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Audio mixer/amp for overflow audio

Most of us are familiar with connecting speakers to a stereo system: you pull the two conductor speaker cable, connect the red wire to the red terminal on the amp, connect the black wire to the black terminal on the amp, repeat on the right speaker, and then repeat on the left speaker. It’s all pretty simple and straight forward… and it works great for stereo audio in a single room.

But what do you do when you need to distribute audio to speakers in multiple areas? Or if the application won’t really support left and right stereo audio? That’s where a 70/100 volt (or “70/100v”) system comes in…

70/100v amplifiers have a higher signal voltage than conventional stereo audio amplifiers (commonly referred to as “8 Ohm” systems) and allow for more speakers and longer signal distances. This is ideal for any room or building requiring more than two speakers.  These systems are commonly used in paging or background music applications, but are a great way to distribute audio anywhere using a very simple wiring concept.

The TL-A70-40W provides 40 watts of power and four audio inputs—a microphone input, two analog stereo line inputs), and a digital audio input (typically a CD player, streaming audio player, or other media player). You can select from any of the three line inputs, and mix it with the microphone together into a single audio stream.  That audio stream can be broadcast to multiple speakers simultaneously.
  • Technical Features
  • Resources
  • Accessories
  • Installation
  • FAQ
  • SKUs
    • (1) Mic/Line input
    • (1) Stereo audio input
    • (1) Digital audio input
    • Auto-ducking on the mic channel
    • Microphone mixing with source audio
    • 48 dB of microphone gain with phantom power
    • 4 dB of line gain
    • 40W Class D amplification
    • 70V or 100V output
    • Front panel, IR & RS232 control
    • Built-in EQ
  • Specification Sheet

    1. Mount or position the TL-A70-40W amplifier in its permanent location.
    2. Connect the audio sources to the TL-A70-40W.
    3. Adjust the TL-A70-40W settings to accommodate your audio inputs (select 48V for mics needing phantom power and gain, MIC for mics just needing gain, and LINE for line level sources).
    4. Connect the speakers to the TL-A70-40W according to your speaker type (70V or 100V).
    5. Connect a control system via IR or RS232 (if desired).
    6. Connect the power supply to an AC outlet or power source.
  • What comes in the package?
    Each TL-A70-40W includes a mixer/amplifier, mounting hardware (great for wall or under-table mounting), rubber feet for table top use, an RS232 control cable, a power supply, and an installation guide.

    Do I need to power the unit?
    Yes, the TL-A70-40W requires power and ships with a power supply.

    I understand a 70V/100V system is more powerful, but how does it work?
    A 70V or 100V system makes the audio signal more powerful by using a transformer after the amplifier to increase the signal voltage, and then another transformer is used at each speaker to decrease the signal voltage. This allows an unlimited number of speakers to be added to the circuit, provided the total wattage does not exceed the max wattage load of the amplifier. In the case of the TL-A70-40W, the max wattage is 40 watts (also known as “40W”).

    So I can connect an unlimited number of speakers to the TL-A70-40W?
    Well, sort of… An unlimited number of speakers can be connected in parallel provided the total combined wattage of ALL speakers is less than 40W. To ensure long-term performance and signal quality, we recommend limiting the total system wattage to 80% of the TL-A70-40W total capability (or 32 watts). For example, 16 speakers tapped at 2 watts each would equal 32 total watts, or the ideal system rating.

    How can I tell how much wattage each speaker will draw?
    70V and 100V speakers have a rated “tap” that tells how much wattage they will draw, and typically they even have multiple taps so you can customize the wattage used.

    Is there a benefit to tapping a speaker with a higher wattage?
    In general terms, higher wattage equates to higher sound levels. Less speakers in an area will typically require a higher wattage, whereas more speakers covering the same space will require a lower wattage. Most installers will recommend installing more speakers at a lower wattage because it will provide a more complete, smoother audio coverage.

    Are there other advantages of a 70V or 100V system?
    There sure are… 70V and 100V systems are much easier to install when multiple speakers are required because you do don’t have to worry as much about speaker placement or impedance issues (too much impedance can overload and damage a traditional 8 Ohm amplifier). Plus, you can “daisy chain” speakers together, or run the speaker cable from one speaker to the next and so on, as opposed to running home runs from the amplifier to each speaker. Long term, 70V and 100V systems are also much easier to maintain because damaged, removed, or added speakers won’t affect the performance (and signal level) of the other speakers in the system (provided you don’t exceed the maximum wattage of the amplifier).

    Do I need to purchase specific speakers for a 70V or 100V system, or will any speaker do?
    Yes, you need to purchase speakers rated for a 70V or 100V system. Standard stereo audio (left/right audio) speakers will not work. Do not even try to hook them up to the TL-A70-40W…bad things will happen… bad things to your speakers…

    Are there disadvantages to using a 70V or 100V system? Why isn’t every speaker system 70V or 100V?
    70V and 100V systems are only monaural, or mono, and do not support stereo audio. This is fine for overhead ceiling speakers, but not so great for home theaters or demanding conference rooms. Furthermore, 70V/100V speakers typically don’t have as broad of a “frequency response”—or signal spectrum capability—which translates into the quality of audio you hear.

    What type of cable do I use to wire the TL-A70-40W to the speakers?
    We recommend a high quality 18 or 16 AWG (gauge) speaker cable.

    Is there a maximum recommended distance between the TL-A70-40W and the speakers in the system?
    70V and 100V systems are ideal for running speaker signals longer distances—much longer distances than a traditional 8 Ohm system. Speaker runs can easily exceed 300 feet from the TL-A70-40W.

    My microphone sounds really faint. Can I adjust the signal levels of audio inputs?
    Absolutely, the TL-A70-40W supports 48 dB of gain for microphones signals (which are notoriously low volume) and 4 dB of gain for line level inputs.

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