Journey to the Center of a Tube

Your host Robert Hull takes you on a journey to the center of a tube. You will be astounded at the beauty of this SED 6L6GC tube, so close you can almost touch it. From the outside glass to the deepest filament, see every element in vibrant color ... just please, refrain from feeding the electrons.

[@moendopi5430]

Pretty cool to see inside a tube. Quick note: mica isn't a rock, but a mineral. It's actually a group of minerals that are sheet silicates with Moh's hardnesses of 2-2.5.

[@ILIEKCAKESAM]

I love how enthusiastic Rob is about electronics. He has really taught me alot :)

[@spitfire27028]

when i was younger, id always imagined blinking myself small and tiny, and wandering about inside the old tubes i found around in the family TVs and radio. Yes, ive taken a rear television cover off when i was about 5yrs. old. I took all of my toys and things apart. Usually, got it all back together. Back then when i was a child. Awesome video TY so much.

[@paulj0557tonehead]

Had a 1945 Stromberg Carlson field PA made for the navy. It was housed in a green ammo style box with latches around the center. Flipped it over to remove bottom and inside was the pristine circuits. Used a dynamo instead of a transformer. 12V in one armature and the other side was 600V on that armature ( commutator brushes like any motor). Another box the same size, roughly 18''x9''x9'' was the 12V & 8V battery supply for this amp. It had a 5.2ohm output transformer. 60 watts RMS.1 volume knob

[@kenw.1112]

My experiences as a electronics technician for over 4 decades has taught me that TUBES ARE SWEET! They are tough under various situations like spikes , surges , Emp. , etc. That's why Rf transmitter , microwave devices use a MAGNATRON . Think of a Tube like Hercules /Arnold. Believe me I have seen during troubleshooting a Horizontal 15,757hz (scan freq) 6LF6. Horiz. Output tube with a grid screen problem of incorrect bias which caused over saturation of current from cathode to plate causing the tube to over heat /glow red. Found a open bias resistor that corrected the bias issue. The tube survived the overheating esp since the customer would run the set with such bias failure . Anyway mr. 6fl6 kicked ass. Transistors under such biasing situation will cause "avalanche " of the pnp/npn junctions. Avalanche directly leads to junction thermal runaway. ( leakage/dead short in the junction.) TUBES SOUND GREAT OVER SOLID STATE NO EXCEPTIONS! Thank you for reading. Ken

[@gillsy58]

Robert Hull! A very helpful guy. I have a '96 Fender blues Deluxe. V1 and V2 JJ 12AX7, V3 JJ 12AT7, outputs SED 6l6GC. SED's are biased at 425v plate, and 32mA. Idle disapation is 45%.A very sweet combination. The high end of the SED's are smooth and sweet. My Tele' rings like a bell without harshness.

[@MoronicChannel]

Extremely creative title!! Vacuum tubes are superior in power output circuits..to this day..noise reduction is awesome. When younger, I was technician.

[@metasonix]

The screen grid runs very hot, because it is absorbing some of the cathode current. It is coated with graphite, both to help cool it by improving infrared radiation, and to keep it from emitting secondary electrons (graphite is very good at this). This has nothing to do with "improving the tone". The control grid is plated with gold, also to help prevent secondary emission. Gold gives a smoother surface than graphite, so it's better suited to the control grid.

[@veryoriginaluserid]

Thanks for taking us inside the tube! Next you can take us to a tube factory so we can see how they are made?!?!?!?!

[@KP11520]

A very long time ago, my mother's first job out of HS was a tube assembler at Amperex in Hicksville. She was a perfectionist so she got HQ duty to build tubes used in ICBM's. Unfortunately, not Bugle Boy 12AX7's. If we had a crystal ball, we should have bought cases at a company discount, direct from Holland. It would have made up for the poor pay and conditions and the insulting pension for almost 25 years. Interesting to see the dis-assembly! Thanks!

[@TubeDepotTV]

Your mom had a cool job ...

[@patcoughlin3104]

+TubeDepot aaah ya mudder works in a tube factory,, sorry couldn't hep mysef

[@GBlunted]

This was quite the teardown video! Nice camera work, editing, narrating and exceptional audio mix quality! Would love to learn more from whomever crafted this piece of media... =)

[@Satchmoeddie1]

Wow I am gonna call you, "Fire Fingers" for yanking that hot tube out of that Mesa Boogie! I though the getter was flashed with heat and a high freq inductive wand. I want to see you reassemble the tube. Philips had a great tube book with photos & drawings. I have one of the few copies in English. Pete Millet has it in Dutch (PDF download for free), & many more audio books/telco/misc, (mostly vacuum tube) including RCA Designer's manuals. There is even one with 3D diagrams, but no glasses.

