Does this amp distort? [Aiyima T9 Pro] 

That last bit is brilliant.

You are an acquired taste and you have successfully grown on me. Congrats! You are now my favorite high fidelity RU-vidr. Of many (I knew you would ask). I’ve learned so much. And that you’re comedically dry and British is just the gravy as we say over here. Keep up the good work for us!

Great vid again. Thanks... So many people think that distortion is that high output where the amp starts clipping. I try to explain that any distortion is when we hear something sonically out of place and the crackling high output is NOT distortion. It is the amp clipping the signal. It's like telling the amp to play louder than it's able to. So, the amp starts clipping the signal. "Warmth" in the final reproduction of the original recording therefore, is distortion. 💜

Always the best!

The T9 Pro is very well designed and if you have fairly easy to drive speakers then it's all you need but if you need more power like I do the T8 - A08 Pro combo is better but I still keep a T9 Pro around because the DAC is fantastic and it's a nice backup.

People today can't tolerate unhearable amounts of distortion (I'm looking at you Audio Phil). Putting things in perspective I built my first transistor stereo amp from an Eico kit back in the 1960's. That thing had DISTORTION but it didn't have tubes so that was good, therefore I liked it. Fortunately someone stole it after a party when I was passed out so I was forced to get something better.

Wow the quality of cheap gear today is miles ahead of when i was starting out in the late eighties. I remember one of the first cd's i got, Yello - All the mix had ADD on the back. Analogue Dig Dig. That was a buzz being there for the crossover.

During the 1950s and well into the 1960s, all my electronics had vacuum tubes contained within the cabinet. Some radios and televisions had splendid wooden cabinets concealing the innards. Our Grundig Majestic Console was as much furniture as it was HiFi. I have noticed that contemporary electronics have exposed vacuum tubes as a design feature and often incorporate ‘Steampunk’ 19th Century styling. No doubt that naked vacuum tubes sound better. Since switching from kerosene lamps to beeswax candles all the classics read so much better.

Another excellent video. I might need to get an Eames chair in which to sit and listen to the newest unboxing music on my (so far imaginary) Quad ESL63s. Should I use this amplifier to drive them instead of my noisy (and real) 303?

similarly 'vinyl' sound is a distortion because of all the electronic and physical jiggery-pokery needed to get the source master to work as a trackable little groove.

Good explanation and a lot of good work done, thank you, I have the LOXJIE A40 Audio Power Amplifier and Ear Amplifier All-in-One Machine, MA5332MS Chip NJW194, Vinyl Phonograph Input, EQ Mode, 5 Filters Available, Bass Output, Bluetooth 5.1, with Remote Control, and I would like to put MORE EXPENSIVE models next to them that are 10 to 15 x more expensive and see who is the best.

Great video! I am an avid viewer of your videos and greatly admire your extensive expertise in your field. Given your profound understanding in the world of music and tech, I was wondering if you could consider creating a video sharing your thoughts on the recently launched Udio AI Music Generator? I would love to hear your views as a seasoned producer, as to what role AI holds for the future of music composition and production? What do you see as AI's biggest pros and cons for the future of music? Thanks and keep up the amazing work!

Does low distortion mean the gear is short on details on these Chinese amps?

Audio Phil nails it once again!

I like the ‘Audio Phil’ label up front, clever 😊

Best unboxing ever!! xD

Is 100Hz a good test of something like this? Surely a sweeping tone would tell us much more.

Consider to add the distortion of the speakers you are listening with. Very rare ones go bellow 0.1,% at 86db-1m. Most of them are above 10% at 50Hz. IMD results bad sound? ShureV mk3, pickup cartridge used in radio stations in 80's has 3%IMD 2% 2nd harmonic and 0.5% 3rd. There are many issues with high current classAB amps that high negative feedback assures correction, in consequence the THD measures very low. This why people hear better sound with very low THD measuring amps. Warm sound definition depends on the person who is expressing it. For some, it is inverse of bright sound, others think worm is backstage or lack of resolution.

it not just tubes that gives it a warm sound it's also the audio transformer that gives it a warm sound tbh

I used to think that warm sound is that with emphasis on lower frequencies, e.g. those below 1kHz. But this only a convention, we say A sounds warmer that B, B sounds brighter than A. Why is it relevant? Perhaps because human ear is most sensitive to middle to high frequencies, whose exces will be unpleasant for many listeners. On the other hand, it conveys the most details, likely due to that same, human, psycho-acoustic perception. Some amplifier designs (cynically?) emphasize these frequencies to pack more detail. People with impaired hearing will applaud this practice.

Remember cassette tapes? 3.0% third harmonic distortion was considered acceptable. That is -30.5 dB. Yet I remember saying "the harmonic distortion on this tape is unbearable" exactly no one, ever. Nowadays, an audio device with SINAD of 100 dB is considered below par. I guess because it cannot transparently capture the 120+ dB dynamic range so commonly available in "high-res" content...

