Simple power supply tweak using HDMI - amazing improvement!

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Re: Simple power supply tweak using HDMI - amazing improveme

Postby jesper » 01 Apr 2017, 00:38

Thanks Frank,
I like to learn too and learned a lot from others sharing their wins too. I still have to learn more about the RPi and programming it. I like to get a good Room EQ installed. Any tip on this is appreciated.

I have been tweaking speakers and audio equipment for quite some years, but I must admit these RPi:s are fun to tweak! :D

I have another tweak in the pipeline too - adding a Class A non-feedback balanced output direct from the DAC output. It´s LC Audio´s ZAPfilter 2, a really nice one. It´s without OP:s, just pure transistors. That might just set everything up into the strata... :D
Kind regards,
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Joined: 12 Mar 2017, 01:55

Re: Simple power supply tweak using HDMI - amazing improveme

Postby Audiohrdwr » 06 Apr 2017, 13:50

thanks for the info.
On the BOSS which uses 3.3V we have 4 caps:
1> 4.7uF ceramic after LDO
2> 22uF film
3> 0.1uF film
4> 0.22 F !!! Super cap. That's 220,000uF

We know that it takes about 50h to break in the film caps but from reports we got, it can take up to 2 weeks to break in the super cap.
Judging by your feedback and set up, you have golden ears and we don't doubt you heard an improvement after adding your 1.5uF capacitor but could it be that the capacitor in question was already broken in ?
Please confirm.
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Joined: 23 Sep 2016, 16:06

Re: Simple power supply tweak using HDMI - amazing improveme

Postby jesper » 18 Apr 2017, 23:01

Hi André,
The 1.5 uF polypropylene capacitor was not new but never used.

As you might be aware of, all capacitors of same size and materials does not always have the same specifics and characteristics in audio. What I used was a quality audio filter capacitor. Capacitors have different parameters and one important one is its inner resistance, which should be as low as possible, because it acts like a resistor in series. If that inner resistance is higher it blocks the delivery speed of electrons in and out of it and that, in audio, will result in a less stable voltage output. A wobbling output, even if very little, by my test results obviously disturbs the signal.

In this case the midrange improved noticeably, and it opened up the whole soundstage and especially voices became more natural and less "compressed".

If you have the BOSS DAC I urge you to try my two capacitor tweaks - it´s worth it! (at least if you have quality amp and speakers).
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Joined: 12 Mar 2017, 01:55

Re: Simple power supply tweak using HDMI - amazing improveme

Postby bertie » 23 Apr 2017, 13:15

Hi Jesper, these posts are so interesting!
If I had the slightest soldering skill :) I would have new capacitors soldered right way.
Still, at the rate new circuit boards are appearing I doubt it will be long until some manufacturer advertises a new 'low internal resistance' RPi with crazy-ass capacitors dwarfing the board and I will be their first customer.
I see you have an Emotiva processor, I use their stereo balanced XSP preamp and, like you, am very happy.
Thanks for posting your improvements
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Joined: 03 Mar 2017, 06:47

Re: Simple power supply tweak using HDMI - amazing improveme

Postby Waluan » 02 Mar 2018, 00:10

jesper wrote:Ok, an update on the Allo Boss DAC:

I kept playing it now for a while, but still up in about 20-25 hours, so it´s not yet run enough time for final decision. I can say it´s improving, but the mid range and voices I'm not satisfied with.

I decided to look into the Boss DAC's analog power and found that the DAC uses 3.3V, not 5V. this means there needs to be some proper capacitor to stabilise the 3.3V as well. Out with the DAC and solder another capacitor onto the board :D

I took a polypropylene capacitor of 1.5uF (ICEL MPL 160V K5 1.5uF 1%) and soldered it to the Boss DAC board at the big capacitor located between the PCM5122 and the left (white) RCA. It looks blue and yellow on's pic of the Boss DAC.

Now, the troubles in the mid range and voice are gone and the sound opened up - just an amazing improvement!
Now the sound is already fantastic! Wow!

So, the power supply of 3.3V MUST have a bigger, better capacitor to get the ALLO BOSS DAC to perform better in the mid range.

Now get out your soldering iron and a few capacitors and rock the place! I´d like to hear from someone who dared to try this tweak too. You won´t regret it (unless you don´t know how to solder)!

Hi Jesper,

Well, you inspired me! I have a Boss DAC v1.2 and I run it off independent power supply, ifi as well. Although I plan to do the power supply tricks you suggest in the future the Cap on the analog path of the DAC caught my eye as the easiest and fastest to try. So I tried to find a cap with similar specs to the one you mentioned and ended up buying a (Mumford Mcap Zn – 250 VDC 3% tin films condenser, Capacity (µF): 1.5).

And we soldered it. My impressions the middle frequencies became more crisp and clear and instrumental separation was better, also since I have a sensitive (right) ear that squeaks at high frequencies, it now is much more comfortable. REALLY GREAT! In short I felt most music sounded more audiophile and clean even when some of it clearly wasn't audiophile produced music.

However.... The bass went to the background and shrunk, loll. I mean it really went down.
I won't go back since i like the new sound more, but what can I do to save the low frequencies from limbo?? lolll

I am no expert at electronics but I am considering upgrading the super cap which Allo and others claim is a reason of these rich lows the Boss DAC is popular for.

The one on the Boss is rated at .2f 5.5v. will replacing it with a 1f or 2f alleviate the problem?
Would love to hear your and others suggestions on how to solve this issue.

Thanks again for your inspiring post!

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Joined: 01 Mar 2018, 23:48

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