[@FransvandenBergeMuziekschuur]

Thank you so much..... What a wonderfull presentation...

[@coal4life]

Way cool. Thanks for explaning what each part is and what it does. Gave my 100 watt Mesa from the early 80's to my metalhead son. After I replaced the tubes and went over everything it sounded much better than when new. Wished I'd let him have a different unit. After destroying vacume tubes back in the 60's and picking through the parts I have a whole new perspective. I think I'll get that old turntable out and................

[@Sniper3100]

Very nice presentation - well done!! Thank You

[@RODALCO2007]

Awesome video and excellent explanation. Thanks for showing

[@shyleshsrinivasan5092]

Thanks a lot for this video ! Very informative and satisfying ! Please put more of these !

[@dercebe]

Nice illustraion, good work on the video. A few additions I might want to add, though: The tabs that center the assembly in the envelope are most likely not made from aluminium. I am not 100% sure by the looks of it, but solid aluminium does not lend itself very well to be used inside an vacuum environment due to the oxide layer on the surface. It is used on anode coatings but this involves some processing on the pump to make that work. Cooling fins on the grid are to keep the grid cool enough so it does not become an electron emitter itself. The proximity to the hot cathode and the posibillity of barium migrating to the grid from the cathode coating can cause the grid to become able to emmit electrons as well which is not wanted. The getter usually does not contain pure barium as this would be difficult to handle during production, instead it is usually an alloy of barium with other metals such as aluminium and magnesium, both of which are not very good getter materials by themself but help to keep that alloy reasonably stable and workable. Sometimes nitrogen compounds might be added to help with dispersion, I am not sure how common this is, though. Sometimes there is an additional protective coating over that alloy to protect from moisture. When the getter is evaporated this will burn of before the metal evaporated onto the glass. The layer on the glass however is mainly barium in the end. The coating on the cathode is a mainly barium oxide, strontium and calcium oxide might be added, too. Usually it is applied in the form of barium ( or other ) carbonate as the oxide would not be practical to handle in production. When the cathode is first heated in production, the carbonate will convert into the oxide and the gassy byproducts are removed by a vacuum pump or the getter. In operation some of the oxide is reduced to metallic barium which effectively is the electron emitter, not the oxide iteslf. This is btw one reason a tube with this kind of cathode needs a getter, no matter how clean you materials and process are ( which today they are usually not ;-) The cathode itself produces some oxygen in operation which has to be removed. The gold plating on the grid also helps in reducing unwanted electron emission from the grid, but there might be other reasons I am not aware of.

[@lewismrotzek1115]

Amazing visualization ! Thanks for the great video!

[@CoolDudeClem]

You're video answered a lot of questions I had about tubes (known over here as valves), also, i enjoyed the music, really nice!

[@bryanswain962]

Killer video! Thanks for showing us how they work!

[@nomorokay]

The difference in sound seems to be audible even within the linear range of tubes, if they truly have a linear range. Swapping tubes to change the tone is called "tube rolling" and is popular with some tube amp lovers in their home stereos. Some tube fans keep sets handy, so their amp can sound one way for a while, and then a bit different when they feel like a change. It's almost like changing the flavour of your food. I use Class D amps myself, so I spend more time listening than tweaking.

[@stratdude83]

very cool video...ingenius design behind tubes

[@44avalanche]

Excellent video!

[@ianwlad]

amazing video!

[@Tony-Tequalla]

Fascinating! I always wondered how the tubes were assembled.

[@moga1968]

Great! When i was 10 years, last 42 years i colect tubes and always Impres from all this inside. Wstching hours, want to understand all this.... thsnks a lot, Moti from Israel

[@B2Rockin]

This is so cool! Thanks so much for doing this!

[@viswesh713]

awesome video..

[@ourlifeinwyoming4654]

This is FANTASTIC!

[@PeterPug]

Fantastic vid. Thanks!!

[@tpmbe]

Thank you , enjoyed the detailed journey.....amazing

[@PaulGaijin]

Absolutely loved this video, I'll never look at my tubes the same way again! Thanks

[@AusRadioHistorian]

If you're talking about CREATING a musical sound - then yes, the distortion in the amplifier (ie an electric guitar amplifier) becomes a part of that sound creation. However, distortion of any kind plays no useful part in sound REPRODUCTION, so that in the playing of records, the distortion introduced by a valve amplifier is difficult to justify.

