Chinese Tube Amplifier Kit Build (6Z4, 6N2, 6P1) (Ep. 174 )
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- Опубликовано: 11 май 2023
- Today I build one of those Chinese stereo tube amplifiers from start to finish. Good project for a rainy weekend.
Entry level amplifier kit that has good performance and sounds great, moderate difficulty.
I am quite pleased with the outcome.
I purchased this kit from Aliexpress;
www.aliexpress.com/item/10050... 
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I built a similar kit, except mine was the 300B, power amp. I've found that these kits can be quite rewarding.
How was it? Do you mind if I ask which speakers you use? Was it single ended or push pull? The single ended ones are crazy cheap.. I just can't imagine the iron is any good..
@@martinda7446 I've had it hooked up to some KLH speakers....... and have been using it for a year. It has adequate volume.
OK I'm a minute in and I know this is gonna be awesome... I've been looking at these too over the years. I had a couple of my own designs and wanted to know if I was utterly wasting my time. I have not seen this particular one, but its so simple, the output tranny is of course the absolute make or break and sat there thinking they must be poor for the cost... A single ended EL84 is truly capable of remarkable results with the right speaker. You might never want anything else. A pair in push pull makes it suitable for almost any speaker with 11W or so class A. People, a decent valve amp can change your outlook on life.
Sweet little kit, i have a smaller tube chassis from an old hifi console that a guy was getting rid of, I'm getting 1.75 W / ch and i just love it. I have been trying to amass the transformers and such to build something similar to your unit but i can't bring myself to pay that shipping. It's clean & simple with the warm glow of tubes - perfect.
Get transformers local or order elsewhere see if you can buy the kit without.
I just finished watching xraytonyb Electinics 101 1/2 series on these Chinese amp kits. And now your vid shows up in my feed. Time to get this kit!
Great! I had been wondering if you would ever do another kit build (after the radio one) at some point again. l look forward to watching this.
I like doing kits. Maybe you guys can offer some suggestions for kits.
The tube amp kit was fun to build and even more fun to listen to
Just put the best caps you can put on this amp kit. NOS tubes, and a TKD volume control done! These additions would bring the sound quality up 100%
hello Trevor, ..Nice to sse you working on tube amplification for a change .
There's a lot to say about this kit and tubes in general,
Indeed there must be a bleeder and not only to bleed the capacitors but also conditionning the the powervdelivery ( current on an optimal place on the specified curve traces of the used type of rectifier(s).
One solution I use is to install a adjusted value on the circuit in use and another on heavy low resistance bleeder on a BI-polar on/off/on switch .......when the amplifier is switched off the beeder bleeds fast the capacitorss and protects the tube from catyhoide stripping when the HV is still present .....long life to tubes by preventing applying HV when switched on ( cold cathodes ) and at shut down .( a switch on the filament of the rectifiers ! .....minimum 45 seconds delay before swith on the HV ) )
Another issue is the MAXIMUM value of the input capacitor used with rectifiers ......;you can look it up in the datasheets ....
6Z4 is a chinese rectifier ...........not very good quality ...........but cheap !
You can replace the 6Z4 by the better 6X4 us style tube with an adapter or resolder the different pin outs of the socket ........better reliability and longer life and sound !
Be gentle on the sockets ( choinese ) they blook good wit steatite but the contacts are crap , beware of tube rolling ......!
Otherwise it's a fun project for starters to learn about tube gear and face sopme issuers and problems to solve with this kind of kits.
now I will continue to watch and curious about the outcome and results...
Happy building Trvor .
Some info if you like ...
With capacitor input on the power supply the MAX value of the input capcitor is 10µF !!!!
Because ther'e are two in paarallel it goes up to max 20µF .
The 6X5 is the OCTAL version of the 6X4..........
There's alsothe impedance of the transformer that is often forgooten TODAY !
rectifiers need to see an minimum impedance on the transformer ...
AVOID hot switching od rectifeirs .....let them cool down before swithing on again !!!!!
They need a fair impedance for the plates ( rather high in this case ) there's aformula to calculate and tone can compensate for to low a impedance.resistane of the poqwer transformator ........( datsheets for 6X4 )
have a nice ady and lots of fun buiilding !
