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

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

  1. Cspirou

    Cspirou They call me Sparky

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    Especially since its a 10 layer board.

    I think that's also why the average DIYer can create a pretty good Class AB amp and linear supply but need to resort to modules when it comes to SMPS and Class D.
     
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  2. Luckbad

    Luckbad Traded in a unicorn for a Corolla

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    @atomicbob Thank you kindly! The answer was about 9.8x as thorough as I was anticipating (because it came from you... for others, it's about 47x as thorough as I'd expect).

    @Cspirou The magic is not in the switching power supply, it's inside the chassis. I was reading about it earlier, mostly with regard to the ADI-2 DAC, and I figure the Pro has at least as much going on with the power inside as the DAC version.

    From the ADI-2 DAC manual (yes, I like manual pron):

     
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  3. highflyin9

    highflyin9 Almost "Made"

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    Very simple and interesting solution. Thinking it might be just what the doctor ordered for the Amp Camp with Meanwell PSU. Looks like Hammond makes a 1.5mH and 10mH inductor at 5A. I'm thinking I may try the 1.5mH (156B). There should be enough real-estate to mount the circuit right in the unit.

    Just to confirm to others as you can't see in the image, but the caps are in parallel, and adding a film bypass would be in parallel as well.
     
    Last edited: Jun 8, 2018
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  4. bilboda

    bilboda Florida boomer

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    Just to confirm, caps wired in parallel, positive with choke lead to center pin tab of input jack. Negative to negative tab of the input jack, Output jack has the other choke lead to the center pin tab and a jumper wire between negative tabs on both jacks.
    Is this correct?
     
  5. atomicbob

    atomicbob dScope Yoda

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    The two 6800 uF capacitors are wired in parallel to achieve a total of 13600 uF.

    Here is a more pictorial type of diagram to complement the schematics in the original posts:

    atomicbobs noise nuke pseudo diagram.png
     
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  6. bilboda

    bilboda Florida boomer

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    There , I think I got it. No shorts!! Making the out put cable now
    [​IMG]

    [​IMG]
    In action. Enjoying what I am listening to. File seems more dynamic I will have to put on some more familiar music for a good comparison.
     
    Last edited: Jul 15, 2018
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  7. Wushuliu

    Wushuliu Acquaintance

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    Atomicbob, out of curiosity, what would happen if you wired up two sets in series (LCLC)?
     
  8. atomicbob

    atomicbob dScope Yoda

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    More filtering but diminishing returns.
     
  9. Wushuliu

    Wushuliu Acquaintance

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    Ah, ok. The thread inspired me to try LTSpice for the first time and I was able to model (I think) the circuit and yes, looks like not much improvement in series and only moderately so with increased inductance. Got some Hammonds on the way to try this out... Thanks!
     
  10. Dr J

    Dr J Friend

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    For those not inclined to DIY, would this Capacitance Multiplier from Allo be something similar and potentially useful, based on the circuit?

    https://allo.com/sparky-eu/capacitance-multiplier.html

    Wimpier components, and seems to do slightly different things. (I am not an electrical engineer)
     
    Last edited: Apr 11, 2020
  11. batriq

    batriq Probably has made you smarter

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    @Luckbad I just noticed, do you have the amp connected to the input side in your picture? It should be connected to the side with the caps. Sorry if I'm reading the pictures wrong.
     
  12. Luckbad

    Luckbad Traded in a unicorn for a Corolla

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    Nah, the pic of the inside is upside-down so when I flip the whole thing over, the right side is the output.
     
  13. batriq

    batriq Probably has made you smarter

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    ah OK, it looked like you're using the left side as the output in the picture with the amp.
     
  14. batriq

    batriq Probably has made you smarter

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    Here's my 'build'

    [​IMG]

    I went schiit-style and put the output on the left.

    For connectors I used the switchcraft 721a. I first built the parallel caps by attaching them to eachother with RTV silicone, then connecting their leads:

    [​IMG]
     
  15. Luckbad

    Luckbad Traded in a unicorn for a Corolla

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    Nice! One thing I'd recommend is to grab an in-line power cord switch so you can turn off the power to whatever switching power supply you're using rather than flipping the switch of whatever you're powering.

    Something like this: https://smile.amazon.com/gp/product/B01HGNN30M/

    It can prevent issues with some switches burning out (like with the Garage1217 amps). Without switching off my SMPS before toggling the amp off, I managed to kill two different power switches on a Project Sunrise and Project Horizon. Since flipping the in-line switch first, I've never murdered another G1217 on/off switch (that said, I usually use a linear power supply anyway).
     
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  16. purr1n

    purr1n Finding his inner redneck

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    Similar function but different approach. No idea why Allo calls it a capacitor multiplier. Looks likes a regulator there, another stage of regulation, designed to go inline with their products.

    @atomicbob's approach with the choke is a brute force method of nuking noise. The downside is that chokes are heavy and not cheap (particularly as we go up in power requirements), thus typically not used in power supplies of audiophile gear.
     
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  17. Armaegis

    Armaegis Friend

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    Their page states it's not a regulator... looks possibly like a transistor cap multiplier (at least that's what my google-fu tells me).
     
  18. purr1n

    purr1n Finding his inner redneck

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    Still wondering WTH is that package with the heatsink.
     
  19. Armaegis

    Armaegis Friend

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    Trimpot to control the voltage drop and amount of heat dissipation off the transistor? (wild guess)
     
  20. Scott Kramer

    Scott Kramer Friend

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    @purr1n Re: Allo Cap Multiplier
    Screen Shot 2020-06-06 at 2.57.29 PM.jpg
    From my box of Allo back in the day... I never played with that cap multiplier... thought it was meant to be used with their classD volt amp only (also have not tried) -- it needs a 19volt laptop* power supply, it's odd. Close up:
    *not kidding... my relic dell friggin' latitude powersupply fit the connections on this thing Not sure what they were thinking. (and why it's in a box)
    IMG_0124.jpg
    When I first saw it, though it was for an instant burst of current to the amp if needed.
     
    Last edited: Jun 6, 2020

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