Elekit TU8200 - 6L6 Single Ended Tube Amplifier build Part 1 4K

[@williamstaten8102]

Hay, I'm color blind and love this stuff. I just cover up the other colors so I'm just looking at one at a time. Like your build video's. Working on building a amp but without tubes. Been seeing tube amps coming back. I know a kid 15, he wants a tube guitar amp!

[@12voltvids]

Tubes are back in a big way. All one has to do is listen. Of course musicians knew this all along. Most professional musicians use tube gear.There used to be a color blind TV repairman out in my neck of the woods, and after he fixed a TV the owner would bring it to my shop to get the color fixed! It was hilarious. They would phone the shop I was at and ask the hourly rate, then call the guy with the mobile truck, and then bring the set in working but with very bad color, and we would charge the same price to fix the color as we would have to fix the thing right in the first place.

[@williamstaten8102]

Thats funny. I just mix up red and green while there together. Red ball in green grass, I'm lost.. Keep up the vids. Fun to hang out.

[@THEtechknight]

EnChroma glasses. it fixes red-green colorblindness.

[@petr8068]

Sir "12voltvids" thank you for your detailed video that helped me in my own construction of the Elekit TU8200. Fo this money, amplifier play astonishingly, no doubt about it! I wish you much good.

[@MarcelOoms]

Very nice! The power transformer is even an R-core transformer by the looks of it: unlike the C core, its core is one solid piece. More expensive to produce, but they are very efficient and have very a low stray magnetic field! Outperforms the toroidals.

[@12voltvids]

Right it very well could be an R core. Doesn't specify what it is, so I just assumed C core from the look initially.

[@grodard9]

Hi, I read in a forum that there is a "surface mount" something on this TU-8200 kit; looking forward to see how you do it as I am planning to order one soon. I am pretty confident with the soldering but I still ordered a little practice gizmo. Being very small it will be a good practice. Your very detailed work is appreciated, thanks et bien le bonjour de Montréal.

[@swarfrat311]

Ah, yes! Back in the day, I lived about a half mile from a Heath Kit store (Redwood City CA). Like you, I built a ton of audio stuff, test equipment, etc. I also built some Knight kits (Allied Electronics). I still have some of the stuff tucked away and haven't been used in eons. The electrolytic caps are probably shot, but I might revisit me stuff and get it working again. Thanks for the video. BTW, where did you order this kit?

[@12voltvids]

The first Heathkit I built was an osciliscope. Was nice, but no calibrated inputs, so it would show waveforms but little else. The power transformer burned up so I tossed it and got the Iwatsu that still sits on my bench.I have a Stereo receiver around here I will put up some day. I also built a digital clock, that used a numitron tube display. I sure wish I still had that clock. I never though the numitron displays (they are incandescent for those that don't know) were that cool. The neon panaplex (plasma) were much cooler.Heath also had one of those, but it was much more expensive. The numitron filiments eventually burned out, and I have no idea what happened to it. I have a panaplex stop watch board kicking around, I should see if I can get that working again. I remember the last time I played with it I got a nasty shock from the dc-dc converter, but it was cool just to see light up.

[@markeastman8494]

Back in the day (late 70’s), I worked at the Heathkit in St. Paul, MN. My first kit was a 25” color TV 😩. After that, the store manager and I split building all the demo kits. My favorite job.

[@zx8401ztv]

Doing a smahing job sir :-D Sounds like your solder needs a better quality rosin core, i used to use multicore brand, the thin stuff was better for melting, better control too, later i used savbit to make tips last. Some solders have a very sweet smelling rosin, almost good enough to eat lol. Yes i understood your diagrams, valves arnt my thing but they do have a different sound, ive seen a lot used in tv sound output, and small portable record players. Ive tinkered with a few valve based radios, but most of them had good valves, the capacitors and old carbon resistors were the ones to fail. Enjoyable to watch you assemble it, ive done kits too :-)

[@DAVIDGREGORYKERR]

I have seen an Vacuum tube amp like the one you are building, I think it was made by KRONUS Electronics LTD in Dungannon Northern Ireland. while at a HIFI exhibition in Stornmont Hotel in Belfast 15 years ago, just a stones throw from where the Titanic and the Olympic was built, You could try and source Multicore Solder 60% lead 40% tin from the guys at Loctite from some of your Hardware store or just ask for solder made in the UK.

[@garykelly2267]

My TU-8200 volume drops and sound gets gritty after 1 hour of music, regardless of the source. When turned off for an hour and back on it does the same thing over again. Tubedepot tech is no help. Any idea on what the problem may be?

