 Hello everybody and welcome back to my V-Log, to my channel. Now, I have on the bench today this rather nice SimSyma Sim 5-3. And I have it connected up to my power supply over there. So we've got 32, I'm going to have to refer there's 26, 27 coming inside. But it doesn't matter. It doesn't matter what I'm doing at this minute in time. I have the outputs of this, these two, the left and the right, and the common ground, virtual ground connected up to my dummy loads here. There's a 100 watt dummy load and another 100 watt dummy load for the left and right channels. I have those, my probes, which would be normally going off to your oscilloscope, going off to this little circuit here, which is now for two channels. And I will show you, in the next video, I'll show you how to set this system up. Because this is the inputs, this is probing off the heat sinks. They're the heat sinks, the dummy loads. And then it goes through this attenuator. And that's attenuated to minus 20 dB, right? So if I put one volt, if I put 10 volts in, I get one volt out. Yeah, just to keep it simple like that, one volt in, 100 millivolts out. And there's also a diode clump there, so I can't exceed the maximum input of the line in on my onboard sound card. Now, the reason why I've set this up like this is because my onboard sound card is just what comes with the main board of my computer, of my PC. And so, you've all, the majority of you have got computers, and you're interested in this sort of thing. You can set one of these up for yourself to be a voltage probe. Alright, so you could be doing your own type of measurements with this sort of stuff. So this is why I've done it this time within my own sound card on the machine. And what I've got coming out of my speaker output, well, let's go back down to here, my speaker output of my PC. So we speaker out, yeah, normal front speakers. I've got the two channels here, left channel and the right channel. And that just feeds underneath the table at the moment into the speaker output of my PC. So in between that for doing the measurements, we have Arta. Arta's over there. With that, I'm going to flick over to the... No, in actual fact, before I flick over to that screen, I'm just going to go through with the voltage probe and how you can make one of these. Now, I have gone along with, on the Arta website, there is, of course, a manual. And in the manual, it shows you how to, or tells you that you need to build a voltage probe because the input of your line input is not going to be able to take, let's say, for instance, 25 volts. You're just going to kill it. It's going to clip and it's going to die. So what you've got to be able to do is you've got to set up this little system. So if I just turn this like this, because this is exactly how it is, and move that out of the way, this is all you've got to do. I am using 3.9. It says use 4.1, I believe, because that's what's written here. 4.1 value diodes. So the black line of the diode is here and the black line of the diode is here. So back to back. 4.1. So I haven't got 4.1, so I've got 3.9. And it doesn't really make much difference. It just means I'm clamping at a lower voltage rather than a slightly higher voltage. We don't need to go into all the technical details of all this sort of stuff. All you're going to know is that you need a resistance here and it's going to go all the way to the line input. This would be the positive side, the line input. And that resistance needs to be 8.2 kilo ohms. Now there aren't any 8.2 kilo ohms resistors. You're going to have to make one up. For that, this is the way I did mine. I put in series, I put 3.3, a 3.3, a 1.5 and a 120. And that gives me just round about what I need. Pretty much on there is what I need. So that's good enough. And that's where you can see them here. Let me just zoom in a bit. There you can see them here. Here's the 3.3, 3.3, 1.5 and a 120 ohms. And that gives me the resistance here. Now here, you're going to want 910. And again, there is no 910. So what I did was I've used two 1.5s because two of those in parallel gives me 750 ohms and two 3.30 ohms because two of those in parallel gives me 165. You put those two together and you've got close enough to 910 ohms. Alright, simple enough. And there, what go across here. 910 ohms of resistance you need. So this will be your positive line in to your input line in. This will be the negative line in to the input line in. And here, you'll have your wires going off which will clamp onto your dummy loads and act as your probe. Okay, so here, let me just show you across here. Here is the negative line in. Yeah, and the positive line in. Has me depicted it. Channel left, channel right. These come back off just to these. Whoops, ones fell off. I'm making a difference just at the moment. Let me just pop that back on again. To the negative side and to the positive side of our outputs, of our speakers. Again, let me just show you on here quick because it is really, really so simple. All this resistor is those four resistors I have in series that make up the 8.2 kHz. And this 910 ohms are the four resistors I have. Two lots of two in parallel giving me 910 ohms. Well, thereabouts. It doesn't matter if it's just very slightly out. I'm talking, you know, a few ohms. And that doesn't really matter. And here, I've got two, because I don't have 4.1s. I've got two 3.9s acting as a clamp, a voltage clamp so we don't go any higher to blow the inputs of our lining on the board. All right, so let's have a little quick look at the results we get through Arthur. I like that. All right, so let's look first at this frequency response here. So this is it. I think I did that at full power. Yeah, frequency response. Now, if you looked on my community part, you'll see that I put a few of the responses up. And this is the one from the onboard sound card. And you see this little bit where it drops down here and goes up here. That's the onboard sound card. This is also the response of the onboard sound card. So if I say here, 35.16, with that drop off on the onboard sound card, this is what we've got 0.09 deeply. Nothing to worry about particularly. Now, if I just go in a little bit closer on this and do this all the way around and do this look, you