A tiny amplifier with a weird switch in a strange place

This amp can work in stereo or bridge-mode mono for twice the power. But why does it need a mystery hidden switch?
Product page - www.aiyima.com/products/aiyim...
Purchase link - amzn.to/4aBN1MU
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Disclaimer: Videos on this channel may include affiliate links and may feature software that has been received free of charge with an NFR (not for resale) licence, equipment that has been loaned or donated by a manufacturer or distributer, or equipment that has been bought for less than full retail price.

[@artysanmobile]

That switch is exactly in the right place. Perfect design.

[@ThomasTVP]

In real world use, it doesn't matter that it doesn't reach 2 x 300 watts. Every company brags with theoretical watts power. What matters is if it puts out enough power to drive your speakers reliably and over time. The Aiyima amps are very reliable, I've had 3 of them (1x I sent back for a newer model by the same company, 1x I'm using in my living room stereo, the D03, which has more inputs, and 1x T9 Tube Pro, which I keep in reserve). All three were reliable and EASILY drive my Klipsch RB-75 speakers (their largest bookshelves). I wouldn't use them for tower speakers with a sensitivity below 90db though. I've been using the D03 every day now for over a year without any problems. Not a given: A Loxjie amp died on me within a fortnight.

[@Douglas_Blake_579]

This is a TPA3255 chip-amp. They all work about the same... 3:35 ... you don't get the highest voltage supply for 2 reasons. 1) The 48 volt supply is unable to provide enough current to prevent shutdowns and 2) more voltage means a lot more heat. The best all round supply for these amplifiers is 36 volts at 10 amps. 8:10 ... lets clear this one up right away ... _There is no power increase when using mono mode_ This is not a class AB amplifier. The stereo outputs are already in Bridge Tied Load (BTL) mode. When selecting mono you are reconfiguring the amplifier to Parallel Bridge Tied Load (PBTL) mode. The two channels are connected in parallel, not series. You do not get even 1 extra watt for doing this on 8, 6, or 4 ohm speakers. What PBTL mode does is allow the amplifier to provide extra current for 3 or 2 ohm loads, provided the power supply is up to it. 16:00 ... those power charts are at 1% distortion. Also, the 2 x 300w spec they're quoting is from the TPA3255 data sheet, and represent the absolute maximum output, not anything even vaguely representing normal use. With the 36 volt supply, expect about 70w/ch on 8 ohms, 120 on 4 ohms and (in PBTL mode) about 220 watts on 2 ohms. 22:10 ... Chip rolling in these Mini-Amps is strange. Getting the NE5532 out is the goal. It really doesn't matter which one you replace it with... beyond that initial swap there's no change in sound or fidelity.

[@earthoid]

You managed to attract me to your 30+ minute "review" of a 73.59 USD amp because it has a weird switch. I watched the whole video at a speed of 1.8x where I can still make out your every word and then have more time to watch the clouds block the sun on this solar eclipse day. I'm not going to buy one, and Amazon warns that it is a frequently returned item but they will relunctantly sell you one if you insist. Audio Phil was wise to distance himself from this!

[@AudioMasterclass]

Yes, I had the total solar eclipse experience in 1999. Note that I didn't say I saw it.

[@user-it6jy3zl3g]

The TPA3255 chip amplifier is among the best performers in Class D . I don't know why you say that, but what I understand is that everyone has different usage preferences and a different listening experience

[@artysanmobile]

I love that Amazon has taken the step of warning buyers. It’s pretty rare to see such protections and it must be very effective.

[@ianjohnhorwood2605]

you're a real audio comedian , you're so funny you're a laugh a second 🤣🤣🤣 .

[@smith971]

I'd be willing to bet Audio Phil can hear the high end drop off.

[@AudioMasterclass]

Even if he can't, he'll tell you he can.

[@ac81017]

Audiophile masterclass

[@Du1uxDog]

Who listens in Mono mode ? A person who is deaf in one ear. I’ve never heard stereo. All I hear in stereo mode is a slight better quality. But I have to switch to mono using headphones. But I’m good at checking if the recording has been been recorded well in stereo. And many are not

[@turbomustang84]

I think that the A07 Max is much better value than the latest Fosi Audio V3 mono offering because it's half the price and performs as well and can be used in stereo if you wish. I personally still like the A08 Pro because it has tone controls and perfectly matches the T8 preamp which together they complement each other but both having Bluetooth makes no sense

[@graememorrison333]

Fosi soon to be releasing a V3 monobloc with balanced inputs. I'm getting in 'cos my ancient Pioneer/Technics amps are shagged and I'm a cheapskate. But I do miss highendery discussion about class A and whatnot.

