atomicbob's SMPS Noise Nuke for HP amps with external SMPS

Discussion in 'Headphone Amplifier Measurements' started by atomicbob, Sep 26, 2017.

  1. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    Performance wise it's not a bad solution - you cram a lot of capacitance in a small package. And probably those price breaks at quantity are sweet too.

    The real fun starts once you need to find the bad one...
     
  2. Azimuth

    Azimuth FKA rtaylor76, Friend

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    No idea the difference between power caps. Maybe just larger "power caps" like on power lines and sub stations?

    Anyway, that chart is from this article with tons of good info on all the different types of capacitors: This makes the polymer capacitors excellent for power supplies and audio applications.

    He also notes how good ceramic is for filtering due to it's low ESR, however they suffer from internal noise (vibrations) and have to be quite large in physical size for higher voltages and cap values.

    Then goes on to mention polymer caps:

    "A significant downside of traditional tantalum and aluminium capacitors is their high equivalent series resistance. When used for filtering applications on a switched-mode power supply, it’s hard to obtain a shallow voltage ripple or mitigate conducted electromagnetic interference. The ESR of polymer capacitors is similar to many ceramic capacitors, which makes them ideal for filtering applications as they offer significantly higher capacitance values than ceramic options."

    "...polymer capacitors are excellent for high frequency applications...[that] makes the polymer capacitors excellent for power supplies and audio applications."
    He then goes to show polymer caps on a DC-DC converter/regulator that has lots of high frequency switching. I mention this for other DIY'ers who follow this threat who like to change out caps.

    PS - For the Noise Nuke,I already looked and the biggest cap in a aluminum poly you can get in 63V and that is 1100µf. So to get the required 13,200µf would be 12 of them, and one 400µf. And the size of those are .75in (18.2mm) diameter and 1.5in (36.5mm) tall. That would be one rather large Noise Nuke box!
     
  3. Armaegis

    Armaegis Friend

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    Well sure... but what other manufacturer can say they've been subtly flipping us the bird with capacitors all these years?
     
  4. Aklegal

    Aklegal Friend

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    Threw this together today. @atomicbob is a genius. I really didn't think the SMPS to my Pi2AES was that noisey but wow. This is a considerable difference.

    Could I place one of these on each rail of say a AMB sigma 22?
     
    Last edited: Feb 3, 2023
  5. Azimuth

    Azimuth FKA rtaylor76, Friend

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    The Sigma 22 is already an LPS. No need for stuff like the Noise Nuke.
     
  6. Aklegal

    Aklegal Friend

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    I guess I am just piggy backing from the original posts where measurements showed a slight improvement between an LPS and a LPS with the noise nuke.
     
  7. goodvibes

    goodvibes Facebook Friend

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    Available values )at a reasonable size and expense) are too low on those solid caps for this purpose but if, for some reason, the noise nuke got a bit too warm or heavy sounding, you could always try polymer caps across the electrolytics. Bypassing is pretty common. This isn't a power supply per say but bypassing across the filter caps should function similarly.
     
  8. peef

    peef Friend

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    I've not met a power supply that didn't benefit from choke filtering. Most LPS rely on feedback to reject line noise. At very high frequencies, the regulator will run out of feedback and the noise can rip right through it. This is true regardless of whether your supply is a switcher or a mains transformer; there will always be some HF junk on the line which the transformer (particularly toroids) can pass on to the circuit.

    My suggestion would be to put the noise nuke between the raw filtered supply (i.e. after rectifier and last power supply cap) and the input of the regulator. This gets you all the noise rejection without impacting the regulator's output impedance.
     
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  9. Azimuth

    Azimuth FKA rtaylor76, Friend

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    Where is this HF noise coming from? If power line noise, this can be addressed before even hitting the LPS with a good power conditioner. The NoiseNuke is addressing at removing the noise generated by the SMPS itself.

