 Hello everybody and welcome back to my V-Log, to my channel and on the bench today we have one of these. This is a, well the sort of brand name that goes with it is Wellylang. Way, Way-V-Lang? Anyway it doesn't matter. It's a stereo amplifier, it's based on the LM1875s that you got here and what I liked about it when I first saw it was the fact that it's got a redirector fire in the kit and so all you need is a transformer. Let me just zoom that out. All you need then is the transformer. You need a positive and negative. They say you can go up to 22 volts but that gives you 61 volts close to and the maximum for the LM1875 is 60 volts, positive and negative 30 volts. So I'm using a 18 volt transformer here, it's 120 VA and so I'm centre tapped to the middle for the virtual ground. I'm going to positive and negative. That doesn't really matter which way you put those around on the inside. Now the other thing that I've changed here is everything that comes with this is I didn't like the look of these capacitors. Let me just go in. I didn't like the look of the capacitors. When you get these nice green capacitors they say moves and I'm not sure if they are around but let's say they are and I've just stuck in these gold ones because I think they look nicer. Another nice thing about this circuit is it has a protection circuit that's the 12 regulator for this and it has this protection circuit which is all nice. This is a UPC1237 and it gives you a delayed muted turn on. So when you first power on if there's any sort of pop or anything like that on there if you're going to hear that through your speakers you're not going to with this because there's about three and a half seconds so you turn this on three and a half seconds later the relay kicks in and you've got output to your speakers. Another nice thing about this particular circuit I see is that if it detects any any more than one volt DC going through the circuit it again it shuts off the relay so your speakers are disconnected and you can repair the fault. Else it could be a case of it would just because it's DC going into the coil it would just burn it up and you can end up spending a lot of money on a new cone. I found that out for myself cost me 81 pounds to replace the cone in one of the one of the cones and one of my speakers. Not very good especially when you can buy a board like this if we take a look at the screen though you can buy a board like this with this kit on it for 10 pounds seven points what that will be in let's have a look dollars let's see we can just save that and it would show us in dollars there you go look 12 dollars all right and in euros let's say so great you can actually do this isn't it in euros we got it there is 1166 I'm gonna put it back to I can't go through every country it's just at these ones are here all right so 10 pounds you got to pay the tax on it I believe so you know but that's the way it is uh I do love these uh inductors that you get on there there's the kit you can buy it pre-built cost you a few pounds extra and um but where's the fun in that thing I'm not building these things up now we're gonna quick look at the specifications and let's have you know this uh this is from the from the um datasheet for the animator in 75 and here operating voltage AC 12 times 2 up to 22 times 2 like I said it's like 61 volts and the maximum the maximum is 60 volts going in I'm using 18 volts I had um we'll have to do that in the calculator but it's not quite 60 I'll stick it up on the screen what that equals to and here it looks like this actually so this is the speaker protection and the voltage regulator on regulator on there there's the two circuits individual circuits for the actual left and right side stereo and there's the power supply so that's all pretty good and that's that's basically it there's nothing really much else to look at apart from there's one thing here on when you see that on the board you see here right hand side would indicate that that would be the right hand side there the ground and then the left hand side there well I wish they do the wiring because the white that should be the red one really but never mind it doesn't matter so without further ado let's put the um I'm just gonna put that down there where it is put those here you can see this power up there you go there we go um so I'm just gonna click this down hopefully everything's okay you see the little red LEDs come on click and you see the relay jump across there so that's that that's on now and um I'm gonna just go in if I haven't actually started off what we got connected onto this so we want the audio analyzer just do it a few seconds there we go all right now I've only got one channel connected at the moment and that is the left channel I've been playing around with this particular circuit I don't know if you can see quite faintly there's an L there and that indicates something to me so let me just go with this channel one there's a range 50 average 50 steps there as well I just take a peek at this this is on 0.3 volts rms 0.3 so let's just see what we get here okay so it doesn't look too bad it's not quite down in that um not quite down in that level that might be suggested on the screen there but there's a bit of a caveat to this this is not able to see as low as Arta and so I will be