Kenwood KF 8011 Brochure

Page 2

THE MERITS AND USES
OF THE AUDIO DENOISER

Like the Dewy Noise Reduction Unit, the Audio Denoiser
reduces noises included in the program sources. But these two

A Graphic Representation of How a Dolby Unit Works

The Denoiser works!

When there's a lot of
noise during FM
stereo reception ......

Dolby won't reduce
that noise.

equipments are two different things. Here's how. A Graph 1(a)
Dolby works only with program sources which have been
recorded in a Dolby system. The Audio Denoiser works with all
types of program sources. :13
Dolby cannot eliminate previously included noises. The Audio g \
Denoiser can. é " 8005
a /
AUDIO DENOISER DOLBY gr-/T-r
3 Recording
: nOISG
OK" No Good.
The Denoiser works! DOlbY WOW! FGdUCG >
that 56- Audio Frequency
mgseprgrgfirtizfgéfl Take a look at Graph 1(a). To put it simpler, when recording is
Miller sound track done using a Dolby unit, the higher frequencies are boosted.
record ...... However, the amount of boost changes automatically with the
recording level. When the level is high,f|at frequency character-
OK" NO GOOd istics are obtained. But when the level is low, the middle fre-

quencies are boosted, and the amount of boost grows larger as
the level goes lower. During recording, noise is increased by the
hiss. Since hiss is internally derived noise, even if the frequency
characteristics are boosted, the noise is not. It remains fixed

throughout all frequencies.

No Good.
Dolby wont elimi- A
nate previously in-
cluded noise

OK

The Denoiser works! Graph 1(b)

O .33.

When there's a lot of
hiss from your tape..

W/ CUt'Off

Let's put it this way. At present, there are neither FM nor AM
Dolby broadcasts being conducted. This means that no matter
how famous or effective Dolby is reputed to be, its range of

noise reduction function is limited to pre-recorded music tapes WReduced
or home recordings and dubbings in which a Dolby system has 0'58

been used. But with the Audio Denoiser, anything goes (FM, . >
AM Records, Tapes). And like the Dolby, it suppresses noise AUd'O Frequency

increase during recording and dubbing. Thats how the Denoiser
gives you a wider range of use values!

Take a look at the following chart showing various points of

Isa/(91 >peq/erd

Take a look now at Graph l(b) showing conditions during re-
production. During reproduction, an operation opposite to that
during recording occurs. This time, the higher frequencies under-
go a cut-off, the amount of which changes with the reproduction

comparison. level. The Dolby is automatically controlled to cutoff less when
Availability the level ishigh and morewhen the level is low. As shown in the

Source Denoiser Dolby of Source graph, during reproduction, house Introduced during recording

FM Broadcasts Effective ineffective Widespread are cut off by an amount Indicated by the downward curve. If
AM Broadcasts Effective Ineffective Widespread during both recording and reproduction processes, the amount

of boost and the amount of cut-off are set at the same level, the

Ineffective Widespread flatness of the frequency characteristics is preserved. Likewise,

Record Reproduction Effective

gfgiensrepéiifiyfin E22223: giggifige Widespread there is no lowering of sound values and noise is suppressed. (At
Dubbing, 9 Effective Effective approximately lOdB).When the levels during recording and re-

production do not match, the lowering of sound values becomes
conspicuous (Dolby level). This is the big problem with regard to
Dolby bothering various audio makers today. The Peak Level
Indicator and the DL Level (Kenwood) are among the various
devices designed to match the levels at the appropriate point.

~>I

lnexistent
Extremely limited

Ineffective Effective
Ineffective Effective

FM(Dolbyized)
Tape (Dolbyized)

Dolby has one big demerit.
It can't take away previously included noise."