ISO Regen performance Improvement Cheap!

[JohnSwenson]

As far as I can tell there are two possible things going on with this configuration:

 

1) sort of star quad

 

2) transformers in the path

 

#1:  these PoE adapters inject DC into the the center tap of Ethernet transceivers, the result is an almost star quad arrangement of the wires inside the Ethernet cable. The result of this is much lower inductance than a usual DC cable. See the DIY DC cable thread for details on using star quad cables for DC power.

 

The description specifically states this works for CAT7, which has shielding, has someone tried this with a same length CAT6 and found it only works for CAT7?  I'm not sure what these adapters DO with the shield connections, can someone do a continuity check of the setup above and see if the cable shield connect to the DC negative on the DC connectors?

 

#2 the DC power is going through the Ethernet transformers, this may offer some high frequency filtering, but it may also increase impedance, it is hard to tell without actually measuring.

 

I would like if a couple people that are already using a star quad cable DC cable could compare that with this configuration.

 

Thanks,

 

John S.

[JohnSwenson]

3 hours ago, sligolad said:

Thanks for the thoughts John.

 

Could be this particular implementation of Star Quad and wire gauge alright so would also be interested to hear feedback from someone with a good home made star quad compared to the plug and play option presented here.

 

The passive POE setup has no transformers involved so the 2 pairs in the network cable go direct to the positive and negative on the DC ends.

Works with all network cables i tried from CAT5 up but benefits improve as you go higher, CAT7 was best but someone suggests after tests that CAT8 (hard to find a cheap 1 metre) is even better so I have one on order.

 

There is no continuity on any of the cables i have between the shielding and the DC negative on the POE ends.

The only way to do a passive POE without transformers is two pairs for data and two pairs for power, thus limiting the Ethernet part to 100Mb. I know you are not using the Ethernet part, but is it rated at only up to 100Mb?

 

If there really are no transformers involved then this really is just getting something similar to star quad cable.

 

On the cable front, some cables use 24AWG and some use 23AWG wires. It MAY be that the 23AWG ones sound better. The higher CAT numbers have tighter tolerances on the wire geometry, I'm not sure this could have anything to do with a DC cable though.

 

John S.

[JohnSwenson]

I just got some bulk Supra CAT8 to try this out, how are people wiring this for DC cable? There are 4 twisted pair, each individually shielded. Is it just two pairs "-" and two pairs "+" or something interesting like all solids + and all stripes - ?

 

Boy is this stuff stiff though. The shielding around each pair is VASTLY thicker than the usual foil shield you see, which is usually  a few atoms thick of aluminum deposited on mylar. This actually looks like heavy aluminum foil bonded to the mylar.  The foil part is on the outside, so the foil from all the pairs touch each other. There is a sparse weave of wire around this bundle, which as far as I can tell is not an extra shield, it is just a "drain wire", an easy way to solder to the shields and tie all the shields together.

 

Anybody know what the material is around the wires? I could not find that out. It seems very soft, it might be a foamed material.

 

I have the setup to run an impedance VS frequency test, I can compare this and a Canare cable.

 

It might be a couple days before I can work on this.

 

John S.

[JohnSwenson]

4 minutes ago, charlesphoto said:

Wiring brown pair to orange pair for +ve and green pair and blue pair for -ve. I tried all solids and all whites but didn’t sound as good imo. 

 

So you’re saying that all of the foil from all of the pairs should be twisted together for the JSSG and not just the outer web? 

No, the outer web IS the way to solder to the shield, that's what it is there for. The foil is aluminum which is VERY difficult to solder so they add the outer wires made out of stuff that IS easy to solder to. The web and the foil is in contact all the way along the length of the cable. So you just need to solder to the web when connecting to the shield.

 

John S.

[JohnSwenson]

My current ideas as to what matters for a DC cable is inductance and dielectric absorption. The inductance is primarily determined by the geometry of the wires, and dielectric absorption is determined by the insulation on the wires.

 

Starquad is by far the lowest inductance geometry, much better than twisted pair, 1/3 the inductance.

 

PVC (a very common wire insulation) has very high dielectric absoorption, polypropylene and teflon are very low (100 times less than PVC).

 

I think what has been happening here is that different cables have been trading these two off with each other. With the multiple twisted pairs you get inductance higher than starquad, but things like shielding, how tight the twist etc. are causing some differences in the inductance, and different cables have different dielectric materials.

 

I really think we need to try true starquad with low dielectric absorption insulation. The Canare is true starquad but uses PVC.

 

VH Audio is now selling just such a cable V-Quad Cu21 and Cu24  (21 and 24 AWG conductors) with true starquad and very low dielectric absorption. I think this would be a very good cable to try. It's not cheap ($24 or $27 per foot) but it may just be a very good combination.

 

Another cable I have been using for interconnects is Belden 1804A, starquad with polypropylene, but 28 AWG. If you guys are finding that 28 AWG conductors are all right it might be a good candidate. It is a LOT cheaper than the above VH cable.

 

Just some thoughts.

 

John S.

[JohnSwenson]

On 5/29/2018 at 7:42 PM, lmitche said:

Over the weekend, I sent a length of the Gotham cable, a pair of POE adapters and a 1 meter Ibra cable to John Swenson.

