Kinki Vision THR-1: Will It Blow Up?

[@Matt_Aquila]

"If you don't connect anything silly to it, it won't blow up!" - best electrical advice ever!

[@luminousfractal420]

and ive been told that before. my grandpa when he was teaching me to wire a mains plug as a nipper 😂 my parents werent so happy. and i proved them right when i plugged my scalextric to the mains in an attempt at a 30ft car jump out of the window. i got my bed on fire instead 😂

[@matthewseymour8972]

@@luminousfractal420That's known as the Clarkson approach "More POWERRRRR"

[@mr_b_hhc]

On par with "Don't touch it when you're wet"

[@AntiDot70]

Mark, you really need to start selling stickers and t-shirts with "If you don't connect anything silly to it, it won't blow up!"

[@nudebaboon4874]

I'd buy one!👍

[@AstrosElectronicsLab]

I want a t-shirt with his facial reaction after being shocked with that SMPS, with the caption: "Cor! Fkn hell!" haha that'd be funny.

[@RickMahoney2013]

I totally agree !

[@abigailhowes5944]

I wish you lived near me, as I would bring some of my electronics that need repair to you. Mark you are a true technician., not just a parts replacer. I watch you repair things, make new parts from scratch, and analyze a problem. I have only seen once where you couldn't fix something, but everything else you could. You are a joy to watch! Thank you and keep up the good work!

[@andrewwturner]

It's always a treat when you release a new video and what a gem this was. Not many people could explain thermal dissipation without sending their audience to sleep but you pulled it off perfectly. I bet you spent a considerable amount of time working on this short video... Thank you.

[@glennbarker222]

Good job you decided to do the follow up test and identified the duff input socket. Nice bit of testing, interesting.

[@thedevilinthecircuit1414]

There are so many little things that occur in your diagnostics and demonstrations that are unintended teaching moments--but when I pay attention I pick up stuff that's not in any book. Thank you sir!

[@BenState]

Like what?

[@BoredSilly666]

I have no idea what you are doing half the time or do I understand Electronics but I find these strangely fascinating to watch. : )

[@mortjoer]

I'm a carpenter by trade and people seems to love to look over my shoulder when I work on stuff. This is where I get my own curiosity satisfied about other trades thanks to people like you Mark, Thank you 😊

[@danhorton6182]

Would have been cool if they had made it so that when you put the top of the case on that it would made connection to the heatsink and drawn heat from it. Essentially make the whole case a heatsink.

[@allantoft9961]

And mark would have so much fun getting the case of then I tell ye!

[@Edisson.]

I have a 100W test amplifier for SW cooled in this way - a 50x20x17mm aluminum monoblock connects to the entire case - total external height is 30mm.

[@hashtag-shaneiacs]

Naim amps are made this way but they're bolted to the case floor with a thick substrate. I imagine the top would be too hot to touch if they're bolted to the lid instead.

[@Edisson.]

@@hashtag-shaneiacs I don't know about Naim amps, I built it myself

[@codebeat4192]

Exceptional amount of detail, very talented at many fields.

[@edwardpeak4937]

A great film, many thanks Mark. I know it must take ages to make these, but the extra technical stuff in this one was very welcome. Best wishes

[@rvmeushaw]

Fantastic repair as usual and an engineering lesson to boot! Great job.

[@DominicClifton]

Thanks for answering my question regarding the use of Kapton tape, very interesting. So essentially it's good for protection, but is definately worse than a thermal pad which is what I thought, but not quite as terrible as I thought.

[@peterlarkin762]

Kapton is better than some thick silicon pads. Thin Mica is better than silpads but you need thermal paste then, which makes them equal. Aluminum oxide is best.

[@davidg3944]

Greatly appreciate this follow-on video to the original repair. Seeing the temperature chart was useful for confirming power dissipation and thermal transfer from the hot components.

[@gordonm2821]

Thanks for the in depth reply to the comments. I know there were many armchair expert comments on the original video but great to see the science behind the design. Still over the top for a headphone amp IMHO!

