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The Arai Lab MT-1 Step-Up Transformer for Moving Coil Phonograph Cartridges

09-26-2017 | By Jeff Day | Issue 93

One look at the Arai Lab MT-1 step-up transformer (SUT) and you'll know in a moment that it is a very serious, ultra-quality, audio product.

Arai Lab MT-1 step-up transformer

The fit and finish are impressive and impeccable, yet what really stood out for me was the Arai MT-1's considerable size and weight—it wasn't that much smaller than one of my vintage McIntosh MC30 monaural power amplifiers!

The Arai Lab MT-1 is the creation of Mr. Toshio Arai (above right) in Isesaki, Japan, who has been developing audio electronics and test equipment for Hitachi since the 1970s.

Arai-san opened Arai Lab so he could focus on the design of his personal audio interests, like the Arai Lab MT-1 step-up transformer that is the subject of this article, and the vacuum tube amplifiers that he currently has under development at his laboratory.

The Raison D'être Of Step-Up Transformers for Moving Coil Phonograph Cartridges

Before I go in-depth about the Arai Lab MT-1 step-up transformer (SUT), I thought it might be useful if I provided a short primer about why SUTs are used for moving coil (MC) phonograph cartridges in high-performance audio applications, and to explain how they work.

An MC phonograph cartridge is an electromechanical device whose stylus traces the record groove. As it does so its stylus/cantilever is moved by the tiny modulations of the record groove's mechanically encoded waveform, which moves the tiny coils connected to the stylus/cantilever in the magnetic field of the cartridge's internal magnets, producing an output signal in the fractional millivolt range that is an electrical analog of the mechanically encoded waveform of the record groove.

For a few MC phonograph cartridge output voltage examples, my Ortofon SPU Classic GM MkII (above top) has an output voltage of 0.2 millivolts (mV), my EMT TSD-15N (above bottom) has an output voltage of 0.21mV, my Denon DL-103 (below top) has an output voltage of 0.25mV, and the just reviewed (Issue 92) Murasakino Musique Analogue Sumile (below bottom) has an output voltage of 0.35mV.

Using my beloved vintage McIntosh MX110Z tuner-preamplifier (below left) as the example, the sensitivity of its phono inputs 1 & 2 is 3 mV at 47kOhms.

Given the 0.2 mV to 0.35 mV range of output voltages from the aforementioned MC phono cartridges, they need to be amplified by approximately ten times to put their output into the sensitivity range of the phono inputs (3 mV), so that adequate "live-like" listening levels can be achieved.

Mr. Arai says that the "gold standard" way to increase an MC phono cartridge's tiny output signal to a level that is appropriate to the input sensitivity of a preamplifier's phono inputs is to use a SUT, and he tells me that he thinks that using a head-amplifier for an MC phono cartridge is not as good because it "… receives a signal by resistance which robs energy … and there is no energy loss through a SUT, and furthermore, the inductance effect of the coils improves the driving and braking force."

Using the Sumile MC phonograph cartridge as an example, the 0.35mV AC output voltage from the Sumile is connected to the input winding (or coil) of the SUT. The output winding of the SUT is connected to a load resistance, which in this case would be the 47kOhm resistor of my MX110Z's phono input.

The SUT's input winding that the Sumile is connected to, and SUT's output winding that is connected to the load at the MX110Z's phono input, are insulated from each other and there is no electrical connection.

The magnetic field created by the Sumile's AC current flow into the input winding generates a flux in the SUT's core, where the output winding converts the flux back into current flow and produces a voltage at the 47kOhm resistor in the MX110Z's phono input.

In a SUT, the number of turns in the output winding is greater than the number of turns in the input winding, so the resulting voltage in the output winding will be greater or "stepped-up" compared to the voltage in the input winding.

The amount of amplification the SUT provides is dependent upon the impedance ratio between the input and output windings, which is determined by the number of wire turns in each winding.

To get that ten-fold amplification I want of the Sumile's 0.35mV output, the SUT's output winding would have to have ten times the number of windings of the input winding, which would "step-up" the Sumile's output to 3.5mV, putting it into the right range for my MX110Z's phono input sensitivity of 3.0mV.