get to see that more in a closer look. Yes, you get to see this. And this is exactly what the onboard sound card does. So it has replicated this the same as the onboard sound card. So that's what we're looking at. But we've done it through this amplifier anyway. So now we're going to have a look at the total harmonic distortion and the total harmonic distortion and noise. I'm not just going to kick it in straight at 4 pound and then just drop it down. And then turn this on. This is the left channel. And there we have that. Let me just bring that range down about 140 there. If I keep everything at 160, because that's where I normally keep it for the other, the sound card. And if I just pop this, pop that like that. So we can see we've got this up slightly. Oh, I'm trying to go on the internet. And that's how you turn this up. Can you turn it up? Can you turn it up? We're going to put it on full blast. We have here, take that pressure off the system a little bit because we're running two and a half amps. We have here a total harmonic distortion. Now remember, this is just measuring it on the on board sound card. Just what's on the main board. The socket on the back of your PC will probably have a line in and the speaker out. And as long as it's got those two, you can do this. Chancellor, the AC97 drivers as well. And again, you know, you can do this. So the noise floor here, as you can see here, we're talking like 120 on the other device I have in my machine. We're down here sort of closer to 140. So there's a 20 dB difference on the actual noise within the system. But if you notice, I don't have any little peak here on 50. And I certainly don't have a peak up to about 100 on the 100 hertz, which I believe would be coming from a power supply. Okay, because now we're not running through, we're running directly from the board, which means that there's going to be a lot tighter circuitry, which means less interference, which is why we're not seeing it here particularly. The USB type device for doing these types of measurements could possibly be better, but I can't actually find one with the noise floor that's around about 130 or 140. I can only find them 120s. But never mind, that's another thing. So what we can see here then is our total harmonic distortion. Now is 0.006. And our total harmonic noise and total harmonic distortion plus noise equals 0.047, which is a much better result than what I got before when the noise floor I had was more like 105. So all this noise here would be sat up here and I could only read off what was off the top, which meant that with the noise and everything else it was giving me is an order of magnitude less. The natural fact, yeah, an order of magnitude less because we were more like 0.0, maybe 5 here or 6. So this is a much better way of doing this like this. Of course I can't run the other test of frequency noise with this bit of software, but it makes no difference. This just gives a little bit of extra in to seeing that now. You can see here with the 2K, which would be our first harmonic, there's nothing. Nothing really. If I just tweak that up to close as I can get to 2K, which would be 199.551, we're talking 100A-114.27 dB down. You don't have no chance of hearing that. And if we hit it on there for the 3K, which is, you know, that only a little bit. And this actually comes in again. If you look at the community part, you'll see that when I do a loop back, you'll see these two here on there. And this is really just coming through from the sound card. It is not the amplifier. And I'm really glad I can say that. If I just stick a bit of average on, just the tide in that line up there, it makes it look a lot nicer. Take that off there. And if I just stick a little bit of average on, you can see how well that is actually doing. I can't go all the way up to 4.5 dB of dBFS, as explained in the community part. That's because this sound card only puts out of the speakers a maximum of 0.9. And really, I need it on a volt to be able to correctly do this. So there is a slight bit out, but if there was anything dodgy there at all, we'd see it. Because in actual fact, that would probably even be slightly lower. We'd probably have that slightly lower if this was set up. So we could peak up there because we'd have less of a distance here. And that means that there'd be more distance between the noise flying everything and our main peak going in. So we could probably expect that to be a little bit better. All right, I just wanted to be able to clear that up because it was one of the things that was very challenging to me because I was trying to do the test, I was doing it and I was showing another output. But this is good, you see. Because it challenged me, again, it challenged me to build up this little thing here. It challenged me to investigate into why this could be happening and start learning about this type of testing in more depth. So I'm really grateful to that fella that put that up, even though it was only a few seconds for me to look at and get, Darn it, how did he do that? You know, what's going on here? And he used, for nearly the same sort of result, he used a PCI sound card. And this isn't with one. The reason I'm using this is because the output looks better on this than what it does with my sound blaster. The only reason for that is because there's so many cables coming off the sound blaster and going back into the computer. I believe I'm picking up noise from there. So I have to look at how I do those tests again and make some tough decisions with myself. If you've got this far, I hope this is helpful to you. I hope you're learning. You want to get in to building one of these things here and you want a bit of understanding behind it. The R2 website is great, but if you just wanted to build yourself a minus 20 UB attenuator with a voltage clamp on it, that is the way to go. Like I say, there the resistors you use. 1.5K, 1.5K in parallel, gives you 750, 2,330 is in parallel, gives you 165, and that is a total of near enough 910, it's 915 maybe I think. And then the same for the 8200, 3.33, 3.31, 1.5K, 1.20, gives you the 8, I think it's 8196. But that's good enough. That is good enough for here. Bye guys, catching the next one. Thanks for watching.