Connecting 6 Speakers To a 2 Channel Amp
By Robert Jones · 2020-08-19
Do you want to connect 6 speakers with only 2 channel amp?
So, you've got a two-channel amp, but you're itching to hook up six speakers? Happens more often than you'd think, especially if you're trying to get a bit more coverage in a larger room or perhaps even get some decent sound in a workshop or garage. I've been there myself, trying to squeeze a bit more out of what I've got, and it's definitely doable. It just takes a bit of thought, and frankly, a bit of understanding about ohms and impedance. You can't just wire everything willy-nilly, or you'll end up with a blown amp – and nobody wants that. ### The Nitty-Gritty: Understanding Impedance Before we go any further, let's quickly talk about impedance. Think of it like resistance. Speakers have an impedance rating, usually 4 or 8 ohms. Your amplifier is designed to work with a certain load, a minimum impedance it can handle. Push it too low, and it's like asking a small car engine to tow a massive truck uphill – it's going to overheat and eventually give up the ghost. Most stereo amps are happy with 4 or 8 ohms. Drop it below that, say to 2 ohms per channel, and you're asking for trouble unless your amp is specifically designed for it. Most aren't. ### Why Do It This Way? Now, you might be asking, "Why not just buy a multi-channel amp?" Good question. Sometimes it's about budget. Sometimes you've already got a perfectly good two-channel amp you don't want to replace. And sometimes, you just want to experiment – that's how I learned half of what I know about audio, to be honest. Testing things, getting them wrong, and then figuring out why. It's a cracking bit of fun, really. ### The Series Wiring Method One way to connect more speakers is to wire them in series. Imagine a chain. You connect the positive terminal of the first speaker to the positive output of your amp, then the negative of the first speaker to the positive of the second, and so on. Finally, the negative of the last speaker goes back to the negative output of your amp. What this does is add up the impedance of the speakers. So, two 8-ohm speakers in series become 16 ohms. That's a handy way to keep the overall impedance high and safe for your amp. **Pros of Series Wiring:** * Keeps impedance high, safe for most amps. * Good for adding more speakers without overloading your amplifier. **Cons of Series Wiring:** * Power is shared, so each speaker gets less power. * If one speaker fails, the whole chain goes down (no sound). * Sound quality can sometimes be a bit uneven, as one speaker's characteristics can affect the others. ### The Parallel Wiring Method Parallel wiring is different. Here, all the positive terminals of your speakers connect to the positive output of your amp, and all the negative terminals connect to the negative output of your amp. It's like multiple roads leading to the same destination. The catch here is that parallel wiring *reduces* the overall impedance. Two 8-ohm speakers in parallel become 4 ohms. Two 4-ohm speakers in parallel become 2 ohms. This is where you need to be careful, as dropping below your amp's minimum impedance can cause damage. **Pros of Parallel Wiring:** * Each speaker gets the full power available (up to the amp's limit). * If one speaker fails, the others usually keep working. * Often results in a more dynamic sound. **Cons of Parallel Wiring:** * Reduces impedance, can easily overload your amp if you're not careful. * Requires more careful calculation of impedance. ### Series-Parallel Combination: The Best of Both Worlds? This is often the best solution when you've got a few more speakers to hook up. You combine both methods. For example, you could wire two speakers in series, and then connect that series pair in parallel with another series pair. This way, you can balance the impedance to a safe level for your amp while still getting all your speakers connected. It's a bit like a jigsaw puzzle, but when it works, it's very satisfying. Let's say you have six 8-ohm speakers and a 2-channel amp that's happy with a 4-ohm load. You could run three speakers per channel. How? Wire three 8-ohm speakers in series. That gives you 24 ohms. Then, the problem becomes you've only got three speakers on one channel when you could have more. Or you could wire two 8-ohm speakers in series (16 ohms), and then do that three times. You'd then have three 16-ohm loads. You could then try to parallel those, but you'd quickly get into tricky impedance numbers. A better way for six 8-ohm speakers on a 4-ohm stable amp: Group them into three pairs. Take two 8-ohm speakers and wire them in series. That gives you 16 ohms. Do this three times. Now you have three 16-ohm "units." If your amp can handle 2 ohms, you could try paralleling two of those 16-ohm units per channel, giving you 8 ohms per channel. Then you'd need to think about the third pair. See? It gets complicated quickly. The goal is to get to 4 or 8 ohms per channel. A more practical approach for six 8-ohm speakers: Wire two pairs in series on one channel (8 + 8 = 16 ohms), and another two pairs in series on the other channel (8 + 8 = 16 ohms). Sorry, that's only four speakers! For six speakers, you'd need to get creative. For instance, if your