Voltage gain is not the only consideration when using a SUT, as the SUT's impedance must also match the internal impedance of the MC phonograph cartridge you are matching it to or it can rather dramatically alter the high and low-frequency response of the cartridge, depending upon the direction of the mismatch.

For example, my Ortofon SPU Classic GM MkII has an output voltage of 0.2 mV and an internal impedance of 2 Ohms, my EMT TSD-15N has an output voltage of 0.21mV and an internal impedance of 24 Ohms, my Denon DL-103 has an output voltage of 0.25 mV and an internal impedance of 40 Ohms, and the Murasakino Musique Analogue Sumile has an output voltage of 0.35mV and an internal impedance 1.2 Ohms.

As you can see from my examples above, internal impedance varies significantly between the cartridges, ranging from the Sumile's very low 1.2 Ohms to the Denon's very high 40 Ohms.

To get the optimum performance from a particular MC phonograph cartridge, the SUT should have both the needed signal gain, as well as have the same impedance as the internal impedance of the cartridge.

For example, for my Denon DL-103 phono cartridge, I have a dedicated Auditorium 23 SUT designed to complement the Denon's needs, and for my Ortofon SPU Classic GM MkII I have a bespoke Intact Audio SUT optimized for its needs.

The Arai Lab MT-1 Step-Up Transformer for Low-Output Moving Coil Phonograph Cartridges

Now let's take an in-depth look at Arai-san's Arai Lab MT-1 step-up transformer.

The Arai Lab MT-1 SUTs are bespoke items that are custom built with an impedance that is matched exactly to the internal impedance of the cartridge that the customer is ordering it for, so that the performance potential of a particular phono cartridge is maximized.

In the case of my review sample, this particular Arai Lab MT-1 was designed specifically for a cartridge with 2 Ohm impedance (see photo above), which happens to be the same value I need for my primary phono cartridge for stereo music listening, the Ortofon SPU Classic GM MkII, which has an internal impedance of 2 Ohms.

The quality of the input and output windings (also referred to as coils) used in step-up transformers are critical to their overall performance, with their quality described by the quality factor, Q, which is the ratio of a winding's inductive reactance to its resistance at a particular frequency, and is essentially a measure of the windings efficiency in being able to transmit the signal without losses.

The larger the value of Q is, the more efficient the winding is at transmitting the signal. Arai Lab says that their MT-1 has an input winding Q that is more than 30 times higher, and an output winding Q that is more than 70 times higher, than the other most expensive audio step-up transformers available on the market today.

Arai-san has a proprietary technology and special method that allows him to wind a coil so accurately that it can achieve exactly an equal impedance for the cartridge it is being ordered for, so it can bring out 100% of the performance a given cartridge is capable of.

Arai-san's windings are of such a high quality that his Arai Lab MT-1 SUT has a flat frequency response from 1.5Hz to 140kHz, whereas as other SUT's start attenuating frequency response below 100Hz and above 115kHz, he says.

Arai Lab says the specific materials used in the construction of the Arai Lab MT-1 SUT contribute significantly to its performance.

The materials used in the construction of the MT-1's chassis will be familiar to owners of Acoustic Revive products, and there is in fact a close collaboration between the two companies. It turns out that Arai-san and his laboratory, Arai Lab, are located in Isesaki-city, Gumma Prefecture, near Ken Ishiguro's home and his audio business, Acoustic Revive, and as a result a close collaboration has developed between the two men.

Like the Acoustic Revive RPT-6 Absolute NCF Power Distributor that I reviewed in Issue 91, the chassis of the Arai Lab MT-1 is constructed from CNC machined A2017S Duralumin alloy.

The MT-1 SUT has four height-adjustable rhodium-plated machined brass footers attached to the bottom of the chassis, with the footers being fitted with a pad of high-tech vibration control material sourced from specialty company fo.Q. The fo.Q  pad converts vibrational energy to electric energy, which is then converted to heat energy.

The combination of the Duralumin alloy chassis, the rhodium-plated machined brass footers fitted with fo.Q pads, is considered by Acoustic Revive and Arai Lab to be the ultimate materials combination for chassis vibration control.

