 Hello everybody and welcome back to my V-LOG, to my channel and today we're going to be taking a look at this more modern version of the Quad 405 by LJM and Quad is a British brand and these amplifiers seem to have their own following and they sound nice. I've listened to a couple of these for a while and I think they do sound nice. So let's see what we got here. On this for £20.97 and it's not going to be much more in dollars I'm pretty sure. You get two of these quad boards, so you've got the left channel and the right channel. All the components are correct, the ones I've had come through are correct. The nice thing about it is you've got some fuses as well are provided for these black boxes here. Pretty easy to set up, you do need a positive and negative power supply so you're going to need a positive on here, 30 volts, zero and a negative 30 volts and it says we're going to power between 15 and 100 watts at eight ohms. It doesn't say anything about four ohms so I'd stick the eight ohm loads and there we go. So we're going to look at the frequency response as we can see what it does here. 10, 15k it's sort of dropping off but it's not dropping off by far and we should also be looking at, this is a total amount of distortion and noise and here it's saying it's quite hard to see what that says actually but it's I think it's trying to say it's like 0.02 across this line which would indicate pretty good and here we have one kilohertz fundamental and we have here we're just encroaching it to that 80 minus 80 dB and a noise floor of roundabouts. This could be their test equipment, it's not necessarily saying this is what the amplifier is going to do. Here could be their test equipment. All right so that's that and here on the bench this is the one that I've built up of these. Now I've done another video on this and I've used different equipment to show the power output and search and so I'll put the link into that at the end of the video but this is more because I've got a different test set up now for total harmonic distortion noise which is always you know a lot of people want to know what that is. This is what we got and I'm going to be using my bench power supply over there which I actually need to switch on to make to do this and just bear with me while that's kicking in and yeah I mean it's a very simple circuit to build everything's nicely laid out all the information on the circuit is there. Another good thing is if you can actually I mean I don't know but you can swap out these uh up pumps. I've not tried it myself yet and I would read up on the up hump first before I did that. I'm using a couple of clumps you should screw these in with the driver chips down the back of there as you can see see where it says PMP there that's one of the driver chips and the output chip is next to it and the same one the other one you see the PMP over there and the output chip and I've just used clamps just for now because I can't bother to screw it in. These clamps are great six inch plastic clamps great for this sort of thing and you can get them off. I got mine off eBay I've got 12 of them for £9.99 and that's including the delivery which is nothing really is it. So let me just set up the tracking on my power supply that's it we're done and I'm just gonna set up the output voltage so it's not just gonna hit it all hard just in case there is something wrong as I set this up last night. Everything seems to be okay so I'm going to put the upper limit on that I can put on which on mine is 32 volts. Okay so I'm going to be using Arta for this because it's a pretty good bit of kit and first of all we're going to do a quick frequency response and I just chuck that in oh let's turn our power up. Well in actual fact let's go into it it's going to be easy for me to see where the power's at. I'm just going to drop the range slightly there I mean opposite way and we are now going to hit that and get a measurement. Right let's just get my finger to work the way I want it to. All right so what we are going to do because I don't normally do this is I'm going to go all the way to zero and you can see there that is looking nice and clean down there and as I start going up to a listening volume we can see where the total harmonic distortion is and as I start going up to even allow the listening volume we can see where the total harmonic distortion is it's just you know when I first thought about it I thought as you start going up the listening you're more and more likely to get distortion but of course that's not exactly true it's you're pulling us up out the noise floor to start off with making the distance between that and your input signal in this case being this fundamental one kilo more more of a distance from each other so you can see here how 34 on my setup that's like a third power going in we've got a total harmonic distortion 0.0026 and the noise added to the total harmonic distortion is 0.0024 which is good I wonder why that just moved sorry my echo show thing just moved on my power supplied by itself it's quite a heavy lump as well I'm not quite sure I did that so at 50% input and we are looking at rms minus 13.2 dbfs the total harmonic distortion there is 0.00094 which is pretty darn good with the noise 0.0021 if I start going up higher now we're going to start seeing distortion but how many really push their amplifiers all the way forward you see the distortion coming down as I go higher and higher with this input signal now using one and a half over one and a half amps 1.63 amps and the distortion if I push it all the way to minus 3 and this is using 1.8 amps that's at 98% we'll see the distortion on there yeah uh 0.016 so that's you wouldn't normally do that in natural fact I've read on the stack exchange on the audio side of the day if you take to minus 20 db which is where most people when they turn up loud you can look at the distortion there and get a good idea of what you're going to be getting so that's what I'd put out to those who are not just going to be you know pushing it to the highest limits just because it says 30 on mine don't worry about that that's just uh we were looking at the actual amplifier here not at what my sound card does so there you go that's um that's nice for distortion you know that's even better than what they put on their uh on their information so let's take a look at the frequency response that a quick hit can't actually see it there I'll do it again at a higher volume so it gets a little bit closer to where we want to be oh get off and do a hit again so self aligns that let's go find it here we go all right uh we want to probably take a bit of this range out if we can you know it's going the right way yeah it's always a bit of a little fiddle doing this or she would go a different way but that'll do so what we get to see here really is there's no big great deal we can just take from this this is 30.7 hertz and we're at minus 26 but if we look at uh just above 100 hertz minus 2.67 uh 2.6 and back here it was 2.63 wasn't it so there's a 0.03 difference hardly anything hardly anything nothing really to be that bothered about but to be honest with you when you get down to like 18 uh kilohertz 19 kilohertz it's dropping off a bit into the 20 but you're not going to hear that anyway so that's perfectly acceptable and like I said I've listened to these amplifiers and I couldn't find any fault with them I couldn't find any fault with them they actually made me think to myself I realized why there is a following for them and at the price that they're at here 20 pounds 0.76 for the two channels this is a real worth bargain it's definitely worth bargain if you want to build up your own little amplifier and like I said I put the other video on the end here now so you can see how it does for power and and for the frequency response against power and such like that got this far thank you very much for watching and I will catch you guys in the next one bye bye for now