ASL INTERCOM ROXX Series User manual

Brand: ASL INTERCOM

Model: ROXX Series

Category: Musical Equipment

Type: User manual

ASL INTERCOM ROXX Series is a versatile professional stereo headphone amplifier for personal use. It has been designed with great precision to provide users with great audio quality. This device is commonly used for the applications such as practicing through headphones, creating a monitoring system for studio or on stage use, boosting a headphone output, checking microphone signals or even setting up a battery-powered two-station intercom system. ASL INTERCOM headset ROXX Series is compatible with balanced and unbalanced signals at microphone, line or speaker level.

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

RoXX-Series

301 Personal Headphone Amplifier / Line Checker Manual

The RoXX-Series 301 by ASL is a versatile professional stereo headphone amplifier for

personal and portable use. The unit is battery powered and accepts all commonly used

audio signals: balanced and unbalanced signals at microphone, line or speaker level.

This Personal Headphone Amplifier has been designed with great precision. However, designing equipment like this

is always a matter of finding compromises between: max. gain, noise, max. output power, distortion, power

consumption, flexibility, mechanical aspects, costs etc. The starting point of this design was to make a versatile unit,

which can be used for many purposes in different circumstances, with long battery life and as little as possible

controls. We hope we managed to meet your requirements. Read this user manual first.

Applications for the ASL RoXX - Series 301 Personal Headphone Amplifier

Practicing through headphones Checking microphone signals

An electronic instrument (guitar, keyboard) or a CD Very usefull to, for instance, boom operators.

player can be connected to the (stereo) Jack input(s),

and a dynamic microphone can be connected to the

XLR input. These signals can be mixed to the stereo

headphone output to practice. Even two headphones

can be connected in order to allow a singer to practice

together with an instrumentalist.

Creating a monitoring system for studio or on

stage use

An output of the mixing console can be connected to

the stereo input of the PHA, and a microphone or

instrument can be connected to the XLR input with a

loop through to a mixing console input. The performer

can make his own mix between his own voice /

instrument and the signal from the mixing console.

Headphones can be used in a studio, ear plugs on

stage.

Boosting a headphone output

Whenever the headphone output power of any equip-

ment is not sufficient, the Personal Headphone Am-

plifier can be connected to that headphone output.

The output power of the PHA will be high enough for

most circumstances/purposes.

Trouble shooting

A sound engineer can check lines, microphones or

outputs, to locate signals or to solve problems.

Routing two headphone outputs to one headset

For instance the monitor outputs of two mixing con-

soles, or the monitor output of a mixing console and

an intercom signal.

Setting up a (battery powered) two station inter-

com system

A dynamic (headset)microphone can be connected to

the XLR input of each of the two PHA’s. The loop

through XLR’s are interconnected. The two users can

hear eachother (and themselves) through the con-

nected head(set)phones. Two identical microphones

need to be used, and the microphone signals are

summed by there output resistance.

Sending an audio signal to many headphones

Two headphones can be connected to one PHA.

Personal headphone amps can be interconnected

using the loop through connectors.

More applications to be discovered by yourself!

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

FRONT PANEL

1 Power switch

With this switch the unit is turned on and off.

2 Power-on LED indicator

This LED illuminates green when the unit is

switched on.

* When the Personal Headphone Amplifier is

prepared for charging Ni-MH batteries within the

unit, this LED also indicates fast charging of the

cells. During fast charging, while the unit is

switched off, this LED lights up burns red. During

fast charging, while the unit is switched on, this

LED lights up orange.

3 Stereo headphone 3,5mm mini jack

Two headphones can be connected to this

headphone amplifier at the same time. A headpone

with a 3,5mm mini jack can be plugged in this

connector.

Both high and low impedance headphones can be

used (when using 2 headphones at the same time,

use headphones of the same type). The internal With this switch the sensitivity of the balanced input

power amplifiers are short-circuit and overload can be selected.

protected.

4 Stereo headphone jack 1/4”

A headphone with a 1/4” jack can be plugged in signal can be controlled.

this connector.

5 -20dB switch

With this switch the gain of the unbalanced inputs

can be reduced by 20 dB for monitoring speaker or

high level line signals.

In the normal position the input impedance of the

unbalanced inputs is very high (1M Ohms),

enabling the monitoring of electric guitar signals (or

other pick-ups).

6 Stereo/mono switch

In mono position a stereo signal on the unbalanced

input(s) is made mono.

7 Unbalanced input Volume control

With this knob the volume of the unbalanced input

signal can be controlled

8 Balance control

With this knob the left / right balance of the

unbalanced input signal can be adjusted.

9 Mic / Line switch

10 Balanced input Volume control

With this knob the volume of the balanced input

11 Pan control

With this knob the left / right panning of the

balanced input signal can be adjusted.

