Axel Technology Boxtel- Basic Telephone Hybrid

BoxTel is a very small analog telephone hybrid, which can be easily connected to the most popular of mixing consoles in the market. BoxTel features a high-tech ( heart ). In addition to automatic line compensation, it provides transformer balanced audio connections and both local and remote control capabilities. BoxTel does not require AC Main voltage: power comes directly from the telephone line. This interesting feature together with its compact dimensions make BoxTel a highly recommended equipment for live broadcasts in addition to studio applications.

Main features:

- Balanced audio input (jack 6.3 mm) with level control

- Balanced audio output (jack 6.3 mm) with level control.

- 2 wire interface with parallel connection to an external telephone set

- Remote and direct control of line hooking and incoming call signalling functions

- Automatic line compensation

- Internal buzzer on/off

- Powered by telephone line

AUDIO PROGRAM IN / OUT

Connectors Jack stereo 6.3 mm,.

Input impedance 4 KOhm (transformer bal)

Output level * -inf to + 7 dBm

Output impedance 2 KOhm (transformer bal)

Noise on Receive output less than - 80 dBm (DIN noise)

Send / Receive separation less than 20 dB**

LINE INTERFACE

Connector RJ11

Nominal input level - 6 dBm

Nominal output level - 6 dBm

Compensation mode electronic

Impedance 600 Ohm

GENERAL DATA REMOTE INTERFACE

Power Supply Powered by telephone line Ext signaling for incoming call optocoupled

Dimension 44 x 106 x 114mm Remote line hooking relay closure, ext. powered

Weight 430 g

The Avalon VT-737SP features a combination of TUBE preamplifiers,
opto-compressor,sweep equalizer, output level and VU metering in a
2U space.
PREAMPLIFIER
The VT-737SP has three input selections: 1. The VT-737SP features a
higher-performance microphone input transformer with +48v phantom
selection. 2. Instrument DI high source input with jack located on front
panel. 3. Balanced line input, discrete high-level Class A. The Class A
preamplifier utilizes two cascaded, dual vacuum tube triodes configured
with minimum negative feedback. A high gain switch boosts the overall
gain of the preamplifier. The four high quality tubes are configured as
singled ended anode coupled followers. A passive-variable high pass filter
and hard-wire relay bypass completes the input signal conditioning. The
phase reverse relay is available on all three inputs.
OPTO-COMPRESSOR
The opto-compressor features a minimum signal path design with twin Class
A vacuum tube triodes for gain matching. The optical attenuator acts as a
simple passive level controller. Full dynamic control from soft compression to
hard- knee limiting can be achieved with threshold, ratio-compression, attack
and release controls plus gain reduction selection on the large VU meter. Special
spectral control including de-ess is available with the dual sweep mid EQ to side-
chain switch. The EQ section can be flipped pre or post the opto-compressor
via a front panel switch for alternate effects and tone shaping. Two VT-737SPs
can be linked via a rear panel link cable for stereo tracking. The compressor
bypass is a sealed silver relay for the most direct signal path.
SWEEP-EQUALIZER AND OUTPUT LEVEL
The VT-737SP equalizer utilizes 100% discrete, Class A-high-voltage transistors
for optimum sonic performance. The high and low frequency bands provide the
smooth characteristics of an all passive design, while the dual mid bands include
variable frequency and switched Q-width selection. The enhanced range of the mid
bands is extended into the high and low bands by the use of X10 frequency multipliers.
The bypass switch incorporates a sealed silver relay for the most direct signal path.
When the EQ to sidechain is engaged, the high-low EQ remains in the audio path for
"tone enhancement“. The output level control provides a variable control of the overall
signal path. The output amplifier utilizes another dual triode vacuum tube driving a
100% discrete, Class A, high-current, balanced and DC coupled low noise output
amplifier.

AVALON VT-737SP FEATURES
Vacuum tube triode signal path, transformer balanced microphone input, high-voltage
circuits for maximum headroom to +30dB, low noise -92dB, internal discrete power
supply with toroidal transformer, soft-start tube life extender, stereo link for compressors,
all discrete Class A equalizer with musical passive filter design, sealed silver relays for
signal routing, large control knobs with professional conductive plastic potentiometers,
VU meter for output level monitoring and compressor gain reduction.

