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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: PP GND offending and the charger noisePosted by N-set on: 11/8/2020
I followed exactly Romy's advice. I disconnected EVERYTHING from PP1500 apart from the Endoflife phono. The phono output was monitored via RTA software on a battery powered laptop. There was only phono connected to the PP. [I don't have GND loops anyway as the only GND point in the system is the phono, all the rest being lifted & relying on the negative RCA terminals for the GND distribution]
Under these conditions:
1a) If the phono GND is connected to the PP1500 GND -> HEAVY NOISE
1b) The noise is somewhat diminished when PP1500 is on BATTERY
-- Shorted MM input -> QUIET
-- Decca cart -> STILL UNLISTENEABLE, NOISE MASKS EVERYTHING
2a) If I lift the phono GND from the PP1500 -> ALMOST QUIET in ONLINE
2b) 100% QUIET on battery. Actually the output spectrum is cleaner then from the wall.
This all with the PP1500 below the TT, so some 1.3-1.5m from the carts and the phono.
So there must be some interaction between my EndofLife GND and the PP1500 GND, amplified when the PP is charging. I have no idea how it comes about as my Endoflife is rigorously star grounded inside.
I tried to diminish the noise in 2a) case as with the sensitive Decca it was still clearly there. I tried moving the PP away to some 3m. NO RESULT. The residual noise after lifting the ground propagates via the line, not through the air.
Summarizing today experiments:
-Lifting phono GND from PP helps tremendously
-But there is still a charging noise in Online mode, not disappearing with the distance
-There are no mechanical noises - both PP and my Endoflife are as quiet as normal
Since my phono worked without problems in 3 locations in 2 countries in the past 10 years, I start to suspect some hidden problem with my PP battery charger.
PS The unit did have a minor issue when it arrived: One of the batteries was not fixed strong enough and was rattling inside and also got disconnected. I reconnected the battery before powering the unit up for the first time (there was some 30Vdc potential difference and a little discharge). Could that affect the unit?
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