TIRED OF BLOWING YOUR HORNS?
March 21, 2008
Tired of blowing your horns? Need horn loud speaker protection? The RDL ST-HP3 is the device for you. The ST-HP3 is a high quality dual high pass filter offering big horn protection in a small package. The ST-HP3 has one input and dual outputs. The input may be wired either unbalanced or balanced and accepts line-level audio (+4 dBu nominal). One of the two outputs is filtered at 300 Hz and the other output is filtered at 500 Hz. The ST-HP3 operates at unity gain. The two outputs maybe wired either balanced or unbalanced and may be used simultaneously, allowing the filtered audio to be tailored to the exact requirement of the audio system. Just wire the ST-HP3 between the audio source and the power amplifier or in the processing insert loop of an integrated amplifier, choose the low frequency attenuation that your audio system requires and that’s it. No field adjustments required to protect your horns from damage from excessive low frequency content.
Multi-point Twisted Pair
October 17, 2007
RDL Format A twisted pair products make it easy transmit up to three channels of high quality audio from one point to another using twisted pair cabling. Format A products utilize RJ-45 connectors which make field terminations fast and easy. The flexible design of these modules also makes them useful for multi-point applications.
Format A modules use one of the available four pairs for power while the three remaining pairs (conveniently named A, B and C) are dedicated to sending and receiving audio. Sending audio from several different locations is made easy by utilizing the selectable-pair feature of the Format A senders. The single-pair senders allow the user to feed their audio source to one or multiple receiving modules on pair A, B, or C. Two RJ-45 jacks on the rear of the single channel senders allow loop-through of a single "run" of cable.
An ideal application for Format A products is to send the signals from three remote microphones to a central location. This is achieved by using three Format A senders and one receiver at the central location. If one or more of the microphone signals is needed at another location, the user may use the loop out feature of the Format A receiver which allows the signal to continue on to other locations. The active twisted pair receivers bridge the balanced line level audio on the cable so there is no significant loss when using multiple receivers along the same cable.
DON'T FORGET YOUR POWER SUPPLIES
July 12, 2007
Every active RDL module requires a 24 Vdc power supply. However, because multiple RDL modules may be powered with one power supply, RDL modules do not include a power supply. This saves our customers money on power supplies and freight. This also affords more flexibility when designing RDL modules into a system.
If the RDL modules are being designed into a system that already has 24 Vdc power available, there is no need to purchase a power supply for each module as you can simply use the existing 24 Vdc power to power the modules.
All Flat-Pak modules and some Rack-Up modules feature a power bus and an interconnect cable that allows the modules to be powered from a single 24 Vdc power supply.
Another option for powering multiple modules is to use either an RDL ST-PD5 or ST-PD5U. The ST-PD5 is a linear power supply distributor featuring up to 5 power distribution points and works with any of our linear power supplies. The ST-PD5U offers the same number of distribution points but is only designed to work with the PS-24U2 2 A Switching Power Supply.
To make the power supply selection process easier, we have developed a Current Consumption Calculator. It’s as simple as selecting a product and entering the quantity needed. The calculator then provides the power configuration (ground referenced, floating or SupplyFlex), the current requirement of each of the selected products and the total current requirement to power all of the selected modules.
Click here for the current consumption calculator.
Ganged operation of multiple ST-VCA2 Voltage Controlled Amplifiers
October 4, 2006
It is possible to use one RLC10K to control several or even half a dozen ST-VCA modules in tandem. The current requirements at the Control terminal are low enough that one ST-VCA2 10V Output through a single RLC10K can operate multiple modules. (Additional modules are tied together through their Ground and Control terminals.) This is a good solution for common control of feeds to a multi-zone system. This method is not recommended for stereo gain control however. Two ST-VCA2 modules may not maintain stereo balance across their full range of attenuation. For stereo applications, the RU-VCA2D is the recommended product. The design of this device guarantees balance from full on to maximum attenuation.
