Crown OC-150A - Input;Output Specifications and Operation; Meter Response and Signal Interpretation

IkNPUT/OUf Pm SPECS
Since it is a mechanicat (~~"stelhing) device, the DC-
150A dwr not alter the output fram an amplifier in
any way. The swikhing Is pr~ckse and uses break-
before-me ke coo~rbe% to protect $ha assxiafed
ampiif ier eaurtputs from aeeidentsl shafiing, Bn addi-
tion, the amglifi~fr i~puk hawe analgctricai Imk~ut to
fu~hef guard against aeeiden&l paralleling*
AC pwer is plrmid~d br Xhla OC-15OA only to power
Eh rn~tering ~ireuifs, Th@ swlt~hing mmhanibm wiII
hfiabon
wgh the mwr turn& 8@.
In add Rim, faita r conw;nienee outjets are prov*@ad an
the rear panel ta PGWQ &CC%SQT~~~ qui pmant . P he*
outlets are unswitch~d and remain an as la~"rgnsths
86-1 5QA power plug is plumed into
""live" murca A
ve~ conmagiant wurca is alt"lsei? sf the $w&ch& OUEI&S
on the pfg-amp.
METER RESPONSE!INTERPRETATIOMS
Wny HI-Fi sptcms include a mehring system which
reads the output voltage acrass the amplifier tgr-
miinail%, The tendency far most users is to make
some tym of assxiation ktwen mter readings
and pawr sutpuk White a relationship does exist
w voltage and wwr, it is oat a simple ma%@r
to det~rmina in a hi-fi system - paflicularly when a
complex waveform, such as musie, io used as a
program source, So 3% a takeaR pint, w n~ed $0
review the basic eharacteristies of measuring cir-
cuits and meter mavements, t&erns~tv~$~
As the frequency of a signal iner~ases, it bcsms in-
creasingly didaicuit far a meter mowm8nt ta follow
the sodden changes of signal i@v8lx In fact if an A@
signal of abo& 10 Hz or higher w~e applied to a
center-zero, dc meter, the wiflX@et.~~~id only manag@
to vibrate arsund zero, Because of the physical
pram&ies of ths movement, it simply $=au not "Ilfow
%ha rapidly changing voltage. The srssuit is a
smmthing aut sr simpliving 04 the w~vefarm~ the
reading bing an avemge* If that wawefarm is a sine
WVE, the av8rage is zeqo, sa the meter, king en
average reswnding meter, reads zero.
We could try to use a dire& AC reading
again because sf mechsrnial di@icu&ies,
frequency limit is En the viciniw af 400 Ht,
If we would rectib a sine way8 with a ful! wave rm-
tifieu, end connect a DC m@t@r to this o~tput, the
metgr w~ufd smooth out Zhs wev~faa*m and indicab
an avarage value of about .637 times the mk wt-
put. flhe rectified waveform consis& of positiva
halv~s only af the sin@ wave; NO ~sitive halves mr
cycle of input*) W@ couM calibrate the scale ta rwd
snflhixag w8 wanbd, gueh ar av@r1g@, @#web'
(rms), w paak. As ktng as the signal rgmains a L%@*
~ioe wave, we can make accurab ~W@P earn-
partations when meaguring acrws a knwn ia~d
where:
P Powr in w%$
Ez
(BV@MB, fm, ~8k, @tee); of &b %~@Q%JII
in w~it3
F@ R~gistance 02" the load in ohms
fl
What hapmns &e~ the 8ig~al iti na Imger ar %t@ady
sine wve'? LetP$ Iwk at OLLP mter when the inp& b ;a
mudc pFogYa me
Even thaugh our mter i$ &cclilmt@ty c;alibrat@gS b
read rns or peak voltages with a sine ww , msn -8b
cornpi@x musie signal is rrs&ifi@d and applied ta the
mter, the &st tha sfu~ish mter can ds is indim&
some tym sf ayerag8 readirrg* We tatally miss aXI tb
quick waks aF the high frequencies, QWr@ an eSm
G~~~QSGOW muld k the only masuring &vice
capable of responding fast enaugk to catch snd die
play these =&s. ~wveu, our eye is nd alw~s %st
enough to sw ths wak, so ewn this 1% wok gr?;stiy
secumte,) At this paint, whet katl hap~$s@d OM$
vohap readiugs and pswr corwap&atioras!
It takes a 10t af camplieated mthamtits to versg~der
~RQSIE?! witage readings US~U~ for mwt CO~
putations. Using an analysis tmif ebfied the &ussiran
didributian cuwe, it is possible to pr@di& (mr a
Bong prisd of tim) what the signal iewl% @fa ~US~C
prognm will be Most of US IV~W~? g"Bi-fiT@r$ an%
have the mathematical know-how or the patience to
'
use this prscsss, 98 for us the mekr readin@ ;are