I got a marcof ppa1 and it has chassis hum/grounding issues. When I put another piece of equipment nearby the marcof, it hums louder, and it does the same when I touch the chassis. I’ve already re soldered the output jacks and I’ve recapped it with elna silmic 2’s. Any ideas on if this is fixable? Any and all ideas are welcome!
Marcof PPA-1 chassis hum issues
- Thread starter Bnoyes12
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HalfApt
Well-Known Member
I'm surprised no one has responded yet, but it might have got more attention posted under Turntables.
Is this a new unit you just obtained, or have you had it in use for a while & the issue just started? Where are you connecting turntable ground?
I don't have a PPA1, but it's been around for a while & discussed many times. It is essentially a clone of the Leach Common-Base head amp. Leach was quite explicit that signal grounds should NOT be tied to chassis ground, yet Marcof (I believe) did so, and that might cause hum problems in some setups.
I've built 2 Leach variants, signal grounds isolated from chassis, TT grounded to pre-amp, and don't have hum issues.
You may have to try different ground paths (TT/PPA1/pre-amp), or in worst case disconnect the PPA1 internal PCB-to-chassis ground strap.
Is this a new unit you just obtained, or have you had it in use for a while & the issue just started? Where are you connecting turntable ground?
I don't have a PPA1, but it's been around for a while & discussed many times. It is essentially a clone of the Leach Common-Base head amp. Leach was quite explicit that signal grounds should NOT be tied to chassis ground, yet Marcof (I believe) did so, and that might cause hum problems in some setups.
I've built 2 Leach variants, signal grounds isolated from chassis, TT grounded to pre-amp, and don't have hum issues.
You may have to try different ground paths (TT/PPA1/pre-amp), or in worst case disconnect the PPA1 internal PCB-to-chassis ground strap.