Infinity · Floorstander · Around 1981
The Reference Standard 2.5 is a big tower, about 51 inches tall and 53 kilograms, built as a smaller take on the flagship RS 4.5. It's a three-way with five drivers: a 12-inch polypropylene woofer, two EMIM planar midranges and two EMIT planar tweeters, one of each pair firing backward so the speaker radiates to the front and the rear. The woofer has two voice coils of different impedance, and the second takes over near the woofer's resonance to flatten the bass. The planar drivers use samarium-cobalt magnets, and Infinity quoted the EMIT's response to 32 kHz. It sat in a lineup of around 1981 with the RS 1.5 bookshelf and the RS 4.5. Listings sometimes describe it as a slim 40-inch tower with an 8-inch woofer and a 6-ohm rating. Those numbers are wrong, and the real one is a 4-ohm heavyweight.
With the grille off
Ask for a photo of every driver with the grilles off, on both speakers. They should match each other and this list.
With four planar drivers per speaker, two of them on the back, there's a lot to test. At 53 kilograms each and 4 ohms, it also needs a plan for moving it and an amplifier that can handle the load.
New to old speakers? How to check a used pair walks through every driver, the crossover and the cabinet.
We haven’t been through this model’s listings yet. Search eBay and run every listing through the checklist above. Ask for photos of both speakers with the grilles off and the serial labels on the back, and pass on any seller who won’t send them.
Search “Infinity Reference Standard 2.5” on eBay ↗eBay searchInfinity · 3-way
FloorstanderSpecs and what to check →
Infinity · 4-way
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Infinity · 3-way
FloorstanderSpecs and what to check →
Infinity · 2-way
BookshelfSpecs and what to check →