    What you are describing is more like a choke. Which is more common on unregulated power supplies rather than regulated ones. However, there can still be a benefit to using one on very sensitive circuits, ie. DAC’s, DDC’s, etc.
     
  10. Cspirou

    Cspirou They call me Sparky

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    that’s pretty much what the noisenuke is

    3DEFB390-AE00-4D25-9E69-AD1CE92DA81F.jpeg
     
  11. Azimuth

    Azimuth FKA rtaylor76, Friend

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    Well…a choke that is tuned for specific frequency. It’s a filter network really.
     
  12. NeilBlanchard

    NeilBlanchard New

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  13. peef

    peef Friend

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    I don't think these inductors are rated for DC. If that's the case, DC will saturate the core and cause the inductance to drop, which ultimately impacts the filter's ability to attenuate the noise.

    The big benefit of an air core is that there is no core to introduce non-linearities or to saturate. The drawback is that the coil requires many more turns of wire, as the core increases the coil inductance. More turns usually means more stray capacitance (which means the coil is less effective at very high frequencies) and more DC resistance. You can get around the DCR issue by bumping up the wire gauge, but this could aggravate the capacitance issue. Tradeoffs.

    If reducing ESR (and ESL!) is the goal, the usual approach would be to bypass the 13600uF with smaller film caps. 1-10uF would be a good place to start.
     
  14. Justin S

    Justin S Friend

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    I am going to put another one of these together and am having a difficult time finding 6800uF caps here. If I go bigger: 2 X 8200uF @ 50Vdc caps, will this function properly. I will be using this on a digital device (PI2AES).
     
  15. NeilBlanchard

    NeilBlanchard New

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    Thanks for the replies - I will look at the other coils at Parts Express, but the unit spec'd in the Noise Nuke parts list is ~$21 at Parts Connexion: https://www.partsconnexion.com/HAMMOND-63098.html

    They also sell a snap lug version of the 6800uF 63V Nichicon cap for just ~$8: https://www.partsconnexion.com/NICHICON-73626.html

    Can someone link to the case and jacks, if you have them handy, please?

    Is the 6mH value critical, or can it be slightly lower / higher?

    Would higher value caps be beneficial?
     
  16. Biodegraded

    Biodegraded Friend

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    Digikey is still showing stock of the BOM Nichicon UKW1J682MRD (93 remaining but now obsolete so will not be re-stocked) at $CAD 10.42 ea. Shipping to Canada is $CAD 8; buy some solder or something else to make it worthwhile.

    Or see @NeilBlanchard 's post above, which came in as I was writing this :rolleyes:
     
  17. Justin S

    Justin S Friend

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    I found the snap-lug versions at partsconnexion as per @NeilBlanchard. They were not there last week but are now! I used the 80V versions in my last build - they're pretty fat. These will be easier to work with in the case, I think. I picked up a handful of them and another couple chokes and am just going to go whole hog and build another batch of three of these. Thanks for your help @Biodegraded and Neil.
     
  18. Azimuth

    Azimuth FKA rtaylor76, Friend

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    @atomicbob, is there a recommendation for an inductor for something for these new class D amps? The Aiyma A07 is 36V 6A. This noise nuke is limited to current less than 2A. I think it will even take up to a 48V 10A input. It seems silly to build such a large LPS that will just eat power and at that point it might as well be Class A or A/B amp with no power savings at all, and then also generate a bunch of heat. So something like a bigger noise nuke would be great.

    I really don't need the headroom of a 480W input, but I think it would benefit from something like this with the existing power supply I have (216 watts).
     
  19. atomicbob

    atomicbob dScope Yoda

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    There is a 5 amp version, Hammond 159ZJ, that would increase current capability while also making an improvement on the noise nuking. However I'd be hesitant to use a brute force LC filter with a TPA3255 design as evidenced by Aiyama also warning against using an "industrial" power supply with the amp.
     
  20. caute

    caute Lana Del Gayer than you

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    can i use the noisenuke if im not using stock smps but cheap jameco LPS for pi2aes?
     

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