FIDELITY RESEARCH STEP-UP TRANSFORMERS

With my FR-7fz and previous FR-7f i've been using this toroidal silver sut, they are superb for all LOMC cartridges, 3 inserts available for different impedance.  

FR-7f and FR-7fz are great cartridges for sure, when you’re using them on FR-64s tonearm you don’t have to adjust azimuth if the arm mounted on flat surface as it should be.

I am not so concerned about silver phono cables, i have them too, but i like high quality copper phono cables.

SUT is oldschool classic solution for LOMC, but you can always try something new like CURRENT INJECTION phono stages. They are designed for low impedance cartridges, 47Labs Phono Cube is magical with my FR-7fz. This is a "current-injection" type o the PHONO STAGE.

@nandric used 47 Labs phono cube goes for $1500 minimum, new it was very expensive device. Phono cube itself is very compact, but power supply is big and heavy, together it was about $3k new. This product is no longer available from 47Labs (discontinued model). 

Someone even cracked it up and made a replica for less $$$

Dear chakster, May I conclude that you don’t own an phono-pre
which can drive outputs of, say, above 0,15 mV? I need my
Denon transformer only for my Ortofon MC 2000 with 0,05 mV
output. However lew(m) also mentioned an ’’current injection’’
type for his Ortofon MC 2000. I asked what this ’’current driven
thing ’’ means but was not ’’honored’’ with an answer.

Nikola @nandric i think i tried all possible types:

SUT, Headamp, High Gain Phono Stage, Phono premps with built-in SUTs ...

0.15 mV is not a problem at all with my phono stages (i have 4 different)

Even 0.05mV is not a problem with Gold Note PH-10 i’ve been using with my MC2000

1) What is new for me is Current-Injection type of the phono stage, various manufacturers made them. You can read about one of them here. MCCI is MC (Moving Coil) CI (Current Injection).

here is more about principle:

"The basic difference between the Phono MCCI and virtually all other phono preamps is its current-injection input, which takes advantage of an MC cartridge’s very low impedance, its inherent current-generating capabilities, and its balanced, floating-ground architecture.Instead of a traditional voltage-gain stage, the Phono MCCI’s input stage is a current-to-voltage converter. According to the Candeias, the cartridge directly injects its current into a system of "balanced DC currents," creating an amplified output voltage. The resulting amplified voltage is claimed be made "directly of the original cartridge’s current" with virtually no loss, and certainly less loss than is claimed for any voltage-gain circuit."


2) My current-injection phono stage is 47 Labs originally designed for MIYABI cartridges! Read here about it.


3) If you want to go further i’l tell you that power amps can also be current source, like this Nelson Pass design i am using.

Nelson Pass about this principle:

" A given input voltage results in a particular output current. Ordinary amplifiers are voltage amplifiers – an input voltage translates into an output voltage. This is not that kind of amplifier, and as of this writing, the F1 and now the F2 are the only such amplifiers available for audio use. Being current sources, these amps operate differently with a loudspeaker. A regular audio amplifier supplies an arbitrary output voltage, and the speaker draws current according to its complex characteristic. As such, the current through the loudspeaker is not exactly proportional to the voltage in either amplitude or time. A current source amplifier delivers a precise current to the voice coil of the loudspeaker driver, ignoring the series impedance elements in the circuit, including the wire, connectors, the inductance of the voice coil, the resistance of the voice coil versus temperature – all that stuff. This is potentially valuable in that the current passing through the magnetic field of the loudspeaker produces the force and acceleration on the voice coil and cone, and this translates directly into sound pressure. A current source is simply the most direct way of controlling the acceleration of the voice coil. In the linear range of a loudspeaker, the acceleration is directly proportional to the current, and in mass-controlled loudspeaker drivers the sound is proportional to the acceleration. Since most loudspeaker systems are designed around a voltage source, there is only a subset of products that can take advantage of this effect. In general, these are high-efficiency drivers (ones that produce more than 90 dB per watt). Of greatest interest is the performance offered to high efficiency full-range drivers, where not only is the loudspeaker very efficient, but also covers a wide or full range of the audio spectrum through a single radiating surface. Often this translates to delicate single cone drivers such as the products from Lowther or Fostex, with big motor assemblies coupled to light fragile paper cones. These are the speakers that often don’t sound good with “high quality” solid-state amplifiers, most often because the two are mismatched in impedance and wattage. This is an unusual amplifier that will not give its best performance with most of the loudspeakers on the market. It requires careful attention to loudspeaker loading to get the best performance. The accompanying white paper “Current Source Amplifiers and Full-Range High-Efficiency Drivers” is required reading. This is a tinkerer’s amplifier. "

manual here.

Sadly Miyabi 47 and its predecessors MCA,Standard also discontinued, but this is not the reason to ignore them. 

New Current Injection phono stages still available from several manufacturers for much higher price than my 47 Labs

I am not going to get a single input step up transformer. I have what one will call a 'bijou' room so multi inputs are the 'way to go' for me.

For this reason i have line preamp with 4 inputs, so i can connect different phono stages for my 4 tonearms (two turntables).

The SUT i have mentioned has one base with insert for 3 different silver toroidal transformers designed for ALL type of MC cartridges (8030 for 1.5 - 3.5 Ohm // 8025 for 3 - 40 Ohm // 8020 for 20 - 40 Ohm ). This is SUT if the most versatile. 

In my 'nearfield' set up I am being drawn more and more to a warmer tonal palette than ever before. I make no apologies for it and do not want to be a 'slave to neutrality' - that said a thick syrupy sound - yuck:)

Even if your phono stage is neutral who said that your amp is neutral, especially tube amp ? This is where you can get your warm tone. 

SUT is oldschool technology, learn as much as you can about "Current-Injection" PHONO stages for low impedance cartridges, this is the most direct and live sound ever. This is ideal for low impedance MC cartridge.  

It's better to plug/unplug not RCA connectors on the SUT side, but DIN connector on your tonearm when you want to switch from one to another. You just re-direct a cable (DIN) from one tonearm to another if needed. For this reason i designed custom made rack with open bottom for easy access to the tonearms. SUT swap on Luxman base is easy as changing tubes in the amp.  I also have WBT RCA on some cables. 

But this is not what i'm trying to say. 

Current-Injection phono stage for FR-7fz is the best solution, better than SUT 

Denon 103 with conical tip in 2020 - are you serious ? 
You like rolled-off sound ? 

Frequency response of the silver SUT from Luxman is within 15hz - 100kHz is very good for vinyl. Distortion ration 0.003 %, step up ratio is from 1:10 to 1:32. Multiple Electromagnetic shield. Excellent core material of Toroidal type. 

For example Denon AU-340 has 0.05 % distortion ratio, this is much higher distortion.