The core of the MT-1's transformer is made from a "nanocrystalline Fe-based soft magnetic material with high saturation flux density" called "FINEMET" (a registered trademark of Hitachi Metals, Ltd.), and features "high saturation flux density", "excellent temperature characteristics", "high permeability", "low core loss", "high squareness", and "low magnetstriction" that Hitachi says makes it superior to any other material for transformer cores. You can read more about FINEMET HERE.

Arai Lab says the FINEMET transformer cores of the MT-1 SUT are very large, and that the gap of the cut core is polished to a mirror finish.

The input winding of the MT-1 is made from oxygen free copper (OFC) wire, and the output winding is made from Furutech PC-TripleC wire made from a special forging process where micron level impurities are removed from the OFC. Furutech says that the PC-TripleC is designed specifically to be an audio conductor and can be drawn into very fine wire capable of transmitting even the most delicate audio signals.

The gauge of the output winding varies depending on the matching impedance desired. For example, the gauge used for a cartridge with 1-Ohm internal impedance is a very sizable wire, say 4 mm, so a very accurate winding is necessary to achieve high-performance from such a thick coil.

Mr. Arai says that no other manufacturer can achieve such a super-accurate winding with thick coils like he can with his winding technology, and the result is that he can produce ultra-performance windings for even very low impedance cartridges like the Sumile.

Often transformer windings are potted as a way to damp hum and vibration in a transformer, but Mr. Arai says the technology used for his transformer windings is so accurate that his transformers do not generate hum and vibration problems, so he does not pot the transformers, and by doing so he actually preserves nuances in the signal that would be lost if the coils were potted.

The coils are screened from RFI/EMI induced noise by using "A perfect electromagnetic shield and an ideal earth connection."

The 2.0 Ohm version of the Arai Lab MT-1 SUT that I have in for review is approximately 8 x 7.75 x 5 inches, and weighs approximately 15 pounds.

Review Equipment

For this article, I used my primary music listening system.

My loudspeakers are Tannoy Westminster Royal Special Edition's, rewired internally with vintage Western Electric WE16GA tinned-copper wire, with the internal crossovers bypassed in favor of custom external Duelund Coherent Audio CAST crossovers (below), which themselves are wired internally with the Duelund DCA series of tinned-copper wiring (see the Positive Feedback review of the Duelund line of DCA tinned-copper cables/wires HERE). 

I'm using restored & hot-rodded vintage McIntosh vacuum tube electronics for amplification. For line and phono amplification & equalization I'm using the McIntosh MX110Z tuner-preamplifier, and for power amplification I'm using monaural McIntosh MC30 amplifiers (below).

My turntable is a highly hot-rodded Garrard 301 from Classic Turntable Company, the Classic 301, installed into a plinth from Artisan Fidelity, and mounted with a Pete Riggle Audio Engineering Woody SPU tonearm and a Thomas Schick tonearm (below).

My Thomas Schick tonearm is generally mounted with an Ortofon SPU Mono CG 25 Di MkII mono phono cartridge that I use for listening to mono records, whose 1.5mV output does not require a SUT.

However, during the review period the Ortofon SPU Mono CG 25 Di MkII was replaced with the superb Murasakino Musique Analogue "Sumile" MC phonograph cartridge (reviewed HERE), mounted on a Thomas Schick graphite headshell (my favorite headshell).

My cabling varies quite a bit over time as I test new combinations. The cable complement I used at the time this article was written was a shielded pair of Duelund DCA16GA tinned-copper interconnects to connect the Intact Audio SUT to my vintage MX110Z preamp, to connect the MX110Z preamp to my vintage MC30 monaural amplifiers I used unshielded Duelund DCA20GA tinned-copper interconnects, and to connect the MC30 monaural amplifiers to the Duelund CAST crossovers of the WRSE's I used Duelund DCA12GA tinned-copper speaker cables.

All of my electronics are plugged into an Acoustic Revive RPT-6 Absolute NCF power distributor, which is connected to my wall outlet with an Acoustic Revive Power Reference TripleC NCF AC power cord (recently reviewed HERE).

My wall outlet consists of an Acoustic Revive CB-1DB receptacle base plate, CFRP-1F carbon fiber outlet plate, and an Acoustic Revive modified Oyaide R-1 receptacle, which makes for a very good sounding AC wall outlet, and provides a very solid & secure interface to plug the Power Reference AC power cord into.