[@AusRadioHistorian]

I know that my comments are not popular on this subject, but it depends upon whether one is aiming at sound REPRODUCTION - in which case one wants maximum transparency, no colouration, flat response, maximum loudspeaker damping and a linear transfer characteristic. That can ONLY be produced by a well designed solid-state amp. If, however, you're using an amp for sound PRODUCTION, you want tube distortion to suit part of the sound coloration of an electric guitar.

[@qi5bz]

Awesome Tube Disection Video :-) Now tell me a secret how to get rid out of rattle on Bugera V5 EL84 or rather 7189A, as that drives me crazy ;-)

[@dave1812]

Nice Idea! Thanks for answering my Question.

[@jackp1351]

Very informative and fun to watch video! A beam tetrode 6V6 was chosen instead of a pentode 6V6. Cool to see what a beam former looks like!

[@SonicProvocateur]

Great video! Thanks for sharing! (and Boogie on!)

[@tubical71]

Very cool demonstration...;) TANX for sharing..!

[@Lydomina]

I should have been asleep a long time ago. Instead I'm watching all your videos o.O

[@AusRadioHistorian]

If that is what you believe, and you are happy with that, so be it.

[@spewdog]

Wow, you are very knowledgable. Thanks for this great video!

[@KernowGarage]

great video :)

[@BlueTubeProject]

5 Stars from the Blue Tube Project!!

[@fergozzi1]

Nice video! Thank you!

[@HMohr]

You guys are AWESOME

[@AusRadioHistorian]

As a trained electrical engineer, 55 years old, I have to say that the fascination with tubes escapes me. The need for an output transformer between the output tubes and the speaker wrecks phase response and loudspeaker damping, especially at low frequencies. Tube distortion figures, even with moderate feedback, are bad. It may be an acceptable type of distortion, but it's distortion nonetheless. I would reccomend reading books by the the solid-state designers Douglas Self or Linsley Hood.

[@silasfatchett5693]

To a guitar player the distortion produced by a tube amp is not only acceptable, it's desirable. It may be called an amplifier, but it is really an amplifier/effects unit. I agree that if you're looking for hi-fi and you don't have money to burn, then solid state is the only way to go.

[@mr1enrollment]

As a mature 65 year old EE, I suggest you listen to a Vintage MC 75 system playing vinyl. And then reconsider. Yes there are a bunch of myths about tube sound. And there are nonsense terms dangled around the audiophile community, yes they think power cords and crystals improve the sound. Nut case exist. But these system do sound fantastic. Also note the Mcintosch transformers are amazing devices. Chill Mr. Trained, and listen to the music.

[@Chromatype]

I know what you are talking about, however, that subtle tube distortion adds TONE...thickening the overall sonic presentation in a noticeable way...judiciously applied low level harmonic distortion adds characteristics that can be manipulated by the variable attack of the musician...aspects which seem unavailable which many solid state amps...so it really is an interesting discussion and depends on what one is after in expression.

[@Nephilim-81]

Unbelievable. Amazing tech. I just love it. A beautiful science.

[@murmaider2]

thanks! this will help me with my project

[@jlazelle1]

Tube Depot rules. Fast shipping and great quality on matching/testing. Just changes out tubes and it made a hug difference in my amp. Also on sale.

[@emppudst]

Good stuff!

[@ericbusa]

Great video thanks

[@TubeDepotTV]

glad you liked it.

[@gjtube37]

What an excellent video and lesson!!! Any chance to have a similar video on the 300B? I have a Felix Audio Envy headphone amp and would love to learn how the 300B works. Thanks very much!

[@Thirdgen83]

Perhaps you should listen to a Fender Twin Reverb guitar tube-amplifier. It just doesn't get any cleaner than that. The tone just "sparkles", and distortion is very low until the amplifier is driven into saturation...

[@Satchmoeddie1]

I found the misplaced test lead wire, & my parts are here from China so my new curve tracer test jig is nearing completion! I made it like a 570 test jig, only with P1, P2, G1, G2, and K1, K2 coming from the tracer, and G1, G2 and htrs coming from separate supplies. You patch in to a row of 2x12 5 way jacks accordingly. R174 cabled with BNC cons go to a switch that selects tube 1 or 2. The heaters just stay on in both tubes. I have every common socket except subminis. Forgot them, Hmm>??

[@turboslag]

Your missing my point. Valves do not have a sound. It's only the circuitry they operate within that imparts a 'sound' perceived by the listener. So if the HF response is rolled off early for example, this may be perceived as a warm tone, but it is not the valve causing that. Two valves of the same type may sound differently, only due to manufacturing tolerances that require different circuit adjustments. There is no mystery to electronics.