If the results do not match the Technics from the 80s "New Class AA" THD of 0.005%, then I don't want it... (just a comment for the algorithm) Another down-to-earth review. Thank you.

That old chestnut, and I can't argue with Phil. Have you had any holiday cards from the girls ? I'm assuming their on holiday....cheers.

Using a tube this way does add a little coloration - i.e., distortion. Nelson Pass has done some research and he says adding certain distortion in small amounts can sound to most people as greater depth in the stereo image. Not the same as warmth, but and interesting. There is also "sighted bias" and so on that could be going on here. Many of us in the Hifi hobby have heard that "tube gear sounds warm" - and in fact since tubes are thermionic devices, they have heaters - which is the yellow-orange part you see glowing cheerily inside the tube. And tubes actually do get warm or even hot. Hifi enthusiasts know this, and this knowledge can influence what people feel that they are hearing. So even if the tube were not in the audio path at all, a number of listeners would feel that the audio device in question provides a warm sound. Ears and not microphones and the brain is not a piece of test equipment. It is impossible to listen to some piece of gear and make an objective pronouncement - any "how does it sound?" comment will be a subjective opinion, coming from the mind of the listener and human minds are terrible drawing making objective conclusions of subtle sensory observations - such as evaluating the "sound" or a gain stage. So, even if this slight amount of harmonic distortion is not audible, many listeners will FEEL that the amp produces a warm sound. Now, tube audio output stages are another matter - the source impedance of a tube amplifier will interact with the complex impedance of a speaker which results from an interaction between the electrical characteristics of that speakers drivers and crossover- this interaction follows Ohm's law and results in variation of frequency response of the amplified sound. Sometimes these variations are very small and are essentially inaudible, but sometimes the response through the amp/speaker combination varies by as much as ± 4 dB- which is definitely audible. Personally, I LIKE the way a certain tube amp of mine sounds through a pair of 2-ways speakers that I have- the coloration is very much to my liking. So, in a sense, I am using this tube amp as a TONE CONTROL.... 😎

Hi sir what your sound system ?

What about higher frequencies?

True. Volume matters. The louder, the better (up to 100 db).

Do you have a title an "unboxing" date for your unboxing music album yet? "Mellor Unboxed" maybe?

AFAIK: Warmth = Add enough harmonic distortion to slightly hear it, and turn down the treble.

So, what do you think of the amp?

Yep that warmth or even order distortion is coveted in the guitar world where tube (valve) amps are considered the defacto king of guitar tone.

In the 90's I baggered my dad to make me a vale amp for my band (for guitar) and he reused he said we went to transistors for a reason

In a catawampus Universe if the Buddy Holly era used transistor amplifiers and tubes were discovered in the 1960s we might all be harking for the cold hard precision of the ceramic transistor.

Unboxing music was almost groovy this time. Might I recommend Lloyd Christmas' most annoying sound in the word on infinite loop for the next

There is a crappy GPX “boombox” in our shop @ work. Manufactured in early 90’s and it has control face nearly identical to the T9. That bothers me. Yuck. As far as distortion goes, it’s a 130 dollar amp and where I use these type units…not a concern. I have an A03 that gets used, abused and hasn’t given me any trouble. I really like it but haven’t bothered putting it on the HP distortion analyzer because frankly, I don’t give hoot.

Tubes add distortion that many enjoy. I watch tube TVs when young.

Sure I want to hear warmth and distortion! That is: the warmth that is captured at the recording stage, and the distortion of any guitar driven valve amps that were used at the recording stage. But I require my system to reproduce these things with as much fidelity as possible. Without adding any further warmth or distortion whatever!

I'm in favor of using a 2-tone intermodulation distortion test and checking for IMD products at f2-f1 for even order and 2f1-f2 for odd order distortions respectively. Such spurious inharmonic products cause most, if not all, of the subjective degradation of sound quality due to non-linearity, so why not measure these directly? Use of 8000Hz and 11950Hz as test tones, resulting in products at 4kHz -/+ 50Hz for even and odd order products respectively used to be a standard.

