ISO Regen performance Improvement Cheap!

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11 minutes ago, totoxio said:

I use a Singxer F1 to feed my Chord Mojo. It has isolation after the conversion to I2S  and a DC-DC isolator. I use a Jitterbug, a LT3045 board and a ferrite bead before the Singxer to filter some high freq noise. Not as effective as more complete options, I guess, but I read that people who use those solutions are reporting the same benefits with the CAT cables for DC. 

And (high frequency) noise is AC.

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44 minutes ago, mansr said:

If noise blocking has anything to do with it, a purpose-built filter would be preferable over a cable that randomly happens to have suitable properties.

An (extra) active filter may throw back more noise to its input (and from there into other audio gear) than it clears at the output. A passive cable that simply rejects common mode noise by virtue of its geometry might be preferable..

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33 minutes ago, mansr said:

Who said anything about an active filter?

Could a passive filter with capacitors and inductors reject common mode noise?

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33 minutes ago, mansr said:

Since a cable is merely a distributed network of resistance, capacitance, and inductance, it follows that a network of resistors, capacitors, and inductors in their usual component form can do whatever a cable can and more since the component values can be chosen freely.

Hm.. I think the geometrical action of a cable (e.g., a noise canceling effect of the twisted pairs of an ethernet cable) can't be modeled in a passive filter consisting of resistors, capacitors and inductors, which can only be a network of high- and low-pass filters.

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13 hours ago, marce said:

A common mode choke can very effectively....

 

Thanks. But for an ethernet cable to function as a common mode choke filter, POE should use the two wires of a twisted pair for DC power and return connections, i.e., solid colored wires for (positive) power and dashed white wires for (negative) return. The POE adapters don't do this. As @mansr stated above, they connect both wires in one differential pair to the negative side and both wires in another pair to the positive side of the DC power supply.

 

So, it seems that most mechanisms thought to be at work in tightly twisted pairs (e.g., common mode noise rejection, impedance matching of the two conductors which helps common mode noise rejection, reduction of inductance and inter-wire capacitance) don't apply to POE.

 

Perhaps the twisting of two conductors for each DC connection cancels out the magnetic field that a single wire would generate around itself, thus preventing it from inducing noise into the other twisted pair and/or other audio gear. I wonder how relevant this can be for a DC power cable/connection?

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8 hours ago, marce said:

Second reading a cable cannot act as a common mode choke! As said use a ferrite on the cable.

Well, I think a single twisted pair of wires for DC positive and negative conduction could function exactly as a common mode choke. But PoE doesn't do this because both wires in one twisted pair are connected to the negative side of the DC power supply and both wires in another twisted pair are connected to the positive side.

 

In this configuration a possible mechanism for PoE to improve SQ is that each twisted pair cancels out the magnetic field that a single wire would generate around itself, thus preventing it from inducing noise into the other twisted pair (or in other audio gear). The specific shielding of the Ethernet cable may also be an important factor..

 

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19 hours ago, mansr said:

You might think so, but you'd be wrong. Sorry, that's just how it is.

 

No, it wouldn't do that. The magnetic fields from two roughly parallel conductors carrying current in the same direction do not cancel. At a distance of an inch or more, the magnetic field will be very close to that from a single conductor.

I was thinking that because in a twisted pair both wires are tightly coiled around each other in opposite directions, their respective magnetic fields may be (partially) canceled and/or HF common mode noise may be attenuated. But I accept your opinion..

 

Then the only possible mechanism left for SQ improvement with PoE relative to a regular (star quad) DC cable, seems to be specific isolation and/or used dielectric materials of an ethernet cable.    

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22 hours ago, mansr said:

If the current flowed in opposite directions, sure. In this case (PoE), the current flows the same direction through both wires of a pair, the return being a different pair.

Just for my understanding, doesn't the 'corkscrew rule' indicate that if two wires are twisted in opposite direction then current in the same direction will generate opposing magnetic fields in both twisted 'coils' that will (partially) cancel each other out? The same corkscrew rule would then suggests attenuation of AC (noise) in a twisted pair, even if it's connected to one side of the DC power supply, the return being a different pair. And if the resulting AC impedance is (much) higher than DC impedance, each twisted pair would be a (HF) noise filter.