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

REAR PANEL

12 Balanced input + loop thru XLR’s

These XLR-3 female and male connector are

paralleled and are the input & loop thru for a

balanced signal (mic. or line level).

13 Mono left / stereo input jack

This 1/4" jack connector is the input of the left

signal of a stereo signal when a mono jack is used

(input 14 is the right input), or the left and right

signals when a stereo jack is used (input 14 is not

used). It accepts signals of line or speaker level.

14 Mono right / mono input jack

When no signal is connected to the left jack input

(13), the mono signal on this input is sent to the left

and right cans of the headphone. When there is

also a mono signal connected to the left jack input

(13) the signal on this input is sent only to the right

input (input 13 is the left input). It accepts signals of

line or speaker level.

15 Stereo loop thru connector

This jack connector is always configured as a

stereo loop thru for the signals connected to the

unbalanced inputs 13 and/or 14.

When a stereo signal is connected to input 13 this

connector provides a stereo link. When mono left

and mono right signals are connected to inputs 13

and 14, this connector outputs those signals as a

stereo signal (left=tip, right=ring). When a mono

signal is connected to input 14, this connector

outputs the mono signal (on tip and ring). This

connector is especially useful for connecting

multiple headphone amplifiers to one source.

SIDE PANEL

16 DC adaptor input

An external DC adaptor can be used to power the

RoXX-Series 301. The internal batteries will

automatically be switched off. The unit accepts DC

voltages from 9 V to 24 V.

* When the Personal Headphone Amplifier is

prepared for charging Ni-MH batteries within the

unit, the external DC voltage can range from 12 V

to 18 V. The adaptor must be capable of delivering

a current of at least 700 mA.

17 Internal battery compartment

Accepts 4 AA-type 1.5 volt batteries or 1.2 volt

rechargeable cells.

The Personal Headphone Amplifier can be

modified so that Ni-MH cells can be charged in the

unit. Consult your distributor for more information

18 Beltclip

Powering the Personal Headphone Amplifier

Battery Operation Open the battery compartment on the side of the unit

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

by turning the knurled screw anti-clockwise. Take out

the battery holder. Insert four AA-size 1.5V batteries in The ASL RoXX -Series 301 Personal Headphone

the holder. Put the holder back into the unit, with the Amplifier can be modified for charging four Ni-MH

holders connection terminals pointing to the side cells in the unit. Consult your distributor for more

where the beltclip is mounted. Close the battery information. Whenever a RoXX 301 is prepared for

compartment by putting back the little coverplate and charging Ni-MH cells, normal batteries should not

turning the screw clockwise. The Personal Head- been used anymore and reverse voltage protection for

phone Amplifier is now ready to operate on batteries. the cells does not work anymore!

Always choose four identical batteries of the same

age. Rechargeable NiCd or Ni-MH 1.2V cells can be Mains Operation

used as well. The RoXX 301 is protected against The ASL RoXX -Series 301 Personal Headphone

reverse voltage. Amplifier can be powered by mains by using a mains

The ASL RoXX -Series 301 can be switched on by adaptor (not supplied with the RoXX 301). Choose an

pushing the power button (1). The unit will start adaptor with an input voltage that matches the local

whenever the total battery voltage is higher then 4.0V. mains voltage. The output of the adaptor needs to

The unit will work until the total battery voltage drops supply a DC-voltage between 9 and 24V at a current

below 2.5V. of 500mA (12 to 18V DC at a current of 1A when the

When the unit switches off because the battery RoXX 301 is prepared for charging Ni-MH cells). The

voltage is lower than 2.5V, the batteries will start to DC-voltage can be either unregulated or regulated.

recover a bit. The battery voltage rises, and when it Connect the adaptor via an appropriate plug to the

exceeds 4.0V, the unit will switch on again. By then, DC-in socket (16) at the side of the RoXX 301. The

the battery voltage will again go down, resulting in inner pin of the socket is hot (+), the sleeve is ground

switching off the unit at 2.5V. This frequently and (-). The unit is protected against reverse voltage.

automatically switching on and off means that the

batteries are empty and that they should be replaced.

Warning !

Always turn the unit on and off without the headphone

on your head.

Connecting and Monitoring Balanced Signals

The ASL RoXX -Series 301 Personal Headphone The Pan control knob (11) can be used to pan the

Amplifier has an independent section for balanced signal between the left and the right channel of the

signals and one for unbalanced signals. Balanced RoXX 301.

signals can be both microphone and line-level signals.

Speaker signals should not be connected to the The unbalanced input is DC and overvoltage protected

balanced input (they are mostly unbalanced and can (except for speaker signals with the Line/Mic. button in

be monitored with the unbalanced section of the ASL the Mic. position).

