Mini Stereo Amp (That Doesn't Suck)

hey everyone it's Colin how's it goin I picked up another one of these mini stereo audio amplifiers the question is it any good let's find out so I picked up this new amplifier off of ebay it cost me all of 20 bucks and there was not much included in the package in fact all that was in the box was just the amplifier itself plus a very brief little instruction manual that was hardly in English at all the reason why I bought this amp is if you remember I did a previous video about another little mini audio amp but I was kind of lukewarm on that particular unit there were some things about it that I didn't like specifically that whenever it was receiving power the Bluetooth function was always on basically this power switch on that unit really only ever controlled the audio amplifier part i modified that amplifier to actually have the entire thing be powered on and off through that switch and it worked but what I found was the output quality of that amp just wasn't very good it distorted very easily and even though I was only planning on using it just for music in the garage as part of a very simple audio setup it just didn't sound very good so I ended up recycling that thing and starting over scratch for good I'll go find something else and hey I can share whatever I buy with you and we can find out together if the replacement is any good so I ended up with this there's really no major like brand name or model or anything on it it says mini ample on the top they're too cheap to put the if fire on there the bottom of the unit says it was designed by a ppj audio I'm not familiar with that but who knows I mean the thing with buying these generic types of products off of ebay is it's like a lottery sometime you win sometimes you lose obviously that the last one I kinda lost maybe I'll get better luck with this one before we get too far into testing this thing out though let's take the very sage words of a fellow youtuber and before we turn it on let's take it apart getting into this thing is a little bit of a question mark for me there's obviously a seam here but when you squeeze it it doesn't really feel like those two parts want to easily come apart so I don't think there's clips here there's obviously nothing on the back that's just the DC power socket and no screws on the bottom so my guts kind of telling me maybe you need to go in through the front panel here let's see what we can do [Music] so yeah the front panel just sticks on with some adhesive and don't worry I didn't scratch it up there's actually plastic film on the front to protect it I'll peel that off when we're all done and then underneath some scrolls and with any luck they're just standard Phillips [Music] so let's see what we can do okay Oh interesting I was expecting as PCB across the bottom it's just a two-part design wow that's that's surprising okay so let's start with this front panel it looks like it handles all of the audio input stuff plus the control over the amplifier itself there's only these two connectors this one has LG aryo hey what up Clint if you Curtin his shoutout I guess now left ground right so that's going to be audio output to the amplifier section in the back and then this one is going to be I'm guessing control and power over the amp itself so there's these labels here that say mg and then +5 V plus 5 volts to actually power this board ground and then I'm not sure what the M in this case specifically stands for but it's likely related to this dial on the front now one thing interesting about this dial is it's not a standard like analog potentiometer it's actually what they call a rotary encoder it just continues to spin and spin and spin and spin plus you can click it in and out to make selections so this is going to send like a digital pulse every time you turn it or click it and that's likely what that M pin is for so instead of turning the volume up and down from the amplifier in an analogue fashion this thing is basically just telling the amp chip itself to raise and lower its own volume digitally they do have the colors kind of in a weird order here normally it goes green to yellow to red at the top if these are traditional vu meters I guess we'll have to see what these do when you plug it in and turn it on but yeah that's that front board I kind of want to see what chips are going on so let's take the screws out and and look at the the circuitry itself see yeah as I suspected this front panel board does all of the audio input for the entire amp three-and-a-half millimeter analog audio in there is the antenna for the Bluetooth and because the casing is made out of plastic that means they can go with an internal antenna plastic is relatively RF transparent if you remember that previous amplifier that I tore down and modified I'll include a link if you want to go check that out that thing had a little external rubber ducky antenna because the casing was made out of metal what I'm kind of surprised by is everything all the audio routes through this single I see it looks like this thing is just doing everything it's taking analog audio from the three-and-a-half millimeter jack it's doing bluetooth the USB port on here is really interesting to see as well and that is I think this amp can work as a DAC if you plug it into a computer we'll test that a little bit later on here but if that's the case that leads to some very interesting opportunities for some people especially if it all just goes through this one chip and it's you know as simple as that so it's a very easy kind of clean design here there's not much going on on the back just this one filter cap what I also like to see here is all of these connectors are on these weird little right angle boards but again that makes sense it simplifies the PCB design plus if you ever have to replace one of these jacks it's going to be not too difficult to do so if you wear out the three-and-a-half millimeter or break the USB or whatever it's a reasonably modular design go in and fix it and upgrade