Inovonics 215 Manuale

www.SteamPoweredRadio.Com

I

OPERATING &

MAINTENANC

.E

· INSTRUCTION

MANUAL

..

MODEL

215

.

BROADCAST

AUDIO PROCESSOR.

io

.

..

....

...

.

:,i:,

• .

■

--

,

.

,.,.

Jl

!

~c~Y9~1

~-~

_______

__,

..

,

--~

·•·

···-

www.SteamPoweredRadio.Com

USER'S

RECORD

Mode]

215-_-_-_,

S/N

Date

Purchased

Harranty

Card

Sent - -

Purchased

From

INSTRUCTION

MANUAL

MODEL

215

MULTIFUNCTION

AUDIO

PROCESSOR

AUGUST

1979

503

-B

VANDELL

WAY,

CAMPBELL,

CA

95008

(408)

374-8300

--

www.SteamPoweredRadio.Com

TAB

LE

OF

CONTENTS

I .

GENERAL

INFORMATION

•.••

..

• •

•••

.

..•

2

I

I.

FUNCTIONAL DESCRIPTION

AND

SPECIFICATIONS.

.

2

III.

IV.

v.

VI.

VII.

Ga

t

ed

A.G

. C. -

Average

Level

Compressor

-

AM

"Integ

r

ated"

Peak

Controller

-

FM

Peak

Controller

-

"Proof

0

Mode -

Stereo

Inter

-

conne

c

tion

-

Spec

i f i

cations

INS

TALLATION

Unpacking

and

Inspection

-

Mounting

-

RF

I -

I

n/Out

Conn

e

ction

and

Consid

e

rations

-

Polarity

OPERATION

AND

ADJUSTMENT

Preliminary

- P .

C.B.

Strapping

Option

s -

Sugge

s

ted

Initial

Setup

Procedure

-

Clipping

Depth

7

9

CIRCUIT

DESCRIPTIONS • . • . • • .

12

A.G

.

C.

Amplifier

-

Average

Level

Compres

s

or

-

AM

Peak

Controller

-

FM

Peak

Controller

-

Bypass

Assembl

i

es

-

Power

Supply

CALIBRATI

ON

PROCEDURES

Not e -

Equipment

Required

- A. G. C.

Amplifie

r

As

s

emb

l y - C

ompre

s

sor

Assembly

-

AM

Peak

Controller

-

FM

Pe

ak

Controller

.

18

APPENDIX

• • • • . 24

Parts

Lists

-

Schematics

Warranty

-

1-

www.SteamPoweredRadio.Com

I.

GENERAL

INFORMATION

The

Inovonics

215

is

a

broadband

audio

processor

primarily

intended

for

AM,

FM

and

TV

broadcast

use,

although

certain

features

make

it

attractive

also

for

sound

re

-

enforcement

and

some

studio

r

ecording

situations.

The

215

presents

an

as

-

needed

approach

to

audio

processing,

as

the

basic

unit

consists

of

a

chassis

supplied

with

signal

bypass

assemblies.

Plug

-

in

options

then

provide

the

three

processing

functions

of

(1)

gated,

·

gain-riding

A.

G.C.,

(2)

average

level

compression

and

(3)

peak

control

with

phase

-

optimization

and

asymmetrical

operation

for

AM

broadcast,

or

variable

frequency-selective

characteristics

for

FM

broadcast

and

recording.

Options

may

be

provided

singly

to

perform

specific

processing

functions

or

to

complement

existing

equipment,

or

the

215

may

be

''fully-loaded"

and

stand

alone

as

a

complete

processing

system.

II.

FUNCTIONAL DESCRIPTION AND

SPECIFICATIONS

A

description

of

each

of

the

three

processing

functions

of

the

215

follows.

Specifications

relative

to

the

described

subsection

are

given

in

the

text

.

Performance

data

not

expressed

or

implied

in

the

descriptions

is

tabulated

at

the

end

of

this

section.