[@Michael-h7y5k]

Mark, I know you hate them but I request more tape deck repairs. Pure joy for me. You are my favourite channel on KZbin.

[@TechGorilla1987]

This is the deep dive that I never asked for, never thought of and didn't know that I couldn't live without. What a fantastic series of tests to gather empirical data. Well done, lad.

[@bask2140]

You often sound like an old radio announcer from the 1930s using a carbon microphone 😄

[@TheStuffMade]

It's a very strange design, usually you'd want the output impedance to be as low as possible so variations in the headphone impedance will not affect the frequency response.

[@enoz.j3506]

Unless someone overloaded the output,thermal stress probably killed it, the cooler you keep electronics ,the longer it lives. Nice one Mark.

[@alphaLONE]

Excellent work of verifying the claims. Love your stuff!

[@Cee.Jay.71]

I've been away for a while but it's nice to see your channel is blooming. Thoroughly well deserved Mark.

[@MrGeoffHilton]

New to your channel and binge watching past videos. Mark, you are a true professional.

[@ravusursi893]

Mark, there are not many people I truly admire. You are one of them. You are a treasure and would definitely be at my dinner table of six celebrities, along with Stephen Fry. Keep up the great videos!

[@JohnCompton1]

$1,300? She's way too Kinki for me...Thanks so much for sharing!

[@Clusterworldde]

Did you see the USB cable with 20cm for $309 🤣

[@Petertronic]

Audiophools and their money 😂@@Clusterworldde

[@PaulHigginbothamSr]

John: when they put an insulater on their mosfets I don't want it either

[@sickofthestupid1067]

China has learned capitalism well ..........

[@markianclark9645]

She's too hot for me..even at my peak 30 years ago

[@tony359]

Thank you for adding science to the previous video!

[@TheFlyingBusman]

For a headphone amp, I’m surprised at the chunky MOSFETS but even more so at such a poor heat sink. The Chinese, bless them, churn out some interesting kit but let it fail due to attention to detail. I’d be much happier with some slots milled into the heat sink to give a bit more surface area or a few vents and small brushless cooling fan. Who would have thought a headphone amp would get so toasty but there you go.

[@chrisbartram3034]

I'm also a bit mystified by why so much power is dissipated in the amp to drive only a few watts into headphones.

[@mohindersembi7647]

Hi Mark 👋 you are really master professional electronics engineer 👏 Always watch your videos and you are the best on KZbin 🎉😊just to find out when are you going to do video of aiwa 3 head cassette player? Follow up ? We all are waiting for it please let us know 🙏 thank you

[@dvsbangkaeedivisi9369]

Yang selalu saya Tunggu....

[@davidtomsett]

Kapton is also used to make membranes for electrostatic and planar speakers.

[@xxxxDuke]

These videos are such a labour of love - thanks Mark.

[@s.wilson5675]

Well Mark, I'm glad you solved that 'heated' debate about whether the Kapton tape was good enough or not!

[@MichoCoban]

Reminds me of the nights spent troubleshooting dodgy circuits while at Uni

[@user-sh4zq4ge1o]

Love this style of video, more of these deeper dives into particular part of a design would be great.

[@stianhus]

that was just brilliant, you never cease to impress (and educade) Mark!

[@bobgrob4]

Alright, Mark! Keep cranking out the vids! Mark I feel in my gut that your channel could be the most popular electronics repair channel on KZbin, given enough time and make a lot more videos. Before you know it, you could be repairing stuff and doing projects just for fun. Keep going, sir!

[@stephenyoud6125]

Nicely done Mark, as per usual !!

[@OldePhart]

Liked this one. First time I've seen the thermal gradients explained at all.

