We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
436 RICHARDSON'S BLUEBOOK OF PROJECTION
(13) Very common, in modern systems, is a network of the type shown in Fig. 171, which is essentially a combination of low Figure 171 pass and a high pass fil
ters. It has been found that better quality is obtained by designing separate loud speakers to handle the low and high frequency sound components, rather than by trying to force one speaker to give satisfaction on both bands. The speech currents supplied to the loud speakers accordingly are divided by a filter network.
In Fig. 171 the low frequency speakers are connected directly across the amplifier output. They constitute what is essenially a choke coil wired in parallel to the L. F. output terminals of that diagram. The high frequency speakers, however, receive only such components as are able to reach them through the 4 microfarad condenser. (The two resistors constitute a pad for controlling H. F. volume.). Fig. 171 is a very simple form of network. Fig. 172 is an elaboration of it. Here the H. F. supi5#i« ply path is traced right
_ — n r^ww — -j — n through 2 microfarads
| 2MF
INPUT I
J*
i
&
down through the H. F. output terminals, at the
=j= 4mp ~ output^ kft* and on through 4
— ' ? microfarads to the other
FlGURE m side of the amplifier out
put. It is aparent that the load is short-circuited so far as low frequencies are concerned, by the choke coil between the two condensers. The low frequency path is traced down through that choke coil, and thence to the 1. f. speakers; those speakers being short-circuited for high frequencies by 4 micofarads. This arrangement is elaborated in Fig. 173.
Where Fig. 173 is used with a single power amplifier the two left-hand input terminals are wired together, as indicated by the dotted line, and connection is made to either of them and the input common, marked C. When