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Do USB Filters Make DACs Sound Better? (Video)
- Thread starter amirm
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charleski
Major Contributor
I have one pair of AudioQuest cables that I bought back in the '90s. They failed after less than 2 years and I had to resolder the connectors (idiotic solid-core wires with insufficient strain relief), so they've been gathering dust at the bottom of my cable box for a couple of decades now. The one criterion for cables that actually matters is that they shouldn't fall apart is you look at them too hard.
solderdude
Grand Contributor
A Filter with a with a high common mode impedance (at the Frequency causing the problems) can also solve real world problems.
The thing is it can solve problem only if the are present. if there is no problem it can't magically improve it
(it can only maybe change some thing and making it worse)
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solderdude
Grand Contributor
Do you SEE any 'high common mode' filters in there in the dog-teardown device ?
Ground just passes and carries all common mode crap.
The 5V is just LC filtered and data has some small caps (on high speed they might actually cause jitter)
In your case wind the USB cable a couple of times (max. 5) through a ferrite and you can filter some common mode noise (mostly radiated) from that USB connection. It will absolutely not solve any ground loops. It can't. A real common mode filter would filter both the ground and +5V on a ferrite ring with windings in opposite directions so the core does not saturate. There you have the difference between common mode filter (which often also sa caps that filter differential mode as well) and a simple ferrite.
Ground just passes and carries all common mode crap.
The 5V is just LC filtered and data has some small caps (on high speed they might actually cause jitter)
In your case wind the USB cable a couple of times (max. 5) through a ferrite and you can filter some common mode noise (mostly radiated) from that USB connection. It will absolutely not solve any ground loops. It can't. A real common mode filter would filter both the ground and +5V on a ferrite ring with windings in opposite directions so the core does not saturate. There you have the difference between common mode filter (which often also sa caps that filter differential mode as well) and a simple ferrite.
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This site, and the recent videos which have the ability to reach a broader audience are restoring my hope for the world.
As a Roon user I originally tried taking part in discussions on their community but after the second or third massive thread about roons sound quality vs other bit exact playback software, and even roon 1.7 vs 1.8 I had to abandon ship.
You may say that this is hyperbole, and there are far more important things in the world to be concerned about. But having the wool removed from your eyes (and ears) in one domain hopefully will lead people to think more critically in general.
Companies sell bogus products because they can, and because people buy them and convince themselves they are effective. This happens in all parts of our lives. Politicians make bogus claims because they can, and people believe them. And so on.
As a Roon user I originally tried taking part in discussions on their community but after the second or third massive thread about roons sound quality vs other bit exact playback software, and even roon 1.7 vs 1.8 I had to abandon ship.
You may say that this is hyperbole, and there are far more important things in the world to be concerned about. But having the wool removed from your eyes (and ears) in one domain hopefully will lead people to think more critically in general.
Companies sell bogus products because they can, and because people buy them and convince themselves they are effective. This happens in all parts of our lives. Politicians make bogus claims because they can, and people believe them. And so on.
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No. and i'm not advocating for this (probably overpriced?) "audiophile" device(s).
I just made a very general statement of "Filter with a with a high common mode impedance can also solve real world problems"
(High being relative therm, solve can mean reduce, and of cause this only applies to some special problems)
This is what i meant and hope you don't take offense from it.
In some special case with a badly implemented source, that happen to have Noise at just the right frequency for this LC filter on the 5V line.
In combination with some special very badly implemented DAC with bad noise rejection...
For a very unlikely combination of special problem and very badly implemented hardware combination (that might not even exist jet)
the mentioned product could potentially(maybe) make it a measurable less worse.
Other produces would be better and the money would be better spend on a new DAC or something.
Not saying it makes a real world difference not saying its a good product!
Marketing it as magic universal cure for all sorts of problems is of cause verry bad marketing ***** one could potentially call it fraud*.
(*But im sure they made there legal work to make sure you can't)
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solderdude
Grand Contributor
Correct, the manufacturers claim is they make an audible differences and suggests in all cases and the more the better.
These devices do nothing but change ones mindset so owners believe it sounds better (and will to most).
All snake-oil despite maybe in specific situations with poor designed dongles there may well be somewhat lower noise floor.
Common mode filtering these devices do not (at least not the jitterbug)
I don't.
My remark about differences between common mode filters and ferrites about cables what indeed a general thing and applicable to the jitterbug.