@@frankgeeraerts6243 20uF not 620 or 330uF like Trevor used? I thought so! Will the rectifiers be actually damaged by the grossly oversized main filter capacitors? - Or their lives shortened?
@@nevillegoddard4966 Yes to both questions. ( even transformers must have the minimum resistance specified as was practice and r'equired in the days of rectifiers )
Interesting project. Thanks for sharing.
Easy does it. I'm amazed it survived the unpacking ; )
Good build and vid Trevor. What would look good on the front of this is an old style VU meter- like the old 30/ 40's electricity power meters look if you know what I mean. Icing on the cake.
I've learned the hard way that shipping transformers of any kind across the world is a mistake. 10 years ago it was expensive enough, but now.... clicking over to see this kit's availability made my eyes bleed at the current $155 US shipping charge. Some kit producers in that region offer the full bill of materials minus the iron.
Hi Everybody, I built a similar AliExpress kit going back some7 years ago. Mine was the single ended version using a Chinese tube similar to an EL34 it sounded ok but a little lacking in power with only 4 watts.I believe that these amps can be parallel bridged which would make a nice 8 watt and I did get two of them as a monoblock pair. as they were only £75 at the time. Also they sound considerably better with a western or Russian tube equivalent, I used some nice KT66's and some tun sol 6SN7's and they sang away nicely. Best Wishes all Dee
I always wanted a tube amp but the price always have been out of my budget for known brand, then I found your awesome video and it gave me the motivation to build a kits.
I am building my kit right now and I just finished cabling the main transformer and would like to thank you for your video full of useful informations.
My kit uses 5U4C, 6J8P and FU50 tubes (I believe they are all chinese clones of russian/american/european tubes).
and the caps I have with my kit looks as fake as yours :)
Thank you for the work that you are doing.
A word of advice before you get too far in your build. The filter capacitors I installed on my amp are grossly oversized and should never be that large for a vacuum tube rectifier.
I would use about 100uF maximum. It will work fine with even less filtering.
Good to hear your having fun. I expect the sound from this will be quite enjoyable to listen to. Cheers
@@TrevorsBench Thank you for your advice.
There was not much choice at my dealer, but I got european made Kemet 450V 150uf, same specs they provided with the kit, and their size is comparable.
I also picked up 8ohm 50W resistors to load the output transformers for testing because I don't have cheap speakers to blow up in case something goes bad.
I am halfway into the build but it looks promising, I hope to finish this week-end.
It is fun and rewarding to build, I can't wait to ear what it sounds like.
Fun video Trevor, I've seen worse kits. Thanks for sharing, let us know what you think of the audio quality once you've had some time with it. 👍
Interesting video, I've always wondered if these kits were worth the money & time, thanks for including the detail and your thought process. Alas I would not have the patience so will stick with occasionally swapping tubes and chips with my Little Dot headphone amps
Thanks Trevor...looking forward to watching your build very soon. And thanks also for posting the link to the amp...looks interesting and tempting!
Thank you Serg, much appreciated, I will put it towards my power bill next month
@@TrevorsBench 👍
$55 for the kit, $150 for shipping.
Nice work 👍I would have chosen the solder lugs instead of that pcb strip. Much easier to build and modify later
Thank you for sharing. Any recommended diy tube kits that are better made? Looks like this one failed the initial QC inspection.
Smashing job Trevor ,a bit fiddly but well worth the effort :-D
Maybe add a treble-bass circuit to Taylor the sound.
Nice little kit :-D
Just use a preamp with tone controls.
Trevor nice build, like you said the kit is a little with cheap parts. Good to use better electrolites.
I build a lot of tubeamps you gave me a lot of good advices for semiconductor designs 😂just want to give you a good tube related advice. To prevent noise and all kinds of noises. Do earth each connection to your star point earth. Even two caps in one connection in series to the starpoint may make problems.
I have noticed in the past of my wireing that some crazy things happend.
Always fun to watch your videos
Good show!
Thank you
Good stuff, thanks.
Please share your thoughts about the amp after having used it for few months. How does it compare to other amps (tubes, SS) you've used? Thanks
Thanks so much for you video. It would have been too much for me on my first attempt!