amp is stable at 4 ohms, you could wire two 8-ohm speakers in series (16 ohms) and then put *three* such series pairs in parallel *per channel*. No, that's not right. Three 16-ohm parallel loads would be around 5.3 ohms, which is doable on a 4-ohm amp. So, three pairs of series-wired 8-ohm speakers, all connected in parallel to one channel. Do that for both channels. That's six speakers per channel. Wait, no. That's six speakers total wired to *one single channel*. You need to distribute them across two channels. Right, let's try this for six 8-ohm speakers on a 2-channel amp, aiming for 4 or 8 ohms per channel: * **Channel 1:** Take two 8-ohm speakers, wire them in series (16 ohms). Take another two 8-ohm speakers, wire them in series (16 ohms). Now, connect these two series pairs in parallel. 16 ohms in parallel with 16 ohms gives you 8 ohms. Perfect for one channel. * **Channel 2:** You're left with two 8-ohm speakers. Wire them in parallel. That gives you 4 ohms. Also perfect for the second channel if your amp is 4-ohm stable. This way, you're running a safe load on both channels. You'd have four speakers on one channel and two on the other, but they'd all be working. It's a compromise, but it works. I've done similar setups in my old garage for background music, and it holds up fine. ### Wiring Diagrams and Tools Honestly, sketching it out on paper before you start is a lifesaver. Keeps things clear. You'll need some speaker wire, of course, and a decent pair of wire strippers. Make sure your connections are solid; loose connections lead to crackling and, in the worst cases, can short things out. ### A Word of Warning Always, always, *always* check your amp's impedance rating. If you're not sure, look it up in the manual. Running an amp below its minimum impedance rating is a surefire way to damage it. And trust me, getting an amp repaired is a lot more hassle and expense than buying a few more bits of cable or even a multi-channel amp in the first place. I've seen folks try to push their luck with this kind of setup, and it rarely ends well. I even blew a perfectly good vintage Marantz amp years ago trying to run too many speakers in parallel without really understanding the impedance. Lesson learned, expensive lesson at that. Don't make my mistake. ### When to Call It Quits (and Buy a Multi-Channel Amp) Look, sometimes you just have to admit defeat. If you're trying to hook up six speakers and end up with ridiculously complicated wiring schemes or an impedance that's just too low for your amp, it's time to consider a multi-channel amplifier. They're designed for this sort of thing, and they'll save you a lot of headache (and potential equipment damage) in the long run. Often, for a bit more money, you get a much more solid and flexible system. I've got a few multi-channel amps running around the house for different zones, and they're brilliant. A Denon AVR for the home cinema, obviously, but also a smaller integrated multi-channel amp for feeding speakers in the kitchen and conservatory. Sometimes, the right tool for the job really is worth the investment. #### Summary of Wiring for 6 Speakers (8 Ohm) on a 2-Channel Amp (4 Ohm Stable) * **Channel 1 (4 speakers total):** * Take two 8-ohm speakers. Wire them in series. This gives you 16 ohms. * Take another two 8-ohm speakers. Wire them in series. This gives you another 16 ohms. * Connect these two 16-ohm series pairs in parallel to Channel 1 outputs. This results in an 8-ohm load for Channel 1. Safe and sound. * **Channel 2 (2 speakers total):** * Take the remaining two 8-ohm speakers. Wire them in parallel. This results in a 4-ohm load for Channel 2. Also safe and sound. This setup works and keeps your amp happy. You get all six speakers playing, even if a couple of them are sharing a channel with more friends. ### FAQ **Q: Can I mix and match speakers with different impedance ratings?** A: You can, but it makes the impedance calculations a lot trickier. I'd strongly advise against it if this is your first time messing with speaker wiring. Best to stick to speakers with the same impedance for simplicity. **Q: Will wiring multiple speakers affect the overall sound quality?** A: Yes, it can. Series wiring, in particular, can sometimes lead to a slightly less dynamic sound because power is shared. Parallel wiring generally maintains a better sound, but you have to be vigilant about impedance. **Q: What if my amp rating is 8 ohms, not 4 ohms?** A: If your amp is only rated for 8 ohms, then you'll need to be even more careful. You'd have to ensure your total impedance for each channel *never* drops below 8 ohms. This might mean only using series wiring, or fewer speakers overall per channel. My old NAD amp, for example, really didn't like anything below 8 ohms. **Q: Is there an easier way to connect more speakers?** A: Short of buying a multi-channel amplifier, you could consider a speaker selector switch. These bits of kit let you connect multiple pairs of speakers and switch between them, often with built-in impedance protection. They're a good middle-ground solution if you're not quite ready for a new amp but need more flexibility. Though, usually, you'd still only play one or two pairs at a time. It's not usually for simultaneous playback of all six.