it and modify it later on if you feel like it let's get this front panel board out of the way and start focusing on this amplifier section it's buried down in there with four screws it looks like those four screws correspond to the binding posts let's try taking them out and see what we get so that's really clever with the screws you'll notice on the PCB here those screw holes are actually pads same thing on the opposite side so the screws are actually what completes the electrical connection between this PCB and the banana Jack's on the back of the case so you don't have to take the banana jacks out and they don't have to solder them directly to this PCB that makes for really easy assembly on their part that's that's quite surprising I'm seeing a lot of signs that they were kind of thinking ahead with this design and not just slapping a bunch of random parts together couple of really big caps on here not else much else going on on this side just the two cable inputs from the front panel this side looks to be where a whole lot of the amplification stuff is going on but there's not a whole lot of hardware to do it actually just the the four the four coils there and I'm guessing under that little bitty heatsink is the amp chip so unfortunately while it's great to see this heatsink even on here that they bothered to do that they stuck it down to the amp chip using thermal adhesive instead of thermal paste I've been trying to kind of pry this thing off delicately and it's it's not going anywhere that adhesive is too strong if I put brute force into it I could remove the heatsink and I might be able to scrape enough of the adhesive off to get some of the numbers off the top of the chip which is really what I'm interested in but at the same time I want to not only test this amp to see if it's any good but hopefully also use it if it is good so I don't really want to destroy it quite in the name of science if I can help it one thing that does knock this unit down a little bit of a peg is check out these pins on these caps like they couldn't get in there and trim them down a little bit the rest of the amp seems to be constructed like half decently but they couldn't do that now in terms of power this thing claims to be 50 watts times two and that's going to be one of the numbers that is going to vary let's just say depending on how you use the amp and specifically how you feed power into the amp and then what kind of speakers you hook up to the amp this thing will accept an input voltage range of anywhere between nine and 24 volts DC which is very typical and in general if you look at the data sheets for amplifier chips basically the the higher voltage and the more current the power supply you hook up to it is able to deliver the better the amp chip will perform if you've got a good power supply laying around if you know what you're doing and you are able to feed this thing all of the current that it wants Yeah right side up then it may work out okay what I ended up doing was digging out an old laptop power supply and the power supply that I've got to use with this thing can output something like just a bit over 50 watts this thing is rated for 50 watts times two I don't think I'm ever gonna hook up speakers that will require that kind of power nor will I ever drive the speaker's that I hook up to this thing loud enough to need that kind of power and in general I don't think too many people are going to expect a tiny little amplifier like this to be able to drive giant inefficient speakers so 50 watts input into this thing I think is gonna be fairly reasonable stick the front panel back on here I did mark up the plastic that solar trim a little bit just kind of bummer but this thing's gonna live in the garage if it does work so it'll it's the least of its worries so you know if you use it with small speakers and give it a decent power supply I kind of suspect a lot of these little mini amps will work decently the question is how do they sound and then what's the overall user experience with them like let's hook this thing up now and find out I've got a variety of speakers that I could test these with some of them are relatively easy to drive things like my JBL control 1 plus models they don't require a whole ton of power they're relatively efficient little speakers yeah I mean that's probably indicative of what most people would use with an amplifier like this just little near-field monitor type of situation but at the same time that I don't think is a very good test of the amp chip inside this unit because it was only when driving less efficient speakers specifically the ones that I plan on using with this amplifier in the long term in my garage that I noticed on that previous amplifier it didn't sound very good so instead of soft balling it with this thing and giving it an easy to drive set of speakers we're gonna pick it up a notch and go straight to the big boys if you remember these from a previous video these are a set of commercial bows 102's that have been modified from running on a 70 volt constant level system to regular I think they measured in at about 6 ohms I also added a small filter network inside these to fix in quotation marks the EQ output because they are just a single full range driver there is no separate tweeter but for this test they're actually a really good option because these are super freakin inefficient speakers they were inefficient to begin with and they're even more inefficient now that they've got that extra filter network and they've been converted to a regular impedance and blah blah blah so I figure you know what let's give that amp and exercise on these guys and if you haven't watched the video for these go ahead and check it out it was an interesting audio engineering experience so plugging in the power gets you one LED on the front what does the phone say I am not seeing it showing up in the list with just power applied ok so far so good let's turn this thing on and I think you do that by pressing and holding okay the second