How to Wire a Basic 70-Volt System on Pro Acoustics Tech Talk Ep. 5

Ever wondered how to wire a basic 7-volt system? On this week's episode of Pro Acoustics Tech Talk, Nathan and Coltin break down how 70-volt systems work. Using products from Yamaha, Atlas Sound, and Pure Resonance Audio, Nathan and Coltin show how to wire a basic 70-volt system.

Hey guys, thanks for joining us for another edition of Pro Acoustics Tech Talk. I'm Nathan, and I’m Coltin and today we are going to show you guys a little bit about basic 70-volt wiring and how to wire up the basic 70-volt system.

All right Nathan. So what do we have here? What's going on with all these wires and kind of guide me through this process of how 70-volt works.

Sure, sure. So, we have found that the average person does not know what 70-volt audio is. They don't know what 8-ohm or low impedance audio is. So, we wanted to do a real basic diagram or a way to show you guys how a 70-volt system could work for you in your application. We can kind of picture here a small restaurant, a small office, small bar with an outdoor patio or with speakers in the restroom, anywhere where, in this particular case, where you might need two zones of audio. Without getting too technical about how 70-volt works.

Rather than there just being an impedance value assigned to the speaker, like an 8-ohm or 4-ohm, and then you connect that to an amplifier, it's actually a transformer inside of the amplifier. First, it steps up the voltage and then sends that wattage down a line into the transformer at the speaker. This transformer sometimes is built into the speaker, sometimes mounted on the speaker. But in a true 70-volt system, it's always there. There are also at that point, what we call transformer taps, where you set the wattage of how much wattage you want that speaker to receive. The transformer at that tap steps down that voltage back down to low impedance to power your speaker.

Okay. So you can kind of think of those transformer taps, kind of like a governor on a car kind of thing.

Like it's only going to get that amount of wattage right when you have it set to that level. So, what we have here is our Pure Resonance Audio MA30BT Bluetooth mixer amp, which has one 70-volt output. You're normally just going to find one output on a 70-volt mixer amp. You're going to have a common, which is the terminal for your negative, your common, and then you're going to have a 70-volt positive terminal. That's where you connect your positive wire. Red. Yeah, red normally. So, from there you can then wire out to, for all intents and purposes, as many 70-volts speakers as you might need. Wow. So yeah, exactly. So, if you had an 8-ohm speaker, it would be 8-ohm and there's an 8-ohm, I'll put it in the amplifier. You can only hook up one speaker.

So, what ends up happening in those cases is if you need more speakers, you need lots of amp channels, you need lots of cabling. Whereas with 70-volt, you take your output connected to your speaker, set your desired tap setting, go onto the next speaker, onto the next speaker. You do that as many times as you need. You can also add as many in-wall volume controls as you need. We just have to keep an eye on what is the wattage of the amplifier. And we always want to leave about 15 to 20% headroom on an amplifier whenever possible. So, we've got a new MA30 here today, so that means we've got 30 watts available. We want to add a little bit of headroom though and not exceed with the amplifier can do.

Gotcha. And what're the benefits of doing that? I mean, does that kind of make the life span a little bit longer for the amplifier? Cause most people, you know, say I have 30 watts available on my use every single, you know, why I paid for it. Yeah. I paid for it. I'm going to use every single watt available to me.

So yeah, I mean, I get that question a lot, so kind of what's the benefits to doing that? Yeah, sure. So, the reason why you want to leave headroom is the same reason to a degree why you don't drive your car at 120 miles an hour every day. That's great. You know, your speedometer, it'll go all the way around, but that engine isn't going to be wanting to run at max capacity day in and day out. That's going to lead to failure and breaking. And without getting too complicated, it's also bad on the audio side of things to have things dimed.

Two to 10 or 2 to 11, all the time. Yeah. Eventually, that can cause distortion and unpleasant audio signal to be listening to.

Gotcha. So today we've added to in line 70-volt transformer, in line 70 volt-volume controls. So, what we can imagine like I mentioned, is say this one over here is the inside speakers at a restaurant. Okay. And say this is the private dining area or this is the restroom speakers or this is the outdoor patio. When this amplifier is running, I can adjust this dial to whatever level I want the speakers to be without impacting this run over here. There can even be additional. All I do in that case is actually wire the positive wires to positive wires from this amplifier out to the volume control. And on your volume controls, you'll have an amp input, positive and negative, and then a speaker output.

Positive and negative. Pretty simple. Yeah. So, one side's for the feed from the amp, one side's for the feed to the speakers. If you're doing more than two, you might want to contact us. There’re other ways that we can connect these volume controls, paralleling volume controls can get a little bit more complicated. And it's generally a good idea to have a chat with us when you're doing that, just so we can make sure everything works appropriately for you. But basically, this type of system, like I mentioned, will allow you to set the levels on these different volume controls 100% independent of the other. Basically, just set the main volume at the amplifier to where you want it. Make your adjustments and away you go.

These can be in-ceiling speakers mounted directly into the sheetrock. These can be wall mounted speakers, these can be pendant speakers. These can be big huge stadium speakers as long as the amplifier has the wattage available to drive what we need. And as long as we haven't exceeded the wattage range of the volume control, we're good to go.

Man, that sounds easy, easy and simple. And like he said, if it gets a little bit too complicated with volume controls or, if you're just mind boggled by all of this, feel free to give us a shout and, we're here to guide you through the process. Absolutely. Absolutely. The transformer taps on the speakers themselves can be a dial on the back. It also can be a series of multicolored wires coming off the back of the speaker. That applies to many of our packages that you might find on our online store or on Amazon.

Basically, the same concept applies. Add up the wattages on your speakers on those taps and make sure you're under 15 or 20% headroom on your amplifier and always keep speakers and volume controls in what's called parallel. Just to throw it back to fourth-grade science, parallel just means positive to positive, negative to negative. If you've got, you know, a red wire in most cases, you want that to go to your positive black wire in most cases to your common which is your negative. So very simple connections, easy to use. If you do have questions you're always welcome to get back in touch with us. This is a system that has two zones, but the same input source goes into both places. If you need different input sources, going to different zones, give us a ring.

We do have many other options available that we can help design, you can reach out to me directly at nathan@proacoustics.com. You know coltin@proacoustics.com. Or hit us up on our 800 number – (888) 256-4112 or go to our website www.proacousticsusa.com. Make sure and leave us a note below if you like what we're talking about here. If you have any thoughts, if you have any recommendations or questions or things you'd like to see us talk about here, we're happy to accommodate as best we can and make sure and check out our website, check out our Amazon store, our eBay store. See If you can find anything that you'd like from us. And other than that, thanks for joining us today. We'll see you next time. Bye guys.