VT-737SP SPECIFICATIONS
Circuit topology Four dual triode vacuum tubes (Sovtek 6922), high-voltage discrete
Class A
Gain Range Microphone: Transformer balanced 850/2500 ohm, 0dB to +58dB Instrument:
Unbalanced 1 meg ohm, 0dB to+30dB Line: Balanced Class A 20k ohms, -27dB to 28dB
Maximum input level and connector types Microphone26dB@25Hz, +30dB@1kHz balanced
XLR Instrument+30dB unbalanced front panel jack socket
Line +36dB balanced XLR
Maximum output level +30dB balanced 600 ohms, DC coupled, discrete Class A
Output type and gain XLR connector, output trim gain -45dB to20dB
Noise 20kHz unweighted -92dB
Noise microphone EIN -116dB, 22Hz to 22kHz unweighted
Distortion THD, IMD 0.5%
Frequency response -/2.5dB 10Hz to 120kHz input filter included
Frequency response -3dB 1Hz to 200kHz line in-out
VU meter and gain reduction High quality illuminated OVU =+4dB and gain reduction to -20dB
High cut filter Variable 6dB per octave 30Hz to 140Hz
Compressor type Optical passive attenuator incorporating twin vacuum tubes and stereo link
Threshold - Ratio Threshold variable -30dB to +20dB, ratio-compression variable 1:1 to 20:1
Attack - Release Attack variable 2mS to 200mS, release variable 100mS to 5 seconds
Equalizer type Discrete Class A, variable active and switched passive design
Frequency bands (4) Treble - switched 10kHz, 15kHz, 20kHz, 32kHz, +/- 20dB range, shelf
High mid - variable 200Hz to 2k8Hz and 2kHz to 28kHz, +/- 16dB range, hi-lo Q Low mid -
variable 30Hz to 450Hz and 300Hz to 4k5Hz, +/- 16dB range, hi-lo Q Bass - switched 15Hz,
30Hz, 60Hz, 150Hz, +/- 24dB range, shelf
AC power Internal toroidal 100v to 240v, 50-60Hz selectable, 75 watts maximum
Dimensions 19 x 12 x 3.5 in (482 x 305 x 89mm)
Weight 22lbs (10kg)
Dimensions-shipping carton 21 x 18 x 8 in (533 x 457 x 203mm)
Weight-packed 26lbs (11.8kg)

Features
Enhance switch to restore spectral balance of compressed signal
Switchable Mode - Dual Channel or Stereo linked
Above or Below Threshold LEDs
Balanced XLR and Jack Inputs and Outputs
Intuitive, user friendly layout
Flawless performance

Innovation
The ARX COMPO? is a unique compressor/limiter designed for use in any
professional audio dynamics control application, packaged in a compact 1
RU chassis.The COMPO operates as two independent compressor/limiters,
with 'industry standard' variable Threshold, Ratio and Output gain controls.
A Stereo Link switch on the front panel lets both channels track as a stereo
pair in a Master/Slave configuration.
Enhance Switch
The COMPO features an 'Enhance' switch, which provides frequency restoration
to preserve the spectral balance of the audio signal, compensating for the sagging
Low and High frequency response of compressed program material.
The best way to think of it is as a 'smart' loudness control.
Wide Scale metering
There is comprehensive LED indication of all operating functions and status. Above
or Below Threshold LEDs on each channel give you instant visual confirmation of
compressor activity, as well as easy to read LED Gain Reduction meters.
Balanced Inputs and Outputs
On the rear panel, each channel has true differential Balanced inputs and outputs,
on both XLR and TRS jack connectors. Other features include an Active/Bypass
switch for each channel, and passive RFI filters on the inputs.
Universal AC Power
AC power range is a universal 100 to 120V or 220 to 240V AC, and is connected to
the unit via a removable power lead and standard 3 pin IEC connector, with built-in
fuse and voltage change switch.
ARX Quality
With its smooth compression, intuitive user friendly layout, high density precision
circuitry, and extensive user-variable operating parameters, the ARX COMPO is the
ideal installation 'set and forget' compressor, and is also equally at home in Studio,
Broadcast and Sound Reinforcement environments.

Every day, ARX Audio interface products solve audio problems for thousands of people
around the world.

T E C H N I C A L S P E C I F I C A T I O N S
Input Impedance Balanced 20 Kohms, Unbalanced 10 Kohms
Input Headroom + 22 dB
CMRR >60 dB, 20 Hz-20 KHz
Output Impedance Balanced 300 ohms, Unbalanced 150 ohms
Output Level (Max) + 22 dB
Frequency Response 20Hz to 20KHz ±0.4dB
Signal to Noise ratio -85 dB Unweighted, -99 dB 'A' weighted
Distortion .02% THD @ 0dB,1KHz
Dynamic Range 107 dB
Enhance Section
Low Enhance 50 Hz, High Enhance 10 KHz
Power Requirements 100/120 V AC, 220/240 V AC
Weight 5 lbs/2.2 Kg
Dimensions 19“W x 1?“H x 6“D, 482 x 44 x 155mm
Input/OutputConnector type XLR, Balanced Jack

Front Panel Controls
Channel A Active/Bypassed IN/OUT switch
Threshold, Ratio and Output Gain controls
Numbered marker panel for labelling compressor assigns
5 segment LED Gain Reduction display
Above/Below Threshold status LEDs
Enhance switch and status LED
Stereo link switch and status LED
Channel B controls identical to Channel A
Rear Panel Connectors
Balanced XLR Input and Output connectors.
Balanced TRS jack Input and Output connectors.
AC input connector, with voltage switch and fuse.