Okay, so we're just going to test out the PA and listen to the system. I've got on my laptop, I've got some pink noise. I'm going to use my pink noise around the pink noise in the desk because I'm familiar with it. I know it's a fairly reasonable pink noise. Always go what you know, really? Yeah, yeah, and they do vary enormously don't know, particularly the modest, modest Pink Noise generators are random.

And so we're going to use a source that we know and trust, okay, and we're going to put it back through one channel on the desk. We're going to pan from right and left. Now, we've already discussed this because we've been around the back a couple of times, and we're already expecting that there's gonna be slight difference to retrain right and left. Just in why would that be? Well, in a situation like this, john, there are quite a number of variables that you have to think about between the two speaker systems. First of all, as we discussed before, the the cabinets are old.

Let's be generous and say they're 15 show Well, also out of the house guy and actually repaired one of the speakers and took a newspaper at the back dated 1979 which actually predates both of our careers, which is pretty old. So, they've been around a long time. They're Yes, they're old, old. So some, you know, they're all slightly different ages as well. There's one cabinet it's 35 years old. One is 30 years old, maybe 25 years old, but all old cabinets with new speakers in the trolleys, they don't make those speakers anymore.

I know. So we're going to have an assortment of different cabinets, and we're going to have an assortment of different speakers. And there are a couple of other things. The Amtrak here is situated in a little room that is on the other side of the stage, left corridor. And in order to get to the stage right pay stack, I think there's something like 10 or maybe even 15 meters more cable. Yeah, I have also noticed that all three boxes on that side are being run off one cable.

Yeah. It's gonna be called load on that as well line length the cable, we're gonna have a couple of things happening. I think that possibly for the 15 inch loudspeaker, there may be a resistance there that there's not actually enough current to getting down the cable to to operate the speakers properly. And of course, there's going to be some loss in high frequency detail as a result of the capacitance over the length of the cable. Yeah, so we're already expecting slight differences, hopefully not too great between the right hand side and the left side, we're expecting the right hand side maybe to be slightly louder, and maybe slightly less detail on the left hand side. But we're going to take a mono signal and we're going to pan it from right to left, it's important to use a monitor so not just use a stereo.

So we're using going to listen to exactly the same thing through each side. So first of all, listen to just the right hand side. Now we'll pan it across the left hand side Now I should just pan it across so we can instantaneously hear the difference. Yeah, it's slight differences tonally, you can hear it slightly different with a pink noise. Absolutely, as we suspected. Now, there are a number of things that we can do about this.

But I think that at this stage, it is safe for us to accept that no matter what we do, we'll never be able to get them to sound exactly the same. It's a physical impossibility given the parameters that we've already discussed. In this situation, generally speaking, I would be tempted to go and find a system processor and listen to it band by band. So the high frequencies first and the high mids and the low mids and then the subs left for right and we make the course level adjustments with amplifiers actually turning the outputs of the AMP For up and down, two, we've got the same level. And then if there are still, there's still anything that is substantially different, then we do it on the graphic equalizers. Yeah.

Well, I think we'll go ahead and do that now. And we'll test everything and let you know how we get on. Okay, so the first thing we did, obviously, is we changed the we swapped the left and right over so we swapped the left and right to see if it wasn't what we suspected if the problem actually moved. What if we swapped the left and right of the problem have moved, then we'd know it was? Well, if we swap the left and right at the output to the console, if the problem moves, then it's the output of the console. Yeah.

Now there are a couple of things that we have. It's important to be aware of here and this is not always the same. Usually a graphic equalizer like this, which is the main system EQ should be inserted on the left and right that is decided that the signal path There's actually in the console I was here, it's actually in line. So it's going out of the desk into the graphic than out of the graphic and into the processes that the camera. Now this means that you don't hear any of the differences in the headphones at the desk. And yet the output meters of the desk can be showing a similar output, but not necessarily having that reflected in the system.

So yes, in this situation, it's the cables that come from the main left and right output into the graphic and the cables that come from the graphic into the system, which we will also need to investigate. Make sure that they are the correct cables for the soul in phase. So that's why that's why we changed the cables from the desk. we swap those over then we went and swapped over the graphic. We saw that the problem never changed. We've got back all the way back to there the problem never changing things.

So it's actually what we thought it was the speaker will listen to all the individual band that was quite important as well to listen To speakers, because often it's quite, it can be the speakers not actually working themselves. So by checking all the speakers and we had sound coming out of all the speakers and an equal sound out of each speaker, so we know all the system components are working. So it's not a fault that it is what we suspected, well, there are degrees of not working in audio, of course, you can have a situation where some of the pins on the on the connector that actually supplies a signal to the cabinet can be dirty, tarnished. There can be all sorts of other issues, for example, amplifiers that are not evenly matched with each other. I have seen plenty of situations where the system crossover is a digital system.

