KLH Model 12 (c. 1962–1968)

The KLH Model 12 is a large acoustic suspension loudspeaker. KLH built it to go head-to-head with Acoustic Research's popular AR-2ax and AR-2a. It sat above the Model 6 and below the Model 24 in the lineup. The driver complement is the odd part: two 12-inch woofers, a 10-inch midrange, and two 2-inch tweeters. A 10-inch midrange is unusual in a speaker of this class, and it gives the 12 its character. The woofer fires downward. The crossover between midrange and tweeter sits at 400 Hz, and the tweeter level is adjustable with push buttons on the cabinet. It's a closed-box design throughout, and two pairs of binding posts are set up for bi-amping.

The sound is smooth and slightly warm, with a bit of extra body in the lower midrange. The tweeters are clean but don't extend all that high - some owners find the top end a little short on air. The bass is tight and well-defined, which is what you'd expect from a well-executed acoustic suspension design of this era. One contemporary reviewer praised its ability to handle large orchestral passages without strain. Many owners prefer it to the AR-2ax for jazz because of the stronger midrange presence. The midrange can come across as slightly recessed, though the treble controls help with that. HiFI-Stereo (October 1966, p.177) ran KLH's own introduction of the Model 12. It described the speaker as the finest moving-coil loudspeaker the company had made - not by a spectacular margin, but by some important degrees - with adjustments that let the listener tailor the musical balance to the room and program material.

A few things to know if you're looking at a pair today. The original units used paper cones with cloth surrounds, and later production runs had improved surrounds. The foam on original woofers rots and will need refoaming. The push-button tweeter switches often detent poorly after decades of use. The crossover capacitors drift out of spec and are worth replacing. Replacement midrange drivers are hard to find, and some owners substitute the 10-inch from the KLH 24. Fair market value for a restored pair runs roughly $400-$700. The original price was $225 each in 1965. Sensitivity is often quoted at 91 dB @ 2.8V/1m, and the impedance dips to about 5 ohms at 70 Hz, though the nominal rating varies by source. No exact dimensions or weight are documented in the sources available.