can anyone understand this ground loop issue

[Bending]

I have a somewhat unconventional system as it uses line level crossovers:
Naga streamer - SDIF coax -Mola Mola DAC - XLR interconnect 1- Xkitz active crossover -XLR interconnect 2 - Hypex Nilai mono amps to woofer
and from XLR interconnect 1 to Orchard Audio Starkrimson 25 mono amp to bending wave driver
I used as XLR interconnect 1 Neotech Nemoi 3220 which are 2 central ribbon conductors with a double shield connected to pin 1. With cable there is no noise at all.

Then I decided to build a simple tri-braid cable using silver conductors (AST). That cable sounds significant better but I was getting noise typical for ground loops with the Starkrimson 25.

Both cables have low resistance (below I can measure reliable with my meter) and that should not be anyhow an issue with an amp with 44kΩ input impedance. The Neotech cable has higher capacitance than the tri-braid cable what should be expected as it is basically a coat cable with 2 internal conductors but capacitance should not have any influence.

If I am using that tri-braid cable with the Nilai amp there no noise at all with either woofer or bending wave driver.

I connected the ground post of the Nagra steamer with the case to the Mola Mola DAC and the noise disappeared.

So why has one cable causing ground loop noise, both have a Pin 1 connection with similar resistance, likely because of using a copper braid the Neotech cable even lower.
Why is it amp specific? Why connecting streamer ground to DAC case eliminates it (both are connected to the same outlet so identical ground potential at power cord)?

 

[Bwaslo]

Is there continuity between yhe metal shells on each cable?

 

[Bending]

no the connector shells are not connected on both cables

 

[terryforsythe]

no the connector shells are not connected on both cables

I would try grounding the shields at both ends to determine whether that helps or makes the noise worse.

 

[Bending]

there is no shied on the tri-braid cable, so it has lower capacitance, the other one I could experiment with also connecting the connectors but that does not have any noise issues anyhow so it could only get worse. I am planning to test a shield on the tri-braid but I would expect not better sound but may be less noise.

 

[terryforsythe]

I am planning to test a shield on the tri-braid but I would expect not better sound but may be less noise.

I wouldn't bother.

This is your biggest clue:

I connected the ground post of the Nagra steamer with the case to the Mola Mola DAC and the noise disappeared.

Do both of those units use power cables with 3 terminal plugs (hot, neutral and ground), or is one only two terminals?

 

[antcollinet]

I have a somewhat unconventional system as it uses line level crossovers:
Naga streamer - SDIF coax -Mola Mola DAC - XLR interconnect 1- Xkitz active crossover -XLR interconnect 2 - Hypex Nilai mono amps to woofer
and from XLR interconnect 1 to Orchard Audio Starkrimson 25 mono amp to bending wave driver
I used as XLR interconnect 1 Neotech Nemoi 3220 which are 2 central ribbon conductors with a double shield connected to pin 1. With cable there is no noise at all.

Then I decided to build a simple tri-braid cable using silver conductors (AST). That cable sounds significant better but I was getting noise typical for ground loops with the Starkrimson 25.

Both cables have low resistance (below I can measure reliable with my meter) and that should not be anyhow an issue with an amp with 44kΩ input impedance. The Neotech cable has higher capacitance than the tri-braid cable what should be expected as it is basically a coat cable with 2 internal conductors but capacitance should not have any influence.

If I am using that tri-braid cable with the Nilai amp there no noise at all with either woofer or bending wave driver.

I connected the ground post of the Nagra steamer with the case to the Mola Mola DAC and the noise disappeared.

So why has one cable causing ground loop noise, both have a Pin 1 connection with similar resistance, likely because of using a copper braid the Neotech cable even lower.
Why is it amp specific? Why connecting streamer ground to DAC case eliminates it (both are connected to the same outlet so identical ground potential at power cord)?

I am struggling to understand your connection set up. It would be useful if you could provide a sketch identifying the devices and the interconnect being used. A photo of a hand drawn sketch would be fine. Also good if you can indicate positioning of components relative to each other and length of interconnect.

It is difficult to see how you are getting audible ground loop noise with balanced interconnect unless one of the cables has a fault or is not wired correctly.

And forget about cable capacitance - unless you are going ridiculous cable lengths it is not going to audibly impact the sound. You don't need to jump through hoops to minimise it.

 

[sam_adams]

there is no shied on the tri-braid cable

This defeats the purpose of a Shielded Twisted Pair (STP) balanced connection for noise immunity. It also presents a higher impedance path for inter-chassis ground currents as compared to a braided or spiral shielded cable.

so it has lower capacitance

Unless you measure your 'cable' properly, with an LCR meter, to determine the actual capacitance of your 'cable', you are fooling yourself.

 

[Bending]

I wouldn't bother.

This is your biggest clue:

Do both of those units use power cables with 3 terminal plugs (hot, neutral and ground), or is one only two terminals?

All the equipment has power cables with ground. Everything is on the same circuit, the DAC and streamer are even in the same wall outlet, the amps have a different wall outlet but only 6 feet away. One experiment I just did is using a cheater plug to lift ground either on the streamer or DAC. No ground connection on the steamer has no influence on the ground loop noise but when the DAC has no ground connection the noise goes away either with or without DAC case connected to streamer grounding post. I am not sure I would like to use the DAC without safety ground

 

[terryforsythe]

Naga streamer - SDIF coax -Mola Mola DAC

I connected the ground post of the Nagra steamer with the case to the Mola Mola DAC and the noise disappeared.

Have you tried a different coax cable? It's a long shot, but worth a try; I have had issues with the shield coming loose from the connector, but those cables had been around for a while. If you don't have a spare coax cable lying around, just try something inexpensive off of Amazon for test purposes.

If that doesn't work, I would connect a wire from the Nagra ground post to the Mola Mola case and be done with it.

 

[Bending]

Have you tried a different coax cable? It's a long shot, but worth a try; I have had issues with the shield coming loose from the connector, but those cables had been around for a while. If you don't have a spare coax cable lying around, just try something inexpensive off of Amazon for test purposes.

If that doesn't work, I would connect a wire from the Nagra ground post to the Mola Mola case and be done with it.

I have 2 coax cables and could measure continuity of the shied on both cables. Yes the Nagra ground post to the Mola Mola case works but I don't understand why, especially as the coax ground connection is fine

 

[terryforsythe]

Yes the Nagra ground post to the Mola Mola case works but I don't understand why, especially as the coax ground connection is fine

Some devices use a digital audio pulse transformer for ground isolation on the S/PDIF output. Hence, their grounds may not be connected via the coax cable. (That is why I called trying a new cable a long shot).

 

[antcollinet]

There should be no audible ground noise if the cables between DAC and Amp(s) are properly balanced, even if there is a ground loop. Start there.