red LED comes on when it's turned on and then now I've got the Bluetooth light blinking okay and there it is mini damp that's with the name on this thing it doesn't even match the mini ample on the top anyway so it shows up only when powered on let's connect ooh quick little pop out of the speakers as soon as it paired not loud by any means but I didn't really like that anyway blue lights on looks like we're paired no visual feedback when you change the volume okay so that's clearly the bottom - nothing the orange whatever yellow lights turn on to let you know you're at zero but as you turn it up there's no indication like where you are in the range that's kind of a bummer let's turn it all the way down to zero and I don't know maybe play some music Oh what is that what vu meters are gone I've got the music playing but it's not actually outputting any audio just that noise except when it's all the way down to zero anything above zero ooh let me check my connections real quick okay so I took it apart just to check everything check this out [Music] [Music] yeah that's no good I'm guessing it's just some kind of loose connection inside here I don't know if it's a bad solder joint or the like these connectors themselves or what yeah okay so that's gonna be something to consider with this amplifier I guess is maybe the build quality is a little sketchier than I was anticipating well let me see if I can't get this book thing buttoned up like for good and reliable and then we can do some real audio tests with it let's play a track and see one if it at least sounds halfway decent and to kind of what max volume ends up being like I realize playing audio through speakers on YouTube is stupid I mean it's only gonna sound as good as the microphones in whatever I'm recording with and the speakers are headphones you're listening on but in the very least we can kind of tell if there's any obvious distortion and then I'm just curious as to like this this thing even get loud driving these super inefficient speakers or what we'll see how this thing performs [Music] it looks like the vu meter on the front doesn't really relate to the audio output level just whatever it's getting in so that's max volume you can see it turns the orange light solid for a second when you hit the top I can tell you this from where I'm sitting and we're knowing that it's these speakers and they're not very efficient this is a lamp is pretty damn loud I think it'll totally work for what I need it to do in the garage [Music] so there's one other thing I want to test and it's this little USB port on the front the blue light on the front is lit up and when I plug the cable into the computer it detected a new device let's see if it does what I think it's gonna do okay so let's wrap this thing up this unit definitely has some pros and cons to things I'm concerned about first is of course what was with that noise when I first powered it on granted I had taken it apart and put it back together but still even when I had it half apart you saw I was just barely touching the front panel and it was making all sorts of crazy scratchy noises than everything so maybe the electronic build quality isn't quite as good as what I was hoping the other thing I'm a little bit concerned about is the amplifier section we saw that there's a small heatsink on the amp chip in the back the problem is the casing on this thing is made out of plastic and it's otherwise sealed so there's really no air flow going through this is that little heatsink inside a sealed plastic case gonna be enough to keep that chip cool over the long term that's hard to say granted I don't think very many people are going to be using a unit like this full blast for long periods of time so while that could technically be an issue with overheating maybe for the majority of people it just won't matter it's kind of hard to say and time will tell I'll definitely be running this thing through some more tests but otherwise there's a lot to like about this unit it's compact it's physically pretty well built like it doesn't feel cheap at all the power output on this thing is fairly impressive yeah it says 50 watts times 2 and I don't know if that's right or not but powering those relatively inefficient speakers it got to a pretty decent level and it sounded good the entire time I couldn't pick up any Distortion the other thing I really like about it is the usability I like that it keeps the Bluetooth turned off unless you actually turn the amplifier on I like that it has multiple inputs and it tells you which one it's using based on the light on the front I like the fact that it also has this USB port on the front and that may be the killer feature for some people the use case that comes to mind for me with that USB port is actually the Raspberry Pi those modules are famous or infamous for having relatively dirty not very good analog audio output but a lot of people like to use them for audio setups or use audio through them like with a retro PI setup this could make a really good piece in a kit like that or a project because well you can bypass that ugly analog audio and just go straight into the USB DAC if you want one of your own my only advice is to search on eBay there's just random sellers selling these and no doubt if I put a link in the description it'll stop working pretty quickly because that's a bay but anyway just search around if you want one of these I approve if you like the video I would appreciate a thumbs up be sure to subscribe if you haven't already you can follow me on Twitter and Instagram at this does not comp and as always thanks for watching [Music]

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Views: 445,227

Rating: 4.6391835 out of 5

Keywords: audio, amp, amplifier, stereo, music, sound, class-D, tpa3116, Miniampl, APPJ Audio, digital, Bluetooth, USB, DAC, Raspberry Pi, speaker, JBL, Control 1, Bose, review, teardown, Dan Mason, This Does Not Compute

Id: Il4oR6Qbi4E

Length: 23min 51sec (1431 seconds)

Published: Fri Jul 19 2019