 

Sorry for repeating myself, just trying to understand what's happening here. It's difficult to believe that the SQ improvement as described in this thread is merely the result of proper shielding and dielectrics.. 

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40 minutes ago, mansr said:

That would be the case with two counter-wound coils. In a twisted pair, both wires turn in the same direction.

Yup. That was the error in my argument.  Thanks! So back to shielding and dielectrics..
 

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On ‎6‎/‎25‎/‎2018 at 6:15 PM, BigGuy said:

Do we have a theory as to why the addition of a Kemet, etc., across the v+ & v -  could have such an effect?

It seems that a polymer aluminum capacitor (e.g., Kemet A750) across DC input may improve SQ by DC buffering/smoothing, shunting AC noise (decoupling and bypassing), and fast transient response to load change. I will try it with my active crossover boards and if that works one might ask why such a simple, cheap and obvious tweak isn't implemented as standard in all audio equipment?  

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2 hours ago, mansr said:

You're the one saying adding an external capacitor improves the sound. Taking that at face value, the logical conclusion is that all those devices have inadequate internal power regulation.

According to @marce the quality of the main supply is as critical (for SQ) as is local decoupling and DC buffering close to each IC. The whole power delivery system has to be addressed. That would imply that if the main supply is inadequate then no amount of local DC buffering could remedy that. Now since polymer aluminum capacitors (such as Kemet A750) have very low ESR, low ESL and large capacitance, they have excellent response to transient changes in the load. So adding one directly at the audio device's DC input (close to the circuitry) makes sense and may well improve practically any (external) DC power supply and may therefore improve the *overall* performance of an audio device.. 

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10 hours ago, bit01 said:

Hi,

I find that the  screw terminals loosen with time. I do have to re-tighten them from time to time and would not think of shrink wrap over them. Do you have the same experience, if so how do you get around it, holes in shrink, bonded screw to housing, solder?

b.

Did you apply solder to the wire ends? Basically there's nothing wrong with a screw connector, but you should never tin the wire. A tinned wire will slowly give way to the screw's pressure and become loose.

https://electronics.stackexchange.com/questions/29861/tinning-wires-that-will-be-screwed-in-to-a-chocolate-block-terminal-strip
 

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11 hours ago, sandyk said:

That is exactly what I do, and for the same reasons.

Neither is there anything wrong with tinning just the tips of the group of wires to keep them together, as they also pointed out..

Just do *not* apply solder on the copper strands of a wire when using a screw connector. As said, tinned wire strands will give way to the pressure of the screw and become loose. Simply twist the copper strands together and tightly lock the screw. That will be an excellent non-degrading, non-loosening connection.  
 

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14 hours ago, sandyk said:

...

If you will be often removing and reinserting the lead(s) with prototype equipment, then lightly tin the leads after twisting them tightly before reinsertion

...

Why do you insist on tinning the leads? Are you trolling? People should *never* apply solder in any way to the leads when using screw connectors. As I said multiple times by now, tinned wire strands will give way to the pressure of the screw and become loose. I know this from personal experience. Prototype equipment or not, tinning wire when using screw connectors is *asking for a problem*. Just don't do it, regardless what @sandyk says.

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10 hours ago, charlesphoto said:

... To tin or not to tin won't make that much of a difference on a dc supply I wouldn't think. 

Yeah, I "wouldn't" think so too. A bad (loose) connection will introduce resistance and thus lower (DC) voltage or worse, short your DC supply. If you think "that won't make that much of a difference" then by all means go ahead and tin the wires before inserting them in screw connectors. The connections will come loose, guaranteed. One here (@bit01) complained about loose screw connections. Although this individual didn't bother to respond to my query, I'm pretty sure he/she tinned the wires. Anyway, I'm done with this. Too much trolling.  
 

