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.
One morning, I discovered the right channel of my Ortofon STM-72 was dead. While waiting for the Weller WTCPS soldering station to heat up, I carefully peeled the foilcal to pull apart the 2-piece tubular housing so I can resolder the broken cable connection(s).
Looking back to my late 90s home brewer article for Sound Practices issue 17, I noticed that a good number of components in my hifi system then are still serving two and a half decades later. The Tamura TKS83 moving coil step up transformer is one of them.
After building a hifi system for my cousin during lockdown, the Hashimoto HM7s made me realize that while the Tamura TKS83s can equal the HM7s in terms of bandwidth, the TKS83s can sound mechanical. It also became apparent that there are areas in which the classic Altec 4722s and 15095As can be improved upon.
When I finally heard a pair of Peerless 4629s, I was very impressed by their uncanny ability to reproduce very lifelike 3-dimensional vocals. However, I was quite disappointed when I played anything greater than a string or jazz quartet because the sound started getting mushy and dynamically compressed.
Overall, my ears still prefer the smaller and more affordable brother, the Altec 4722!
Upon our return from the expedition, a sumptuous dinner prepared by Tish + a bottle of Ripasso awaited us. We capped the evening by hooking this wooden box to my hifi. Our jaws dropped each time we played an LP!
In the ensuing days, I did further evaluation and indeed, these Finemet MC transformers are doing something extra special. My only reservation was, in spite of the potted construction, the FM-MCT1s are more susceptible to hum induction compared to the Altecs and Tamuras. Even if John lined the wooden box heavily with copper shielding, I still had to keep them away from power transformers, AC motors, etc.
Kimura-san specified a 3-4 week window for delivery. So I downloaded the spec sheet, studied the schematic and ordered a cast aluminum project box from Amazon.
Within 18 days, the transformers were at my doorstep.👏
These are very well made and quite hefty! They're heavier than the TKS83s which, if memory serves me right, are about the same weight as the HM7s.
I chose a different layout for the 145mm x 121mm x 40 mm MC step up transformer chassis for neater routing of RCA cables.
Under the hood
The input and output RCA jacks are on the backside mounted on top of the chassis. Only the ground lug was mounted on the side.
I installed the 3-position gain/impedance load selector in front of the chassis.
No matter which cartridge I used - Denon DL103, -R, -C1, Fidelity Research FR1 MkII, Ortofon SPU #1s, -G, -GM, Supex SD900, etc. - male and female vocals + instruments are portrayed with 3-D presence and realism in a deep and wide sound space. The musicians are in my man cave!
Boosted by the Finemets, even the most analytical and dry-sounding MC cartridges in my stash, like the Goldbug Clement II and Sony XL44 came to life with more warmth. If that's a coloration, it's certainly most welcome!
These Finemet MC transformers seem like they were configured to resolve every note in the complex musical score and massive instrumentation of late romantic symphonies along with the wide range dynamics from pianississimo to quadruple fortes inscribed therein by the composer. They also excel in reproducing the ambience, airiness and spaciousness of the concert hall's acoustics embedded in well recorded LPs.
I finally found a pair of MC transformers which combine the organic midrange and harmonious richness of classic vintage iron + the wide bandwidth, detail retrieval, and dynamic range of modern magnetics!
Ever since I became an audio DIYer, I pride myself in not being impulsive about upgrading components in my hifi. This is a rare exception!😉
CODA
As luck would have it, last week we had a family get together because a cousin based in Tokyo was visiting and brought some goodies!
Since Denon recommends a 1000 ohm load for flattest response, I tried soldering a 1k ohm resistor in parallel with the 47k input (47,000 x 1000/47000 + 1000 = 980 ohms) of my variable EQ phono preamp. Unfortunately, the sound became even more glacial.
I could have been basking in warmth by now (without losing stereo LP compatibility) if I saved up for an Ortofon SPU mono but the DL102 body fits a Gray Research or clone tonearm slide perfectly. Besides, I would rather add more stereo SPUs to my cache.😉
Since I've been using 1:1 line transformers as digital sound processing devices at the output of my CD players for ages, I decided to try the same trick by wiring the Altec 15356 and UTC A20 with a mild step up - 150:600 and 125:500, respectively. Even if both primaries reflected significantly less than Denon's recommended 1000 ohms, what I heard encouraged me to continue to experiment.