 

I look forward to John's analysis.

 

Larry

It's going to be awhile before I can work on this. I have a whole bunch of high priority tasks right now and my wife has said I have to cut down on the number of tasks at the same time, I have been so stressed out over things my health is starting to suffer and I'm making bad decisions.

 

So until some of the other stuff gets finished I won't be able to add anything new to the task list. I'm still doing the little PC board for the Philmore adapter (that is going out tomorrow) which will make putting together test cables a lot easier, but that is about it right now.

 

John S.

[JohnSwenson]

19 hours ago, lmitche said:

Hi John,

 

Your wife is right, taking care of your health is job one! Please take it easy, you are in your retirement.

 

There is no need to stress out about this at all. We can easily listen to various cable choices and make observations and debate choices here. So take your time, and if you don't ever get to this task we will still be happy and grateful enjoying the wonderful inventions you have already shared through Uptone Audio, Sonore and directly here on CA. This should be all about having fun by using the time in retirement to indulge in satisfying those nagging curiousities about how this stuff works.

 

Deadline pressure has no place here.

 

All the best,

 

Larry

 

 

Today was our 21st anniversary, I took my wife on a dinner cruise on a river boat along the Columbia river. It was amazing. About 5 minutes out of the docks there was a FULL double rainbow across the river. This was the brightest rainbow I have ever seen, and the second bow was also full over the whole river. Simply stunning.

 

Oh yeah the food was fantastic we had a great time.

 

On the way home the sun set down the Columbia, we had been having storms go through the area all day so there were a lot of cloud formations all over the place. Not only did the clouds look amazing but it lit up the water of the river as well. Almost as great as seeing the rainbow.

 

Oh yeah and while we were all looking at the glorious rainbow the PA system was playing the song "True colors".

 

It was a fantastic day.

 

John S.

[JohnSwenson]

18 hours ago, BigGuy said:

Can someone, perhaps John, please explain again the working theories behind JSSG and JSGT.

 

I have been reading quite a lot (dangerous in itself) about generation and shielding of EMI and RFI and it seems like JSSG might be acting like a quasi Faraday cage.  The difference I see is that a Faraday cage, IIUC, is always grounded.  Rather than a wire or another shield (with insulating layer) attached to both ends of the first layer of post added shielding, would it not be better to attach that wire to a ground?

Here is the post where I covered shielding:

 

It IS like a Faraday cage, that is the whole idea, making a cable behave like a Faraday cage. Read the details in the post.

 

The other is a way to shunt high impedance leakage (note NOT high FREQUENCY, this leakage  is actually line frequency related) generated by SMPS. In my studies into leakage I found that SMPS generate some very high impedance leakage that is very hard to block, it will go all over the place because the impedance is so high. BUT it is easy to shunt to ground (actually the safety ground in house wiring, EARTH connection not actually necessary). It is a very simple concept, connect the negative output of the SMPS to the safety ground and the high impedance leakage is shunted around your system. I posted some simple adapters to do this with common SMPS . This is a big issue for computer audio since most computer systems, networking equipment etc use SMPS. 

 

BTW the traditional low impedance leakage is still there on both SMPS and linear supplies, but there are ways to deal with that.

 

John S.

 

[JohnSwenson]

3 hours ago, jabbr said:

John, so are you saying this Faraday cage is neededon the cable between theLPS1.2 and the ISO Regen? 

A DC cable with a leakage loop running through it (remember leakage loops are low frequency) will radiate the line frequency and harmonics which CAN be picked up by ordinary audio interconnects (the shielding on THEM doesn't stop the low frequency radiation, unless they do the shielding right). I HAVE been able to measure this.

 

In this case the proper shielding (JSSG) on the DC cable will prevent this from happening.

 

The LPS-1.2 will stop any leakage loops through its output, so the proper shielding should not be necessary. It MAY slightly change the inductance on the cable which MAY change sound, but that is not an actual shielding effect.

 

John S.

[JohnSwenson]

1 hour ago, jabbr said:

Are you saying that this is the reason it’s a factor with the LPS1.2 supply, because it has a buck converter? Does the leakage go around the solid state relays/bank switching MOSFETs?

The DC/DC switching converter inside the LPS-1.2 has nothing to do with leakage current. I have exhaustively tested that and it makes no difference.

 

There is some capacitance in the transistors used to switch banks (bipolars BTW, the ones I use have WAY lower capacitance than any equivalent MOSFETS). The low impedance leakage is blocked completely by these transistors, but some amount of the high impedance leakage from SMPS does get through. This is the reason for connecting the SMPS negative output to safety ground, it shunts the high impedance leakage back to the mains so there is very little entering the LPS-1.2, the transistors can easily handle this. The combination produces no detectable leakage at the output of the LPS-1.2. I can detect about -150dBV, what I see is the noise floor of the system.

 

The LPS-1.2 comes with an SMPS that already has its negative output connected to the safety ground just for this purpose.

 

Now if you don't HAVE a safety ground or it is not connected to the neutral of the mains, then the shunt won't be working. Note there is nothing about earthing in this. It is the fact that the safety ground has a low impedance connection to the neutral (or at least it should) which provides a path for the high impedance leakage to get back to the mains rather than going through the audio system.

 

John S.