This is very educational. Now i know better how to read the scematic and what some parts do.
If it's using a 110V transformer (seems very common in these) - use a variac to dial that in. The filament voltages (I think it's 6.3V) will be high otherwise given 120V north american line voltage if that is where you are at.
I never did measure the loaded B+. There's a few other things I'd like to re-visit with this amp.
I'm thinking of posting a followup video to show how things went
@@TrevorsBench Yeah mate! I'd really like to see a follow-up video to this!
Thinking if it would be good to modify the volume control so that it maxes out right before the point where it starts to clip.
It's not the volume control, it's the amount of gain the tubes have.
Any good preamplifier should drive this no problem.
I just watched the unpacking and I'd seen enough
I am right there with you, this dudes going to either cut his thumb off or sever the wires in the package eventually.
If I was tempted before by those ebay kits, I'm not any more.
The caps might have to be reformed for another project. I buy the jameco bags of caps by the kg and never get a bad one
Thanks!
Excellent video. What is the box you are plugging in the power to? looks like it monitors voltage, current, and other?
Nice! I wonder if back in those days They should have used that stripe of contacts.....life would have been sooooo easier for us, repairmen. (sigh!)
Hi Trevor. Can you give an update on this tube amp kit. Whether it sounded good or if it blew up after a week, etc. 😂
I used it for about a month and it does sound great. It has a really clean sound although it does lack bottom end punch. It is only a few watts so it's really only good for quiet listening.
If you're thirsty for more power you'll find it disappointing
I like it and would use it more but my ears are always busy listening to the client repairs to make sure they sound good
get one of those $10 rotary hand deburring tools next time you're shopping for nothing, it only needs one pass to make sharp edges finger safe... much faster and much cleared than any sort of filing/sanding and it works great on holes/pipes too.
i've managed some stupid cuts especially on heavier devices and i'm done w/ that sport. :)
Fun to build, but 3 watts is simply not enough power to get any kind of dynamic range. When you think the complete amplifier could be replaced by a $5 chip offering at least 10 times the power, much lower distortion. Wider frequency range and sound so much better. Why 2 rectifier valves? both could be replaced with an EZ81 or Chinese equivariant. Or, as you said 2 x 50cent diodes. Maybe they had a few hundred in stock!
In fact, the more I think about it, why use valves at all? The only thing really in its favor is you cannot denie the pleasure of building such an amplifier, and not get electrocuted testing it. Would be good to see what the distension is, my guess would be about 2% @ 3 watts. Quite a good size output transformer for just 3 watts.
One thing worthy of note is that a 10dB increase in SPL is only perceived as doubling the intensity by listeners, 20dB will equate to quadrupling it. It is easy to see, that increasing the power tenfold, will only yield twice the perceived loudness level. Add the fact that tubes handle overdrive in a much more gentle manner than the semis and suddenly the difference is not that great. Distortion produced by speakers exceeds that of tube amps by quite a margin- check out a square wave reproduced by any multi-way speaker and yet ... Fun fact: tubes, especially triodes, remain the most linear amplification devices ever invented. One more thing, speakers convert 99% of power into heat on average, if they were half-decent, those 3watts would be more than enough to set the floor on fire.
That's modern thinking ..........more dynamics and detail than solid state ON GOOD HIGH SENSTIVE HIGHER IMPEDANCE SPEAKERS ..............indeed not on low dynamic modern high current hungry and low imperdance, compressed current LS.........wrong thinking in todays audio world ......but sure you believe you are right hahaha.
@@frankgeeraerts6243 Well Frank, I base my opinion on the following. 60 years in the audio industry. Working for Quad, Cambridge Audio, Founder member of Monitor Audio, Retailer Audio T. Three-way loudspeaker design for cinemas. Building testing and reviewing many amplifiers, valve and solid state. But, what do I know? If you think 3 watts is wonderful, that's 100% fine with me.
@@MichaelBeeny you must be deaf in one ear & can't hear out the other! I built a rather large pair of 'Majestic' speakers from the 'Silicon Chip' magazine that are rated at 97db/watt. This means they will produce a sound at a volume level of NINETY SEVEN decibels with an input power of just 1 watt! Considering a lawnmower engine volume is at about 75db, is 97db STILL not loud enough for you? We're talking about someone's loungeroom, or bedroom amp here.