For accessories, I should mention the ever-present pair of Acoustic Revive RR77 & RR888 Schumann wave generators that provide room/system/brain(?) conditioning, …

… the Acoustic Revive RST-38 quartz under-boards that I have under my Intact Audio SUT's and Acoustic Revive RPT-6 Absolute NCF power distributor, which by the way, were the inspiration for the integrated under-boards built into my Duelund CAST crossovers, …

…, the Acoustic Revive RCI-3 cable insulators (lifts), and the three studio-like Acoustic Revive RWL-3 acoustic conditioning panels that you can see demurely standing in the background on the front wall behind my Westminster's, and on the right side-wall (below) …

…, and an Acoustic Revive RPC-1 power supply conditioner for all of the wall AC that is plugged into a sidewall AC outlet.

Listening Impressions

If you've read my review of the Murasakino Musique Analogue "Sumile" MC phonograph cartridge in Issue 92, you know what a spectacular pairing the Arai Lab MT-1 SUT was for it.

I am told that an Arai Lab MT-1 SUT wound to exactly 1.2 Ohm will yield even greater performance from the Sumile than what I heard from it when using the 2 Ohm version of the Arai Lab MT-1 SUT, which is rather mind-boggling, considering how fantastic the Sumile sounded with the 2 Ohm Arai Lab MT-1.

Given that the Arai Lab MT-1 I have in for review was designed specifically for a cartridge with 2 Ohms internal impedance, like my Ortofon SPU Classic GM MkII (below), which has been the primary cartridge that I use for stereo music listening, I thought I would focus on the Ortofon SPU in this review.

My comparator in this review was my Intact Audio SUT, which has been my favorite of the silver and copper wound SUTs that have visited my listening room, until now.

Now on to a little music.

Lately I've been buying a lot of great vinyl out on Discogs, where you can find almost any pressing you want, and in almost any condition you'd like.

I've been having a ball listening to Tommy Garrett's 50 Guitars albums produced back in the 1960s.

The concept of the various 50 Guitars albums is similar to that of the classic audiophile album Music for Bang, Baaroom, Harp, on RCA Living Stereo, except that the focus is on guitars. 

The 50 Guitars albums are all recorded superbly, and in that audiophile "spectacular" fashion that was popular in the 1960s, which the Liberty Premier label refers to as "visual sound".

As a bonus, you can pick up 50 Guitars albums like the 50 Guitars Go South of the Border (below) out on Discogs inexpensively.

I'm a bit of a guitar nut myself, so 50 Guitars Go South of the Border was right up my alley, and hearing those fine old vintage guitars was a true treat!

I could really hear the benefits of the Arai Lab MT-1 SUT's super-accurate windings and high Q (quality factor), and it became obvious that a more intact signal was being passed through.

I found out that my Ortofon SPU Classic GM MkII was capable of more subtlety, nuance, dynamic gradations, and better extension into the bass and treble regions, than I thought it was capable of.

On 50 Guitars the Arai Lab MT-1 SUT gave my Ortofon SPU Classic GM MkII an immense sense of space, and each of the guitars (and the percussive instruments) existed in their own spot-lit image in really spectacular fashion, surrounded by a shimmering acoustic ambience that was full of harmonic development, and easily living up to the Liberty Premier label's touted "visual sound" in a rather wonderful fashion.

With the MT-1 it was easier to pick out the timbral signatures of the different guitars, the timbral textures were more detailed, with the overtones - and string tone generally - being more nuanced, complex, colorful, and interesting to listen to.

I was so impressed by what I was hearing out of the MT-1, I was even inspired to get out some of my own guitars to try and play along, with "try" being the operative word, as these guitarists were so far out of my league I could barely see them in the distance!

Now let's add in vocals with our guitars, and listen to Gillian Welch's and David Rawlings' LP The Harrow & The Harvest on the Acony Records label, which is an amazing album that I've been listening to a lot lately.

Gillian's and David's albums have only been available on CD up until now, so I'm hoping this LP of The Harrow & The Harvest is the first fruits of the rest of their albums coming out on LP.

