Hi welcome back to HowToAV.TV we're still here at ISE 2019 and we've found a
little space on the AVIXA stand and we're gonna be talking audio and when
you want to talk audio who better than the mad sound guy him self Chuck Espinoza.
Welcome back to the channel Chuck, when our viewers know that we're coming over
to ISE they always a few questions for Chuck. First one then we want to talk
about 100 volt line and low impedance audio. Now we're really talking I guess
about commercial audio with a 100 volt line and low impedance gets used a
lot in residential. What's right for the right application? That's a good
question for the right application the right tool for the right application. So
your constant volt line it's going to be used where we have to string audio over
a long distance, but we don't need a lot of power. We just need a few watts to
make some audio happen say for a public address system in a building or a paging
system and usually the loudspeakers are putting out not a lot of audio and it's
in a very specific frequency range. Just the range of the voice, we're not doing a
lot of low end sub, will for work or high end tweeters like we would with a full
range system. And we can string this audio for days, you know if I have a
100 watt amplifier and I'm only using one watt on a loudspeaker I could
theoretically put a hundred loudspeakers on that chain and that would be great
for an entire buildings public address system or paging system. For a direct
couple their low impedance audio system, this is what's used more in residential
because we want full frequency spectrum. We want those lows in the movies to
really impact us, we want those highs to sound really crisp and clear, and also in
the live events genre we use a lot of direct coupled
loudspeakers for big sound. Tons and tons of wattage and tons of fly rigs and of
course we want the bass booming and thumping that kick drum hit me in the
chest and nice full lows and crisp highs like a hi-hat. So we use those
tools for different things, different applications. 100 volt constant voltage
for that long audio that doesn't need a lot of dynamic range, a lot of a big
frequency spectrum and very low wattage and that direct coupled for a large
frequency spectrum I want all the Hertz and I want them big. So putting you on the
spot without having a whiteboard and a calculator or anything else, there is a
significant difference between calculating loudspeaker amplifier loads on
100 volt 70 volt line and low impedance. In my mind 100 volt lines a lot easier.
It's pretty easy, just voltage squared divided by Watts equals
impedance. I got to figure out what the total impedance is, check it at the line,
make sure my amplifier can do that. Usually the manufacturers have worked
this out already. So if they say we have a 150 watt 100 volt
amplifier, as long as I'm you know I'm not kicking a lot of wattage, I'm
doing 100 watts on that they've figured it out they've done the math that you
could just put it on. When you have an 8 ohm or a direct coupled amplifier you
have to do a little bit of math as well. You have to figure out how many watts
I'm going to get at that impedance and with AC impedance it's not always the
same. Like when they say this is an 8 ohm cabinet, it's 8 ohms at a certain
frequency. At different frequencies it's going to be way different, if I try to
put highs into a subwoofer I'm gonna get a lot of impedance on that
frequency range. But at the 60 Hertz and 80 Hertz frequency range, it's going to
be very open 2 to 3 ohms. So they might call it an 8 ohm cabinet at a specific
frequency but it covers a wide spectrum. So you should always read your specs and
do your tests. I test them all myself first.
Plenty more information on audio installation, low impedance, high
impedance, 70 or 100 volt line available on HowToAV.TV. If you've got a specific
question leave it in the comment section below we'll get right back to you and if
we can't find the answer we'll phone Chuck.