Shielded Finemet FM-MCT1 MC Step Up Transformers

 

It's been almost a year since my favorable review of this Finemet MC step up transformer. Overall, it has given me great musical pleasure! However, when tasked to amplify MC phono cartridges with lower output than a typical Denon DL103, in particular the Ortofon SPU and Fidelity Research FR1 MkII, hum could be intrusive in softer passages of classical music, especially when not carefully sited away from motors and power supply transformers.

As I had suspected in my initial review, the FM-MCT1 wasn't as well shielded as the Hashimoto HM7, Tamura TKS83, Altec 4722 and other vintage MC SUTs in my collection.😔 Now, I had no recourse but to compromise my aesthetic preference for an open chassis in favor of an enclosure to provide additional shielding.

Since the TKS83, 4722, 15095, etc. are all potted in magnetic steel cases, I ordered the heaviest gauge steel box I could find on Amazon.

After patching and sanding an unsightly hole, I gave it a coat of silver hammerite paint and let it cure for 48 hours.

Some internet sources claim that copper has the best shielding properties. 

So I lined the interior with copper tape for additional shielding.

Wired and ready to make music

When placed near my idling breadboarded nosTDA1541tube DAC, the shielded FM-MCT1 still hummed unlike my other MC SUTs.😞 But once I turned off the DAC, it became absolutely quiet. This was not the case before I installed it in a shielded case.😊 

I just wish this exceptional sounding Finemet MC SUT wasn't fussy.

Hum used to be a big issue when situated between a spinning Garrard 401 and 301. But now it’s just as quiet as all my other MC SUTs. Even if these Finemet SUTs are still not as well shielded as my other units, enclosing it in a shielded steel box has significantly improved its susceptibility to magnetic induction. 😊👍🏻🍻

Sit back and immerse yourself in Nathan Milstein's Bach!