The Arai Lab MT-1 SUT provided a rich tapestry of textures and harmonies from Gillian's and David's voices and guitars that I found simply mesmerizing.

Gillian plays either a 1956 Gibson J-50 guitar, or 1939 Martin D-18 guitar, and David plays a 1935 Epiphone Olympic archtop guitar, each with a very unique voice and tonal signature, that was rendered with realistic timbral textures, remarkable articulation and nuance, and finely resolved tone colors through the Arai Lab MT-1.

While the album is categorized as folk, David's jazz infused crosspicking is really spectacular, with all kinds of interesting tone color additions as he plays, which combined with Gill's guitar, really makes for a fascinating and darkly beautiful tapestry of notes and nuance.

To put it bluntly, the combination of the Arai Lab MT-1 SUT and Ortofon SPU Classic GM MkII on The Harrow & The Harvest was so spooky real and captivatingly musical that I listened to the album straight through about a half-dozen times before coming up for air!

I don't mean "spooky real" in the usual audiophile sense, either, but rather that it felt and sounded real, natural, and intimately present, just like it would with "real people in the room" playing music.

One doesn't get that "this sounds real" result with the majority of records, no matter how wonderful they are to listen to, but with the Arai Lab MT-1 SUT and Ortofon SPU Classic GM MkII on The Harrow & The Harvest I was blown away by the "real sound"!

Another album that I can't seem to get enough of lately is Ben Harper & The Innocent Criminals' Lifeline album.

Lifeline is a superb all-analog recording of compelling rock & roll music, that was "… mixed … on a 16-track analog tape machine. No computers or pro-tools were used anywhere in the process."

Recorded at Studio Gang in Paris (below), it may be one of the best recorded rock & roll albums you'll ever hear.  

One of the things that stood out on Lifeline was how well the Arai Lab MT-1 delineated bass lines, providing nuance, resolution, dynamics, and with a strong sense of beat that viscerally engaged me, just like they should, driving the music forward with authority and energy in an exciting and stimulating way.

While listening to the guitars, bass, drums, keyboards, percussion, and backing vocals I was again struck by just how much more information there was with my Ortofon SPU Classic GM MkII than I am used to hearing from it with my Intact Audio SUTs, how musically natural it sounded, and how it allowed me to be so totally immersed into the flow of the music, in such a near state of wonderment at what I was hearing.

Another incredibly good album I've been listening to a lot lately is The Alternate Blues, featuring an all-star lineup of Oscar Peterson on piano, Dizzy Gillespie on trumpet, Clark Terry on trumpet & flugelhorn, Freddie Hubbard on trumpet & flugelhorn, Joe Pass on guitar, Ray Brown on double bass, and Bobby Durham drums.

My album is an original pressing that I picked up off Discogs at a modest price, and it sounds great!

The music is fantastic, the recording is fantastic, and I don't know of a better album for investigating the tone of trumpets or double bass than The Alternate Blues.

The Arai Lab MT-1 made a very impressive show of the trumpet tone, sounding as real as I could hope for, while being vividly present, incredibly articulate, and superbly nuanced.

I'm really familiar with this album, and I have been marveling at the difference wrought by substituting the Arai Lab MT-1 SUT for my Intact Audio SUTs. The MT-1 just brings out a whole new level of musicality from my trusty Ortofon SPU Classic GM MkII phono cartridge, which it turns out is capable of providing a lot more natural sounding transparency, detail, nuance, articulation, and sense of space than I ever thought it was capable of.

With the Arai Lab MT-1 SUT on the Ortofon SPU Classic GM MkII, there was just "more" there of the instruments, with the trumpets, flugelhorns, piano, guitar, double bass, and drums having more articulation and nuance, with the overall tone of the instruments still being beautifully natural, intensely colorful, and vividly present.

Prior to this review I wasn't really aware of how much super-accurate windings and a high Q (quality factor) matter in a SUT, but listening with the Arai Lab MT-1 SUT in my system makes it apparent that it is a really big deal.

It's immediately audible that a much more intact signal was being passed through with more of the natural subtlety and nuance intact, and it just sounds more defined and evenly balanced from the very lowest frequencies up through the very highest frequencies.