RoHS Compliance
September 15, 2006
Most of the RDL product line has been RoHS compliant from the date these changes were effective for the European Union. However, there are still non-compliant items in stock in many locations. If your domestic (North American) order requires parts that are RoHS compliant, be sure to specify this in your order so the parts you receive will be compliant.
OPERATING ENVIRONMENT
September 13, 2006
Operating environment for any of the RDL products is specified as 5 to 50 degrees Celsius at 0 to 95 percent humidity, non-condensing. RDL can produce reliability reports for our products as may be required for their use in a government system. Contact RDL technical support when a reliability report is necessary for one of your projects
Power Supply Update
August 11, 2006
The STA-1, which is a line amplifier with response to dc, is the only product that still requires a floating (or bipolar) power supply input. Other modules that previously needed floating power have been redesigned with SupplyFlex ™ power supply inputs. This makes sharing power supplies across multiple modules very easy.
USING ST-UMX3 IN EQUIPMENT SETUP
August 5, 2006
The two LED VU meter found in the ST-UMX3 is a good example of how this simple level indicator can be used in equipment setup. The green LED is an indication of average (VU ballistics) audio level. It starts to illuminate when the line level output of the mixer is at -11 dBu. It will reach full intensity when the level is at +4 dBu. The red LED serves as a peak indicator. It will light when output level is +4 dBu. The nominal line level output of the ST-UMX3 is +4 dBu. At this level, the unit maintains 18 dB of headroom. (The red LED is a peak indicator – not a clipping indicator.)
PHANTOM POWER SPECIFICATIONS
July 11, 2006
Phantom power specifications are well standardized under IEC 61938 and DIN 45 596. Acceptable voltages and current supply capabilities are well defined. Positive phantom voltage is found on the balanced microphone output terminals (pins 2 and 3 of an XLR connector) with the ground return on the shield. There is no such standard for the unbalanced electret microphones that are prevalent in the communications and security industries. It is sometimes necessary to use external components to match the power requirements for some of these microphones when used with RDL mic preamplifiers. When electret microphone specifications are available, RDL Technical Support can help integrate these devices with components designed for conventional phantom power.
LOCATING COMMON CHARACTERISTICS
June 6, 2006
Dimensions and power supply specifications for all the RDL products can be found in the listing titled “Common Characteristics” either at the web site or in the catalog. (On our web site this information is located in the Reference section.) All Stick-Ons are the same size – 3.0 by 1.6 by 0.7 inches.
OPERATING MULTIPLE ST-VCA2 MODULES WITH THE SAME RLC10K
May 1, 2006
Several ST-VCA2 modules can be operated with the same RLC10K. The first unit is wired in the normal fashion. The additional ST-VCA2 units to be controlled by the same RLC10K are connected to share the CTRL (Control) and ground terminals of the RLC10K. If the units share the same power supply, the ground terminals are already connected and just the wiring between CTRL terminals needs to be added.
LED meter on mixer
December 31, 2005
The two LED VU meter found in the ST-UMX3 is a good example of how this simple level indicator can be used in equipment setup. The green LED is an indication of average (VU ballistics) audio level. It starts to illuminate when the line level output of the mixer is at -11 dBu. It will reach full intensity when the level is at +4 dBu. The red LED serves as a peak indicator. It will light when output level is +4 dBu. The nominal line level output of the ST-UMX3 is +4 dBu. At this level, the unit maintains 18 dB of headroom. (The red LED is a peak indicator – not a clipping indicator.)
Phantom Power
November 29, 2005
Phantom power specifications are well standardized under IEC 61938 and DIN 45 596. Acceptable voltages and current supply capabilities are well defined. Positive phantom voltage is found on the balanced microphone output terminals (pins 2 and 3 of an XLR connector) with the ground return on the shield. There is no such standard for the unbalanced electret microphones that are prevalent in the communications and security industries. It is sometimes necessary to use external components to match the power requirements for some of these microphones when used with RDL mic preamplifiers. When electret microphone specifications are available, RDL Technical Support can help integrate these devices with components designed for conventional phantom power.
