I got a great deal on a pristine pair of McIntosh XRT20 Isoplanar Loudspeaker System. I am the second (proud) owner.
If you’ve never heard of them (I hadn’t), they are reported to be an awesome speaker.
As far as their condition goes, the finish was nearly flawless when I picked them up. One cabinet received minor damage on the three hour+ trip home. I’ve replaced the original, tiny and rather weak, spring clip terminals with some equally cheap 5-Way binding posts that accept up to 10 AWG wire (not much room to work with). I have also replaced the three non-polarized AC motor run electrolytic caps on each of the crossover boards. These XRT-20s are a later unit with crossover points at 20 to 100 Hz (from downloaded owners manual) or to 150 Hz (from Roger Russell’s Design Notes from his History #2 site) for the lower woofer, 20 to 250 Hz for the upper woofer, and 250 to 1.5kHz for midrange, with the towers handling what was left. They are equipped with warning lights and fuses. I may replace the fuses with MOVs or whatever the designer used (and recommends) for his next iteration. Both the tweeter and bass cabinets have a trapezoidal shape to promote an awesomely wide sweet spot, but the speakers are not so great on imaging (in fact they’re awful). The bass, without the subwoofer, is simply out-of-this-world. They pass the LEDR test with flying colors, clear, defined bass from low to upper without a sag or bump anywhere. I find that the system performs better with the bass cabinet, or ‘credenza’, pushed close to the tweeter tower, although it can be placed up to 8” away, the spacing introduces a noticeable dip the LEDR vertical step test. These speakers were top-of-the-line in 1978 when they came out, and proved the designer’s concept of line arrays in the home (although he ditched the bass cabinets later in life). They were still pretty hot stuff when the original owner bought them in 1992. Folks report that they sound ‘big’ before they sound ‘loud.’ As I related in a post to the forum, the XRT-20’s have a very different sound to my system downstairs. I wondered what had happened to the sound stage I was used to hearing downstairs. With the tweeter towers screwed to the walls at the manufacturer’s recommended 1/3 intervals, the head must be precisely placed between the speakers to get the full stereo effect. The system can easily fill the upstairs space with sound without consuming more than 10-15 Watts, although my son has pushed it harder. Too much volume tends to cause the stuff I place on top of the credenzas to move around and sometimes fall off.
From the specifications in the Owner’s Manual:
Speaker
Woofers, two: 12" (30.5 cm) diameter;
Mid-range, one: 8" (20.3 cm) diameter;
Tweeters, twenty-four: 1" (2.54 cm) diameter
Cabinet Size
Bass Section: 39-9/16" (100.5 cm) high, 25-7/8" (65.7 cm) wide, and 12-7/8" (32.7 cm) deep.
High Frequency Section: 77-1/8" (195.9 cm) high, 10-3/4" (27.3 cm) wide, and 11-3/16" (4.6 cm) deep.
Construction
The cabinet is constructed of 45 pound density particle board with hardwood bracing. The exterior is genuine walnet veneer with laquer finish.
The high frequency column is constructed of aluminum extrusions finished with genuine walnut veneer and solid wood end caps.
System Weight
170 lbs (77.1 kg)
Shipping Weight
192 lbs. (87.1 kg)
The weight given is for a ‘system’ consisting of (2) bass cabinets, and (2) tweeter towers which each come in two pieces, for a total of three pieces per speaker. Surprisingly light, given their size.
