Amplifier Research 701R Manuel du propriétaire - Page 3

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INTRODUCTION

The system you have purchased is a very portable package

with the flexibility of mixers twice the size at twice the price.

The 701R™ features seven channels, excellent 4-band

equalization, rack-mount versatility, balanced inputs, and

balanced outputs.

Rack-mountable mixers have a special place in sound rein¬

forcement applications, and many times no other type pro¬

duct will suffice. The 701R requires a very low profile, vertical

mounting space, and is exceptionally thin, front to back. These

dimensions are critical, as rack space is usually a premium

consideration. The input circuitry has tremendous dynamic

range and will handle sound reinforcement applications with

ease. As you read the enclosed literature, please try to learn

as much as possible about the product so your job of sound

reproduction will be easier and the results will be an overall

improved performance. The person doing sound or installing

sound systems is actually an extension of the performance

and should master the sound equipment, just as a musician

masters his/her instrument.

INPUT GAIN CONTROL (1)

The Input Gain Control of the 701R Mixer utilizes a dual con¬

trol element configuration so that input attenuation and gain

adjustment occur simultaneously. This arrangement allows

the vital input circuitry to handle almost any input voltage from

low level mics to speaker levels. The function and operational

requirements of this input gain stage are conventional and

should present no operational difficulty.

MONITOR SEND CONTROL (2)

The monitor send control is the channel mixing element for

determining the all important monitor mix. Signals for the

monitor sends are obtained right after the input preamp and

before the channel EQ. These are referred to as pre monitor

sends, i.e. they are before the channel equalization and chan¬

nel level controls. This makes them independent of these con¬

trols and any changes made to the EQ or channel level will

not affect the monitor system. Having the monitor send with

pre-EQ capability is absolutely vital to avoid feedback of the

monitor system when EQ and normal incremental setting

variations are made in the channel fader during the course

of the performance.

HIGH FREQUENCY EQ (4)

This control determines the relative boost or cut of the highest

frequency adjustment on this console and features a 15 dB

boost or cut at 15 kHz. This control operates in a shelving

configuration which prevents any additional gain above the

usable audio spectrum from causing undesirable hiss and

instability. The zero setting indicates a flat frequency response

with no alteration of the extreme highs and clockwise indicates

a boost while counterclockwise indicates a cut or a dip in the

high frequencies. Usually feedback is not much of a problem

at very high frequencies, but the control is very important for

giving that sibilant sound on the extreme highs and on the

s's and t's of the vocals.

HIGH MID FREQUENCY EQ (5)

This control determines the relative boost or cut of the upper

mid or lower treble frequencies and is capable of 15 dB boost

or cut at 3 kHz. A balance of mid range frequencies should

begin with a flat setting of zero so that adjustments may be

made with a cut or a boost of this control. The action of the

control is peak/notch type which interfaces with the adjacent

equalizers in a smoother manner to yield optimum summing

capability of the channel equalization. Usually a minus set¬

ting of this control is desirable to eliminate harshness with

most systems and control feedback.

LOW MID FREQUENCY EQ (5)

This control is operational in the lower mid range or upper

bass region and is capable of 15 dB boost or cut at 400 Hz.

This EQ control exhibits a peak/notch characteristic which

operates smoothly with the adjacent equalizer controls and

allows proper balancing of the upper bass and lower mid

range frequencies. This control is very vital for controlling the

mid range frequencies of the human voice when vocals are

being amplified. (Most vocals require a slight minus setting

of this control.)

LOW FREQUENCY EQ (6)

This control is capable of 15 dB boost or cut at 60 Hz and

demonstrates a shelving characteristic so that excessive lows

are not boosted below the usable range of typical sound rein¬

forcement. The shelving action of this circuit has proven to

yield much more satisfying and effective equalization

characteristics than some of the wide open EQ circuits claim¬

ing 20 to 25 dB boost and cut. Care should be taken with the

low frequency control not to over-boost lows on any particular

instrument or vocal due to the fact that tremendous amounts

of headroom will be used up and a general muddiness will

be apparent in the sound system reproduction. Woofers may

also be blown much more easily with extreme low frequency

boost.

EFFECTS SEND CONTROL (7)

This effects control is post and is effected by the equaliza¬

tion of each channel and its level is also effected by the chan¬

nel level control. NOTE: This action is totally opposite from

the monitor send controls on each channel which are pre and

unaffected by other features on the channel. When the ef¬

fects send control is activated on any particular channel, a

signal is sent through the master effects level control and ap¬

pears at the effects output on the rear panel. This output may

be patched into many various effects devices. (See effects

patch diagrams.) NOTE: The internal reverb drive receives

its signal from the effects send control also and a signal is

then sent to the master reverb control in the master section

in order for the internal reverberation system to function. When

operating an outboard effects device and the internal reverb

system simultaneously, the channel send control on the ef¬

fects mix must be optimized for the amount of both effects

on a particular channel.

PAN CONTROL (8)

This control is most often used to assign certain channels to

one or both subs. The action is conventional and clockwise

rotation assigns to sub "B" while counterclockwise rotation

assigns to sub "A". A setting of 12:00 places the channel

equally in both subs. NOTE: When recording, this control may

be used for stereo imaging (left, right, or both).

CHANNEL LEVEL CONTROL (9)

The channel level is the output control that determines the

mix of the various channels into the master mix. This control

should be operated near the zero indication of unity gain

whenever possible and the input gain control should be ad¬

justed accordingly for each instrument or vocal, etc. NOTE:

Above the zero point on the channel level slider there is 14

dB of gain as you increase to the upper limit of the level con¬

trol. It is virtually impossible to have too much gain during

typical sound reinforcement situations and when a low gain

situation presents itself it is nice to be able to increase the

channel gain by 14 dB with the level control and possibly avoid

having to readjust input gain sensitivity. NOTE: Operation

above "0" increases system noise. Operation below "0"

decreases system noise but at the sacrifice of system

headroom.