Gated

A.

G.C.

(-

01

option)

In

the

typical

broadcast

situation,

program

levels

tend

to

wander

up

and

down

a

bit,

frequently

as

a

result

of

operator

i~attention,

personnel

shift

changes

or

from

other,

usually

human

influences

.

Thus

the

first

major

functional

block

of

the

215

is

a

slow,

gain-riding

A.

G.C

.

This

effectively

erases

long

-

term

input

level

variations

and

presents

subse-

quent

processing

stages

with

a

constant

r .

m.s.

input

value.

-2-

www.SteamPoweredRadio.Com

Capture

range

of

the

A.G.C.

is

±lOdB,

and

A. G. C.

gain

may

be

selectively

displayed

on

the

fron

t

panel

meter.

Correc-

tion

rate

(response

time)

is

about

O.SdB/second,

slow

enough

not

to

alter

program

dynamics.

A

frequency

-

weighted

"gating"

feature

inhibits

A.G.C

.

action

during

program

pauses,

and

slowly

returns

gain

to

OdB

in

event

of

extended

signal

loss.

The

gating

circuit

has

-3dB

sensitivity

points

at

300Hz

and

3kHz

to

guard

against

erro

-

neous

gain

"

hunting"

caused

by

non

-

program

nois

es.

Gating

threshold

sensitivity

is

prese

t

at

a

value

which

will

open

the

gate

when

midband

program

en

ergy

rises

above

-

25dB

rel-

ative

to

nominal

program

"zero

"

level.

It

is

generally

acknowledged

that

program

components

below

a

particular

frequency

contribute

nothing

to

perceived

program

quality

and,

in

fact,

may

sabotage

intelligibility

and

both

perceived

and

measured

program

loudness.

The

choice

of

a

low-end

cutoff

frequency

is,

nevertheless,

a

matter

for

sub

-

jective

consideration;

thus

the

215

offers

three:

50,

70

and

lOOHz.

The

L.F.

cutoff

frequency

is

selected

with

a

series

of

straps

on

the

A.G.C.

Amplifier

board

.

Strapping

instructions

are

given

on

page

9.

A

digitally

-

generated,

pseudo

-ran

dom

Pink

Noise

generator

is

an

integr

al

part

of

the

215

A.G.C.

Amplifier

assembly

.

Pink

Noise

is

a

very

useful

audio

test

signal;

its

constant

-

power

-

per

-

octave

(or

equal

fractions

thereof)

energy

distribution

and

characteristic

crest

factor

more

closely

approximate

pro

-

gram

material

than

do

discrete

oscillator

tones.

A

switch

substitut

es

this

test

signal

for

the

input

program

in

any

operating

mode

to

aid

in

system

setup

and

maintenance

.

Average

Level

Compressor

(-

02

option)

Program

dynamics

are

firm

l

y-y

et-unobtrusively

compressed

by

t

he

21S's

averaging

Comp

res

sor

assembly.

This

circuit

util

izes

gain

-

control

circuitry

yielding

a

"soft

knee,"

or

gentle

transition

from

linear

to

compressed

operation.

In

fact,

the

actual

compression

ratio

increases

as

more

compression

is

employed,

With

lOdB

or

so

of

indicated

compression

the

ratio

is

about

2:1

,

increasing

to

4

:1

at

lSdB

.

The

result

of

this

program

-

controlled

compression

ratio

is

an

exce

edin

g

ly

smooth

sound,

even

with

considerable

compression

in

effect.

Never

-

theless,

a

control

loop

from

the

Compressor

back

to

the

A

.G.C.

circuit

guard

s

againstovercompression

by

reducing

A.

G.c.

gain

and

flashing

a

warning

indicator

when

the

Compressor

works

too

hard.

Compressor

attack

and

release

ti.mes

are

fixed

at

-3-

www.SteamPoweredRadio.Com

values

insuring

an

optimum,

rapid

operation

consistent

with

an

acceptable

distortion

figure

at

low

frequencies

.

