Spectral amps and lifting their grounds

[Kingrex]

Ok, here is some fire. The problem is most likely in your amp. But its not going to ever be fixed, so you want a solution that won't end up killing you. People cheat grounds all the time and maybe 10 to 15 people around the world die because they did as such. Or so I read somewhere. Pretty small number.

The easiest way is to open the ground at the receptacle in the wall.

Davids idea sounds good, but since the signal is tied to the chassis in your amp, you will have a worse ground loop tying chassis to chassis.

The HumX is excellent for sources and low power amps. For high power amps I am considering making a product that is similar but will be much more robust and built with Furutech cable and receptacle. I am in the same boat. My amps hum as soon as a grounded source hits them. I have the ground lifted myself. I asked First Sound why my amps don't hum connected to his preamp. He said because he hates grounds. They are super noisy. His signal is not tied to the chassis.

For now, try a HumX. It's a basically an open circuit on the ground until enough current flows and it allows it to pass through. Mili volts wont pass but volts will. So when your transformer or something fails and 600 volts goes to your case, it will pass right through the HumX and open the circuit breaker. If your equipment is working correct, it will act as if there is no ground.

 

[DaveC]

Ok, here is some fire. The problem is most likely in your amp. But its not going to ever be fixed, so you want a solution that won't end up killing you. People cheat grounds all the time and maybe 10 to 15 people around the world die because they did as such. Or so I read somewhere. Pretty small number.

The easiest way is to open the ground at the receptacle in the wall.

Davids idea sounds good, but since the signal is tied to the chassis in your amp, you will have a worse ground loop tying chassis to chassis.

The HumX is excellent for sources and low power amps. For high power amps I am considering making a product that is similar but will be much more robust and built with Furutech cable and receptacle. I am in the same boat. My amps hum as soon as a grounded source hits them. I have the ground lifted myself. I asked First Sound why my amps don't hum connected to his preamp. He said because he hates grounds. They are super noisy. His signal is not tied to the chassis.

For now, try a HumX. It's a basically an open circuit on the ground until enough current flows and it allows it to pass through. Mili volts wont pass but volts will. So when your transformer or something fails and 600 volts goes to your case, it will pass right through the HumX and open the circuit breaker. If your equipment is working correct, it will act as if there is no ground.

Tying chassis to chassis if the system has only one ground point will actually reduce noise due to leakage currents, etc. It will also improve safety of the non-grounded component. There are literally no downsides. Noise is reduced because of ohm's law, V=IR. If V is the noise voltage created by leakage currents from power trafos, then I is the current that flows and R is the resistance it flows through. It's plain to see if R is reduced, so is V, and hence you get less noise by improving grounding.

IMO, it's likely you can modify your amp by adding a Schurter DENO between the IEC ground and chassis ground, this will probably work. I have used DENOs in some of my own components successfully.

 

[Kingrex]

Tying chassis to chassis if the system has only one ground point will actually reduce noise due to leakage currents, etc. It will also improve safety of the non-grounded component. There are literally no downsides. Noise is reduced because of ohm's law, V=IR. If V is the noise voltage created by leakage currents from power trafos, then I is the current that flows and R is the resistance it flows through. It's plain to see if R is reduced, so is V, and hence you get less noise by improving grounding.

IMO, it's likely you can modify your amp by adding a Schurter DENO between the IEC ground and chassis ground, this will probably work. I have used DENOs in some of my own components successfully.

An inductor is not the answer. It's more of a test tool. IMO. In some situations people think they hear a benefit with say the Environmental Potential EP2750. Choking current flow to ground can help slow noise, but its not a cure for ground faults. You need a brick wall. You want back to back diodes. That is what a humX is. A brick wall till the diodes capacity is exceeded, then current flows.

If your gear is as reactive as mine and supposidly his spectral, as soon as any equipment ground closes with the amps signal ground, the circuit is complete and milivolts of current flow causing the hum.

If his Spectral amps are just sensitive to ground noise, then a choke or inductor on the ground may work wonders. If his ground is noisy. He may also have a ground loop in his main distribution panel that is circulating around in there and manifesting itself at his high sensitivity audio rack. But its not a bother to his computer, tv, toaster etc so it's not noticed, till it is.

I also noticed the paint does not seem to be cleaned from the amp case where his grounds land. He could just have a poor connection at that spot.

Just tossing out thoughts. Ground loops are probably the most complex issue to resolve.

 

[Kingrex]

My assumption is that his amps signal ground is of high enough impedance the electrons are moving slower than the chassis ground. When he lands an interconnect from a properly grounded source, the electrons from the source signal ground run back up the interconnect to his amps and make a hum.

I have been told by people I trust that many manufacturers don't have grounding worked out as well as it could be. One small mistake is all it takes.

 

[Hiempie]

So I decided to open up my amps and do some dusting, and given the opportunity, take some pictures.

First the ground wire, from the socket (thin black, running against the grey transformer case) to the star-grounded screw. @Whbgarrett Did you remove your ground from that screw?

View attachment 70932 View attachment 70933


Next, anyone know what that red On/Off switch on the top-left of the power supply board is all about? I've been told it lifts the ground, others have said it's for testing purposes

View attachment 70934

Hi Ack I asked the same question about the proctecion board zipper More Music told me it is for testing purpose