Power Connectors
November 15, 2005
The connectors used on those RDL power supplies that are supplied with connectors are sized 5.5mm O.D. x 2.5mm I.D., equivalent to a Switchcraft part number 760
POWER SUPPLY SPECIFICATIONS
September 8, 2005
Dimensions and power supply specifications for all the RDL products can be found in the listing titled “Common Characteristics” either at the web site or in the catalog.
RDL XLR Wiring Configuration
September 5, 2005
The RDL wiring conventions for XLR connectors have the Ground connection on pin 1, + on pin 2, and – on pin 3.
POWER SUPPLY POLARITY
June 29, 2005
The striped wire on the RDL power supplies indicates the positive lead.
FLOATING AND GROUND REFERENCED POWER
June 28, 2005
For our products, a "ground" reference is a common electrical return for both audio and power, while a "floating ground" reference indicates that there is in our product a separate electrical return for power that can not be grounded with any common electrical return. Also, devices employing floating ground references can not be powered by a power-supply that has its return grounded, or is powering a ground-referenced device. Products with a "floating" power input are marked with a "+" and a "-". Products with a ground-referenced power input are marked with a "+" and a ground symbol.
POWERING MULTIPLE MODULES
June 26, 2005
We recommend that an ST-PD5 be used if more than two modules will be connected to the same RDL linear power supply. If an RDL switching supply is used, the ST-PD5U is recommended for power distribution. The sum of the currents used by connected modules should never exceed the total available supply current, and good practice dictates it typically should not exceed 80%. Module current requirements are summarized in the Common Characteristics section of the RDL catalog.
POWERING RDL PRODUCTS WITH 12 Vdc
June 16, 2005
Some RDL products may operate from 12 volts with greatly reduced headroom; certain modules may operate directly from 12 volts, while other products simply can not operate at that voltage. The individual data for each product indicates the permissible input voltage range. In mobile applications, it is frequently desired to operate any number of RDL modules from 12 volts dc. The RDL FP-DCC1 (dc-dc converter) provides up to 400 mA at 24 volts dc from a 12 volt input to operate RDL 24 volt dc modules.
POWERING RDL MODULES WITH 24 TO 33 Vac
June 14, 2005
With exception of the TX-VLA1, TX-AVX, TX-VCR, and System 84, all RDL modules will not work properly if supplied with AC voltage. In fact if you supply AC voltage to any of our products that cannot be powered by AC voltage, you will most likely destroy the unit and void the warranty.
RU-SPC1 DIGITAL CONVERTER
June 10, 2005
The RU-SPC1 Digital (SPDIF) to Analog converter allows input on either BNC or phono coaxial inputs or an optical input. The unit automatically senses which input is being used. It also does automatic selection of sample rate and resolution.
ROOM COMBINING SYSTEM: RCX-5C
June 9, 2005
The RCX-5C is a stock rather than a custom component. The user has the option of using it to operate a room combining system in a wide variety of layouts for groups of two to five rooms. Because it is not a custom item it is usually available off the shelf and is likely to be the most cost effective solution for the systems it supports.
SYS-84 HAVING PROBLEMS?
June 8, 2005
If you're having problems with the SYS-84 models where channels 3 and 4 seem distorted or do not work at all, You may have the power supply connected to the wrong power input. The power supply shipped with the System 84 is a DC supply and is intended to connect to the DC power connection only - if the DC supply is connected to the AC power connection, the voltage is dropped internally to the circuit, causing Channel 3 and 4 outputs to possibly distort or appear dead. These characteristics can be resolved simply by moving the DC power supply's connector from the AC power connection to the DC power connection.
ST-TC1 TELCO LINE SIMULATOR
June 7, 2005
The ST-TC1 is a device that simulates a telephone company (telco) line for connection to a telephone switching unit (KSU). The ST-TC1 becomes the provider of an inbound line to your switch, so when any of your instruments pick up the line provided by the ST-TC1, a contact closure is provided and bi-directional audio is available through the module. In this manner, audio can be routed through the telephone coupler to or from the telephone equipment. This connection can be used to add paging zones to a phone switch, or control communications radios. Because the ST-TC1 simulates a phone line, it can also connect directly to a telephone instrument for constructing private intercom systems.