The

AM

"

In

t

egrated

"

Peak

Controller

(-

03

option)

Asymmetrical

modulation

of

positive

and

negative

peaks

yields

a

modulation

advantage

only

when

the

program

material

is

asymmetrica

l

in

nature.

Most

music,

because

it

is

a

blend

of

complex

waveforms

which

are

not

phase

-

has

a

very

even

balance

of

peak

energies.

Solo

instruments

and

the

human

voice

,

on

the

other

hand,

possess

a

more

or

less

fixed

relationship

·

between

the

phase

of

the

fundamental

tone

and

the

harmonics

.

This

leads

to

an

appreciable

and

consistent

imbalance

between

positive

and

negative

peaks,

and

can

be

used

to

modulation

advantage.

To

maintain

optimum

asymmetrical

modulation

of

an

AM

carrier,

program

peaks

should

be

predominantly

positive

-

going.

Current

practice

is

to

switch

program

phase

whenever

necessary

to

a

ss

ure

the

highest

incidence

of

positive

modulation

. Common

phase

-

swit

c

hing

techniques

usually

cause

an

annoying

"

click

"

or

"

pop"

at

the

instant

of

reversal

.

The

Phase-Follower

of

the

215,

on

the

other

hand,

features

a

novel

"phase

-

rotation"

circui

t

which

gen

t

ly

and

inaudibly

"

rolls

"

the

phase

through

a

180

-

degree

shift

when

required

for

maximum

positive

modulation.

Sensitivity

of

the

phase

-

detection

circuit

of

the

Phase-Follower

is

fixed

,

yet

a

function

of

the

degree

of

peak

limiting/clipping

in

effect.

With

a

consi

s

tent

lOdB

of

peak

reduction

,

asymmetry

of

10%

will

cause

a

phase

reversal

.

With

lSdB

peak

reduction,

5%

asymmetry

will

initiate

a

"roll."

The

215

AM

Peak

Controller

represents

the

mos

t

radical

depa

r-

tur

e

from

peak

reduction

systems

.

To

satis£y

the

particular

requirements

for

optimum

AM

carrier

modulation,

an

interrelated

peak

limiter/clipper

circuit

functions

without

compromising

the

features

of

either.

Here

is

the

basic

principle

of

i

ts

operation

:

the

output

from

the

Phase

-

Follower

is

fed

to

a

true,

low

-

distortion

peak

limiter

of

the

Santana

configuration.

This

is

followed

by

an

active

hard

clipper

with

the

unique

ability

to

quantita-

tive

l y

monitor

the

degree

of

clipping

it

performs

.

This

information

is

routed

back

to

the

peak

limiter

through

a

control

loop

which

allows

adjustment

of

the

limiting

/

clipping

ratio

.

"Clipping

Depth"

may

be

set

to

a

desired

value,

and

once

set

w

il

l

rema

i n

constant

regardless

of

pr

ogram

content

.

An

optimum

operat

i

ng

peak

-

to

-

average

ratio

may

thus

be

sel

-

ected,

from

a

very

clean

signal

without

audible

clipping,

to

a

slight

degree

of

clipping

for

a

definite

gain

in

loudness

-4

-

www.SteamPoweredRadio.Com

with

negligible

sacrifice

in

listenability,

or

even

heavier

clipping

for

decided

modulation

advantage

with

an

attendant

audible

harshness,

particularly

on

voice.

Because

of

the

interrelated

l

imiter/clipper

c

ir

cuit,

Peak

Controller

attack

time

is

virtually

instantaneous.

Even

the

first

half

-

cycle

of

a

20kHz

,

20dB

overload

is

reduced

to

the

final

limited

peak

value.

The

release

time

i s

fixed

at

a

value

which

yields

less

than

1%

distortion

at

SOHz

with

lOdB

limiting.

