So... that IFI thing is good?

By all accounts, yes. I had been recommending the Vaunix Lab Brick to people which is the same basic idea, but the the iUSB promises a much lower noise power supply than what Vaunix is using, and it's designed specifically to be able to handle Y-type USB cables such as those from Ridge Street and Acoustic Revive that the Vaunix isn't. For the same price, I think it's a no brainer. The SoTM card costs almost twice as much, and out of the box it needs to draw from the computer's power supply which of course is not ideal. You could rig up a battery supply for it, or use a custom one or a LPS, but that's even more cost, and I'm not sure exactly how much benefit there is vs. the iUSB.

Again I feel like I should point out that if you're hunting RF and EMI on a general purpose computer that changes clock speeds, is running all kinds of programs and services, anti-virus, etc. you are kind of wasting your time. General purpose computers make for bad hifi music players. If you want the best sound, you want your computer to do essentially NOTHING but play music. Taking that to the extreme would be a dedicated JPlay box in hibernate/overdrive mode which literally does nothing but play music, but a box with Fidelizer using Foobar, JRiver, or cPlay will at least get close.

By all accounts, yes. I had been recommending the Vaunix Lab Brick to people which is the same basic idea, but the the iUSB promises a much lower noise power supply than what Vaunix is using, and it's designed specifically to be able to handle Y-type USB cables such as those from Ridge Street and Acoustic Revive that the Vaunix isn't. For the same price, I think it's a no brainer. The SoTM card costs almost twice as much, and out of the box it needs to draw from the computer's power supply which of course is not ideal. You could rig up a battery supply for it, or use a custom one or a LPS, but that's even more cost, and I'm not sure exactly how much benefit there is vs. the iUSB.

Again I feel like I should point out that if you're hunting RF and EMI on a general purpose computer that changes clock speeds, is running all kinds of programs and services, anti-virus, etc. you are kind of wasting your time. General purpose computers make for bad hifi music players. If you want the best sound, you want your computer to do essentially NOTHING but play music. Taking that to the extreme would be a dedicated JPlay box in hibernate/overdrive mode which literally does nothing but play music, but a box with Fidelizer using Foobar, JRiver, or cPlay will at least get close.

I'm about to retire my Macbook aluminium late 2008 with core 2 duo CPU that can't go turbo so I can delegate that to a music player purpose for sure!

i have a custom encapsulated/shielded TX from SumR arriving in the mail.  for optimal wiring layout and TX placement i specified that the exit of the primaries and secondaries be opposite.  does this mean that reversing the primaries wrt N and L will have no effect on any potential induced hum if both are separated by the diameter of theTX?  or am i reading this incorrectly?

That would depend on how the transformer is constructed.
I realise I wasn't complete in the describing the shield in the transformer.
These aren't standard type of transformers.
I meant the screen is a separate layer of conductive material (that doesn't act as a short circuit winding) between the primary and secondary layer.
This layer must be connected to the common of the input filter and housing.

An encapsulated transformer is not different from any other transformer in an electrical sense.
A screened transformer (metal encapsulated) is normally (or should be) made from mu-metal and it's only purpose is to ensure no magnetic field lines (that could potentially induce small voltages in highly sensitive inputs) are present outside the transformer and should be present all around the transformer.

So to answer the question.
You still have to test for lowest leakage currents as they will be the same as with any unshielded transformer.

The best transformers (in this aspect) are R cores (or C cores), followed by E- core and the worst ones are the toroids.
In efficiency the best is toroid (and smallest in size) followed by R cores and then E cores.

Quote from: fishski13 on December 22, 2012, 03:28:50 AM

i have a custom encapsulated/shielded TX from SumR arriving in the mail.  for optimal wiring layout and TX placement i specified that the exit of the primaries and secondaries be opposite.  does this mean that reversing the primaries wrt N and L will have no effect on any potential induced hum if both are separated by the diameter of theTX?  or am i reading this incorrectly?

That would depend on how the transformer is constructed.
I realise I wasn't complete in the describing the shield in the transformer.
These aren't standard type of transformers.
I meant the screen is a separate layer of conductive material (that doesn't act as a short circuit winding) between the primary and secondary layer.
This layer must be connected to the common of the input filter and housing.

An encapsulated transformer is not different from any other transformer in an electrical sense.
A screened transformer (metal encapsulated) is normally (or should be) made from mu-metal and it's only purpose is to ensure no magnetic field lines (that could potentially induce small voltages in highly sensitive inputs) are present outside the transformer and should be present all around the transformer.

So to answer the question.
You still have to test for lowest leakage currents as they will be the same as with any unshielded transformer.

The best transformers (in this aspect) are R cores (or C cores), followed by E- core and the worst ones are the toroids.
In efficiency the best is toroid (and smallest in size) followed by R cores and then E cores.

makes sense.  i'll contact Richard at SumR for the details of the winding and take some measurements.  thanks!!!!