After repairing the Kinki Headphone Amp, Mark puts it through a Kinki Endurance Test, to see if he can blow it up again. Is it really over-engineered? Follow the link to see what's new and behind the scenes: / menditmark
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 😂
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.
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!
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!
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.
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.
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.
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.
Hi Mark 👋 you are really master professional electronics engineer 👏 Always watch your videos and you are the best on RU-vid 🎉😊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
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.
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.
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 😊
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!
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 RU-vid, 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!
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.
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!
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?
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.
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.
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.
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.
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?
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.
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.
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.
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.
Wow! Nice new concept Mark! Love this! Something different for a change. If you ever find a stupid design, please show it! It's always nice to see pro-brands doing silly things!😂
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.
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.
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.