Nevertheless,

a

strap

on

the

Peak

Controller

board

permits

a

speed-up

in

release

time

by

a

factor

of

4.

The

result

i s a

tradeoff

:

an

audible

modulation

advantage

against

an

increase

in

low

frequency

distortion.

The

1%

distortion

frequency

moves

up

to

200Hz

,

and

distortion

at

SOHz

increases

to

about

3%.

Both

Peak

Limiting

and

Clipping

Dep

t h

may

be

selectively

displayed

on

the

front

panel

meter.

The

215

permits

the

value

of

positive

modulation

peaks

to

be

continuously

adjusted

up

to

150%

of

the

negative

peak

value.

Although

positive

modulation

is

legally

restricted

to

125%,

many

plate

-

modulated

transmitters

require

drive

i n

excess

of

+125%

to

reach

the

legal

maximum

.

It

must

be

warned,

however,

that

transmitters

which

fall

into

this

category

are

incapable

of

linear

operation

up

to

+125%.

The

very

slight

gain

in

perceived

signal

loudness

must

be

weighed

against

probable

high

s i

gnal

distortion

in

these

cases.

An

active

Low-

Pass

Filter

follows

the

AM

Peak

Controller

and

serves

to

restrict

the

bandwidth

of

the

processor

output.

Higher

-

order

harmonics

generated

in

the

limiting/clipping

process

are

significantly

attenuated,

thus

substantially

reducing

the

tendency

for

the

modulated

carrier

to

"splatter"

into

adjacent

frequencies

.

Moreover,

transmitter

power

is

not

wasted

in

modulating

those

audio

frequencies

normally

lost

in

the

AM

broadcast

receiver

. An

H.F.

cutoff

frequency

of

7,

10

or

15kHz

may

be

selected.

Selection

is

made

with

a

series

of

straps

on

the

circuit

board;

instructions

are

given

on

page

9.

The

FM

Peak

Controller

(-

04

option)

The

FM

Peak

Controller

is

very

similar

to

the

AM

assembly

in

the

concept

of

an

"integrated"

limiter

/

clipper,

but

the

phase

-

following,

asymmetrical

modulation

features

are

,

of

co

ur

se,

no

t

included

.

Instead

,

complementary

pre-limiting

pre

-

emphasis

and

post-limiting

de

-

emphasis

are

employed

to

satisfy

the

requirements

of

FM

broadcast

pre

-

emphasis

. A

series

of

circuit

board

straps

permit

selection

of

the

standard

7

5ps,

"

Dolby"

25ps

or

"flat

"

characteristics.

-5

-

www.SteamPoweredRadio.Com

The

optional,

faster

release

time

selection

and

variable

Clipping

Depth

features

are

retained

in

the

FM

Peak

Controller,

but

it

is

anticipated

that

these

will

be

used

conservatively

(if

at

all)

in

FM

broadcasting.

The

low-pass

filter

which

follows

the

limiting

circuitry

is

fixed

for

a

high

-

end

roll-

off

beginning

just

above

lSkHz.

"Proof"

Mode

A

single

button

places

the

215

in

"Proof

. "

The

A.

G.C.

is

defeated

and

Compressor

inhibited.

The

Peak

Controller

is

similarly

defeated,

and

both

the

High-

and

Low-Pass

Filters

are

electronically

set

to

their

obvious

extremes.

All

signal-

path

circuitry

is

otherwise

active.

Stereo

Interconnection

Two

215's

may

be

interconnected

for

stereo

operation.

Com-

p

ressors

are

slaved

for

identical

operation,

and

one

Phase

Follower

may

be

slaved

to

the

other

or

both

defeated,

depending

on

which

system

of

AM-stereo

transmission

is

ultimately

approved.

215

Specifications

This

is

a

tabulation

of

those

performance

specifications

which

are

not

expressed

in

the

texts

of

the

foregoing

discus-

sions.

