 Hello everybody and welcome back to my vlog, to my channel. Now I'm doing this again to show you and I'm doing it again. So first of all I'll tell you why I'm doing it again. This time we're using this Focusrite Scarlett 2i2 and it's an audio interface and it's got a lower noise floor than the Oxna with the lining input. I made a boo boo before when I used the Oxna because there's an ALT setting in there which I was reading through the RMAA when I did the audio analysis in there to see what it was like and that was the best setting to go look back. But you're supposed to take it out of that setting and use the line in and I did try that but it seemed so messy but I've installed some drivers called Uni Oxna. That cleaned up the lining but the noise floor is not as low as it is with this Scarlett so if we just take it, well let me just first of all say I'm sorry for anybody's time that was wasted when you got to see the results of the amplifiers when it was in the wrong setting because like it was pointed out they were too incredible, too incredible to be true and that's because there was a mistake so I'm so sorry for that. I've checked and double checked and triple checked and I can't make a mistake the same with this setup and so we're gonna get to see it through here. Now the reason why I'm saying I'm doing this again is because I use a microphone or wireless microphone and I noticed that there was some noise being introduced into the system and I disconnect the microphone turned it off and I'd start playing around with the wires and I think I saw that the noise out I'm thinking I assume it did the way my wires are they're all screenshielded cables I don't know why that would happen but anyway this seems to be the thing and I'd go back into setting up and I put the microphone on without doing recording it. The noise is there again what's going on I'm thinking and so I show you the noise because see this noise here well when I the power is on on the amplifier now if I turn that off we'll see that change you see the noise floor drop that's of the setup so that's my cables that's the scarlet that's everything there and then I put the power supply on and we're going to introduce noise because the amplifier is going to come on the power supplies are going to come on it's all going to introduce a bit of noise and that's what we got all right but if I show you it now with this bit of video I'm going to put over the top is look at the noise floor here it's not the way it's supposed to be do you see that one before the 1k and before the 2k that extra bit and it all goes all the way through right let's get rid of that and I can see now as I start to turn up the volume here we don't have that we have what it's supposed to look like there's nothing before the 2k there's nothing before the 1k this is because my microphone isn't on it's not transmitting all why was this all become very sensitive okay you know I'll figure that out but for now we're recording on the phone and we're just going to go along with that so let's uh let's start this now you can't expect these old amplifier circuits to run up full power and give the greatest results they think they're not going to distort or anything like that is ridiculous they're going to distort they weren't made to run up full power they were made to run at a comfortable volume and give it enough dynamic range at a comfortable volume and in some ways you know these are the amps that came after tubes um I got a funny feeling that some of them were the way they were like this as I turn the volume up here like when you go from like 30db shop you start getting this your first fundamental input signal and then you got the second and the third and the fourth fifth sixth and it all degrades down that's a sort of warmth harmonics you get off a tube you can imagine going straight from tubes to transistors and the sound would have been quite a bit different like a lot of people didn't like cds straight away because that clean cut sound and they preferred to have a bit of noise from the the record that they'd listen to a bit of crackle a bit of whatever because hey fundamentally people don't like change this is what we got so now we got a nice low noise floor as we can see and noise that we're incurring into this is the harmonics which is very nice let me go back down to that sort of run about 30 mark could be a decent listening volume you know you're just listening to music you're not blaring out trying to get the names annoyed I'm going to put this here look at the volume as it goes up so we've got our 30.6 dbfs and our total harmonic distortion is 0.01 and that's pretty respectable that's pretty respectable but the noise is 0.028 against the respectable now we go up the stack exchange audio suggests that up to minus 20 is a good you know that's like you're running it high it's like I mean if your car can do 120 you're not going to be doing 120 everywhere you'd be cruising that sort 80 90 that's still above the speed limit all right I'm not suggesting anyone go and do that I'm just saying that that's you wouldn't be blasting it everywhere just the same as with your yeah your audio amplifier so let's start turning this up and we go to the minus 20 to be fair I'm not trying to overdo the system okay it's close as we can yeah I think that's probably about yeah 198 and now we can see we just dropped that I don't get that third harmonic down and so we say all I'm trying to do is get that third harmonic to the same level as there there we go so minus 21.3 the reason why I go for the third harmonic because second harmonic even harmonic sound nice the unevens are not so good all right and so if that's just slightly the same level or slightly down that'd be beautiful and get that nice warm feeling that nice warm sound so it's not a terribly bad it's not got anything really in between or anything that looks like it's going to be bad but it and it's more realistic 0.03 okay that's much more realistic than I can't remember what it was on the other one but it's a lot more realistic now let me go to a snip that I did once I went in with this let me just turn enough to the pressure of the system a bit and this is the frequency response and what I've done is I've just gone into this sort of zoomed in a little bit just to show you this so as we can see here at 30k don't worry about these numbers here because you can see between here let's say we've got 1618 there's 2d minus 2db there so we're sort of like one the you can't really say because we're right on the middle of line so between that sort of 17 and 17 and a half you know there's a little bit of drop off there which would be normal and if we go across it's very near instead let's just do it here right so here we are and we can see it across this top line look so yes we are dropping off we get to the 30 hertz I suppose we start dropping off really around about 100 it very slowly tapes itself down 18.27 we get here 18.28 we get here 18.32 you know it's dropping off dropping a fairly little time of it 18.36 we get to around about 30 18.40 and 21.18.78 so there is a drop off there but this bit here look this seems quite interesting I think this is the harmonics this is the harmonics this is that sort of noise that's been introduced into that I'm not sure whether it's because we've got a lower noise floor now and we can see this what it's doing let me just put that back to where it is because look we're on a minus 160 here minus 140 here before with the other setup using the Digilent the Animal Discovery 2 I can only see down there's 110 let's say in the middle here and my noise floor was at 105 minus 105 so these little bits would have been peeking up from that noise floor realistically with you know all this other space here we couldn't see any of this until you know we'd be pushing up higher of course then we'd see this coming through his distortion so it may look like it's pretty bad but it's nice just that the noise floor is pretty low here on our measuring so there we go that's that's what I'm showing you there we got the total harmonic distortion if we did if I show you trying to go up to the full minus 3 dB as you can see we've got a thd now of 0.6 somewhere at 15 and if I try to push that up all the way it's just getting ridiculous 30 30 so I'm just going to reduce that down to a more acceptable level all right there we go you know it's a it's an old design and this is a copy of the old design so I can imagine that the quad 405 with all of the other components that would have come with the quad 405 would have been a much better amplifier this is just the board you know it's even the power leads but too long you wouldn't really have them going that long having long leads like this can introduce its own noise and in the original set of course none of those would would be there but if you're going to be building one of these kits chances are by the time you use shorter cables and everything else you're going to get a better and better output I'm gonna you know all I can do is show you from here but this time now there's no mistakes so thank you very much for watching and thank you for you know being patient with me when I made a mistake and and I will catch you guys in the next one bye for now