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John_BS · 2nd Aug 2020, 5:52 pm

I can't add anything to the excellent theoretical & practical posts in this thread, other than the following peripheral tip.

Back in my youth I made an RIAA preamp which was housed in a tin can (for screening) and located up under the turntable. With all that gain down at 50Hz it's very easy to end up with hum issues, and I'd decided to remote the RIAA stage close to the cartridge.

Now, the problem of supplying ultra-clean DC supplies? I used simple (decoupled) zeners on the RIAA board, and fed the unit from constant current sources back at the main amplifier. Hence no ripple DC current in the earth lead. It worked a treat.

John

2nd Aug 2020, 5:52 pm	#117
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,780	Re: Very low noise op amp recommendations? I can't add anything to the excellent theoretical & practical posts in this thread, other than the following peripheral tip. Back in my youth I made an RIAA preamp which was housed in a tin can (for screening) and located up under the turntable. With all that gain down at 50Hz it's very easy to end up with hum issues, and I'd decided to remote the RIAA stage close to the cartridge. Now, the problem of supplying ultra-clean DC supplies? I used simple (decoupled) zeners on the RIAA board, and fed the unit from constant current sources back at the main amplifier. Hence no ripple DC current in the earth lead. It worked a treat. John