Thanks, Jim. I also use the preamp with a solid state amp that has no ground lifting switch, and keep the preamp switch in the "float" position. Any danger in that??
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. The buzz disappears when I flip the preamp switch to the "ground" position. Irrespective of the buzzing, is there any sonic advantage (or disadvantage) to "floating" the preamp ground in this situation??
Thanks for your informed opinions...
Thanks for your informed opinions...
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- 41 posts total
@weebeesdad , No danger at all. The switch only lifts the audio circuit from the chassis ground. (The AC mains safety equipment ground) The AC mains safety equipment ground remains connected to the chassis at all times. In the event of a Hot to chassis ground fault event the safety equipment ground wire in the power cord connected to the preamp will carry the fault current to the wall receptacle equipment ground contact. Are you using the preamp with the SS amp at the present time with the switch on the preamp in the float position? I also use the preamp with a solid state amp that has no ground lifting switch, and keep the preamp switch in the "float" position. Jim |
Jim - I have always used the preamp in the "float" position, whether it was with a solid state or tube (including the DeHavilland mono blocks) amp. My impression was that sonically this was the preferred position, and as I mentioned the manual for the mono blocks even states a potential sonic improvement keeping the switches in the "float" position as long as there are no accompanying noises or buzzes (I can't seem to find the preamp manual to check, however it was planted in my head from somewhere (probably the manual) to keep that switch at "float"). Only recently did the buzzing begin which corresponded with some connectivity problems related to the preamp's power cord. Now that I have switched to a different power cord, there is no more buzzing or noise, and all grounding switches are set at "float". |
weebeesdad said: 09-16-2017 7:54pmI would say that rules out an interconnect/s causing the buzzing problem. Audio system sounds fine now, no buzzing, same interconnects. Through experimenting, listening, you found the power cord you were using on the preamp was causing the buzzing sound you were hearing. Exactly why is still the unknown, imo. What puzzled me you said, in an earlier post, when you closed the ground lift switch the buzzing would stop. If the integrity of the continuity of the equipment ground wire connection, of the power cord, was compromised somewhere from the male plug >>> through the IEC connector, >>> through the ground contact of the preamp IEC inlet connector, closing the ground lift switch would not make any difference. But you found closing the float ground switch did..... What exactly could be the cause of the buzz? At one point I considered poor contact pressure between the hot and or neutral current carrying conductors between the IEC female connector, on the end of the power cord, and the male inlet connector on the back of the preamp. Even a slight arcing would induce RF noise into the preamp, imo. Sounds plausible to me..... But why closing the ground lift switch would stop the buzzing sound? When closed it connects the preamp’s audio circuitry, signal ground circuit, back to the chassis of the preamp. This is where John Curl would say, this is where the test equipment is brought on board to measure and found out the why. Something to throw into mix of thought for the why. Here is a response from Charles Hansen to a post of mine. Close And then his response to another post of mine. RE: Thanks Charles for your response, but you left us, me, hanging.https://db.audioasylum.com/mhtml/m.html?forum=general&n=525553&highlight=double+insulated+po... Now keep in mind the responses from Mr. Hansen are in response to my posts for audio equipment that have double insulated AC power wiring where the power cord is 2 wire with a 2 prong plug. AC mains equipment ground is not used. So how does the above relate to your situation? Not really sure. But what if the AC mains equipment ground is broken, open, somewhere in the bad power cord. No continuity, or sometimes intermittent continuity. With the ground lift set to float wouldn’t the chassis be acting exactly as Mr. Hansen said in his post? All just conjuncture on my part..... Al, (almarg), If you are reading this post of mine what are your thoughts on the "why the buzz" ~ ~ ~ ~ ~ @weebeesdad, Question. What are you using for front end sources connected to the preamp? Do they use the AC mains safety equipment ground? There in, a 3 wire grounding type power cord and plug where the equipment grounding conductor, wire, in the power cord is connected to the chassis of the front end source/s ? Jim |
Jim - My only front end source is a Resolution Audio Opus 21 cd player which uses a three prong power cord which presumably grounds it. The cd player and preamp are both plugged into a power strip which I was told is recommended for use with Naim equipment and also utilizes a three prong cord and receptacles. I initially thought the buzzing was caused by the interconnects between the pre and power amp, however swapping them out for different interconnects did not alleviate the problem. I was have issues with the IEC female connector on the power cord making consistent contact, and, as I reported, changing that has seemingly solved the problem. As to why the buzzing stopped when I switched to "ground" position, the technical answer is above my pay grade and I will let those of you with greater expertise ponder that... |
- 41 posts total