RoXX -Series 301).

Before connecting any balanced signal to the XLR The ASL RoXX -Series 301 Personal Headphone

connectors, turn the Balanced input Volume control Amplifier is not equipped with a phantom-power

(10) down. Press the Line/Mic. button (9) if you plan to facility. Nevertheless, sources which are phantom-

connect a microphone level signal. Release the powered by another device can be monitored.

Line/Mic. button if you plan to connect a line-level

signal. Connect the balanced signal to one of the XLR Connecting the RoXX 301 to the circuit of source and

connectors (the other one is for loop thru, the male phantom-powering device will cause clicking of both

and female connectors are paralleled). Turn up the the headphone amplifier and the other device (the

Balanced input Volume control (10) carefully and you input capacitors of the RoXX 301 need to be charged).

will hear the connected balanced signal. To reduce or prevent this clicking, a so-called ground-

The volume control button not only acts as a volume connectors of that cable) can be used.

control but it in fact controls the gain of the

preamplifier and the signal level send to the power-

amps at the same time. This reduces noise and

creates the capability to handle a great range of input

signals with only one knob.

Monitoring phantom powered signals

lift cable (e.g. pin 1 not connected in one of the XLR

Connecting and Monitoring Unbalanced Signals

The ASL RoXX -Series 301 Personal Headphone Unbalanced signals may be signals produced by

Amplifier has an independent section for unbalanced instrument pick-ups (electric guitar), line outs of

signals and one for balanced signals. mixers, CD-players etc. or speaker signals. They can

range from -16dBu to (almost)+4. For your own safety

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

do not connect AC-signals higher than 40Vrms (e.g. When the connected signal is higher than +6dBu, the

outputs of power amps >200 Watt into 8 ohm; a 1/4” -20dB button (5) needs to be pressed. Turn up the

jack is not a safe connector for these kind of signals). Unbalanced input Volume control (7) carefully and you

Before connecting any unbalanced signal to the 1/4” balance of the signal can be controlled by the Balance

input jacks, turn the Unbalanced input Volume control control knob (8). A stereo signal can be made mono

(7) down. by pressing the Stereo/Mono knob (6). This is usefull

There are three possibilities of connecting unbalanced headphone.

signals: The unbalanced inputs are DC and overvoltage

* Suppose you want to connect an unbalanced mono

signal on a mono 1/4” jack. This signal should be

connected to the Jack input labeled "Right/Mono" Linking the unbalanced signal(s) to another ASL RoXX

(14). The input labeled "Left/Stereo" (13) should be -Series 301

left unused. The mono input signal will be sent to The connector labeled ‘Unbal. Stereo Loop Thru’ (15)

both left and right channnels of the Personal will allways provide a stereo signal of the signals

Headphone Amplifier. connected to the input connectors. The unbalanced

* Suppose you want to connect an unbalanced Headphone Amplifier (or other device) by connecting a

stereo signal on a stereo 1/4” jack. This signal stereo jack-jack cable between the Unbalanced

should be connected to the Jack input labeled Stereo Loop Thru (15) connector of the first and the

"Left/Stereo" (13). The input labeled "Right/Mono" Left/Stereo (13) of the second. Never use a 1/4” mono

(14) should be left unused. The stereo signal will jack on the loop thru connector (the right input signal

be sent as a stereo signal to the left and right will be short circuited).

channel of the Personal Headphone Amplifier.

* Suppose you want to connect an unbalanced Using the RoXX 301 with an electric guitar (or any

stereo signal on two mono 1/4” jacks (e.g. Left and other instrument with pick-ups)

Right). Connect the left signal to the input labeled A pick-up will sound best if the load of it is very low

"Left/Stereo" (13) and connect the right signal to (e.g. input impedance is very high, like an active DI-

the input labeled "Right/Mono" (14). The signals will box). ASL RoXX -Series 301 has a very high input

be sent to the corresponding channels of the ASL impedance on the unbalanced inputs (as long as the -

RoXX -Series 301. 20dB button is not pressed). So an instrument pick-up

will hear the connected unbalanced signal(s). The

when a single muff headphone is used or when you

want to pan the unbalanced signal to one side of your

protected.

input signal(s) can be linked to another Personal

can be connected to the RoXX 301! Normally the

Right/Mono input connector would be used for this

mono signal. But then the pick-up is loaded by both

the left and right input amplifiers of the Personal

Headphone Amplifier, making the input impedance

half its value. It would be better to connect the pick-up

to the Left/Stereo input and pressing the Stereo/Mono

button. The input impedance is now 500k ohms and

the pick-up will sound best.

Volume Control

The unbalanced input section and the balanced input Series 301 can be ear damaging and destructive to

section both have their own volume control knob as

descriped in the above sections. The unbalanced

input(s) and the balanced input can be used at the

same time with the possibility to make a mix between

the signals with the two volume control knobs (and the

balance and pan knobs).

