Hope this is the right area for the post.
Will start with my setup, then the problem and lastly my troubleshoot.
Amp is a 2014 VA Predator
Phono amp is Audiolab PPA800 (Connected to VA with VAn Den Hul The NameIC)
CD Player Sony SACD
TT 1 Pro-ject RPM Carbon 1 with Ortofom 2M Blue MM
TT 2 Clearaudio Concept with CA Concept MC
Speakers Martin Logan CSL II
Now the other stuff:
Power consists of:
From wall outlet to Shunyata Hydra Alpha 4 filter running a shielded mains cable with standard wiring.
VA connected with Shunyata mains cable connected to filter.
Audiolab connected with shielded mains to filter (Audiolab power recepticle only has L and N pins, IEC connection)
Both TT's stock power supplies connected to filter, earth wires connected to appropriate earth points on Audiolab
CD Player running off standard extension
Speakers powered from another filter.
Problem:
I picked up a hum on my speakers when listening to TT 2 with MC cart, first heard it between tracks, running VA at 12 o clock.
Troubleshooting:
I lifted the stylus off the record, hum still audible, getting louder as I increase volume.
Switched over to TT 1 with MM cart, hum only audible at 2 o clock on volume.
Switched input to CD Player, zero hum even at full volume.
Unplug CD, unplug TT 1, also disconnect IC from CD and TT 1, thus the only component connected is TT2 with MC.
Hum still there.
Unplug TT2 completely, so the only connection is the Audiolab to the VA using VDH IC, hum is still there.
Plugged speakers now into the filter so all equipment running of one filter, hum there.
Connect speakers to a wall outlet on a separate circuit than the VA and Audiolab, hum there but less.
Connect VA to separate wall outlet than the Audiolab, hum same as above.
Removed filter and all power cables. Replaced all cables with your run f the mill pc cable, straight off extension cable, hum reduced, now starts at 2 o clock volume position.
Also swapped out speaker cables, no impact on level of hum.
Do not have the funds at this stage to change the Clearaudio TT cables to balanced.
Do not have IC's I am confident in as being fully shielded.
I am thinking a ground loop somewhere that has a bigger effect on the MC cart sensitivity than the MM cart.
Oh, I have two VA's and the problem is the same on both, I do not currently have another phono amp to test this with.
Long but I believe detailed summary of the problem.
Any help appreciated.
Will start with my setup, then the problem and lastly my troubleshoot.
Amp is a 2014 VA Predator
Phono amp is Audiolab PPA800 (Connected to VA with VAn Den Hul The NameIC)
CD Player Sony SACD
TT 1 Pro-ject RPM Carbon 1 with Ortofom 2M Blue MM
TT 2 Clearaudio Concept with CA Concept MC
Speakers Martin Logan CSL II
Now the other stuff:
Power consists of:
From wall outlet to Shunyata Hydra Alpha 4 filter running a shielded mains cable with standard wiring.
VA connected with Shunyata mains cable connected to filter.
Audiolab connected with shielded mains to filter (Audiolab power recepticle only has L and N pins, IEC connection)
Both TT's stock power supplies connected to filter, earth wires connected to appropriate earth points on Audiolab
CD Player running off standard extension
Speakers powered from another filter.
Problem:
I picked up a hum on my speakers when listening to TT 2 with MC cart, first heard it between tracks, running VA at 12 o clock.
Troubleshooting:
I lifted the stylus off the record, hum still audible, getting louder as I increase volume.
Switched over to TT 1 with MM cart, hum only audible at 2 o clock on volume.
Switched input to CD Player, zero hum even at full volume.
Unplug CD, unplug TT 1, also disconnect IC from CD and TT 1, thus the only component connected is TT2 with MC.
Hum still there.
Unplug TT2 completely, so the only connection is the Audiolab to the VA using VDH IC, hum is still there.
Plugged speakers now into the filter so all equipment running of one filter, hum there.
Connect speakers to a wall outlet on a separate circuit than the VA and Audiolab, hum there but less.
Connect VA to separate wall outlet than the Audiolab, hum same as above.
Removed filter and all power cables. Replaced all cables with your run f the mill pc cable, straight off extension cable, hum reduced, now starts at 2 o clock volume position.
Also swapped out speaker cables, no impact on level of hum.
Do not have the funds at this stage to change the Clearaudio TT cables to balanced.
Do not have IC's I am confident in as being fully shielded.
I am thinking a ground loop somewhere that has a bigger effect on the MC cart sensitivity than the MM cart.
Oh, I have two VA's and the problem is the same on both, I do not currently have another phono amp to test this with.
Long but I believe detailed summary of the problem.
Any help appreciated.
