Hypex Ncore

[nyt]

Having slight trouble figuring out the orientation of the XLRs - can you tell how they are wired (which wire goes to which pin)?

shield is wired to 1 and chassis, signal on 2 and 3.

 

[Julf]

shield is wired to 1 and chassis, signal on 2 and 3.

Good. Might be worth checking (using a multimeter) that the patch cable connects pin 1 to sleeve and pins 2 and 3 to tip and ring.

 

[nyt]

Good. Might be worth checking (using a multimeter) that the patch cable connects pin 1 to sleeve and pins 2 and 3 to tip and ring.

It does. lifting the ground on the patch adds a heap of hum. lifting 1 or 2 adds noise.

It's quite strange the motu works fine on a different amp :/ At a loss here. It's something to do with the combo I think.

 

[ds23man]

If I read the spec's correctly, the Motu has 8db more output.

 

[nyt]

If I read the spec's correctly, the Motu has 8db more output.

Not sure why that matters, this noise is when no signal is present.

 

[Julf]

Are both the amp and motu using grounded mains sockets? Are they plugged in to the same mains outlet?

 

[nyt]

Are both the amp and motu using grounded mains sockets? Are they plugged in to the same mains outlet?

The amp is not mains grounded. They're both plugged into same outlet.

 

[Julf]

It shouldn't really matter, but maybe try grounding the amp chassis?

 

[nyt]

It shouldn't really matter, but maybe try grounding the amp chassis?

Probably not a good idea connecting the earth ground directly to balanced ground. I lifted the ground on the motu though, and same issue.

 

[Julf]

Probably not a good idea connecting the earth ground directly to balanced ground.

Why not? You want to be sure both grounds/chassis are equal - lifting the ground just floats it.

 

[ds23man]

Not sure why that matters, this noise is when no signal is present.

Gain structure my friend. The Motu has 8db more gain, so your noise floor will go up by 8db on the same amp.

 

[nyt]

Why not? You want to be sure both grounds/chassis are equal - lifting the ground just floats it.

You're right, was thinking if it was unbalanced, derp. Either way, tried it, no change.

 

[nyt]

Gain structure my friend. The Motu has 8db more gain, so your noise floor will go up by 8db on the same amp.

The motu is one of the most silent interfaces I've seen. The issue isn't present when using another amp with identical gain. Just because it can run higher voltage, doesn't mean the noise floor increases.

 

[Julf]

Either way, tried it, no change.

Hmm. I am running out of ideas... 🙁

 

[nyt]

Hmm. I am running out of ideas... 🙁

Me too, hence my posting 🙁 I've run through just about everything I could think of.

 

[pieter t]

Try different line voltage groups; maybe it's an EMI related problem, or SMPS's which don't like each other.
It's not a gain structure problem.

 

[nyt]

Try different line voltage groups; maybe it's an EMI related problem, or SMPS's which don't like each other.
It's not a gain structure problem.

I'm leaning towards smps. What do you mean different line voltage groups?

 

[pieter t]

I guess your house electricity has different groups, each individually fused.

 

[nyt]

I guess your house electricity has different groups, each individually fused.

Oh, I tried it off a different phase from the amp, same noise 🙁

 

[pieter t]

That's not a different group.