[@russellesimonetta3835]

Looks easy, resister don,t have polarity?easier that p2p. Japanese quality. Can,t argue with it. Perfectly organised. Where can you get it.

[@pfloydphanatic]

I love your videos... just please bring the old theme music back please lol !

[@12voltvids]

It will return, I have a few versions I will be mixing up.

[@glenngoodale1709]

Great video (as always)!!!

[@diljithtinku]

Sir can you please suggest me a best 6l6 circuit?

[@vonzigle]

Tubes forever! 😄

[@zeoNRider]

Nice, comm. with part 2.

[@12voltvids]

Part 2 is being edited now. Should have it ready to upload tomorrow.

[@Washburn-rr5eh]

I am looking so forward to tutorial !!

[@kevin2960]

You can do class A in Push pull. Class A class B ect. Is really just a bias and circuit type. You are talking about class A single ended, even in this there is A1 A2 ECT. In se.

[@12voltvids]

This is a class A amplifier. Class A is a single ended amp. Just a single tube per channel. This has 2 per channel, a preamp and a power tube. The 12ax7 is used as a 2 stage triode preamp. To make this a class b or an, would require 2 output tubes and the 12ax7 would be driving each output out of phase. The 2 plates would be tied to an output transformer with a center tapped primary. A class ab and class b are the same thing, just the bias is set higher so that at idle both tubes are kept slightly in conduction. Class A on the other hand is under heavy conduction at all times. There is about 50% of the available current flowing through the tube under no signal condition. As the signal is presented the current increases and decreases with the waveform which induces the signal into the secondary of the output. Class a are the most accurate and lowest distortion but are very inefficient and low power.

[@kevin2960]

@@12voltvids I was just explaining that multiple tubes can still be class A.

[@12voltvids]

@@kevin2960 Class A is single ended. By nature all the preamp stages are class A. This applies to solid state amplification as well. All your amplifier stages in rf, if, audio, and video are all class A. Where class B comes into play is the output stage as they become much more power efficient. A class A amplifier is well below 50% efficient. Let's talk in low voltage transistor power. You have 12 volts onto your output single transistor stage. With no signal the voltage on the collector would be about 6 volts. The input to the audio output transformer 12 volts and the transformer would be partially saturated if you used a transformer output. Of course you could use a resistor to provide the load for the output collector load, or use an emitter resistor between emitter and ground or both. Generally there would be a low ohm resistor on emitter. Say .2 ohms. Under no signal about 50% of the max power would be flowing through transistor or tube and this will generate much heat. The dc is blocked from getting to the speaker by either a capacitor, or use an output transformer. All tube sets use output transformer but solid state can as well. As the signal modulates the base of the transistor or grid of the tube the collector, or plate will follow. As the signal falls, the transistor goes out of conduction allowing the voltage to rise. As the voltage at the bass goes up, the transistor goes into conduction and pulls the supply towards the emitter potential which is close to ground. That is how class a operates and coupling capacitors between stages block the DC from the prior stage. Not efficient but accurate and clean. Class B (class AB is the same thing, just biased a little higher to keep the non conducting stage from going into full cutoff) uses 2 output transistors or tubes. One Npn and one Pnp type. One transistor has collector connected to positive rail, the other to negative rail. Emitters connected together (through low resistors) and the speaker to emitters. The wave is split in 2. Positive side of waveform goes to positive output and negative to negative output. At every cross over point the transistors switch. On class B one cuts off completely as the other starts. This causes what iij s called cross over distortion. Class AB adds more bias to keep both transistors slightly biased on so that as the cross over is taking place the opposite polarity stays slightly I conduction to reduce crossover distortion.

[@mango3586]

very very interesting video thanks

[@RobertKohut]

Nice!

[@BlankBrain]

Don't sell your TU-8100! Build an active crossover and bi-amp your system. If you don't love it, you can always sell it later.

[@12voltvids]

Yes I was thinking along the same line, as my Altec Lansing speakers have dual woof / tweet inputs for bi-amp setup.

[@umajunkcollector]

agree, bi-amp is kewl

[@zeoNRider]

What is the price of this kit?

[@12voltvids]

Runs about 750 USD. Up here in Canada 1000 CDN, Not cheap, but relatively inexpensive as far as tube amps go.

[@zuheyr1]

Still on? Can I still buy?

[@tawilk]

hey, don't knock my Yaqin MC-13S. it sounds great and is a push-pull amp.

[@12voltvids]

I know how good the yaqin sounds. I have an mc10 and it replaced my McIntosh 1600 in my music room because it kicks it's ass.