[@JPa311979]

I am wondering what your opinion is on a hybrid amplifier? A tube used for the preamp stage, and transistors for the driver and output stages. If made correctly, could you eliminate the need for an output transformer? You would probably need one between the preamp and output stage:( ? You should still get that tube sound though, a friend of mine eliminated the need for an output transformer by wiring a bunch of cathodes of preamp tubes together. That seems like a waste of tubes though!

[@jspinks2388]

I ran those JJ 6v6s right about 420-430v on plates 400-410 on screens for a good 6 months sounded totally kickass I loved the midrange of them when wound up it was almost EL34 like in a way or maybe still kinda 5881 or 7591 like hard to explain but still it was a more interesting midrange character as well as nice bass the highs were a bit on the harsher side for my taste though. but after about 6 months they started sounding lifeless pretty much.

[@Thirdgen83]

There is a reason why the most prestigious and expensive home theater equipment is tube-amplified...

[@JLConawayII]

It's really amazing that such a primitive technology still hasn't been surpassed by solid state circuitry.

[@Fendervana]

@Timmy Mcfistfull, the beam forming plates and staggered grids were added to power tubes in the 1930s as a solution to the Pentode patent owned by Philips/Mullard. The Pentode has an extra suppressor grid with no beam plates. Anyways, read the wiki on pentodes and tetrodes before making more rediculous comments..

[@RODALCO2007]

@TubeDepotTV Thank you

[@skipplet]

Playing Steely Dan there... nice!

[@honkmagic]

so the stronger the positive signal the more electrons to the plate if im understanding correct? so the harder you play?

[@marvinlemartien2186]

tube amp are the best !

[@picobyte]

That tube looks exactly like the ones I dissected in the seventies. Are modern audio amp tubes still exactly the same?

[@dave1812]

Cool Video! How did you cut the Tube's Glass? Can you cut them with a normal Glasscutter?

[@jspinks2388]

I'm enjoying my old Tungsol 6550s mostly right now :) stunning highs and lows waaay too laid back of a midrange though. KT88s are far more musical in the mids in my opinion xD. I thought about getting these SEDs though or Svetlanas to try out not sure doesn't sound that bad though, I had some JJ 6l6 and 6v6 they both died within 2 years and after a year they sounded lifeless lol. and the JJs have the most horrible matching I ever seen lol talk about drifting to hell and back lol.

[@perfuzz]

Might be true, but there are iron alloys much cheaper then gold that can be used if duration is the main focus.

[@perfuzz]

I don't think the word emit is harder to understand then the word boil. Further, I'm a physicist and I find it equally hard to understand the mechanisms behind the physical terms emit and boil. A well. just a thought. Nice channel you got going!

[@jspinks2388]

Odd though I was running some 6l6 before I put in the El34s never had a single problem with them.

[@murmaider2]

@TubeDepotTV school project actually, on vacuum tubes

[@TheJacobashe]

What's the white cathode coating made from? Does it have a lower work function than the metal and is that why a coating is used? Questions, questions questions....

[@Jennifer_Prentice]

I know this is very old video but if your still around maybe you can answer me a question. That tube you pulled apart looked pretty darn solid and not sure how normal use could cause shorts or make a tube fail. What exactly happens when a tube gets older and starts to not perform as good as it did when new? Does that coating stop producing electrons as well ?

[@Agent24Electronics]

A tube wouldn't typically go shorted in normal operation unless there was a preexisting manufacturing defect. But rough handling or electrical overloading can cause damage.The cathodes do become less emissive over time, however, which is the normal wear-out failure mode of a tube.

[@Jennifer_Prentice]

@@Agent24Electronics Thanks for the response . So when older people say they used to used tubes in there amps for 20 years without changing them this is actually possible?

[@FarleyHillBilly]

@@Jennifer_Prentice Cathodes are supposed to last 1000 hours, but many will do much more than this.

[@Jonathan_Doe_]

I hope no one attempts to pull a hot tube out of a live amp after seeing that intro. It was a cold one set behind the amp people. Power tubes get hottt don’t scald yo self.

[@cactus445566]

Lol, any part of the circuit that shapes the sound has a sound. Valves are no exception; they aren't just a simple amplifier, they're very complex and hard to describe. They're as much a part of the circuitry as the biasing resistors, high-pass and low-pass filters around them. When we say they have a sound it's in that context, how it shapes sound there, just like you'd describe a strat's tone in the context of being connected to an (clean or dirty) amp. Not my fault you can't hear it ;).

