McIntosh XR19 Speaker System
A History
Copyright 1996-2003 by Roger Russell
All rights reserved
No portion of this site may be reproduced in whole or in part
without written permission of the author.
The XR19 was designed to
be an alternate to the XRT20. This system takes up less than 26" of wall
space, has good dispersion and provides high power handling at high
frequencies. The XRT20 column and bass cabinet takes up 45" of
floor space. The production XR19 has the same bass cabinet as the XRT20
including the two woofers and 8" mid-range.
Since a column of
tweeters do not fit the design criteria, the first prototype had twelve
tweeters arranged in a semicircle around the top. The woofers were mounted on
two faces. At the right top a capacitor decade box can be seen. We made several
inductor and capacitor decade boxes, both with series resistors that could be
switched in and out. This saves lots of design time winding new coils and
soldering them in place. Casters are attached under most of the larger system
prototypes so they could be moved around the lab easily.
We found that there
was too much high frequency output to the sides of the system. This could be a
problem if the system is located against one wall in a corner. Also, the angle
between tweeters causes uneven response. By rearranging the tweeters into a
semi-ellipse, more output can be maintained at the front and less to the
extreme sides. Vertical response is inherently very good. Felt strips are
placed above and below the tweeters to prevent edge reflections from above and
below. The curved array is an alternate solution to providing good dispersion
with a short horizontal column. It also worked very nicely on the top of an
XRT20 cabinet and so the final shape was established. Although only 12 tweeters
are used in the XR19, the power handling is still comparatively high at 150
watts of program material from 1.5kHz to 20kHz. Later, with the design of the
XRT18, another solution was found to overcome the directionality of a short
column.
Instead of both woofers covering the same frequency range, the lower
woofer goes from 20Hz to 150Hz. The upper woofer goes from 20Hz to 250Hz. The
use of two different woofer crossovers reduces interference between the woofers
in the upper bass where the distance between them is significant compared to
1/2 wavelength of the sound being radiated. This improvement is used in the
later version of the XRT20. The 8" mid-range is contained in a sealed
enclosure and covers the range from 250Hz to 1500Hz.
The crossover is located in the top section with the tweeters. The top is
easily removed by unlatching two fasteners. The XRT20 laminated crossover coils
and motor running capacitors are used in the XR19.
The XR19 is overlooked gem. Not many of them were sold compared to the
XRT20. The excellent imaging presents an outstanding sound stage with lots of
bass punch from the two woofers. This is clearly a dramatic step up from the
earlier XR7. As far as I know no literature was ever made for the XR19 except
for pictures from the manual that were used in the direct mail advertising.
XR19 Specifications
Response: 20Hz to 20,000Hz
Power rating: 250w woofers, 200w mid-range and 150w tweeters
Output sensitivity: 86dB/watt/meter re: 8 ohms
Impedance: 8 ohms
Woofers: two 12" McIntosh
Mid-range: one 8" McIntosh
Tweeters: twelve 1" custom soft domes
Crossover frequencies: 100Hz, 250Hz and 1500Hz
Overload protection: main and high frequency fuse
Finish: walnut
Dimensions: 45-3/4" high, 25-7/8" wide and 12-7/8" deep
Weight: 151 lb.
Sold from 1981 to 1987
Last retail price: $5298.00 /pair
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More text and pictures about McIntosh will be added as my research continues. Any comments, corrections, or additions are welcome. |
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Created by Roger Russell |
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