Maybe you'd be better off on a cinema/football stadium audio forum, rather than dumping on domestic gear?
Don't forget Michael, this is a $300 valve amplifier, not a $10,000 or $20,000 amp that I've seen on sale. And how much would a 'cinema' size valve amp be worth? - $50,000? Leave us alone & go & play with the 'big boys'.
@@MichaelBeeny For someone with 'so' much experience in the indusry, you STILL have no Idea do you? Very WIDE knowledge with NO DEPTH! Lol!
You would be able to see better if your left hand wasn’t holding an entire spool of solder. You would also have better control of soldering. Try using a smaller diameter solder for ease of soldering. Using liquid flux would give you better joints.
were all soldering done pre-tinned?
I don't know if those yellow capacitors have a "foil" end (low impedance path). I also don't know if you watch Mr. Carlson's Lab, but he has a video on testing them with just an oscilloscope. I'm only 32 minutes in, though. New sub.
those rectifiers are very similar to 6x4 tubes. wonder how they run 100 microfarad caps while being rated for less than 20uf
The caps I installed are wildly oversized. I will replace them with something more suitable
is there a mic pre DIY KIT?
Dear Trevor,
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I’m almost 64, for reference. I love electronics, although I know next to nothing about them.
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From what I’ve seen so far, you do a great job, and I wouldn’t presume, nor know, how to criticize your work, and I don’t.
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The only criticism I can offer, and it’s completely constructive, I pray, is: You’ve got to improve your unboxing technique, at the beginning.
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You’ve got to start with sharp blades, of course, and from my experience, opening packages FROM THE WAY THEY WERE SEALED, is the safest solution.
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In a galaxy far, far away, I used to be an antiques dealer. And one thing I learned is that the transport of items, and unwrapping of, are the two main places where things can get damaged.
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Other than that, Bravo to you.
Wouldn't it have been easier to drill the PCB strip to match 2 of the holes as you weren't using all the connections anyway?
To get the true vintage sound, you need to add a dead spider and a bit of dusty cobweb, it just won't sound right without them, a dead woodlouse is a worthy opptional extra. Here in the UK, a toast rack is mandotory with all valve amplifiers over 50watts.
I'm more of a fan of the hot dust smells that comes off tube gear, can't get enough of that.
@@TrevorsBench Oh, you're one of those "Tube sniffers" I've heard about people like you! 🙂
I might have used pop rivets instead of those little screws for mounting components.
Hope you saw that one forgotten solder contact after you said at 2:24:05 "That's it, everything is soldered". Cap 100µF 50V.
I sat it out... 😂I have only a comment, and you have an amp.
Yes, the joint was soldered before i closed it up, good eye
If you don't mind my asking, how much did you have to pay the Customs people?
I had to pay UPS a additional $15 for taxes and handling fees
@@TrevorsBench Not too bad. I recently tore down and rebuilt that amp's big brother on my channel. I bought it secondhand, though, which is why I wondered about the Customs.
@@ScottGrammer Good to know, I'll come over and have a view, thanks
@@TrevorsBench Subscribed, BTW.
Not exactly a Heathkit. Great vid!
I don't see what your problem with the instruction is.
It was written in perfectly clear and of the best of knowing. The superior language Chinglish is most affective for to make the assembly of great wedding sound technologies and no eye wounds after.
Lol.
I'd check the cleanliness of the power supply...that sine wave looks a bit furry. Could be the source, though. Cheers, --bd
Its refreshing seeing someone bending the wires before soldering to make the connections. I cringe every time I see a video of just soldered pins and wires to make electronic sculptures.
You are genius .You checked the components which gave to you. Remember those are Chinese.😀😀
any follow up??
Not really. I used the amp for about a month. I enjoyed the sound quality but I needed to put it aside as I test many other amps and receivers as I fix them. LOL, I can only listen to one at a time.
It sounded really good to me, a bit weak in the power delivery aspect but that's expected. At normal listening levels it sounds great. Bit of a power hog when compared to solid state stuff.