doing this again we'll be swapping this over in this video to Arta to check that out but there's a couple of other things I wanted to see I would do that one next I would do the frequency response here and just give that a quick little run oh let me just oh no it doesn't matter it doesn't matter it's just so I can adjust these to three up three down okay let me just adjust these here and uh oh thumb do as you're told I just adjust that there so you can see that's not terribly bad a little bit of a drop-off on the uh but you don't expect it to be you know absolutely flawless this yeah a little bit of a rise when it comes to where are we there we're at 15 kilohertz uh 1.5 kilohertz sorry it goes up a little bit a bit brighter there and it starts dropping off here but that's 20 so we're on the on the line now for 20 that's going all the way up to 50 kilohertz there so again not too bad at all let's have a little look at the um square wave I'm going to go to one get a single on the 1k yep I'll just drop this down to 100k hit that yeah not too bad remember we did see the drop-off on the frequency response so you can't expect it to be perfect and I'm going to go straight to 20 here that's not bad seen worse seen worse it's not bad it's not bad and uh let's just have a little look at the power versus the um thd plus noise versus power you're always going to keep in mind as well that this system can only you can't see that as far as what art I can but it gives us a good idea of uh what we're going to get bang for the box we've got load impedance of eight times I'm not going to try on forearms I didn't even check to see if this was going to be happy running on forearms I do believe you can because I am 1875s um but we'll just do it like this for now because most people have got that um we're just looking at one channel at a moment and I'm going to be able to show you the other channel so that's 1.6 that's less than 1 percent distortion that's 35 watts uh that's that's reasonable that's pretty good that's you know it's got there one channel all by itself why shouldn't it be that why shouldn't it be good all right now I want to be able to show you the other channel so what I'm going to do is I'm just going to disconnect the power and you can have the relay just switched across there all I'm going to do is I'm going to do this as quickly as possible now there's a reason why I have barely done one channel at a time and that's because when I show you this one it doesn't matter about the ground they're both connected together on those two middle uh terminal connectors on this board so now we have the other channel I'm just going to switch this over to here so my indicator on there was left just going to leave that down there and let's put that back on again I love that little thing there all right so that's that channel now first of all we're going to just look at the scope all right so we've got it here the square wave 20 hertz let's do a single check on that okay that looks fine yeah that looks just the way the other one does and we're going to go to ah let's go straight to 200 oh that says 220 I'm gonna zero it back again it's gonna make it easier do a single on there well I didn't go very high on the other one did I yeah never mind don't worry about it we'll do it on here let's go to 2000 so we're at 2k okay still yeah a little bad doesn't look bad uh let's go straight 20k actually yeah yeah a little bit of a little bit of a deformity it's not as quick the top is end up there but that's that's still not bad at all and just for anyone who might wonder what 10k was like let's say a quick little look at 10k doesn't really seem too much of a problem I don't like the way this is like this but let's have a look at um the frequency response so that's the one from before we're going to do nice run across there and see what this is like ah now now we can see there's a major problem and what this major problem is is this thing is switching itself on and off so it's on it's off it's on it's off it's on it's off it's on it's all these patches down here anything close to zero is on this line is on everything else is off that's no good yeah that that is uh no good at all we can't use that but interestingly enough in there didn't really show much of a problem and this if I were to run these two together that's why I didn't run them two together is it would screw up it actually upsets the way the power goes and it starts coming back on itself a bit and then going back on itself and going back on itself um so that's a bit of a problem now maybe I should actually stick the other one on the other channel so you get that doesn't really matter I mean you can see what's going on with this one and if we go along on the frequency response as well I'm going to leave this the way it was set for the other one there's no adjustment on the input powers or anything like that it's just the way it was for the other one yep distortion of 25 so it can't sit out so you can see it's an absolute fail weirdly enough though when you plug speakers onto it it doesn't sound too bad or maybe you've got to have it turn up really loud but that is no good and that these are the original LM1875s I'm going to turn the power off for this now these are the original LM1875s I have two been delivered today from RS components