Warmth and distortion are two different things. Warmth is all about frequency response and can "tame" shrill sounding recordings which sound too bright in an accurate system, or just add warmth to an otherwise "bright" sounding system. Distortion is all about a deviation from the original signal and may or may not be audible, depending on how prominent it is. Here's the kicker in my opinion... I used to work in a Hi Fi store and we had a "comparometer" which allowed us to switch from one amplifier to another with a remote control. We had two budget amplifiers which were popular and had the same stated power output and price so naturally people would ask "what's the difference?". What we did was to feed a one kilohertz signal into each amp and match the volume levels so they were indistinguishable by ear. What was also indistinguishable was sound "quality" in the sense that no one could tell which amp was which. However... when putting a complex signal (i.e. music) through both amps and comparing them, it was clearly obvious to everybody which one sounded better - not "warmer" or "louder", but unequivocally better. When we were asked why, we opened the lids and the poor amp had a tiny rectangular transformer, AA battery sized capacitors and an integrated AB circuit while the good sounding amp had a large toroidal transformer, large D battery sized capacitors and discrete transistors so it was kind of obvious. The thing is, measurements although accurate, will only tell you so much, and you need to actually listen to the amplifier or other component because trying to measure something dynamic like music and deciding on which component will actually sound and BE better is next to impossible. Further, you have manufacturers who are so obsessed with measurements that in search of superior "figures" like noise and THD the design of the amplifier will be compromised (too much negative feedback for example) and actually sound worse even though it has more impressive measurements.

Have you got anymore T-shirt please ?

HI, Excelent review, It´would be nice if you make a remark that 2nd Harmonic Distortion is indeed the "nice" distortion usually tubes in class A provide, I say It´s "nice" for that viewers that are not experts and really want to know what is the point of having a little bit (0.1%) off that 2nd harmonix, I you allow me I´ll explain to that viewers that 2nd harmonic is not as harmfull as odd harmonics, I´ll say that if a guitarist play an open G string, with a little bit of 2nd harmonic the listener will hear that same G note an octave above, beeing that high octave note 1000 times smaller than the fundamental open G string, the listener will hear a sweet harmonic distortion. That explanation would be so clear that will reject any black magic effect that valves add to the sound, as for valve or tube warmth i believe It´s related to frecuency response (non linear) , roll off due to old triode single ended amplifiers and the effect the output transformer has on the final sound. That´s why some Audio Pro like, i bet you are, I saw you in a vid at Abbey Road Studios, THAT´s superlative Audio Pro, you may prefer a Neve or API or like EMI in house build trasnformer coupled consoles to an SSL witch is direct coupled. Pros are looking for that subtle change IMHO , let´s call It distortion, but again in the correct amount, .60dB 2nd harmonic. I´m looking for that effect too. But don´t expect a 20 year child with a home studio in his/Her bedroom to apreciate this. They where born in the digital era, perhaps they didn´t even know how nice a 2 inch 16 channel tape, headstock and recorder sounded. (Sorry English is not my main language so there may be mistakes off all kinds, sorry for that, I just don´t like "trasnslators", perhaps because they don´t have tubes :) Oh, It´s a pleasure to just relax and watch any of your videos, thery are ALL excellent. That´s why you´re aproaching 70k subs. and this vid has 257 likes just 12 hours after you post It. That´s a good measurement , don´t you think?

David I dont like warm music - my audio equiptment produces an ice cold clinical sound! Warm is for wimps! Short and sweet, but I am meeting Elton for 6 PM, until next time au revoir

