To Float or not to Float...

I have a DeHavilland preamp which has a switch allowing one to "float" the ground. I’ve always used it in the "float" position, however recently, perhaps due to some connectivity issues with my interconnects, there is a small buzz emanating from my speakers with the switch in this position.

Like Erik said above, which ever way sounds the best.

perhaps due to some connectivity issues with my interconnects, there is a small buzz emanating from my speakers with the switch in this position.

You might try cleaning the male and female connectors with some isopropyl alcohol.

cleeds is correct about substituting the small gauge signal ground wire of ICs in place of the safety equipment grounding conductor of the power cord.

As for the ground lift switch on your preamp.... Do you know for sure what ground it actually lifts?
Does it lift the preamp circuit/ground from the chassis? (User safe)
OR
Does it lift the safety equipment grounding conductor of the AC power cord from the chassis of the preamp? (Dangerous, not user safe. I have read where some manufactures do this.)


https://positive-feedback.com/Issue12/dehavilland.htm

Right off the back, I had to deal with a minor hum problem that occurred upon powering up the UV. This happens from time to time with a component. Normally, I have to pull out my floater plugs, isolate the problem, and float the ground on that side. Fortunately, deHavilland placed a feature on the UV that I don’t see often enough on fine preamps: a switch on the back panel to float the ground. One flip of that switch fixed the hum problem immediately.

I noticed in the picture showing the switch it is right next to the IEC power inlet connector. Does the switch lift the AC mains safety equipment ground from the chassis? IF the switch does lift the safety equipment ground from the chassis then that is the same as using a ground cheater adapter to lift the ground at the wall receptacle outlet.
You can easily find out 100% for sure with a multimeter.

Jim

Thanks for all of your responses.  Cleeds triggered the solution when he (or she) wrote "a properly grounded power cord", which reminded me that I was having intermittent problems with the connecting plug of the preamp's power cord.  Swapped out the power cord and problem solved.  I also have a pair of DeHavilland mono block amps with the same ground/float switches, and in the manual it states that leaving the switch in the "float" position may result in a "cleaner sound".  At any rate, a fully functioning grounded power cord has done the trick... 

This is extremely dangerous - interconnects are not intended to carry safety grounds.

No it’s not as many sources have two pin mains plugs and rely on the ground from the next stage via the interconnect same goes for some preamps.

If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well.

Cheers George

georgehifi

If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well.

It is clear that you are confused about this issue. The matter of ground loops is only an issue when the grounds are of different potential. Having multiple safety grounds in an audio system is not itself an inherent problem.

As for interconnects carrying safety grounds again, you are confused, particularly with respect to balanced connections.

georgehifi
2,763 posts                                                                    09-13-2017 5:08am

 This is extremely dangerous - interconnects are not intended to carry safety grounds.

No it’s not as many sources have two pin mains plugs and rely on the ground from the next stage via the interconnect same goes for some preamps.

What if all the AC powered audio equipment uses two pin mains plugs? (There in the equipment uses internal double insulated AC power wiring.)

The safety equipment ground is for electrical safety. It is not needed for the operation of the equipment electronics or SQ, (sound quality), of the equipment. In fact sometimes an equipment ground can harm the SQ of audio equipment. It can introduce noise and of course, as cleeds said in his last post, it can cause a ground loop when a difference of potential, voltage, exists between equipment grounds.