Nice. I'm just finishing their AB push-pull ampllifier kit (also Nobsound). 2x12W. 260V inside... About $250 on eBay. The power supply cable it came with had the polarity backwards -- the main switch would have disconnected neutral, not live. Careful with this stuff...:)
Good to hear David, thanks for sharing your experience with us
9:50 Just point your smartphone camera at the text and activate Google Translate, it will nicely translate those Chinese characters into good English.
Google translate on an iPhone is great for translating text to English.
Trevor is (obviously) Canadian.
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They’re more refined up there. I think I should flee to Canada pretty soon, myself!
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Just to get away from the stupid United States!
Hey Trevor! Glad I found your channel - or that it found me! Twin rectifier valves is VERY weird for a low output amp such as this ay? I wonder if it would still operate if you unplugged one of the 6Z4's? I reckon 'yep'.
As has been mentioned, the load capacitor for a rectifier valve must suit the valve; it's not 'the bigger the load capacitor the better' at all! 330uF would surely blow the ass right out of your 6Z4! More like 33uF should be used I'd guess! I think you're going waaay overboard with a 620uF load capacitor, but I'm no expert.
I bought a very similar kit to yours from Banggood a few years ago, that used a 5Z4P rectifier, a 6N1 preamp, & two 6P3P output valves. I think it was around 300 Aussie bucks. The 5Z4 is like a 5U4, the 6N1 is like a 6DJ8, & the 6P3P is like a 6L6. I think it was specced at 7W per channel - not that you'd notice the difference to a 4W per channel amp!
My chassis & end timber plates was the same size as yours, but I didn't get a bottom plate, so I stole a piece of 16 gauge brushed stainless from work, which would help prevent the amp blowing away in a light breeze! I filed all the sharp edges of my amp, to save cutting myself up. I saw you were missing a bit if bark off your hands!
The rubber feet that came with amp, like yours, were cheap ass crap. The weight of the amp is too high, so I got some very nice 30mm diameter by 6mm thick brushed aluminium feet from Jaycar electronics.
Each valve socket position on my chassis was surrounded by punched holes like a Swiss cheese, so I decided to use 4 of them on each valve to mount lengths of polished up M4 threaded stainless steel rod. With some trickery using holesaws, I made up a 16 gauge stainless steel 'washer' for the top of each valve position.
These large washers were drilled to align with the 4 threaded pieces of rod, with an M4 nut above & below the washer to lock it in place. The centre hole in the washer was just a little larger than the valve diameter, so that the valve could be removed. The protective 'cage' around each valve was really strong, & looked pretty cool I thought, with each valve about 10mm below the ends of the threaded rods. Now the whole amp can be inverted & placed on the bench with all the valves installed & still be safe.
I wanted to keep the stainless steel 'theme' going, so I have used all s.s fittings throughout the amp, including M4 × 65mm bolts to secure the power transformer.
I used up more of the excessive punched holes in the top of the chassis to mount old school style tag strips for each valve, & I think I had to drill only a couple more holes ( with a COBALT bit!) to mount the large filter capacitors onto their own wider tagstrips.
I didn't use any of the supplied cable tie bases at at all. I got rid of that tiny little volume pot & swapped it for a regular dual 100k pot.
I don't understand why you didn't turn the input selector switch around 90° from where you have it know? Then the direction the switch actuator points is the selected input pair! Logical! Change it will ya please before my ocd causes me to pull my hair out!
I had a bit of trouble with looking up valve equivalents to those in your amp, although the 6P1 seems similar to an EL84.
The gold (?) plated 4/8 ohm speaker terminals they supplied with my amp all looked like they were missing most of the gold! D'oh! So of course, I had to replace them all with some Jaycar replacements. Phew! Those shit looking terminals would have had me climbing the walls!
But yeah, I had fun building mine & watching you build yours too! Now that I've seen this video I'm inspired to go & FINISH mine! That's right! I still haven't finished mine yet, but the thing is I get the most fun out of actually building it.
I have also completed a 130W/channel $2500 full house custom 'Silicon Chip' magazine Ultra-LD Mk4 amp in the mean time, so my little valve amp is just a thing of beauty to look at, at the moment.
Thanks for the video Trevor! It was fun to watch, gave me the inspiration to finish my own amp, & the opportunity to rave on to someone about my little amp!
