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RE: Effect of ferrite beads on dc power lines too P24, P4 and/or too Pico PSU’s

Mark & Theob,

Thanks for the topic, articles/posts, and experiences using ferrites. Very helpful.

I had done an experiment this week that I'd hoped to post about this weekend... And this is a good prod for me to do that!

One thing I did a couple of months ago was implement an SSD for my Op System & my musical favorites (Thanks Mark, Rick, and others who pioneered this!). The rest of my library still resides on an HDD. When I did that, I grafted a 2nd SATA power connector onto the cable coming from the linear regulator on my 'dirty' supply. But I thought that there might be some additional benefit available by adding a separate regulator for each drive... And mounting each close to the drive right at the SATA power connector.

Last weekend, I built these modules/power connectors up using LT3080's as regulator chips & implemented them. They provided a useful SQ increase... Mostly audible to me as a slight lowering of the noise floor and increase in the noticable details. I had not expected it to be a huge change and it was not... Useful, well worth the cost in parts and time, but not something that should be on anyone's top-ten mods list.

But I've also been pondering the use of ferrite chokes on the power side of a computer music setup. This all started after I read Inmate Maxamillion's post (http://www.audioasylum.com/cgi/t.mpl?f=tweaks&m=174374) about the impact of using these chokes on the power cords of all the other pieces of equipment in your home that generate electrical noise... Mostly where there are motors, SMPS's, and/or microprocessors in computers and their power supplies, cell phone chargers, appliances, etc. I had a few chokes I'd gotten back in the late '80s & the 90's that I'd tried on audio equipment power cords & interconnects with at best mixed results... Generally everywhere I tried them back then, they didn't do much if any net good.

But putting them on all of the power cords of the items in my house that I listed above made a very significant difference in my system... Again, lowering the perceived noise. This made the highs much more defined, refined, and 'analog-like'. A nice un-expected result was a lowering of the 'mud' in the bass regions and increase in definition there too. I've yet to try the ones recommended in that thread from DigiKey... Need to get an order into them and see if I hear the same improvements Maxamillion observed.

But in a complex cMP setup (like mine with 11 different linear supplies), there are a number of 'dirty' supplies that might benefit from chokes. This is different than what I tried back in the '80s/'90s because most of my equipment then didn't have separate supplies for the 'dirty' vs the 'clean'... And the 'dirty' supplies then were just not as 'dirty' (think turntable motor or early CDP microprocessor control system versus a full PC for a cMP).

So I tried them on the raw DC power feeds to the HDD/SSD regulators/connectors and got a nice SQ pop there, subjectively larger in magnitude than originally installing the regulator/connectors (although I strongly suspect that without the local regulators separate for each drive, the difference would have been much smaller). Adding one to the 12v DC feed to the Zalman screen increased the effect.

I suspect the mechanism here is that the ferrites are reducing the noise feed back both into the power line and into other equipment (from HDD to SSD, from Zalman screen to the USB power as they share the same raw DC supply).

After that experience, I was thinking along the same lines as what you tried, Theob and you suggested Mark... Putting ferrite chokes on both the DC feeds to the rest of the 'dirty' components (USB power & P4) and also on each of these supplies' AC lines. I'm also planning to try them on the 3.3v, 5v, and 12v lines from my ATX linear supply to the motherboard and also my Juli@ & DAC supplies. All of these are linear supplies in my system and I'm not sure what the impact (if any) will be... But it's an easy & cheap experiment. I suspect the impact will vary based on where noise is being generated & what paths it can take. For example, I don't expect the same result that Theob had putting one on my P4 connection since I have a fairly-quiet linear supply powering it. But it still might be useful... Or not.

Another comment on the use of chokes in power supplies that I found interesting was here http://hifiduino.wordpress.com/2011/05/13/update-to-the-musiland-power-mod/#more-1507.

So again, thanks Mark for starting this thread & posting links to a lot of good reference material... And Theob for contributing the first listening comments and data points.

I do think there's a lot more that we can do regarding noise elimination in our systems. In other posts, Inmate Elizabeth discusses using conductive foam to absorb RFI noise in her equipment. And then there's the 'Mask of Silence' & 'Stealth Mat' being used by Arcam to great reviews in their recent equipment. Search the web for references to these terms & you'll find info that suggests the 'Mask of Silence' is ferrite sheet applied to noisy IC chips and that the 'Stealth Mat' is something similar to (or maybe identical to) ERS cloth. All of these are readily available, the conductive foam and ferrite sheet from suppliers like Digikey & Mouser (but VERY expensive) and the ERS cloth from specialty audio component suppliers like Michael Percy & the Parts Connexion. I am sure there are some great applications of all three of these materials in our cMP machines.

Then there's grounding. I think I've done a pretty good job grounding my linear ATX/P4 supply, with all grounds coming back seperately to the motherboard ground. But I know there are improvements I can make to my 'dirty' supplies where my USB power is actually grounding through the power supply connection for the Zalman screen (as they share the same raw DC supply... Thanks to Rick McI for pointing this out!). A few comments on grounding & power supplies by Paul Hynes towards the end of this thread are worth noting & pondering :http://www.audiocircle.com/index.php?topic=89251.0.

And finally, here's another use for ferrites chokes that I haven't tried yet, but looks to be worth checking out, is on the Bud Purvine-inspired ground-thingies... Either the commercial versions or the homebuilt variants. Inmate Elizabeth posted about that in these two posts (among others):

http://www.audioasylum.com/cgi/t.mpl?f=tweaks&m=177504

And

http://www.audioasylum.com/cgi/t.mpl?f=mug&m=173649

Edit... Theob, I went back & re-read all of these two threads & see that you were already in the thick of them. Have you tried the ferrite-varation ground-thingees yet?

Greg in Mississippi

P.S. Another ground-thingie-related tweak is the use of capacitors across them as discussed by Inmate Unclestu here: http://www.audioasylum.com/cgi/t.mpl?f=tweaks&m=177294.

P.P.S. My next things to try are trying the high-current Belleson regulators in my linear ATX/P4 supply (hopefully this weekend... And again, thanks to Rick McI for pointing these out) and implementing a couple of different DACs to try... the Buffalo II DAC that's been sitting here for over a year & a new tiny DAC card using the ES9022 from DIYAudio poster EUVL (see here http://www.diyaudio.com/forums/digital-line-level/151846-anybody-using-new-ess-vout-dac-es9022-3.html).

The EUVL DAC may be especially promising for mounting on a modified Juli@ with an I2S connection... It is easy to implement as it only needs 9v & 6v power (easily supplied by batteries if that's your power of choice), it has it's own reclocking circuit (although EUVL's latest findings are that there are better ways to implement the clocking than how he did it here... Which is very similar to what Twisted Pear does in their ESS-based DACs), and it is very small & self-contained... And best yet, not terribly expensive.

Everything matters!


Edits: 05/28/11
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