries Recharge
    As mentioned above, in order to get the most out of your batteries, they need to be as close to 100% charged as you can get them. One way to keep your batteries charged is to use an automatic trickle charger. This device detects when voltage from the battery is below a pre-determined threshold. When the threshold is reached, it begins to recharge your batteries. In this scenario, the AC recharge injects noise into the battery’s path, when means your system has to include a filter to address both battery noise and AC noise.

    The other option is to manually recharge batteries when the system isn’t in use. This is a much better option when it comes to noise, but it’s inconvenient to users. Who wants to stop in the middle of a listening session so you can manually recharge your batteries?

    Grounding
    By using a batteries, you aren’t connected to ground in the same way. The connected device is either isolated from an earth ground altogether or it’s directly connected, depending on the battery powered device’s connections to other devices, such as a computer. This means that shields can become noise cages. In addition, it’s easy to end up with a ground loop along your system’s cables as the system tries to find an alternative path to ground. When this happens, it’s not easy to find the cultrip for the loop.

    Batteries vs a Switched-Mode Power Supply (SMPS)
    Noise generated by batteries is usually very high frequency noise, well into the MHz or even GHz range. This noise is very difficult to filter and is exactly the kind of noise we hate the most because of the artifacts it sends down into the audible range. Still, this noise is less than that which is generated by a switched-mode power supply. In comparison, batteries are the better choice, but still not a great choice.

    Linear Power Supply (LPS) with a Super-Quiet DC Circuit

    A linear power supply can be designed with a much wider bandwidth, a super-stabilized voltage and current capacity, a considerably lower noise floor, and much more power than a battery power supply. It does come with trade-offs, though.

    A good LPS is usually very heavy due to the amount of metal needed in its transformers and the size of its capacitors. The more wattage you need, the heavier it is. Nobody in the last 30 years has been able to solve the issue of weight.

    A good LPS is not inexpensive. Again, because of the components that are needed, cost is a major contributing factor into why users elect against an LPS.

    Conclusion
    There’s no perfect solution for noise-free power. Each one we’ve discussed (battery, SMPS, & LPS) come with their own pros and cons. In my opinion, based on how I use my audio system, I rank these solutions as #1: linear power supply, #2: battery power supply, and #3: switched-mode power supply. The beauty of this hobby, though, is that everyone gets to make their own decision. Hopefully now you have more considerations as you decide which method you like most. "

  2. #62
    Join Date: Apr 2008

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    My experience to date is that LiFePO4 batteries are the quietest battery option and possess huge peak current capability. Charging them is a bit of a pain though.
    TT 1 Trans-Fi Salvation with magnetic bearing + Trans-Fi Terminator T3Pro + London Reference
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  3. #63
    Join Date: Jan 2009

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    In general the lower the internal resistance the battery has the lower the thermal noise, but the 1/f noise will depend on the chemical reaction the battery uses and both tend to depend on the capacity of the battery (its size, quoted in mAh) - the bigger the better.
    Last edited by Barry; 22-04-2018 at 15:22. Reason: Addition
    Barry

  4. #64
    Join Date: Aug 2009

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    Quote Originally Posted by Jimbo View Post
    Here you go Geoff, you will find your answer in this article but simply the missing information is part of the sound wave.


    https://www.electronicproducts.com/D...tal_Sound.aspx
    Whoever wrote that article doesn't have a clue what they are talking about. Try this one https://www.audioholics.com/audio-te...reality-part-1
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  5. #65
    Join Date: Jan 2008

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    Sigh.
    There really is no information missing in digitally sampled music.

    If you want to find differences look, for example, at the output stage of DACs.
    What a load of bollocks is being posted by some people on this thread.

    If you like vinyl, fine - but stop making things up so as to justify that preference and give this bollocks a rest.
    .

  6. #66
    Join Date: Mar 2011

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    Quote Originally Posted by Macca View Post
    Whoever wrote that article doesn't have a clue what they are talking about. Try this one https://www.audioholics.com/audio-te...reality-part-1
    The irony is that the article is not quite right for NOS DACs. The classic staircase output does not appear in most DACs because the signal is filtered and the high-frequency noise is removed. However, when JA measured the Audionote DAC he saw the 'classic' staircase output. Obviously, as the NOS DAC has no filters then higher frequencies go straight through and the staircase output appears. Of course there is no additional information as it is noise.

    Whilst I like the sound of NOS DAC, I suspect it may be more due to the use of discrete components rather than cheap op-amps, or even better, valves. But that is a different discussion.

    There may be information missing from conventional DACs but it is not for the reasons in the original article.

  7. #67
    Join Date: Aug 2009

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    Quote Originally Posted by George47 View Post
    Whilst I like the sound of NOS DAC, I suspect it may be more due to the use of discrete components rather than cheap op-amps, or even better, valves. But that is a different discussion.

    .
    It could well be a variety of different things. The problem arises when people hear something they like the sound of and then jump to conclusions about why it is they like it.

    No DAC is going to 'miss' information. It just doesn't work that way. It's possible to have low-level sounds getting swamped by noise/distortion, though, and this is where a well-engineered DAC will have the advantage.
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  8. #68
    Join Date: Feb 2008

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    Talking about battery, power supply, and noise: I finally managed to come up with a solution that beats all of the existing ones. But I am only going to develop it for my own DACs for now. I gave a demo of it over the weekend, and I am quite pleased with the feedback received.
    The main reason that I mention this is because it puts a lot of previous assumptions completely on its head.

  9. #69
    Join Date: Aug 2009

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    Sounds intriguing.
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  10. #70
    Join Date: Feb 2008

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    It is. I spent more than ten years trying to get this thing off the ground, so I am well pleased to have finally cracked it. More info to follow in its own thread at a later date.

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