There's also a certain ease on dynamic peaks, that combined with all the gradations of dynamic nuance all through the range that the Arai Lab MT-1 SUT is capable of, that really made the music compelling and engaging in a very satisfying way.

Pretty much everyone knows that Ray Brown's bass playing is wonderful, but through the Arai Lab MT-1 there's all kinds of articulation, dynamic nuance, and a wonderful sense of touch upon the strings that normally goes missing in action, that when present makes Ray's playing sound and feel that much more lifelike and impressive.

I like a lot of different kinds of music, but more often than not I gravitate towards jazz, rock & roll, blues, and folk.

Every once in a while, I come across a classical album that really appeals to me, like the España For Two album on the Klavier label, that has pretty much blown me away with its combination of superb music and super recording quality.

I picked my copy up at an estate sale for 50 cents USD, and it didn't look like it had ever been played. If you see a copy of this in the wild be sure to buy it, it is a superb album!

España For Two features the duo-pianists of Nadya & Steven Gordon playing Manuel Infante's "Andalusian Dances", "Music of Spain", Isaac Albéniz's "Festival Day in Seville", and of course, Alexis Immanuel Chabrier's "España".

Listening to Nadya & Steven play two pianos on these selections was breathtaking, full of tone color, dramatic dynamics, tons of nuance, and obvious heartfelt emotions between the two musicians (wife & husband), these performances had me on the edge of my listening seat more than once.

The string tone of the pianos was ravishingly beautiful, complex, full of overtones, and was brought out in full by the Arai Lab MT-1 SUT, which really had an uncanny ability to let me become submerged in the emotional and artistic aspect of the music as I listened.

Summary and Conclusions

It's a little hard to know how or when to conclude a review of such a superb audio component like the Arai Lab MT-1 SUT.

After all, how many times and ways can one say something is mind-blowingly good in every meaningful musical and sonic way?

Over the months that the Arai Lab MT-1 SUT was visiting me, whether paired with the superb Murasakino Musique Analogue "Sumile" MC phonograph cartridge. or my Ortofon SPU Classic GM MkII phonograph cartridge, it always performed in stellar fashion both musically and sonically, and brought out the very best from the albums I was listening to.

Is there a downside to the Arai Lab MT-1 SUT?

From a musical and sonic perspective there's only upsides for me, with the only downside being that it is achingly expensive, which means that a lot less people will get to hear what the Arai Lab MT-1 SUT is capable of than I would like.

However, that's the nature of an ultra-quality and impeccably handmade SUT that is custom designed to get the very best out of your favorite moving coil phonograph cartridge, it's just going to be expensive.

The pricing of the Arai Lab MT-1 SUT varies depending on the internal impedance of the cartridge it is designed for, as the materials costs and the difficulty of building an MT-1 increase with decreasing impedance of the phonograph cartridge.

An Arai Lab MT-1 SUT for cartridges with a 21 Ohm or higher internal impedance is $10,995 USD, for cartridges with internal impedances of 20 Ohms to 11 Ohms an MT-1 is $11,995 USD, for cartridges with 2.1 Ohms to 10 Ohms internal impedance an MT-1 is $12,995 USD, and for cartridges with an internal impedance that is 2 Ohms or lower an MT-1 is $13,995 USD.

If I could afford it, I'd unhesitatingly have an Arai Lab MT-1 SUT for every single moving cartridge I love, but alas, that's a dream, as it's out of my price range!

If you're able to fit an Arai Lab MT-1 into your budget for your favorite moving coil phonograph cartridge, I fully expect you will have a very happy future together! Highly recommended!

I would like to thank Mr. Toshio Arai (Arai Lab) and Mr. Yoshi Hontani (The MuSon Project) for the opportunity to experience and write about the Arai Lab MT-1, it was a truly wonderful experience - thank you!

As always, I would like to thank all of you for taking time to stop by and read my article, and may the tone be with you!

Contact Information

In North America, the Arai Lab MT-1 SUT is available from Mr. Jonathan Halpern of Tone Imports on a custom order basis.

In other parts of the world, please contact Mr. Yoshi Hontani directly for information about ordering an Arai Lab MT-1 SUT of your own.