FS: Fidelity Research FR-7f low output MC cartridge

Up for sale is my Fidelity Research FR-7f low output moving coil cartridge. This is a heavy, low-compliance cartridge so well suited for heavy tonearms with high effective mass.

There’s a ton of info on these rather special carts on the web and, in particular, audiogon. E.g.: Audiogon Discussion Forum

Fidelity-Research FR-7f specs:

■ Price in 1980 was 77,000 yen
■ Power generation method: MC type cartridge
■ Output voltage: 0.15 mV (3.54 cm / sec., 45 °)
■ Output voltage: 0.2 mV (5 cm / sec., 45 °)
■ Output power: 2 × 10 -8 W (5 cm / sec 45 °)
■ Needle pressure: 2 g to 3 g
■ Load impedance: 3 Ω
■ Coil impedance: 2 Ω
■ Playback frequency: 10 Hz to 45 kHz
■ Channel separation: 28 dB (1 kHz)
■ Channel balance: 1 dB (1 kHz)
■ Compliance: 7 × 10 -6 cm / dyne (100 Hz, 20 ° C.), the compliance measured at conventional 10Hz will be about 13cu!
■ Tip: 0.15 mm square Refined contact, Solid Diamond needle (LINE CONTACT)
■ Weight: 30 g

Some blurby stuff (taken from: https://www.ukaudiomart.com/details…tyresearch-fr7f-mc-cartridge-in-the-box-rare/) below:

Some key features of the FR-7f (a google translate from japanese manual taken):

■ Push-pull power generation method with magnetic circuit of 2 magnet 4 pole composition. It is possible to take out a sufficiently large output voltage even with a low impedance coil by performing power generation at 4 places. In addition, although the cancellation current is generated in the power generation circuit by the general method, the magnetic circuit of FR - 7f can be taken out as the output in the positive direction in the reverse direction also in the conventional cancellation current generation region. As a result, the phase characteristics and crosstalk characteristics are improved, the electrical conversion efficiency is greatly improved, and the output power is also improving.

■ A samarium cobalt system magnet is adopted as a magnetic circuit material. This magnet has superior characteristics such as high coercivity and difficult to self-demagnetize compared with general Alnico series, and the initial characteristics of the magnetic circuit are retained for a long time.

■ A completely air core coil without a winding frame is adopted as a generating coil, and the unnecessary magnetic body does not move within the power generation magnetic field, and the distortion of the reproduction signal is radically eliminated. Moreover, the effective mass of the oscillator can be reduced to about 2/3, and the mechanical impedance of the high region is reduced.

■ Special aluminum alloy cantilever.This is a straight cantilever which has been optimally thermally hardened (ceramic treated) for high corrosion resistance special aluminum alloy to minimize the moment of inertia and deflection during high speed exercise.

■ Double damper system, two-layer damper structure with different rubber coefficients, it effectively dumps the mid-high range and middle-low range of the vibration frequency, ideal trace can be made over the entire reproduction frequency I am doing it. Moreover, since the rubber coefficients of damper A and damper B are different, the influence of temperature on trace performance, mechanical impedance characteristics and reproduction sound is reduced totally. In order to solve the problem that the coil lead wire vibrates together with the cantilever, unnecessary power generation by the lead wire portion is eliminated by inserting and crimping the coil lead wire between the dampers AB.

■ The head shell part has been taken into consideration to remove the dead space completely causing the parasitic vibration harmful to the sound quality. In addition, a special aluminum alloy is used for the material of the shell part, and further improvement of rigidity is made by impact processing (cold forging) and the occurrence of split resonance is proposed. For cartridge body material, epoxy resin selected with elaborate auditory test is adopted. A special stainless steel lock plate is adopted in place of the conventional guide pin in order to improve strength shortage due to backlash of arm and connector part. This makes it possible to integrate the coupling with the arm more evenly, and it is possible to keep the levelness correct.

It is very interesting to read Jonathan Carr’s comments about FR-7f, he is a designer of modern high-end cartrisdges under Lyra brand.
This is what he said about why FR-7 series made as headshell-integrated only:

"Here you can see just how huge the magnet structure is, and if you understand cartridge design, the uniqueness of the 7’s innards will be very apparent. The magnet structure alone would spill over the body sides of any non-integrated headshell MC cartridge (at least that I am aware of), and underscores why FR never made a non-integrated headshell version of the 7. From my perspective (that of an active cartridge designer), the closest thing to a non-integrated headshell version of the FR-7 was the PMC-3, but even this remained quite a way off. The FR-7 had a radically different coil former (cube-shaped), likewise for the magnetics (dual magnets, quad polepieces). IMO, the FR7s were by far the most interesting of FR’s MC designs, but the 7’s basic design concept dictated that they would always be big, heavy monsters, suited for relatively few modern arms… My favorite FR-7s are the f and fz. The very low coil inductance of the FR-7 implies that loading can be fairly flexible, so I wouldn’t be so concerned with the low impedance. Also, none of the FR-7s are overachievers in detail, and the top end extension is a little curtailed. so the downsides of transformer stepups won’t be overly apparent. However, in consideration of the low coil inductance, should you choose a stepup transformer, I would look for a toroidal-core type. FWIW, I’ve known Isamu Ikeda for many years, and not once has he suggested that the FR-7 was any kind of successor to the FR-1. Even today he appears to remain proud of what he accomplished with the 7 (also the Ikeda 9), but the FR-1 hardly ever comes up in our discussions. " - Jonathan Carr (Lyra)

According to the manual for FR-7F: “A unique refined contact needle which specially polished a solid 0.15 mm square solid diamond is adopted as a needle tip. The refined contact needle is a new system that combines the advantages of the line contact needle and the merit of the elliptical needle, making it less susceptible to adverse effects (noise etc.) due to warping of the disk and dust of the sound groove. Also, scratch noise and surface noise are extremely low, so you can obtain playback sound with high clarity and no fatigue.”

/END BLURBY STUFF

I bought this used from Japan yonks ago, played for a short while (until I got into EMT TTs and carts) , and, sadly, it has sat in a box for many years until very recently. I tested it with my 301/FR64s and Neumann SMB-2 phono (now sold) and it worked perfectly - sounded truly lovely and beguiling. A more refined/relaxed presentation compared to my Decca, but then again all cartridges probably are in that regard. Has a special, sealed suspension (according to J Carr of Lyra). In excellent cosmetic condition.

Comes with stylus cover but no other accessories. Will be packed very well.

Asking £1200 – cash-on-collection most welcome in Dublin but happy to post at buyer’s expense and risk. Payment via bank transfer or paypal friends.

Cheers,
Adrian
Adrian

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3 Likes

Fabulous cartridge - GLWTS

Ta. The hoarder in me loathes parting with it, but too many carts and a right waste for it to sit in a box for any longer!

Price reduced to £1000. Get yourself a cracker of a vintage cart!