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!
Milstein wow! Love that...
ReplyDeleteOf course...😊
DeleteI've bought them as well after I readed your blog. Mister Nariyuki Kimura was most helpfull and package came from Japan to Croatia (Europe) in no time.
ReplyDeleteWithout proper case and connected "in air" just to see if they are working, they pick some hum up.
Noticable on Tannoy MG15 in MLTL cabs when the pot is already toward the loud listening position.
A steel case is to be made for them, and in it will be SUT's placed in one Hammond alu enclosure I already have laying around. It might be overkill, but it shouldn't hurt.
I can tell that right now, those FM-MCT1's have outperformed Haufe, Partridge and 72 Audio custom built on finemet core as well but the cores are a lot smaller then FM-MCT1 though specifically made for SPU.
Thank you for the hint!
It might be all I ever need for an MC SUT.
I'm glad you like them, happy listening!
DeleteTry 3M's AB7050HF EMI/RFI absorption fabric over the copper. It works WONDERS.
ReplyDeleteI'll keep that in mind, thanks!
DeleteI’ve also had great success in EMI/RFI fabric as well as an added layer in different electronics applications, will definitely do here during the build. My only question having studied this and the prior article, wiring and switches easy enough to replicate, but didn’t fully follow the need for two sets of inputs and the related rocker switch given the role of the rotary switch to handle the 3 inputs (blue/grey/white). Many thanks! Excited to get this up and running.
ReplyDeleteI'm not quite sure what you're question was about but I'll try to clarify my wiring.
DeleteThe rotary switch is for the 3, 10 & 40 Ohm taps in the transformer primary and the DPDT switch is for the two inputs.
If you only require a single input and want to omit the rotary switch, hard wire an RCA jack for each of those primary taps and switch your interconnects depending on what step up ratio your cartridge requires.
Super, thank you for the quick reply, was thinking of doing that just to avoid switches in the signal path. Bought a good one from Elna but will do the first one with the direct wiring. Can always compare and see :) Part of the fun of this hobby!
Delete👍😊
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