So the pot is in a separate case? How is the wiring done to/from the pot? How's the ground wiring done? Is there any connection directly between the post?
Jan
ba3&pot and phono pre in the same case.
4 input with relay control>1 output to volume pot>ba3 preamp > f5.
Phono preamp does not connected directly to input selector, female rca goes to phono pre, output of phono preamp goes to relay based input selector.
All analog grounds tied to star ground post.
4 input with relay control>1 output to volume pot>ba3 preamp > f5.
Phono preamp does not connected directly to input selector, female rca goes to phono pre, output of phono preamp goes to relay based input selector.
All analog grounds tied to star ground post.
is the TT PE (ground) connected to the arm COM (ground)?
is the TT PE (ground) connected at the mains plug?
is the TT PE (ground) connected at the mains plug?
No.
No.
TT does not have mains earth connection. It has two prong connection.
Chassis ground termination to signal ground or preamp ground does not have any effect for 50hz triangle wave hum.
Btw, hum is there even tt does not connected to mains at all. Mains connection or motor on status also does not reduce or increase hum at all. It's constant no matter what I do...
My question was to get an idea of the grounding. Please can you tell if there is a direct connection between the pots, like each pot bottom (zero level) goes to a star point? And the RCA screens of the interlinks that go back to the phono pre, are they also connected together (the screens of the two channels) somewhere in the phono pre?
Edit: the background is that what we call ground is just another wiring that can have different signals and voltages along the line. Furthermore, if the grounds of two or more channels are connected in more than one place you have a ground loop. All this is important to find your issue. Where is that 'star ground post' located?
Edit2: if you pull the interlinks out of the phono pre but leave them otherwise connected, do you still have the hum?
How do you know the hum is a triangle? The title of the thread says 150Hz, is that a typo, is it actually 50Hz as you mention above?
Jan
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There is only one stereo potentiometer and both ground lugs goes to star ground post.
L&R channel screens of rca interconnects and female rca sockets grounds goes to star ground post.
Star ground is located between pot&ba3&female rca's and phono pre. Chassis contains two separated transformer and linear psu for ba3 and phono preamp. These psu grounds not connected to signal star ground. Transformers are located far side of the chassis btw.
If nothing is connected to phono pre rca's, it has no hum (but usual noise floor due to high gain of phono pre), if I connect rca interconnects to phono pre inputs and leave other side floating, it has tiny amount of hum. When I connect interconnects to TT it starts to buzz at 50hz. TT is not connected to mains btw.
First I measured hum from the speakers with mobile phone app and it was showing 150hz peaks. Then I created tones from lms plugin and switched between sine,square triangle etc..50hz triangle wave matches my tt hum.
Sorry I couldn't find a way to change title from forum tools.
Jan
Same 50hz sawtooth hum from one channel.
Update: I removed arm and all connections, removed all tonearm wires and begin re-rewire process.
It may fix or not fix my problem.. But.. As you see I'm hopeless 😉
Update: I removed arm and all connections, removed all tonearm wires and begin re-rewire process.
It may fix or not fix my problem.. But.. As you see I'm hopeless 😉
Rewired tonearm and seperated all cartridge signal return wires from chassis and arm ground. Used seperate ground wire from arm tube,arm base and tt chassis and tied them together and terminated on preamp input.
Same.
Problem is definitely my preamp work.
I removed all ground connections at the preamp. Removed female rcas. Re-attached them to chassis and isolated them. Bind all female rca grounds together. Made star ground from ba3 ground-female rca ground (from one point)-phono preamp ground. Isolated preamp chassis from signal ground. Psu ground is also separated from signal ground.
Result; same buzzing noise but much quiter. Still not acceptable.
Same.
Problem is definitely my preamp work.
I removed all ground connections at the preamp. Removed female rcas. Re-attached them to chassis and isolated them. Bind all female rca grounds together. Made star ground from ba3 ground-female rca ground (from one point)-phono preamp ground. Isolated preamp chassis from signal ground. Psu ground is also separated from signal ground.
Result; same buzzing noise but much quiter. Still not acceptable.