so these are original LM1875 genuines and what I'm going to do is I'm going to swap those out on there and we're going to try this again so I shall be back in a bit okay so now we've got two new LM1785s in from RS components I'm going to put this power down a little red LED that's all good so far so good all right so now we've got speaker output let's take a peek at this screen and see what we get now um let's uh write our frequency responses although the place wasn't it so let's uh let's try that again let's try that no there's an issue because I can't see anything on the output that's an issue why can't I see anything on the output there I don't know we're 20 hertz we should see something we should see it coming up like this close to 20 close to 30 we're not seeing anything um okay it did look properly so look and wait let's give it plenty of headrooms we don't want to happen what happened before let's put that back on again uh oh god I don't like this get by that stop button yeah no so it's a miss something is a miss okay uh what I'm going to do is I'm going to check my connections and just uh make sure everything's okay there right so I've uh well I just went over the shoulder joint it's not quite all the way through the holes the back ones uh all these aren't 1875s so let's just see if I've made it worse so far so good all right just trying to get that away from the transformer uh right um so the same thing let's not run the test give us something oh here we go here we go okay oh wow then it looks good because of all this like this look so if I start bringing this down to how it should be we're going to see what it really looks like there we go pretty much like the same as before but this is on the one I think it's on the one that wasn't working I've not changed the output there at all so the last one we were looking at wasn't working let's have a look on here so we'll see yeah well it's all over the place so now that one's working pretty goody all right let's have a little look see what it looks like on here then uh because we can see what it was like before and I'll check the other channel as well okay now again I've got to say that this is um the noise floor is higher on this because of you know this can't see it as low this is a 105 minus 105 d we are here so this is where our noise floor is where when we measure it an outer we'll get to see actually what it is like that so it was just to check to see if it's working that seems to be doing what we want it to so let's do a uh we didn't do that on the other one did we this is left from it on the other socket we didn't do it on uh this one so what did we get then that's quite good so 0.182 let's do it so where it crosses over I think that's a good idea so that's 0.962 we've got 35.3 watts out of it so let's have a look see what this does now 0.7 no we haven't got anything in between have we sort of well go back 0.7 we've got 33.27 watts all right so what I'm going to do now then is I'm going to connect up both of the channels and we can see what happens there yep with a retain so let's just pull that out like that all right I need an extra piece of wire which I have here I don't know if you can hear the noise in the background but it's the microwave no it's not it's the air fryer doing me a jacket potato I'm not eating like this let me just extend that a little bit there both grounds to be able to connect onto this uh not fit both of them on there probably not they're never going to get a good grip of it and um this one on here this one could just make it go on there no make it go on there like that goody goody and then those wires are touching no and then I'm just going to connect up this one onto here so now we'll have both channels on the go okay right just double checking everything to make sure nothing's going to do anything untoward all right let's do a quick test ah we'll do the frequency response first puts the least amount of pressure on we should have both channels work oh no no no stop we've got to set it on to both channels uh run oh I'm in there a little bit a bit apart from each other but I don't think that's going to be uh I don't think you may tell that that's going to be a little bit apart from each other um you're trying to see which one you heard so there it is yeah yeah yeah yeah so we got a uh 0.2 against 0.13 so it's a 0.07 out from each other yeah yeah okay uh we'll do this no we're not is there any point doing this no yeah there is of course there is we can have a little look at this see what this one comes out like let's do both channels um one 200 watts again and I just see what do we get where we get we get we got oh come here come here 0.7 33.2 no no there's a bit of a difference there isn't there well I swear that was going to come up anyway um 0.7 there what's the difference to um order a magnitude difference on the when you look at the uh distortion I'm not sure why that should be so different like that and uh at the same voltage I mean I don't know what to say I don't know what to say do we do this on there so let's just run them both okay are you gonna remember as well this isn't um I mean normally when we look at the THC like in Arta we look at it at 1k don't we so what this is showing us is on both channels at the same time as well is what it's like across the