[@freddielaker2]

Yeah too good - Wish I could shred like that but fingers dont do what they aughta these days lol. sorry if i confused you

[@Sixalienasa]

@TubeDepotTV Thank you, it makes it a little easier to comprehend. I am still a little vague as to how exactly the Triode actually " Amplifies " the input signal, Is it getting a kick from the extra Grid Voltage?

[@jspinks2388]

Part of the problem was the underrated screen resistors those Legacies had lol

[@metalmanin]

actually your anode is what they call a a suppressor grid and your outter plate is actully your collector another words your cathode emits electrons to your the collector and your collector is the outer plate of a tube your anodes are your control grid suppressor grid and your screen grid and that inner plate is actually your suppressor grid thats how a beam power tube such as a 6L6 or 6JS6 or what ever like tube works.

[@JPa311979]

Does the Tube Depot manufacture its own tubes? I am just wondering because of your logo on the bases. Are there other tube manufacturers still in the U.S. ?

[@metalmanin]

@TubeDepotTV @metalmanin nope a 6L6 is a beam power pentode and an EL34 and 6L6 are inter changable with each other

[@coal4life]

Don't recall the model. Bought it from a guy who lost his ass in a poker game. Played the crap out of it for years. I bought a Line 6 spyder 3 awhile back. It's really not too bad but, it's just not scary good like a tuber. Got some software to clean up the old LPs that I'm putting on CD. Then I'll check for subliminal back masking before I stash em away. All this time the old turntable reclaims it's share of daylight.

[@sempercompellis]

combined with shipping from former soviet countries, i now know why they are so damn expensive!!

[@jspinks2388]

I would buy these before getting JJs ever again though I'll tell you that xD

[@robertkat]

In England a tube is the subway, a valve is a tube

[@jspinks2388]

I know right? they are getting harder to come by I still have my STR387s, the 415s I had died :( lol, I got some shorter Sylvanias too with RCA labels I assume they are the the older shorter glass ones anyways. Definitely not RCA though, hell they could be the Phillips the plates do look a bit weird lol. one of them is kinda Microphonic/rattles occasionally :( Need to get some more GE dual side getter's too those were pretty cool as well xD

[@FransvandenBergeMuziekschuur]

Oh boy.... Lotsa notes...

[@AusRadioHistorian]

Sorry, but I'd have to say that in the audio industry, there is more of a reliance on belief and self-delusion than on measurable results. Sure tube amps sound nice - but their cost is horrendously high. Pay as much for a well designed solid-state amp and you'll achieve something better, more powerful and introducing less coloration of every type. A solid-state amp can sound like tube amp by introducing appropriate distortion. Tubes can't, however, provide the transparency of solid state.

[@Sixalienasa]

What is the function of the Screening Grid? This you seem to have glossed over. Anexplanation would help.

[@silasfatchett5693]

A triode is unsuitable for amplifying high frequencies because of negative feedback from anode to grid due to the 'Miller Effect', by which the capacitance between grid and anode is multiplied by the gain of the tube. The constant positive voltage on the screen grid (believe it or not) screens the grid from the varying voltage on the anode, eliminating the Miller effect and enabling high frequency amplification.

[@giuliocoslovich]

How did you cut the tube without breaking it?

[@DC-yb7qd]

He farted

[@stargazer7644]

The same way you cut any glass. You scratch it with a glass cutter, then heat it with a flame, and cool it with ice, and it will snap cleanly along the scratch.

[@HellTriX]

What are these secret coatings on the screens and cathode?

[@daslolo]

how did you cut the glass?

[@jspinks2388]

Their 6v6 is prone to rattles/microphonics as well, I have another pair that tests fine but you put em in a circuit popping/fizzing/cracking etc you know that nightmare crap lol. So if you have a combo amp sure as wouldn't use them lol. That sucks though I thought sounded pretty cool and the fact they handle waaay more plate/screen voltage easily than a typical 6v6 they are not 6v6 its more like 5881 or 7591 with 6v6 pinout lol and will dissipate more than a 12-14watt 6v6, way more 6l6 like.

[@jspinks2388]

The SEDs sound pretty decent actually, they still are not a STR387 or 415 though in my opinion xD, What about the other newer Svetlana? both plates look close but I just want a 6l6 with better/richer mids damn near have to go to KT66 for that more EL34 like midrange. I like 6l6 but just the lack of no mid richness or Presence wears on me making it sound dry/bland and more sterile.

[@edwardcoleman9291]

What are the plates and wire's made of for precious metals recovery

[@FerSpada]

hermoso hace años que queria saber que habia dentro. gracias tube depot tv

[@JgHaverty]

lol I had no idea tubes were so complex! :p