Warming up the Denon DL102

Altec 405A

This ain't no April fool's joke!😆

Since the mid-60s (scroll down to pdf page 31), stateside audio experimenters have been trying to squeeze the last ounce of performance from the Coral/Sony "Holey" and Foster/Fostex FE103/Realistic 40-1197 family of 4" drivers. Meanwhile, Japanese aficionados like Old Joe (above), whom I follow on YouTube, kept snapping up Anaheim-manufactured Altec 405As in multiple quantities to stuff into their mini A7 VOTT projects. 

Because of the dearth of units left in the States and my indifference towards engaging in a bidding war versus fellow Asian hobbyists, I patiently hunted them for 20+ years via other channels.

Altec 405A specs

The 405A is a 4"  60-15,000 Hz wide range driver with a sensitivity rating of 92dB/4ft/1W. It's equipped with a massive Indox magnet that's almost the same diameter as its cone.