Yeah. And has not had the appropriate correct program loaded into it or that there's a difference between the left and the right side. Yeah, especially I mean, on this system, we've got two processes, one for left and one for right. It's quite easy to have one doing one thing and one Not being updated. So it's not following the other one. There's so many things, the important thing to remember is that there's lots and lots of electric spaghetti connecting this to this to this.

And there's so many things to go wrong, which is why we methodically check everything in this way. And while we take something we know, like a good solid source and check from left to right, and go through all this process course, while this is true fault finding generally isn't nearly Do you know, I mean, when we're talking about problems on the stage as well, it's vitally important that one person does the process, not two people only change one thing at a time. Soon as you change more than one thing at a time. You don't know what you're absolutely, then you're giving yourself incorrect information. So we've got a situation now where we're kind of, we've made slight adjustments to the graphic, we've ended up just trying to even things up, we've put slightly more topping on one side to even up that unbalance and we're reasonably happy that it's a reasonably coherent system, and it's something to work with.

And now we're going to get ready to actually do the soundcheck and listen thing. One thing, we've got to do those, we're just going to put a bit of music on and walk the room and listen to dispersion. I always do this with music, and I do do pink noise or I get bored. Listen to pink noise. Yeah, to listen to Dusty Springfield at this point. Yes, yes, I know what you're saying, john.

The problem for me with music program is that by the nature of its dynamics, as you move around the room, the program changes. Yeah. So what I generally prefer to do is to listen to a reasonable level of pink noise. And it's easy to fool oneself fair, because, of course, if you listen to it at low level, the relative loudness of the different bands are all different from each other. And so it's important to listen to it reasonably loud, but you can then hear as you walk around the room, the changes between each individual cabinet as a constant thing. Well, it's just a question of taste, though really at this stage.

Yeah, I will put a bit pink noise in there and we'll we'll walk the room and then we'll put a bit music on and listen to the room onto my tend to use something a bit quiet. I must admit, oh, this is kind of I don't like blasting out as well. Because the other thing is that we don't work independently of other people. I think it's worth saying that as engineers, we're working in a situation where there's other people in the room, there's lighting people, and you go work as part of a team. So if you can't spend hours listen to pink noise at full volume. So we're very careful with the time that we're making noise because it does disturb other people working.

So we're going to be as quick as possible. Yeah. And of course, the other courtesy thing to do is to announce to everybody that we're going to be making some tests, which may be really good time to go and get a cup of tea. Yes, absolutely. lunch. Let's go.

Let's go. I'll go and get a cup of tea and you can listen to the PA go on him. So just to sum Really we've listened to the room we've walked about we've listened to this person, the speakers, and we could have pleased with the way it's covering the room. Well, I don't think that we're going to get a much better result ready, john and I spend a lot more time for maybe a 5% improvement. But I think at this stage, we really need to be thinking forward about actually yeah, to get you know, together. Yeah, shows going, getting getting a band on stage and getting a soundcheck done.

There are some things it's worthwhile trying to bear in mind at this stage. Now we've got what essentially is a show ready PA system. The thing that we really need to think about more than anything is the difference that we're going to encounter between an empty room and particularly a cold empty room. As notes by fact I still got my scarf on you still got your coat? Yes, indeed. Absolutely.

But also there are many factors that are going to change. Not only are we going to have a lot of people in this room service, a city hope we can have a lot of people in this room. They will have a massive effect, particularly on the bass and the sub, but also the ambient air temperature is going to increase. And there are a bunch of interesting to see there's some fairly large air conditioning ducts around the room here. I'm sure they will be making an audio contribution to what's going on. I think there's beer coolers.

I mean, you know, it's gonna be a lot more ambient noise, this noise of people chattering and stuff like that. And, yes, during the ballad, always during the last year and a few things we're going to lose, as soon as the people come in, we're going to lose the largest reflective area, which is, of course, the floor D because they're everyone's hopefully going to be standing on the floor, and not just standing right in the corners. But yeah, we're going to lose one larger flexes surface, we're going to lose these surfaces as well. So and we're not too bad on there's very few big reflective surfaces in this room. Apart from the floor, the ceilings, not too bad. And these kind of the way the sun Walls are broken up is actually quite useful works in our favor certainly does, it cuts down a lot of slap back.

And the way the PA is pointing it's covering most of the room reasonably efficiently. Also, with we were as we saw when we're not suffering from major base bombs, because all the basis pretty much coming from one, one point so we're not getting what we call power alley, where we get a huge amount of sub a big dip huge amount of sub a big deal. Absolutely reasonably smooth, not the greatest 70 Well, but it's reasonably smooth. It's going to remain reasonably constant. There will be some kind filtering between the boxes but not not not going to worry about but yes, in this situation, I think how it should work reasonably well actually. Yeah, so I mean, there's not much more we can do there's certainly nothing Well, we can improve, you know, with a fixed installation like this because we can't go around moving boxes.

If we had the option we'd probably you know, we might tweak the box then but we don't want that to be covering any closer to the stage and it already is no and we are better off putting some little info speakers as we discussed. idea and we're pretty much good to go I think. Yeah. So let's have a cup of tea yes cup of tea insan check