[@williamsquires3070]

Not to put too fine a point on it, but... you do realize that only electron current can flow in a tube, right, since no charge carriers of either polarity can escape the cold plate, and only electrons leave the hot cathode (or filament, in a 5U4, etc...). Conceptually, I suppose it doesn't matter; somewhere, in a parallel antimatter universe, positrons are leaving a hot antimatter filament and rushing towards a negatively charged plate... :)

[@12voltvids]

I know exactly how a vacuum tube operates. Electron are boiled off the cathode through thermionic emission. The cathode is at ground potential, which is negative with respect to the positive charge on the plate. As electrons rush to the plate they in effect bring the plate closer to ground potential, which increases the current flow through the current limiting resistor in the case of preamp or buffer stages, and through the primary winding of the output transformer in the case of the output tubes.In the case of the phase splitter tube, the cathose follower resistor is a little higher value, which allows the cathode to float above ground potential, so when the tube conducts the voltage will rise, as the plate voltage drops, creating an inverted signal through the coupling capacitor, and thus creating the push pull drive signals for the class B amplifier. Believe me I took a 4 year apprentice back in the late 70's. I started it when I was still in high school, and was trained by an old army electrical engineer. He lived and breathed vacuum tubes, and I had the theory drilled into me constantly, including the very real dangers of working on tube gear. Those capacitors typically did not have any bleeder resistors, and could hold a charge for a bloody long time, and yes I was bit many times working on tube gear. Vintage gear needs lots of respect as many things can bite without warning.

[@umajunkcollector]

push pull use smaller transformers and run cooler.

[@12voltvids]

Yes they do, but they also don't sound as good as a single ended class A.Class A is not very efficient, but much more accurate due to no zero cross distortion being introduced.

[@umajunkcollector]

oh well, my hearing isn't that great anymore, and um not that fussy. Funny, tubes and distortion go together, guitar guys WANT TUBE DISTORTION. They prefer solid state for cleaner sound.

[@12voltvids]

It depends on the sound you want.As far as accuracy no tube amp can match a solid state amp. Not even close. Solid state amps are exceptionally clean sterile sound.Tubes by their very nature are not. However saying that there is something almost magical about listening to music through a tube amp, especially a single ended amp. On paper they look horrible, with distortion numbers that would embarrass an engineer, however it the type of distortion that they produce that is what is desirable.When a solid state amp distorts it produces odd order harmonics, and the ear is very sensitive to those types of distortion.Tubes on the other hand produce even order harmonics. Even order harmonics are exactly one octave above the fundamental tone. So the note E for example, will produce a harmonic "e" the next octave up, and so on. This is what many guitar players just love, as it gives their axe a big phat sound. They do the same for all sounds, when they distort. I have both types of amps. I use my hybrid studio amp when I am producing and editing because it is clean and powerful, and due t the 2 12AU7 dual triodes used in the driver stage it has a warm sound.For listening, I use a full on tube amp in my living room, and now with these kit amps I will have a class A for my studio to listen to music on. I definitely prefer the tube sound, any day of the week. My hearing is less than perfect too, and I still prefer the tube sound.

[@umajunkcollector]

I like both too. But cheap tube amps are garbage. I hate anything that used less than a 6" full range speaker, lol. Now a HK Citation ii is a dream amp for me.

[@12voltvids]

Yaquin are considered a low priced amp as tube amps go, yet they sound fantastic, and with a few mods sound even better.I know several people with Yaquin MC10 and none have had any complaints and they are in the sub 1000 range and deliver a fair bang for the buck. I have an MC10T, have had it for several years and it sounds very nice and I am just driving a pair of 8" 2 way ceiling speakers.

[@Synthematix]

Arent chinese valves junk?

[@12voltvids]

No, some of them are very good these days.Early ones were not the best, but I have heard some wonderful sounding Chinese valves. I am running Chinese tubes in my Yaquin amp, and it sounds great.

[@Synthematix]

ahh cool thats ok then m8 init, i was after a valve pre-amp for my tape deck

[@seans1102]

700 dollars...its not that good.

[@12voltvids]

It was 1000.00 here in Canada. That is a lot of money for an amplifier with less than 10 watts per channel, however check out the price of tube amplifiers. A 8 watt single ended amp from a boutique manufacture runs about 2,500.00 for the kit is a bargain, and sounds just as good. There is such a sonic difference in tube amplifiers, especially single ended units. That is why there is a market, and that is why audiophiles pay as much for their system as most people do for a car.