[@artysanmobile]

Even if the amp has 90% efficiency, it will dissipate 60W of heat. Guess how hot that little deck of cards will get dissipating 60W. Why don’t they just rate these honestly? They can perform well when obeying the laws of physics.

[@c128stuff]

The aux out not being controlled by the volume control is what I'd expect. The way you are supposed to use this is by using a pre-amp as volume control, and use the volume controls on the power amplifiers and subwoofer to adjust the balance between subwoofer(s) and full range speakers. The 'weird' setup with 2 amps, with the first amp in mono mode and the second one in stereo mode lets you connect a passive subwoofer to the first amp, but that should also work with the second amp in mono mode and the first one in stereo mode. This setup should also be used together with a pre-amp to control volume. If you want to experiment with subwoofers, there is something to know. The obvious reason for those to exist is to extent the lower part of the frequency response of a speaker system, but there is another use which you may find more interesting. Any room will have modes, ie, frequencies at which standing waves occur. 2 or (for a large or difficult room more) subwoofers strategically placed in a room can largely eliminate this issue.

[@AudioMasterclass]

To add to your last paragraph, there are some interesting videos on KZbin on how to position the subwoofer in the room. When I have one, I'm sure I'll make my own video.

[@c128stuff]

@@AudioMasterclass You also may want to experiment with the difference between using 1 and 2 subwoofers.

[@7and12inchvinyl]

By the way mine or + 4 ..... very nice interesting if muddling video from across the pond you are very unique in your delivery and I love it

[@paulmcdonough9595]

You only have to ask the once, we would like to see your tester thingy in action. Proper measurements are helpful and certainly don’t do any harm

[@Bloke-in-Stoke]

Count me in 🤣I've fond memories of the workshop Ferrograph RTS2 we used for wow and flutter testing back in the mid 80's when I started my TV apprenticeship in the Audio Department of the United Norwest Co-Op TV services based in Kidsgrove, Staffordshire. Great days indeed.👍 Cheers 🍺

[@VicariousAdventurer]

2X is 6 dB - English Breakfast is recommended for British

[@AudioMasterclass]

Twice the voltage is 6 dB. Twice the power is 3 dB. If the voltage rises by 6 dB then the power also rises by 6 dB if sufficient current is available. The real question though is brown sauce or no brown sauce?

[@adotopp1865]

Mains supply In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

[@AudioMasterclass]

Don’t worry. It will kill you. It’s the British way.

[@2626sylver2626]

Im measuring most of the times over 240v here in Dundee where I live

[@verdedoodleduck]

I did not sign on to your channel for unboxing videos! But I like them anyway. :) I for one, would be happy to see culinnary offerings if you were serious.

[@bottomendbliss]

You should get that left side drift looked at.

[@AudioMasterclass]

Eh wot?

[@peters7949]

Does the manufacturer of these devices quote the minimum loudspeaker impedance the amp can drive, or what impedance the specification measurement were made into. I recall many class AB power amps that were rated into 4ohm in stereo mode, were minimum 8ohm in bridge.

[@AudioMasterclass]

All I have are the specs I showed in the video.

[@andymouse]

Lemo are nothing short of gorgeous to look at and use with the characteristics and price tag to match, yep would love to see any test gear you have please. I don't much care for all the opamp nonsense as there are only two NE5532 and OPA1656 !!........cheers.

[@peters7949]

They are indeed gorgeous to look at and extremely rugged, hence their use in military and pro audio applications. But from years of experience; the small ones are extremely difficult to solder cables into & assemble, fortunately their reliability makes this less Farley’s frequent than cheeper ones.

[@2626sylver2626]

Voltage here in Dundee is most of the times when I measure it over 240v

[@AudioMasterclass]

It would be interesting to know whether energy is wasted due to a higher than necessary mains voltage, and who pays for it?

[@logotrikes]

Having the mono switch out of the way at the bottom makes perfect sense. Much more betterer than the Fosi ZA3, two of which I have on order. I expect that once mine are set to mono, I won't be changing them. Ditto if I had bought the AO7 Max, not easy to get at but perfect placement, unlike the ZA3 mono switch which could easily be knocked by accident. So too with the XLR/RCA switch. I would have preferred both switches on the back panel, leaving a cleaner front look, a la AO7Max. It's not a biggy by any means....

[@AudioMasterclass]

I think that if and when I put the ZA3 to actual use I'll open it up and do some soldering to effectively fix the switch in the position I want.