Although I'm not anal retentive about impedance matching, I was curious too see if the sound would improve by using transformers that reflect at least twice the 240 ohm internal impedance of the Denon DL102. I managed to procure the three transformers above: to the left is allegedly a Tamura 600:3k, then I tapped the McMartin MT-4's 10k:60k winding, and at the center is a permalloy 10k:40k, which sells for about $50/shipped from Chinese sellers on AliExpress and eBay.
In the context of my mono hifi set up, the McMartin MT-4 was a bit too warm for my taste. However, even if I upload videos merely for the visual spectacle, the permalloy (above) and Tamura (below) transformers are lush enough for me.😉
When I ordered this pair of MC step up transformers from Mr. Isao Asakura of tube-amps.net (highly recommended👏) for my cousin's system, he suggested the use of high-quality 24-gauge stranded copper wire. I also took note of his MC step up page, in which he discussed his chassis mounting experiments.
Taking the cue from my buddy Nateaka Redboy at HifiHaven.com, who’s a prolific audio DIYer and MC step up builder, I ordered a cast aluminum project box + 24-gauge stranded tinned copper wire from Amazon.
In hindsight, whether commercial or DIY, all the Japanese MC step up transformers I've seen in the metal or in MJ Radio Experiment and Stereo Sound Tube Kingdom magazines, were always housed in all metal enclosures or chassis.
Altec/Peerless 15095A + 4722
Before doing further listening comparisons, I remounted all my MC step up transformers on cast aluminum chassis and used 24-gauge tinned stranded copper for wiring. Since we're dealing with very delicate signals at tenths of a millivolt, very fine strands of high purity copper wire + maximum shielding make a lot of sense!
Hashimoto HM-7
After the playing field had been leveled, the Hashimoto HM-7 no longer outclassed my beloved MC step up devices. However, I'm pleased to say that the HM-7 sound falls somewhere in between the detailed and dynamic TKS83 and the organically rich and spacious airiness of the classic 4722!
Alas, these cast aluminum boxes weren't available when I started experimenting with microphone transformers as MC step up devices in the late 90s. Otherwise, I would've used them since I love the industrial vibe of unfinished aluminum!
Way before I knew about SPUs and DL103s, I experimented with an entry level Audio Technica AT31E MC cartridge. Since my NAD 3020 didn't have an MC input, a pair of Sony HA-T10s were recommended at the same discount NYC store. I mounted the cartridge on a Grace G707 which was perched on a "molested" AR-XA. The sound was very different compared to my Grado GTE+1 - quieter background, more detail, deeper and wider soundstage, albeit less midrange presence and warmth.
I moved on to a Grado Signature 8, 8MX, MZ and lost track of my Sony HA-T10s. I probably loaned them to an audio buddy who forgot to return them. During a moment of nostalgia, I hit the BIN button for a pair @ a little over $100, shipped! I've listened to them with all the MC cartridges pictured above and they make pretty nice sounds!
However, I can only justify the price I paid because of sentimentality. To my ears, the Shure mic transformers below are mucho better performers at ~ $40/pair + some DIY. Remember that HA-T10s were mass produced MC step ups, not limited production transformers using exotic nickel/amorphous/Finemet materials. Thus, sellers asking $200-400/pair are greedy!
Let me just say this to Shure microphone transformer sellers - as good as they are, once you break the $100/pair barrier, you've got tons more competition. So if you've got business smarts, be reasonable!😎
Ben C was hunting for Altec 32s, Emilar EH800s and EH500s at Jammin' Jersey
Tipped off by my buddy, Ben C (dude in the middle), I scoured eBay for Shure Mic transformers that can be repurposed for MC step-up duty. These transformers typically sell for under $50/pair shipped within the USA.
They don't have model numbers so I'll identify them based on their step-up ratio.
Primary DCR = 35 ohms and 3500 ohms in the secondary.
I measured a step up ratio of about 1:17, which suits the Denon DL103 and DL103R well. It can be a pinch hitter for the Ortofon SPU in my system, but ideally more gain is needed.
This unit has slightly less gain at about 1:12, primary DCR = 20 ohms and secondary = 2000 ohms. What it gives up in gain is made up for by slightly wider bandwidth. If I were to split hairs, I'd pick this over the 1:17 model above if I were using a DL103 exclusively.
The tonal balance of both Shure transformers is actually quite similar to the Altec 4722 with just a touch less transparency and authority throughout the audio band. At their present asking price, I can highly recommend these transformers to those who want to sample the delights of listening through a classic Denon DL103 low output moving coil cartridge.