When we're talking audio gear - or listening in general - there are many descriptors that one can use when trying to explain what we're hearing. All in all, however, there are two categories to which all of our descriptors fall - tangible and intangible. Often-times, when audiophiles describe what they're hearing (and all of our ears are uniquely different), they (we) may go off on a tangent describing experiences that may not make sense to some. Tangibles are those descriptors that can be measured and easily referenced (i.e. frequency response, noise, etc). Intangibles, however, are not so easy to measure (and oftentimes they may be impossible), but they are easily heard by critical listeners. With intangibles, we hear descriptors such as: Depth... Sound-staging and imaging... Instrumental timbre... Air around the instruments... Musicality and immersiveness... Warmth (which is distortion - but it may be measured as distortion only) - but "warmth?" And many more... None of these can be measured and it is often between these two areas (tangibles and intangibles), that many arguments ensue. For example, in some cases, I find the warmth of "certain" tubed instruments to be just right, while in other cases, the warmth may be too great for me to really become immersed in the music. Yet if somebody tells me that they loved the tube sound of a particular component (that I may have found off-putting) who would I be to argue? I remember a long time ago, an audiologist told me at an ear examination that no two folks hear the same - in particular when it comes to areas such as music listening. He bases this on our ears and how they are formed. Anyway, I won't bore anyone with this. For example, there are two rather inexpensive tube integrated amplifiers on the market that are often overlooked because they've been out for awhile, yet have, what many who have used and heard them, distinct audiophile qualities. The first of these amps is the Fosi Audio T3 (a tube front end and yes, a class AB back end) - the link to Amazon US is here: www.amazon.com/Fosi-Audio-T3-Amplifier-Bluetooth/dp/B0B4W36C7B/ref=sr_1_1?crid=2GHZZUUQGVNIE&dib=eyJ2IjoiMSJ9.qACQbjJHk-v-EkbPhRVB2XIuv_fMkHAlC-gZs5-FCK0rb9xAMvyV1j55EtzJ4SoWWdz5CvsCZ25pxMiAQ2MuolgJBndBdEtr6yaSdMd3S72YF_dpNncx98AU0IEXIXz8IxueywhUo4WEABGH03e07wJydY0kaZ6xtdviiWQ8khq_INOznwvm4PFd83a_VrtE.sYxdG_qTesOkz8mwJBUPQv61Rd0TanpEObU1EGjrpL4&dib_tag=se&keywords=fosi+T3&qid=1714674539&sprefix=fosi+t3%2Caps%2C107&sr=8-1 I found this T3 (while tube rolling) to be strikingly warmer (well, it has a class AB amp) qualities with superb depth and airiness around the instruments. Now the next person may proclaim "hogwash." The other amp is also a tube front end and class AB back end, and it's the Nobsound (uses 4 unique Chinese tubes that can only be purchsed from them), but the sound (IMHO) is sublime. It is the Nobsound B100 and the Amazon US link is hereL www.amazon.com/Nobsound-Bluetooth-Amplifier-Integrated-Power/dp/B0BLXYBZZ5/ref=sr_1_5?crid=34ETR2JU8V2MO&dib=eyJ2IjoiMSJ9.lvDdqqPMGj32n-IlNpiyy2i2t0zBZXbxaIatkrCD3Zyuon39g77mT7yprC72GOQNkEXZvCHANP75hcEeABntdPlVH2jKm93WaHC15M2BqrOVRqX9KUX0POp36ue1UCmCnxgkrQRwmpnbRCOLc7sgHk0Ypjz1dmLg4PckwvedWuB2vkRvx8191DjND69JLYDWMfx2YUwYZXpdZxPEBbZySaSbWjnieRYVQ1EExmJia0c.LKQix4RjbFYlUBryje2MI_aTqySIjgwVYXdAEgaFsyk&dib_tag=se&keywords=Nobsound+tube+amps&qid=1714674675&sprefix=nobsound+tube+amps%2Caps%2C112&sr=8-5

So, how does it sound? Good? Bad? Meh? I know that wasn't the point of your video, but you might care to share your impressions.

Your inference, that ‘warmth’ and ‘distortion’ are one and the same is spot on 100% correct. All the complimentary words dreamt up by audiophiles and the like are the result of either low order harmonic distortion or some fairly radical equalization. All of them. The implication these fond descriptors just popped up out of the zeitgeist, or somewhere far worse, is truly laughable. Personally, I like ‘clinical’ and ‘cold’ but that’s a whole other issue. Btw, your unboxings are in danger of becoming far more important than the stuff in the box. That’s a good thing. When the Smithsonian comes knocking, they will be coming for the box. You can continue to use its contents.

" Not all that can be measured is important and not all that cannot be measured is unimportant." Einstein. Sound is as mutable as light so get over yourselves so called audiophiles.( Also may have slightly misquoted A.E ). Transistors when introduced in the late sixties were very much cheaper, so as a teenager you could listen to the Beatles, Stones, Hendrix, Dylan, Supremes, Byrds, Kinks, Who, Mamas and papas, Doors just to name a few of the better know all on a small radio and all for free. Thank you Audio Phil for coming down from Mt Hollywood and explaining it to us. The logic would dazzle a modern Ph 'd student.

I thought warmth was a bumped low end.

Dan D'augistinos obscenely expensive signature amp measures really badly. Pass labs amps measure badly. Both exhibit levels of distortion and noise that snobs decry if measured in an inexpensive amp.

Peak-to-peak or zero-to-peak or RMS are not subject to opinion.

Distortion is simple .... anything coming out of an amp that isn't exactly what you fed in is distortion. Audible distortion is more complicated. There are thresholds of hearing, ambient noise, and several other considerations. But David is correct... nobody is going to hear 0.01% distortion.

Amazon labels the Ayima T9 pro as a frequently returned item. I think that's all you need to know. Another Chinese Giant killer sold by a Chinese audio salesman.

QuantAsylum QA403 Audio Analyzer $595 Yankee dollars.

I personally consider warmth as distortion. I don’t like it. But that’s a matter of opinion or taste and as such nondebatable.

Tubes, really tubes? What kind of Englishman are you? LOL 🤣

first Ha!

Any Amp that uses a power brick should be ignored or thrown in garbage no matter how it sounds.

Many modern components have very low levels of harmonic and intermodulation distortion. Test equipment that can measure it tends to be rather expensive. One could argue that a "warm" sound is by definition not a "neural" sound and therefore implies some level of distortion (of some form or other, not necessarily IMD or THD). Even a non-flat frequency response can be considered distortion of spectral uniformity of gain.