[@logotrikes]

@@AudioMasterclass Something like that occurred to me, even removing the switches and bridging the connections. The holes for the switches in the front plate are round so one could easily find a suitable plug to pop in the hole. But you know what I might just not bother, and enjoy the music...

[@AudioMasterclass]

@@logotrikes It might be possible to buy an audiophile grommet. Might be costly though.

[@logotrikes]

@@AudioMasterclass Yes, I'll talk to Randy The Cheap Audio Man. Sith Audio will have something I'm sure. Wouldn't want to go cheap would we?

[@Roddy451]

The glass-half-full specs amplifier.

[@devsysnet]

LEMO connectors are reminiscent of the German DIN connectors used on audio equipment in the 80s. Why are they no longer used?

[@AudioMasterclass]

5-pin DIN connectors are still used for MIDI hardware. I could reach out and touch two of them from where I'm sitting now.

[@artysanmobile]

A sub output not tracking the front panel volume control is worthless, and it is also wrong. Plug it with superglue to get better sound quality.

[@paradoxstudios6639]

I really don't quite understand these strange type amps with 1 input, I thought maybe it was where you place the signal from pre-amp out from a preamp, but then why is there a volume control on this when volume is controlled from a preamp ?

[@mattmiller4978]

Amp "volume" is a potentiometer and is the max volume power you want it to go to. I set it once and leave it alone. These small amps are easy to hide.

[@connorduke4619]

Can someone please post the timestamp of the wonder switch?

[@xvdifug]

"A nose Q, Not a Banana." J.B.

[@jkwhtsll]

Single malt or Irish whisky?

[@marxman00]

But...does it get you pissed?

[@jkwhtsll]

@@marxman00 dose dependent just as juice out depends on juice in.

[@TheHope12322]

That’s what she said!

[@AudioMasterclass]

As the actress said to the bishop in UK English. Works the other way round in an appropriate context.

[@middleearthltd]

The Fosi ZA3 has a “mono mode” and you don’t get mono block output but you do get increased channel power and separation That may be what is going on here I have a few of these chip amps which are okay for a garage or casual listening Excellent review and would have liked some listening impressions but probably just sounds like a chip amp. Fosi is coming out with a Hypex amplifier soon so that should shake the market up a bit

[@G8YTZ]

Have you tested any of these Class D amplifiers for radio frequency interference generation? Try placing them next to a short wave or medium-wave or long-wave receiver and see if you can still pick anything up other than noise? If they are noise generators when they likely have a fake UKCA and CE marking.

[@r423sdex]

Why waste your time doing that.

[@G8YTZ]

​@@r423sdex EMC compatibility with other devices

[@AudioMasterclass]

So I put my prepper radio close to a Class D amp that's handy. Yes there is some interference on both AM and FM, as I guess we should expect. I had to be close though to hear anything. P.S. I'm prepared for the many power cuts we get in my village, not the apocalypse (yet).

[@G8YTZ]

@@AudioMasterclass Thanks for that! FM as well? That's bad what's that the 10 millionth harmonic?... The problem is when this thing is attached to an antenna (speaker wires make a great dipole) it will radiate all over the place and cause chaos to the HF bands for sensitive receiving equipment. It's not surprising really as these things are square-wave generators. We have another "Home Plug Ethernet" and vDSL problem on our hands. OFCOM do act on interference complaints, particularly those plug-in Ethernet things. They should never have passed any Ethernet directive as you cannot control the installation. An AUDIO amplifier should not be generating spurious outputs in the radio spectrum. I could never recommend such a device. Stick to good old Class A, AB and Current Dumping! (I prefer the latter!). It's all down to skimping on the filtering.

[@AudioMasterclass]

@@G8YTZ Yes FM as well, but only when really close, almost touching. It's a very cheap radio though.

[@Synthematix]

PSU info isn't strictly accurate, You can get more power out of an amp, some of them use dc-dc boost converters to get more power

[@AudioMasterclass]

I would expect an honest manufacturer to slightly underestimate the output power, so yes there might be a bit more available from the psu. I expect to be getting out my dummy load resistors for a video on power output at some point in the future.

[@timf-tinkering]

The rating on the power supply is likely to be conservative, so it probably can deliver a few more watts than it says on the label, but you can't get more power out than you put in.

