The absolute preamplifier, a b s o l u t e.
Reviewed in Japan above the contemporary Mark Levinson, Krell and whoever else that was more trendy, had more "aura" or good press agents.
Only the Pioneer Exclusive C7 and the Cello were ranked better, both by a very small margin. That's the league the TA-ER1 was playing in - it still is, up there, at the very top.
If very different, the basic engineering has the same perspective as that of the Exclusive C7 : no super-extra-sci-fi circuits potted in mysterious modules but plain common-sense carried out with ultra build quality.
Extremely high impedance inputs
High-efficieny FET with 4MOhm resistance line inputs to reduce voltage loss and keep input current stable, input signal level's variations notwithstanding : less distortion, no signal loss, better if not perfect driving of the following stages.
All-balanced signal treatment
All-balanced even for the unbalanced inputs to amplify the signal between hot and shield only but not the ground electric potential at chassis. The unbal inputs therefore have three-point connections as well : hot, cold and ground, the latter derived from the cold point.
This also allows the electric potential of ground to not fluctuate even when input sources are connected or disconnected.
Carbon conductive resin attenuator
Apparently custom-ordered from here (yes, ALPS, who else ?), this 3x 30kOhm attenuator has a total range of 130dB, a gang error of 1dB down to -100dB (±0,5 to -60dB). It is entirely gold-plated, brushes included.
This attenuator is housed in solid brass slabs of 9,5mm thickness and is remote-controllable with a supersonic ceramic motor which remains entirely separate from the attenuator itself ; its processor disengages itself entirely one second after having been used.
A smaller variant of that attenuator, again custom-ordered, was used in the TA-E1 and the original was also used by Technics, Accuphase, Micro and a few others (and a bigger one in the Luxman CL-88).
The other features, in no particular order, are ultra-low impedance MOS FET Direct SEPP output, transformer-balanced MC input, entirely dual-mono and two-tier circuit boards for ultra-short wiring and heat repartition, a separate power-supply with a bigga low-leakage toroidal transformer and copper-shielded high-quality ELNAs, dual-sided relays for all signal points, 6N OFC wiring for all signal, power-supply and ground lines, copper bus bars and shielding, a "low extend" attenuator switch - and then some.
Read the TECH1 section and Knobber images #6 and #10 to #16 for the details and the rest !
Visually, the ER1 was designed by Yuuji Morimiya.
The production run is supposed to have been of 100, mainly on order but the highest serial spotted so far however is the japanese #200 185 so the total worldwide count should be of 200 made, of which about 25 were original 230V / EU models. A particular Sony twist, the serial number isn't on the TA-ER1 itself but on the RPS-ER1 power supply.
Many TA-ER1s were discounted to "insiders" and Sony employees as late as 2000/2001, all with ridiculous B-stock prices, three years after distribution had stopped in Japan.
If the TA-E88B is one of the best preamplifiers of the 1970s (and one of the best - period), the TA-ER1 is the best preamplifier the history of 2-Channel audio will have ever heard.
Since that history is now closed, Sony or otherwise, the TA-ER1 naturally is even more desirable.
More soon from the other three dedicated R japanese catalogs which I finally managed to find after four long years of relentless search !