rest when we can look at it 1k in Arta we could go to put the uh the signal source in at 100 hertz but this just shows you across it but we don't have as lower noise floor on this so really this will probably all be a little bit lower but we just look at the THD look that's nice it moves down um or pretty respectable but we can only take this as a guide there's nothing dodgy going on is what we may as well say on this and then look at the THD on Arta because that's going to give us a lot better resolution on that yeah I don't expect to see anything different from the scope to be honest with you if we run this like this a little bit difference is there that's just that little bit of extra power um that's at 10 kilo hertz let's go to 20 not really a great deal of difference to be reported there uh let's go down to 100 as we know 1k is normally pretty good 100 yeah like they fall into line quite nicely as we start going down the frequency then uh we'll go a lot of people speak as around about 50 hertz yeah very good and now we're going to look at 20 just because we're here yeah I mean that's not too bad at all I think this represents like 1 dB uh so that you know that's not too bad and it's nicely in line as well with each other a bit weird though isn't it how we didn't see the fault of the other way in the square wave but there you go so that's that for that I'm going to switch us over to Arta but I'm going to get someone to eat first this video's taking quite a bit of time um but I think it's worth it because yeah this is going to be a nice little bench summit here for me to be playing with testing and it's already got all the protection in it that you're going to want so I'm not going to kill any of my speakers off uh if I'm messing around with preamps through this but let's uh let's see what it's like with Arta first but I'm going to take a break because I need someone to eat so Arta where's it going is here let's turn the volume down on this and plug down the plug and now we can have a little look on Arta uh let's see what this is going to be like there you go so we're on the 180 here not 160 where normally Arta that looks a bit high so we can see our 50 hertz and 100 200 only goes there like that like take that off there yep that's for the power off all right now let's take a little peek at what we got that was just switching over the um speakers start going up I'm going to suggest that I'm on the long wall yeah good possibility easy enough to remedy turn the power off fast and to this one to this one yep let's put the power down if you look really to go across start turning up ah that's much better all right so we can see over here thd thd noise and okay 10 push you push you 33 oh like jump us off a bit there doesn't it okay so around about five four six so point near enough point near enough one percent there that looks horrible that doesn't it all right so you know that's probably about the best we're going to get out of it with Arta let's just put that across and we can see all sorts of going on around these quite sure that's all about but it's probably yeah we're going to be in some noise should probably still not bad it's still not bad we're already seeing 105 wasn't it noise flooring noise we're already seeing this sort of area and up and now we get to see all this down here but to be honest we're not going to be able to hear any of this this isn't going to make any real difference it's quite nice though it drops off as well so yeah so that's that i think that's probably not too bad a little kit i've listened to it and it sounds okay it sounds really reasonable um i don't know what else to really add all i can say is for the money for 10 pound something or 12 dollars or 11 euros it's uh yeah it's pretty good pretty good little setup pretty good you know with all this what you've got here and the protection side of it and you know yeah i think it's pretty good that what i would say though of course is if you are going to buy one of these and you think it might be just ideal just as a little tiny stereo setup for for me for the bench because i don't have um anything plugged in well you know i've got my um the wires the output uh wires are here coming into here from back of my computer sound card i could use the onboard sound card and plug it into this and then have the speakers coming out of here so i want to do video editing in the big machine rather than my laptop because the big machine's got more hard drive space uh then i can actually hear myself so yeah so for the money bang on for the fact that one of and it's not just that one either i actually i bought two of these i must have been having a drink that night because i actually bought two of them and um both of them i've got one faulty on this one actually there's an R you see that i mean the right one works and the left one was working on here but now they both work so that one's actually faulty as well so what i'll do is i'll put a couple of genuine alarm 1875s on on this one and get that working and uh and let's see what's what then just because i've got them i've ordered i think half dozen or something uh of the things so there we go right if you got this far sorry it's been such a long video but it's been my viewpoint it's been worth it and i'll uh catch in there in the next one bye for now