[@Synthematix]

@@timf-tinkering No I mean inside the amplifier, some models have a dc-dc up converter to boost power, its a way around. UL listing so you don't have to use a 60+v power supply which could be lethal in the wrong hands. my class D amp has a 48v input but generates 92V internally, there's no way any government would allow nearly 100volts dc on a barrel connector. yup you can get more power out than you put in if its designed this way. speaker wattage has little to do with power consumption with class D as they use square wave rectification, this mostly applies to the inefficient valve and class AB Stuff, you ought to see just how many chokes and power stages that are inside my amp, its nuts, in a nutshell messing about with it internally could kill you, valve amps are just the opposite they waste power as heat. The primary reason why I avoid the cheap small class D amplifiers and go for the full sized hifi stack components where there's room inside for such circuitry. Think of it like a 12V PC cold cathode light, 12volts go in, 64volts come out. in this example were going from a voltage that's safe to even put in wet hands to a voltage that will burn a hole in your hands. Same goes for CRT TV's 230v go in and 22,000v is generated on the CRTs anode cap. make no mistake this can stop your heart instantly even though its only 2mA

[@Synthematix]

Why has my comment been removed

[@Synthematix]

@@timf-tinkering Not true, decent full sized class D amps have inbuilt voltage multipliers.

[@rabit818]

RCA port, who listens to mono?, UK 240 v. Sarcasm galore lol

[@AudioMasterclass]

I know from comments on my videos that some people do indeed listen in mono. Not many, but it may be worth a video at some point in the future.

[@frogandspanner]

I have discrete active speakers.

[@AudioMasterclass]

Problem solved!

[@frogandspanner]

@@AudioMasterclass And I am currently working on interconnects that provide an end-to-end quantum channel so that a superposition of wave states will collapse to the perfect sound at the doors of perception.

[@peters7949]

@@frogandspanneryou could get a job writing album notes for Prog Rock bands.

[@ianjohnhorwood2605]

i still don't like the class D sound , class D sounds still sounds bad to my sensative ear canals anyway 🤣🤣🤣 . Compared to listening to a pair of active ATC monitors 🤣🤣🤣 .

[@pgdh]

Please could you ask your physics teacher what the ISO units for SQT are. (I presume "SQT" is the international standard TLA for "sound quality tone")

[@AudioMasterclass]

You jest but people try to rate wine objectively en.wikipedia.org/wiki/Robert_Parker_(wine_critic) Personally I just drink it.

[@artysanmobile]

Let me guess. 600W output, 90W power input.

[@AudioMasterclass]

It isn't quite as extreme as you suggest but it is a fact that the psu on all similar amps places a limitation on the power output.

[@artysanmobile]

@@AudioMasterclass I realize that, but letting this manu off the hook is a mistake that encourages a whole line of makers to just pull numbers out of their ass to chase sales. I recall when such choices would result in a product being pulled from the market. I welcome the manufacturer to show me their amp producing 600W constant power. No? Ok, let’s try 600W ‘music power’ a spec that at least has precedents with competitors. If, as I suspect, they are thinking peak power, meaning a single wave at their favored frequency, without so specifying, they should know there are professional organizations that might sanction them as crackpots to protect buyers. Spec standards exist for excellent reasons as you well know. I feel perfectly justified calling out those who blithely pretend standards don’t exist as I purchase a LOT of equipment for pro use. It gets exhausting sorting out the honest from the liars. This company is a liar.

[@artysanmobile]

@@AudioMasterclass Class D amplifiers are among the very best made, serving the pro sound market almost to the exclusion of every other topology. Reputable manufacturers specify them honestly. Those who don’t deserve the enmity of us all.

[@AudioMasterclass]

@@artysanmobile I believe that I have in all of my reviews commented when an amplifier is incapable of meeting its published specification. This has been an issue going back to the 1970s and I very much doubt if anything I say will change anything. I will however at some point in the future make a video on this issue in general and on methods of measuring power output.

[@ac81017]

When are going to review Audiophile gear instead of cheap Chinese junk. Where's Audio Phil? I Miss him.

[@AudioMasterclass]

Don't worry, I have a rather expensive DAC coming up. Phil is on a retreat of silence to refresh his ears and make them more highly resolving. He'll be back soon.

[@ac81017]

Aaah looking forward to that 👍

[@stanmyers5994]

Christ what a waste of time

[@AudioMasterclass]

Thank you for wasting your time and adding to my viewing statistics thus increasing my advertising revenue.

[@adotopp1865]

Hey! Why more cheap Chinese audio? I wouldn't be interested in buying cheap Chinese stuff. Give me good quality gear.

[@EricIolo]

Thank you for the review. I use active speakers - great! 1 amplifier per speaker hidden away! They were made in Denmark - so they must be good! And, well they are! RCA - why change it if it works! Mono bolocks hey! I see it does not have a loudness button or tone controls either! Does it hum David? I had a sub-woofer many yeards back - my neighbour ended up moving out of the semi. Subjective is good! Have you run it in by the way? Wait an hour? what? Please no Wagner!