Whenever only one input section is used turn the

volume control of the not used section down (anti

clockwise).

Warning !

Always turn down the volume controls down before

connecting any headphone or input signal and turn up

volume carefully. The output levels of the RoXX -

your headphone.

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

Choice of the Headphone(s) The Built-In Limiter

The choice of the headphone(s) is highly individual. The ASL RoXX -Series 301 Personal Headphone

However, the ASL RoXX -Series 301 can handle Amplifier has a built-in stereo limiter to prevent the

almost any headset. output amplifiers from clipping.

The headphone impedance should preferably have a The limiter range is 30 dB for the balanced input and

value higher than 32 ohms. The headphone outputs of 25 dB for the unbalanced inputs. So when the output

the unit are short-circuit proof so loading the outputs level of the RoXX 301 reaches the threshold level of

with a headphone-impedance lower than 32 ohms the limiter, the input signals can become 25 or even

won’t damage anything (it may eventually cause 30 dB higher before the output amps will actually clip.

clipping of the output amplifiers before the built-in

limiter begins to operate). If clipping occurs in one of the input stages of the ASL

In general, low-impedance headphones create a it. Carefull fixing of the -20dB button, the Line/Mic.

higher Sound Pressure Level on your ears (also button and the volume control knobs remains

depending on their efficiency), but using them will necessary (the balanced volume control knob also

reduce battery life. These headphones can be a good controls the gain of the preamplifier)

choice in noisy environments. High-impedance

headhones (>200 ohms) often have a lower SPL, but The stereo limiter is combined for the balanced and

will increase battery life. the unbalanced signals. This means that whenever the

In case you want to use two headphones with the ASL unbalanced signal will go down in level even when the

RoXX -Series 301, choose headphones with the same unbalanced signal itself still has not reached the limiter

impedance (> 50 ohms) and efficiency. threshold level.

Please check the specifications of your headphones if

they can handle the output power of the Personal

Headphone Amplifier.

RoXX -Series 301, the limiter can’t do anything against

limiter limits for instance the balanced signal, the

A S L C O M M U N I C A T I O N S Y S T E M S RoXX-Series 301 Manual

ASL COMMUNICATION SYSTEMS

Zonnebaan 42

3606 CC Maarssenbroek

HOLLAND

tel. : +31 - (0)30 - 241 19 01

fax.: +31 - (0)30 - 241 06 38

ASL reserves the right to alter

specifications without further notice.

SPECIFICATIONS ASL RoXX - Series 301

Frequency response

Balanced input 50 Hz - 36 kHz +0, -3dB

Unbalanced input 40 Hz - 40 kHz +0, -3dB

Total Harmonic Distortion

< 0,3% (20 Hz - 20 kHz, 3 dB below limiting)

< 0,5% (100 Hz - 20 kHz, 10 dB over limiter threshold)

Equivalent Input Noise

- 125 dBu (22 Hz - 22 kHz, Rsource = 50 Ohm, max.

gain)

Headphone output Impedance

< 2 Ohms, Short Circuit Proof

Limiter

Limiter Threshold 2,5V rms (10,4 dBu)

(measured at headphone output)

Limiter Range Balanced input 30 dB

Unbalanced input 25 dB

Power

Internal 4x 1.5V AA-Battery

or 4x 1.2V rechargable NiCd or Ni-MH AA-Cell

External 9 - 24 V DC

Supply Current (idle) 80 mA with 4x 1.5V AA-Battery

Battery Life 24 hours under normal conditions

with 4x 1.5V Alkaline Batteries

Dimensions 43 mm H x 94 mm W x 138 mm D

Weight 500 grams nett

Maximum Voltage Gain, Input Impedance and

Maximum Input Levels before clipping

Maximum Input Maximum

Voltage gain Impedance Input Level

Balanced Input

@ mic level

71 dB 28 kOhms -10 dBu

Balanced Input

@ line level

36 dB 20 kOhms +34 dBu

Unbalanced Inputs

pad @ 0

26 dB 500 kOhms +12 dBu

Unbalanced Inputs

pad @ 30 dB

7 dB 23 kOhms

+44

f = 1 kHz, Rsource = 50 Ohm

Maximum Headphone Output Level + Power

Max. Output Level Output Power

R load = 200 Ohm

4.1 V rms 84 mWatt

R load = 32 Ohm

3.2 V rms 320 mWatt

ASL INTERCOM ROXX Series User manual

Brand: ASL INTERCOM

Model: ROXX Series

Category: Musical Equipment

Type: User manual

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ASL INTERCOM ROXX Series User manual

ASL INTERCOM ROXX Series User manual

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