Would it have been too much to ask that you played music on it at the end of this 2 and a half hour video?
Are you on Patreon, or another funding source?
Can you be on a funding source? I’d love to support you !
Only 220 volts not 230 volts for UK.
I was thinking the same for the Netherlands. Too bad everything they sell is 220.
1/2 way thru and so many issues, especially the most expensive components, Tubes with corrosion. Looking forward to second 1/2.
The x-class cap across the power switch makes no sense. When the switch is on, the cap would be shorted out. It should go between line and neutral. you might want to consider a couple of Y-class caps between each of line and neutral and earth ground.
Because the cap isn't for EMI suppression, it's for arc suppression on the contacts
My bad. I've just seen a lot of confusion out there with respect to X- and Y-class caps
I just checked your link to this tube amp on Aliexpress, it's only $57.40 US, but they want $153.12 US shipping charge. Not cost effective for people in the US.
They are about $200 anyway you slice it. They factor the cost into shipping
@@TrevorsBenchI didn't know that, thanks!
Cheap, good for learning only, no resale value and not collectable too.
Heathkit style
This is $55 plus Shipping is 48 bucks 🤷 i bought this exact model already constructed for $100 ..
WELL, IT'S NOT A BUD CHASSIS !
The price looked good but 155 shipping to nova Scotia is my anit tube reaffirmation. Solid state. I love how loud the tube amps are at low wattage though.
we chinese never cut the box from the side
IM DISTORTION, HARMONIC DISTORTION, FREQUENCY RESPONSE ??? TIM ??? NO RINGING AT 400HZ, WHAT ABOUT OTHER FREQUENCIES ??
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show all calculations on paper.......................
DO BAD ITS NOT A HEATHKIT MADE ENTIRELY ( EVERY COMPONENT ) IN THE USA, NEVER AGAIN !!
Don`t say "DC BLOCKING" capacitors. Say "COUPLING" capacitors.
Your killing me opening that package with that peace of shit utility knif !
I Definitely would not want to be around you when you have a knife in your hand. The worst box opening I've ever seen . Simply dangerous with a knife
I'm happy you're not around me either, go back to your safe space
@@TrevorsBench Wow why do you have a channel if you don't take criticism. Talk about someone needing a safe space!
@@vh4504 you’re literally crying about a grown man using a knife to open a box 😂
Shut up and post some box openings of your own you useless twerp.
That was a pretty dull razor knife.
That's some of the worst unwrapping I've witnessed sorry dude. Cutiing the wood open made me wince.
You can tell me I am full of shite but this baffles me. You rake blokes like Lyle Caldwell and Jason from Australia. These two lads build great amps, same as Nik from Ceriatone. Why in the bloody hell would you waste money on Chinese junk like this? I just can't believe anyone would waste their money on something like this. Are you that bloody bored?
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It's....not looking good. This guy can't unwrap a parcel and uses the most dogshit knife in the universe. It takes AGES too. WHY? WHY? WHY?
You wouldn't use it if it's not CSA approved?
I can't stand to watch this.... bye.
Is this soldering learning tutorial? If so, you do it wrong. Never solder a lug, which is screwed to the chassis. Heat dissipates thru it and you need raise your solder temp to get tin flow to make solder. Bit of nonsense. And the cable you cut from the power transformer is not a ground. It is a screen between coil sections. And power transformer will never have a 3v heater winding (it may be center tap from 6.3v only) there are no tubes with 3v heaters (maybe just a few very exotic).
You need to educate yourself a little, ....a lot
Unpacking skills realy bad
Seriously? you're going to judge me on my unpacking?
@@TrevorsBench offcource the way you do that says a lot over the way you are getting to solve a problem or a task….. but no offense….
STOP SENDING LONG VIDEOS REPORTED FOR ABUSE
Are you ok, John ? Personally I’m going to subscribe because of the long video and all the efforts it takes 😀
Don't shoot on thed piano player............hahaha
How are all these abuse reports working for you?
@@TurntableGuy maybe a doll would be useful so John can show us where he touched him 🤷♂️
Clean your solder man , make it easier and faster!
someone get him a sharp knife
Wow, thanks, I will avoid it.