Frequency

Response:

±ldB

,

50Hz-15kHz

Distortion

(with

lOdB

Compression

and

lOdB

Limiting-only):

<O.

3%

THD

above

200Hz,

<l.

0%

THD

at

SOHz.

Noise:

Better

than

60dB

below

100%

modulation

.

Input:

Balanced,

-30

to

+lOdBrn

Output:

Balanced,

Oto

+20dBrn;

+24dBm

output

clipping

level.

Power:

l05-130VAC

(230V

available),

50/60Hz,

20W

Physical:

3-1/2"

x

19"

x

9";

8

lbs.

-6-

www.SteamPoweredRadio.Com

III.

INSTALLATION

Unpacking

and

Inspection

Upon

receipt

of

the

equipment,

inspect

at

once

for

shipping

damage.

Should

any

such

damage

be

observed,

notify

the

carrier

at

once;

if

not,

proceed

as

outlined

below.

It

is

suggested

that

the

original

shipping

carton

and

materials

be

retained

should

future

reshipment

become

necessary.

In

the

event

of

return

for

Warranty

repair,

shipping

damage

sustained

as

a

result

of

improper

packing

for

return

may

invalidate

the

Warranty.

It

is

important

that

the

Warranty

Registration

card

found

at

the

front

of

this

manual

be

returned;

for

not

only

does

this

assure

coverage

of

the

equipment

under

terms

of

the

Warranty,

but

the

user

will

automatically

receive

specific

servicing

or

modification

information

should

it

be

issued.

Mounting

The

215

is

packaged

to

mount

in

a

standard

19-inch

equipment

rack,

requiring

3-1/2

inches

of

rack

space

per

unit.

The

processor

generates

negligible

heat,

and

itself

is

unaffected

by

wide

variations

in

the

ambient

operating

temperature.

RFI

The

215

is

specifically

designed

to

operate

in

close

prox-

imity

to

broadcast

transmitters;

nevertheless,

care

should

be

exercised

in

locating

the

unit

away

from

abnormally

high

RF

fields.

In

some

installation

situations

an

RF

ground

loop

may

be

formed

between

the

input

or

output

cable

shield

grounds

and

the

AC

power

cord

ground.

Use

of

a

"ground-

lifting"

AC

adapter

should

remedy

the

problem,

but

the

chassis

of

the

unit

should

somehow

be

returned

to

earth

ground

for

safety.

In/Out

Connection

and

Considerations

The

215

input

and

output

connections

are

brought

out

to

a

rear

panel

screw-terminal

barrier

strip.

Both

the

input

and

output

are

balanced

(transformer-isolated),

with

ground

terminals

provided

for

cable

shields.

-7-

www.SteamPoweredRadio.Com

Should

the

equipment

which

feeds

the

215

require

output

loading

,

an

external

600-ohm

resistor

should

be

placed

across

the

processor's

input

terminals;

otherwise

the

input

is

"balanced-bridging"

with

a

characteristic

input

impedance

of

l0K

or

more.

The

source

impedance

of

the

215

output

amplifier

(ahead

of

the

line

output

transformer)

is

virtually

zero.

However,

as

the

output

transformer

has

some

reactance,

it

is

important

that

the

output

be

terminated.

in

600

ohms

to

minimiz

e

over-

shoot.

The

output

clipping

level

of

the

215

is

+24dBm.

To

permit

positive

peak

excursions

to

reach

+125%,

the

nominal

100%-

modulation

sine

wave

output

level

should

be

kept

at

+18dBm

or

below.

Polarity

The

input

and

output

of

the

215

are

each

marked

with+

and

-

designations

to

aid

in

maintaining

proper

phase

in

stereo

applications,

or

proper

asymmetrical

modulation

of

program

peaks.

In

the

latter

case,

the+

output

terminal

will

be

positive-going

with

positive

modulation

peaks.

-8-

Inovonics 215 Manuale

Manuali Hardware per computer popolari di altre marche