QSC KS212C Open It up and Change the Settings of the Back Facing Speaker

0:01 It's a cardioil sub

Right, so it's experiment time. I have here the KS212C. It's from QSC. It's a cardioil sub. Two 12-inch, one facing forward or one, yeah, when I say one facing forward, when the cab is placed correctly, you have one speaker facing forward and the other one back. So we have two ports at the front and two ports at the back. Now, a cardioil system works like this. If we break all the technical parts down and we just make it sound simple, is that you get more bass coming forward than you do from behind. So what you've got, you've got this sort of push-pull configuration. While one speaker is going out, the other one's actually coming in. So the other one is sort of, the one speaker is cancelling the sound that the other one's making.

Now, if you had, let's say for example, two speakers and you had them cancelling out facing the same direction, you'd get this hollow kind of sound. Now, you may have had that in the past where you've plugged all your bass cabs in and you can't work out why you've got two fantastic 18-inch subs but they're not producing any bass. It's very possibly because they're out of phase. In other words, the one is out of phase. The other one is pushing out while the other one's pushing in. And that could be something as simple as if you're using, for example, active speakers, sorry, passive speakers, I beg your pardon, and a separate amplifier that you've just wired the speakers in correctly. Anyway, I don't really want to go any further with that.

I want to look at the KS212C which QSC, you have two 12-inch. One is this part of the speaker and the other one is at the back. So at the moment now, it's on wheels and I'm going to turn it on its top. So I have here a whole bunch of screws and I'll just move the camera down. So what I'm probably going to do with this video is sort of when I'm doing things like this, I'm just going to spin it forward so you don't really want to watch me unscrewing all of the screws. Okay. All right. Let's take the camera off. Now, let's have a look. So this is the internal part of the speaker and these are our ports. So all I need to do actually, I don't really have to do anything else which is fantastic. Now, this is the back, okay?

3:18 Is turn those two cables around

And this is the front. So what I'm thinking, all I should have to do... Is turn those two cables around. So put the one on the right to the left and one on the left to the right. So that's what I'm going to do right now. And then, I am going to plug it in. So just for a second, I'm just going to pause the camera and start shortly. Hold on. All right. So this is inside the cab. So you can see here's the port. There's the speaker there. And that is the forward-facing speaker. So that is the base that we want but we don't want the opposite. So I've had to take the port away to get to the wires. Sadly, but don't worry about it, there's always a way around it. The spades on both sides are different sizes which in a way is good because it means that you can't mess them up small and big.

4:45 I'm now going to press play and we're just going to hear the bass

So what I'm going to have to do for this, for demonstration purposes only, is just connect them with a couple of cable ties. But then, of course, I will be replacing them. Mind you, if I do get more bass, I might actually just keep it the way it is. Sorry. No, I shouldn't do that really. Or should I? Who knows? All right. So I'll do that now. Put the port back in and plug it in. And I will let you know if we do indeed. Get some better bass. Right, so I've got it plugged in. I have to admit, I haven't got a brilliant connection on the base speaker that normally faces towards the back because I don't want to start soldering things and messing around with the little plugs themselves. So I've just got one taped on.

I'm now going to press play and we're just going to hear the bass. OK. I'm not... I'm not overly impressed with that, actually. It's quite a lot... You know, it's shaking things but... Nah. Keep that thought, guys. Keep that thought. Hold on. Right, there it is plugged in. All plugged in how it should be. Press play.

I think you can tell there is a definite difference there. You know what I mean? Come on. God, this hell of a difference. Yeah. All right. So what's the moral of the story here? Well, I think... Maybe. You know, I'm no electronics wizard genius but maybe there is some sort of setting in the amp that says, you know, that one speaker, that's how it is. You're not going to piss around with it. Really, I do things like this so you don't have to. So to answer many questions, just don't piss around with kit. This is QSC KS212C. It's a really old twin 12 sub. And like I said at the beginning of the video, the whole idea is so you don't get much bass this way which is, of course, where you may be set up but, of course, the Joe Public will get a shitload that way and that is exactly what's happening.

And I think even by using the mic off this camera, you can tell that there is hell of a lot more bass. You can just hear the room rattle. Yeah, okay. There you go. Need I say anymore? Practice and enjoy. Thank you.

This transcript was produced automatically from the audio of the video and may contain mistakes.