Those that want the filter to do a little bit about HF common mode crap filtering can run the USB cable 3 to 5 times though a ferrite ring.
These devices do nothing but change ones mindset so owners believe it sounds better (and will to most).
All snake-oil despite maybe in specific situations with poor designed dongles there may well be somewhat lower noise floor.
Common mode filtering these devices do not (at least not the jitterbug)
I don't.
My remark about differences between common mode filters and ferrites about cables what indeed a general thing and applicable to the jitterbug.
Those that want the filter to do a little bit about HF common mode crap filtering can run the USB cable 3 to 5 times though a ferrite ring.
Digest? I though the dog had only chewed it a bit.
@amirm in response to an earlier comment about video presentations, I do appreciate your commentary on your written review, you go a long way to explaining what you are measuring and why. Sometimes I am left wondering, due to my ignorance, what criteria and level are important, but hopefully, I will learn to understand this a little with time.
Perhaps, if you are feeling generous you could create a few seminars on the criteria touched upon in your measurements? A few examples might be noise in various systems, jitter etc plus there is a whole world of awe for me relating to your speaker testing.
Many thanks great site.
Perhaps, if you are feeling generous you could create a few seminars on the criteria touched upon in your measurements? A few examples might be noise in various systems, jitter etc plus there is a whole world of awe for me relating to your speaker testing.
Many thanks great site.
I agree with you.
Yes.
That might be more of a theoretical/conceptual question:
would you agree that a usb isolator inside in a black box would look form the outside like a common mode filter with very high impedance at low frequency?
Since your edited your replay let me plese also respond to it.
I know what your trying to say. and in practice this might be right.
But it all depended on the the frequency(s) of the current(s) in side the ground loop.
If we are talking about Mains frequency's and harmonics. then your right!
But in the age of SMPS not all Ground loop frequency's are low.
Please don't take offense in this replay and before your explaining to me how uneducated i'm for using the wrong the terminology please consider my argument anyways.
I might need to explain concepts the seem obvious to you. i'm not doing so to insult you but to make sure we are on the same page.
The winding direction is the only thing that matters. it's the combination of winding direction and current direction that dictates the direction of resulting magnetic flux.
If the winding direction is the same but the current is equal but opposite the resulting magnetic fields will cancel out and not saturating the core.
I Know that's common sens to you @solderdude but please stick with me i'm trying to make sure we are on the same page and talking about the thing even if we apparently use different Names for it.
But that's a typical Common mode choke on a toroidal core for me. The winding is Called "Sectiona"l but one can also wound "Bifilar."
https://www.we-online.com/web/en/el...pbcm/blog_detail-worldofelectronics_63294.php
its constructed different but still the same as this:
Now we just reduce the number of Turns.
And this is why a simple ferrite is the same thing as common mode choke. (to me)
And the Core s not Saturating matter how mush current the usb device is drawing because of the same winding direction but opposite current direchtion ( 1A@+5V and -1A@USB_GND for example)
The core will/can only saturate from common mode but a common mode choke your describing would show the same behavior?
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solderdude
Grand Contributor
No. people will think it makes USB sound better. They do not care about why. reviewers and the manufacturer say so and thus it must be true.
I can never assume what's in a box. I would either have to see the schematics or the PCB and what's on it.
Mains frequencies and harmonics will not be filtered and are differential mode so they will not be filtered. RF components, caused by switching electronic equipment that are referenced to ground (and common mode) will be filtered. This is well above 20kHz and is more in the 100kHz to 100MHz range (depending on windings and ferrite material)
yes. That's the difference between a ferrite with a cable running through it and a common mode filter where 2 signal wires are separated and go around the coil.
Bifilar winding techniques are used to get the minimal possible inductance. It is also used in conductors in specific circuits.
Filters don't work until they do. I don't even think that's possible to work in any realistic sense. Shouldn't it need 1000-10000H while having near zero dc resistance?
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How about a “do digital filters make a difference in sound?”
REK2575
Active Member
Still angry at myself for throwing away $50 on one of these...
Its unconscionable that AudioQuest peddles these things, not to mention thousand-dollar cables that do nothing except empty your wallet.
Its unconscionable that AudioQuest peddles these things, not to mention thousand-dollar cables that do nothing except empty your wallet.