[@kthwkr]

In the studio I needed different types of headphones to be driven at similar volumes with the same Vol pot setting. Some of the ops would bring their own headphones so we couldn't standardize on one type. When driven by low Z headphone amps into the Sennheiser(hi Z) versus AKG(low Z) versus cheap headphone(8 ohm) the volume to the ears would be dramatically different. I put series resistors in the line and got the volumes to the ears to closely match no matter which headphone type. I don't remember the value for sure but I think it was a 47 ohm. The end result was you could adjust the volume for one type of headphone and then unplug it and plug in a different type and the volume would be about the same without touching the Vol pot.

[@PileOfEmptyTapes]

Good lord, that thing can dish out as much voltage as a 150wpc speaker amp! Clearly a very particular design for those who really love their vintage AKGs (aside from the 120 ohm K1000 "ear speakers", the 600 ohm K340s come to mind). I imagine most folks are going to find the likes of a Topping L50 a more sensible proposition.

[@nabman_]

2.2W into 30ohms is 270mA. Why such hefty transistors? Why such complexity for driving headphones? The least sensitive ones would still reach painful SPL with mW. I don't get it.

[@chrisbartram3034]

No, nor me. Loads of power loss heating up the amp to drive a low-level load...

[@nabman_]

@@chrisbartram3034 with 70V rails....the art of snake oil....

[@davidgriffin79]

10:22 Not exactly unexpected. The Heat Transfer Coefficient (HTC) between the aluminium heat sink and air is quite low due to virtually no fluid (air) flow, so the heat sink soaked out pretty quickly. After that, final equilibrium was reached asymptotically as the inside air temperature slowly increased (due to the low HTC) to approach a final ΔT between the heat sink and the outer casing.

[@nordin_gh]

Adding fan on top would be nice but need more work with CNC machine to make the hole. Love your video always.

[@glynnetolar4423]

Oh no. You may end up with electrical noise from the fan.

[@quantumleap359]

Oh goodness NO! That would introduce distortion and offend those "golden ears".🙃

[@chrisbartram3034]

Why not just use the case as a passive heatsink, though?

[@douro20]

Now that's the kind of quality I would expect for 1200 quid. The only thing I would be worried about is stress from acceleration due to shipping from the mass of the aluminium heatsink. They must have a very good supply of those vintage Alps stereo potentiometers.

[@alunroberts1439]

Could this be changed a bit so the lid makes contact with transistor heat sink

[@richbrock9876]

Know yer onions 🏆

[@Dave.Wilson]

He knows his currents as well!!😉

[@ЮраЧернышев-ь9р]

A square wave signal of 500-600 Hz is also necessary for signal passage and transient processes in the amplifier. Always.

[@pantelisEVs]

Thanks for making this video! Really interesting getting into expensive audio equipment (for personal audio project design ideas :-)

[@hw4527]

Thank you for posting. 👍👍

[@eddieMurphy11111]

I often wondered what that plastic was called now I know thank you and thanks for the video

[@nevillegoddard4966]

@@eddieMurphy11111 Yeah capton. Cool name!

[@jinxterx]

@@nevillegoddard4966 Kapton.

[@davidg3944]

@@nevillegoddard4966 A little late, but "Kapton".

[@steverobertsbbc]

I'm not convinced that "heatsink" is for cooling as much as for ensuring that all four output transistors are in thermal equilibrium so that their responses track together.

[@hugh007]

Excellent video. If I hadn't seen this, I would never know how over engineered a headphone amp could be. Cheers.

[@andyb7813]

Another Really interesting video Mark. Thank you

[@sjqideez6626]

Fantastic stuff Mark, much appreciated

[@foxbeef1983]

My new favourite KZbin channel!

[@ulrichfrank4270]

Repair video made me think this device was at the same time over-engineered (for show) and half-baked.

[@gordyboy01]

Mark love the channel 👍, as an example couple of legendary Audiophile headphones such as sennheiser HD600 or HD800s are 300 Ohm Headphones. I own a pair of HD600s myself.

[@edmaster3147]

Thanks for the follow up. Nice work as always.