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56 minutes ago, charlesphoto said:

 

I’m sure you are correct. My point is we don’t need to take this so seriously. Thanks for proving my point.

Why shouldn't we take this seriously? Can't you read?

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5 hours ago, charlesphoto said:

Because it's a hobby, and no one is being torn away from their families and locked up in cages. Also, like I said before, if we were discussing ac cabling and supply that would be a different matter regarding safety. Certainly any advice is great to have and taken on board by all who come here, so thank you for that. Just chill on the tone and trolling accusations - it's not helpful or needed. 

In case you didn't notice, most participants in this thread take DC cables very seriously. Not that their lives depend on it, but that's just your personal definition of 'serious'. And I didn't say a word about possible safety issues, that's all in your own head. Now, if DC cable topology and/or used dielectrics can make a significant SQ difference, then imagine what a bad connection could do. So I simply made a reasonable statement and tried to warn against a common and serious (SQ-wise) mistake: tinning wires when using screw connectors; only to hear you reply that "it won't make that much of a difference on a DC supply". You think that's a proper helpful response? I call that trolling.

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14 minutes ago, Ralf11 said:

He's right about the possible damage form stray or loose strands.  And it is hard to get them all.

We are talking about a one time build of a (hopefully) good quality DC power cable. And if a strand makes a short then the power supply fuse will blow, that's all.

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33 minutes ago, charlesphoto said:

So which is it? Tin or not tin? Since it seems there can be no consensus as to which is best or safest that’s why I said maybe we should all just chill and not take either “side” so seriously as there’s always more than one way to approach just about anything. 

Not tin. To obtain a high quality screw connection there is only one optimum connection method: tightly twist the bare strands of the wire, insert it and tightly secure the screw. This is an excellent non-degrading connection even suitable for high voltage (AC) applications.

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48 minutes ago, marce said:

!!!!! better remove the solder from all the components in your amp etc. then!

The point is that first tinning a wire and then connect it in some kind of screw connector (e.g., the output connectors at the back of an amp) is a bad electrical connection that will come loose. Must I really explain this again for you? Don't you understand this is different from soldered connections on a PCB?

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36 minutes ago, marce said:

What are you going on about... Cut your patronising attitude for a start, the comment was in reference to AnotherSpins comment about tinned copper wires causing the sound to be bad, it was a slight dig as I cannot see how a bit of tinning would make the sound so bad.

...

Sorry, it must be my frustration about not being able to get this simple concept across to even people like you with lots of hands-on experience (though maybe less experience with screw connections). One more time: *When using screw connectors, tinned wire strands will give way to the pressure of the screw and become loose.* Such a connection is almost guaranteed to degrade and must be re-tightened many times before it finally settles. Even when tinned very lightly, why take the risk? Note that many people here use screw connections to the terminal plugs of their DIY DC cables and apparently are unaware of this pitfall.

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1 hour ago, marce said:

As said I don't do it for proper work, but when messing around at home I will often tin the wires to stop it all fraying, when doing a permanent connection with stranded wire I will use a boot ferrule.

Right, and also with a boot ferrule I wouldn't tin the wire strands. I hope this can be the last words said about the subject.

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3 hours ago, charlesphoto said:

“Aye, ‘tis nobler in the sound to tin or not to tin, or to suffer the slings and arrows of the internet forums, that is the question.”

You sound as if you have a personal problem with not tinning wire strands. Is it because you now must redo multiple DC cables (and maybe other connections) that you did with screw terminals and tinned strands?

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8 hours ago, genjamon said:

Ok, after 8 pages of debate about the best way to tighten a screw, I have something actually substantive to report regarding sound quality impressions and DC cabling.

...

A screw is best tightened with a screw driver. And in case you didn't realize this, bad (screw) terminal connections will add resistance and noise to the output of a (DC) power supply which will more substantively impact sound quality than any specific choice of DC cable.   

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26 minutes ago, Superdad said:

... for the LT3042/45, anything more than the required 10uF “stability” cap is technically going to reduce their performance. ...

Do you mean a 10uF cap is required for the Iso Regen, i.e., it is already build into it?