USING PHANTOM-POWERED (condenser) MICROPHONES WITH RDL PRODUCTS
June 5, 2005
Phantom-powered (condenser) microphones can be used with the STM products. Each STM module has two terminals that enable phantom power to be applied. Phantom power can be provided using the same RDL power supply that powers the STM module. The FP-MP1 Ultra Low Noise Mic Preamp has switch-selectable phantom for mics operating from 12 to 24 V.
CONNECTING UNBALANCED AUDIO TO OR FROM AN RDL PRODUCT
June 2, 2005
For most of our products the audio signal input and output wire is connected to the input or output positive (+) terminal. The audio return shield is connected to signal ground. The unused negative (-) input terminal is jumpered to signal ground. The unused negative (-) output terminal has no connection or may be used as a second unbalanced signal source. The negative (-) output terminal is out of phase with the positive (+) output.
However with the STM-2X on the input side only, the signal wire is run to the negative (-) and the unused positive (+) is grounded.
dB DEFINED
June 1, 2005
A decibel (dB) is a ratio unit for expressing signal amplitudes. If the amplitudes are expressed in voltage: dB=20 log (V1/V2). If the amplitudes are expressed in power: dB=10 log (P1/P2). In digital audio systems, decibels are often expressed in dBFS, the voltage value below the value produced by a full scale digital audio signal. Decibels relative to an arbitrary reference value, dBr, require that the reference value be stated. Unbalanced consumer signals are most commonly referred to 1 V, and are called dBV (0 dBV = 1 V). These units are used to specify consumer format unbalanced signal levels. The standard consumer level is -10 dBV. Balanced professional signals are typically referred to 0.775 V RMS, and are called dBu. A balanced 0 dBu signal is 0.775 V. Standard professional audio signals are +4 dBu.
IMPEDANCE SIMPLIFIED
May 26, 2005
Impedance is the resistance of audio circuits to audio signals. Any audio input has an impedance, as does any audio output. Modern input stages are typically high impedance, often 10 kOhms or higher. These inputs accept the input signal without demanding power from the prior equipment output. For accurate amplification, it is generally accepted that an audio input impedance should be higher than the output impedance of the prior device. The output impedance of RDL modules is typically 150 Ohms. The input impedance of RDL products is typically 10 kOhms. This makes all RDL outputs compatible with all RDL inputs. For the user, it is only important to remember that the input impedance should always be higher than the source impedance of the device driving the input. It cannot be the other way around. A high impedance output should never be used to drive a low impedance input. Such connections result in signal loss, quality degradation, and sometimes damage to the output of the source.
CONNECTING A TX-1A BACKWARDS
May 24, 2005
The TX-1A is used primarily for galvanic isolation and format conversion between equipment. Conversion from -10 dBV consumer level up to +4 dBu professional level requires voltage gain. The transformer in the TX-1A has a 1:1 ratio and uses an adjustable attenuator circuit at its output to lower the output signal to the level required. The module cannot provide voltage gain.
RDL offers several premium quality conversion amplifiers to produce professional signals from consumer sources. RDL also offers a passive transformer based converter, the TX-AFC1M. This module provides level and format conversion from+4 dBu professional level to -10 dBV in exceptional quality.
THE DIFFERENCE BETWEEN BALANCED AND UNBALANCED AUDIO
May 23, 2005
Balanced audio carries equal but opposite signals on two conductors. These symmetrical signals are relatively immune from induced hum and noise. Frequently, balanced cables also are shielded. The shield is independent from either of the signal conductors. Unbalanced audio is carried on a single conductor relative to the shield. In unbalanced cables, the shield is the negative signal conductor. Unbalanced wiring is subject to interference, ground hum and crosstalk. Unbalanced wiring is valid only for very short distances where quality is not the highest concern. Balanced wiring is recommended for any high quality wiring, and is necessary for any long distance audio transmission.