[@kerrygleeson4409]

Thanks for sharing Mark 🦘

[@Bigbluevwvan]

nice in depth testing

[@BrendaEM]

Nice test box! Ironically, there is a sizable aluminum thermal mass with a large surface area--just above the "heatsink." Perhaps, leads could be put on the transistors, and they could be affixed to the lid. And if more heatsink is needed, they could be applied to the top.

[@barrybradfordlocksport]

Love the channel need more uploads please mark

[@scossa_vr]

Great Mark, very interesting, thanks for sharing! P.S.: your youtube channel is the only one whose intro I also always watch, too funny!

[@GaitaPonto]

OK, you proved it wont blow up. But I still think this design could be improved. With all this aluminum available, why not use it in our favor and keep components cool and comfortable?

[@acswales]

Head in a shed again. Cheers Mark. Keep 'em coming. Thanks

[@rayc1557]

Really enjoyed part 1 of this! Thank you for the follow-up. The amp is awesome too. If played at normal listening levels with headphones, I'd love to know the temperature of the heatsink. That would give insight about the bias level. If you're so inclined, please see if there's a resistor in the output chain by which to measure the quiescent current. Am interested in knowing how far into class-A it's operating. Also, is the driver stage running open loop or, does the the output backtrack to feedback loop?

[@rjk5559]

Complementary output? Wouldn't a single-ended Class A design be preferable if fidelity was really the goal of a headphone amp?

[@peterlarkin762]

Then it would need a proper heatsink and bigger power supply, and a bigger price tag! Nothing wrong with complimentary, most class-A amps are exactly that. Single ended technically performs worse, and requires and output capacitor or transformer. They do sound lovely though.

[@rjk5559]

@@peterlarkin762 Class A is less efficient than A/B but this thing only need to drive headphones, not speakers.

[@crushboss]

If you are going to use a thermal imaging camera for heat transfer differentials (especially between different materials) you need to study and understand emissivity! Especially when trying to gain a accurate temperature on reflective surfaces. 2 Small pieces of black electrical tape on each surface will help, and set your emissivity to 1.

[@that_thing_I_do]

Can't wait to watch it at home!

[@wdavem]

Most interesting! I'm learning, I'm learning!

[@Dave64track]

Great content that test would certainly show up any problems if it had any. Trouble shooting is great when you find the fault and it works it's when you don't find all the faulty components and you get the dreaded magic smoke coming out.

[@billsmith5166]

Very interesting. Well done.

[@MrJDNJ]

I meant to ask when I saw the first video - I think you said that the XLR plugs on this thing were not really hooked up for a balanced signal. Wondering what the purpose of having those connections if it's only two wires instead of three......

[@kenneths9522]

Thanks, nice job Mark! I always enjoy your videos.

[@vinatechcoy]

Mark!. Thermal transferal from the internal heatsink to the case (top cover)

[@johanneswerner1140]

Kapton tape is actually more like a quarter of a tenth of a millimetre, so it actually is a viable electrical insulator. Just use heat sink paste (as always)...

[@semsem2841]

I watched your video in Thailand.

[@jimwilliams8858]

Good job, but You are making a mistake - 70C is too high a temperature for steady state operating as it leads to thermal runaway and the destruction of the MOSFET even when it is operating within its Vds, Id and Pd ratings. How? Well, you are measuring temp in aggregate for all four mosfets, but in reality, there are regions of each die that will show much higher temps and those regions will fall to secondary break down. This amp needs better cooling. I think you forgot to adjust heatsink height in such a way that top portion of heatsink block would be in contact with heavy top cover. You can adjust heatsink height by choosing to solder mosfets with longer leg height position. To determine optimum height of heatsink block is not easy. Lastly, you can use heatsink silpads/heat-transfer compound for thermal interface between heatsink block and top aluminum cover.

[@chrisbartram3034]

That's a valid point, but surely the amp's designers should have done that, not Mark?

[@paulchisholm9392]

Thanks for the video. I have beem playing with Exicon MOSFETs in a Power Amplifier design and they do like to oscillate at many MHz. Maybe the MOSFETs died due to cross conduction of the N and P channels because of this?