JohnYang1997 thy do work but its the manufachteres job to implement them inside of the devices.
Thats why you don't need extra external filters. The signal is already filtered.
https://www.we-online.com/web/en/el...bcm/blog_detail-worldofelectronics_108744.php
What i mean it in an (functional) "equivalent circuit" https://en.wikipedia.org/wiki/Equivalent_circuit
https://en.wikipedia.org/wiki/Two-port_network
the drop is current dependent the current of CPU/GPU is load determined and ther load varies well within the Audible range.
So USB GND might not be exactly the same Potential as Mains/Earth ground but actually a view mV or µV higer depending on laod/current.
If you connect it to an other mains/earth ground referenced USB device there might be commen mode curren flowing because of the potential difference. (with DC-MHz)
But the one wire going trough it is not one Conductor. its actually 2 (or more) wires in one comment case.
Therefore it is effectively Bifilar
And since i explained and as the this article explains its effectively equivalent https://www.we-online.com/web/en/el...pbcm/blog_detail-worldofelectronics_63294.php
With the Bifilar method having Less Differential mode inductance which is undesirable because the "ideal" common mode choke having only common mode impeance and no Differential mode impedance.
Would you be interested to further discuss this topic in a dedicated thread?
Thats why you don't need extra external filters. The signal is already filtered.
https://www.we-online.com/web/en/el...bcm/blog_detail-worldofelectronics_108744.php
I'm talking about the cheap ones from ebay/amazon they come usually without audiophile marketing
no no of cause it Can't never be assumed. but it would behave similarly.
What i mean it in an (functional) "equivalent circuit" https://en.wikipedia.org/wiki/Equivalent_circuit
https://en.wikipedia.org/wiki/Two-port_network
Yes, differential mode will not be Filtered only common mode.
Computers for example have many amps flowing trough the Mainboard etc. therefore causing some small voltage drop
the drop is current dependent the current of CPU/GPU is load determined and ther load varies well within the Audible range.
So USB GND might not be exactly the same Potential as Mains/Earth ground but actually a view mV or µV higer depending on laod/current.
If you connect it to an other mains/earth ground referenced USB device there might be commen mode curren flowing because of the potential difference. (with DC-MHz)
But the one wire going trough it is not one Conductor. its actually 2 (or more) wires in one comment case.
Therefore it is effectively Bifilar
And since i explained and as the this article explains its effectively equivalent https://www.we-online.com/web/en/el...pbcm/blog_detail-worldofelectronics_63294.php
With the Bifilar method having Less Differential mode inductance which is undesirable because the "ideal" common mode choke having only common mode impeance and no Differential mode impedance.
Would you be interested to further discuss this topic in a dedicated thread?
Are you sure it eliminates ground loop?
It depends on the filter. and the ground loop.
it its only a small voltage and current at a high frequency then yes this can be reduces by a common mode choke on the USB cable
If your talking about 60hz mains Hum then No
EDIT:
@JohnYang1997 the Liked filters of cause are only for the signals not the power lines. so this filters only filter the data lines
Reducing common mode (on the data lines) and limiting slew rate...
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H
Hifihedgehog
Guest
Yes, unfortunately culturally we have gravitated from online text to YouTube videos and podcasts for most things these days. That simple fact, for example, has killed off many non-specialized computer review websites who were not wise enough to expand into audiovisual content. I understand videos speak a thousand words or just say in one visual word things words never could properly convey, but I detest the current state of the medium. Most of these video "reviews" these days are just drones mindlessly regurgitating PR releases, ego-stroking and grandstanding, and only revealing the good while purposely concealing the bad. Because of that, I make it a point to only read articles when I research PC hardware, so AnandTech or bust for me. And I try to do the same with audio products when and where I can. Nonetheless, like you say, I think it is smart and even advisable to publish YouTube reviews because that is honestly the only way you can reach most people these days. Tyll Hertsens, who also on more of the objectivist side of the aisle in the world of audio, saw the value of it himself and he did the same at a point with InnerFidelity, in fact. Man, speaking of which, I wish Tyll was still around writing these days, or InnerFidelity would never have devolved into a clown show (which happened in thanks mostly to "audiophool" extraordinaire Rafe Arnott, who virtually banned half of InnerFidelity's original following from the site's comment section when they called him out for being manufacturers' lap dog) and finally the extinct dinosaur it now is.
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