Just like the previous ST-5950SD, this FM tuner is a real sleeper, lying among the myriad of worthwile but still completely overlooked Sony units.
Probably originally intended as a cheaper alternative to the ST-A7B, the ST-A6B holds its own with a 7-gang varicap and slightly better DX performance. And looks to match !
The ST-A6B starts making music with its 7-gang capacitor and a quadruple-tuned antenna circuit.
Dual gate MOS-Fet RF front end, dual gate Mos-Fet mixer and Fet-buffered local oscillator, Sony Uni-Phase in the IF stage and PLL MPX IC make the rest of the music path.
400Hz test tone, adjustable output level (or not), auto/narrow and muting switching, mono / hi-blend / stereo modes and signal & multipath meters is what you can fiddle with.
What this doesn't say is that, without sounding as incredibly magnificently superbly unbelievably beautiful as an ST-A7B, the ST-A6B is close enough and close enough to withstand comparison with many of the well known mid-end "super" tuners - a comparison very dangerous for most of the latter !
Available worldwide under the same moniker (for once !) and with the same color, too, despite catalogs' large variations, offering grey or clearly cyan versions !
The green / bronze nevertheless came out for all versions in real life - for once Sony made it simple.
Fairly rare in the USA but, as usual, quite abundant in Europe ; there is no reason to pay a fortune for an ST-A6B as there are many around, many.
The smaller sibling is the silver-ish and Japan-only ST-A5 which had the same basic design and the same 7-gang varicap... for half the price.
Do read the FM-Tuner Info review of the ST-A6B !