[@peterlarkin762]

I've seen some references to this... sometimes people don't use gate resistors, or emitter resistors. In real life they are needed, as is a zobel and thiel network. As is a miller compensation capacitor on the n-channel fet. Bad grounding can create oscillations too. Also I found out that lateral mosfets can get minor capacitive interference from the grounded heatsink. So better to use silpads instead of mica or kapton apparently.

[@gijoemolinaro]

Love your vids Mark absolutely brilliant

[@juarezcastelo]

Ok ok! You were right about the kapton tape! You happy now!!? Great vid btw.

[@FirstNameLastName-tp5bu]

Did you check the RCA socket's outer diameter? It appeared that there was very little friction between the plug and socket. Just curious, wondering if it was slightly undersized...???

[@lloydieization]

As it doesn't have a fan or a need to dampen (mechanical) noise a few case holes wouldn't have gone a miss. If anyone puts another hot device below it etc... its too close for comfort temperature wise on £1300 bit of kit.

[@mixolydian2010]

Cheers Mark,nice experiment.

[@jeroenoost6217]

perfect explanation 🙂

[@billmilosz]

That bespoke headphone load box - very nice execution! How did you fabricate that front panel? Very nice. By the way, something like an AMB Labs Beta 22 headphone amp is much more rugged, has lower output source impedance (better damping factor, important with certain headphones) and an be made DIY.

[@davidyates748]

Very nice scientific test methodology to prove the soundness of the design Mark. Just goes to prove that not everything that comes out of China is crap. That's a lovely piece of test kit that you put together, looks like store bought as our Murican cousins might say!

[@oiygfdxssfgg]

I really enjoy your videos Mark.

[@schummiehugo]

good job happyman !

[@christophermarshall5765]

I reckon you could build a decent amp using the Motorola high power output transistors. Those are MJL21193 and MJL21194, or you could use the TO3 package type MJ15003 and MJ15004. The latter require 160V and have output of 250 watts.

[@bunston1000]

Hello Mark, just a quick question. I am trying to re-cap one of my Linn LK 100 power amplifiers. Do you have any ideas where I can obtain audio suitable capacitors. The 10000uf 40x50mm caps. I can get from the original manufacturer (Rubycon). I have tried various other online (vintage electronics) suppliers, but they are either the wrong dimension, or I can’t get the correct working voltage or higher. I’m kind at the end of my tether now (Lol). But I do like the sound of these amplifiers, hence I would have liked to have got it back into operation. Thanks in advance, Mark, I do realise you are a very busy man. Keep up the great work and great videos. Geoff.

[@djdoo]

Very nice answer video ! But now I have a new question: What was that silly thing the owner connected and created some much damage to that expensive, and proved to be, well made headphone amp? In other words define the term 'silly' for this device.... Maybe 4 Ohm speakers?

[@Tintukees]

Hi, I have been watching all your videos. A lot of new things to learn from you. I wonder if you you could make a video on your tools and shop. The soldering iron you use seems to be your favourite, being small yet handy and long lasting.

[@baronofgreymatter14]

Nice one!

[@AnthonyBarry-q1i]

great video as ever.

[@brynybach7741]

Another great video Mark 😊👍

[@BulletmanDoom]

Talking about tape, do you know what the thin felt tape they use to hold wires in place in electronic devices like turntables and Hifis?

[@ralphj4012]

Interesting. This sort of implies (I think) that putting kapton tape to prevent heat reaching other components when hot air reworking etc. has little or no effect.

[@NotMarkKnopfler]

It's all a bit much for a blimmin' head phone amp really, isn't it?!

[@mihaischitcu1917]

At around 2:30, the transistor power drop is 1.37W avg. assuming class B operation; however, being an "audiophile" device it would surely be biased into class A leading to higher dissipation. The temperature you are measuring does hint toward this. Not sure what measures they've taken for idling current stabilization (if any) , but having that solid aluminium box at your disposal and not thermally coupling it to the power devices is just... shameless.