Vacuum Tubes: Current Production and New Old Stock

[@chrislj2890]

When I was a kid in the '50s I saw the tv repairman more than my dad. I was fascinated by his fold out tool box chock full of tubes, mostly in red boxes the way I remember. Damn televisions back then, I still remember laying in front of the thing listening to The Roy Rogers Show because there wasn't any picture, lol.

[@DANTHETUBEMAN]

Mullard sound good when that over drive in Marshall amps. 🤠 great mid tones.

[@wardkoogan127]

I just randomly found your guys channel after learning about your company yesterday and placing a order. Good to know a fun local business.

[@iceberg789]

the world needs new tubes.

[@conwaynoel3715]

In the mid seventies I was doing electronics engineering. The guy who lectured us on electrical science announced that tubes were going to be binned and all lectures were to be about solid state devices. Many years later I was asked to have a look at an old 50s PYE radiogram.. I loved the challenge but I was handicapped by my total lack of knowledge of tubes. I love old restoration but struggle with the the electronics . Delighted that I found your channel and thanks for the info.

[@anoxicfiltrationplenums]

Richardson electronics in Illinois still makes vacuum tubes. Hope this helps. Great video.

[@ronedwards8239]

Yes for radio station transmitters

[@Denvermorgan2000]

I would like to spend time looking at all tubes.

[@amplifiedparts]

You can see our inventory of tubes here: www.amplifiedparts.com/products/vacuum_tubes

[@joey_bonin]

I've spent at least a hundred hours doing just that. They will never cease to amaze me.

[@marcuscarrozza732]

I remember back in the 1970's my dad would have the technician come out and either replace tubes or re bias them and what ever else he would have to to do to get the t.v. to work properly. I use to watch the guy work on the old sets. my dad would complain about how expensive the tubes were back then . he was glad when the t.v.'s didn't use them any longer. lol. the technicians case use to have the two top panels open and fold out with all types of tubes, and tools.

[@amplifiedparts]

Nice memories! We still see some of those old tube caddies every once in awhile when dealing with NOS tubes. They're very cool!

[@bigstick5278]

My dad would slap the side of the TV!!

[@bobboscarato1313]

At one time I was servicing home electronics in 60s. and 70s. and carried two large tube caddies carrying over 350 vacuum tubes (valves in the UK); some TV models carried odd named tubes which we has to special-order; these sets were sold by big department stores.

[@marcuscarrozza732]

@@bobboscarato1313 funny enough I am fron the states/colonies & I call them Valves as well. Sometimes tubes. I feel tubes aren't a good way of describing them.

[@bobboscarato1313]

@@marcuscarrozza732 Valves is a good term as they control flow of electrons!

[@spyderlogan4992]

A terrific overview of what Amplified Parts does for the consumer that buys tubes for all types of applications. Especially for all the people that always ask the question, 'who makes tubes' these days? Definitely puts AP at the top of my list of 'go to' credible suppliers of guitar amp tubes. Great video.

[@amplifiedparts]

Thanks for the kind words Spyder! We're glad to be here for you. Feel free to reach out anytime!

[@deadfreightwest5956]

Don't forget Glasslinger here on TubeYou. He hand makes tubes that crossed the Rubicon over a century ago, but mainly for himself and friends. Fascinating skills.

[@bigbasil1908]

Yeah I watched an old 1950's Mullard valve factory video last night, and there were a couple of parts that they ran electricity through whilst under vacuum to burn out the last traces of gasses before sealing the valves/tubes.

[@joey_bonin]

Good video.

[@ry491]

It amazes me how many nos tubes still exist . Don't know why they made so many back then seeing that they last so long . I restore radios from the 30s and 40s quite often they still contain the original tubes and they test strong and work perfectly . I think back in the day they often got replaced unnecessarily just to boost profits of repairers .

[@alanpecherer5705]

Back in the day, a visiting TV technician would replace some tubes just to be able to charge some money for his visit. This, by the way, leads to LOTS of tubes "in original boxes" being used but sold as new, NOS. *Guess where the tech would put the old tube he yanked out?* Yes, it is pretty amazing how many NOS tubes still exist and likewise fairly amazing that many, many old tubes from the 30's and 40's still work. For one thing, once you have the factory to manufacture the tubes and are making them, it costs almost nothing to make hundreds if not thousands more. So you are making (then) a few bucks out of 2 cents in mat'ls, a great profit. I visited the RCA tube factory in Harrison, NJ on a high school field trip. This was maybe 1970. Quite fascinating. As for older tubes still working, most old radios and amps, etc; have a+/-20% tolerance on voltages, R & C values. *SOME* parts can be incredibly out of what you'd think was acceptable tolerance and the thing will still work. And then, suppose a part is going bad on an AA5 radio you listen to every day. Well, for 60-90+ days, every day the thing works a teeny bit worse, then worse, then worse, until it no longer works. But you don't notice it working slightly worse on Tuesday than it did on Monday. I also believe that nobody expected tubes to last as long as most of them do, plus, how easy is it to yank an old tube and throw a new on in? So they made zillions of them. And how hard is it to throw them out? They're these delicate things, in pretty boxes, they cost $6 or $10 or $12 30 years ago, how can they be worthless now? (Talking about odd tubes, like series filament TV types)

[@DeadKoby]

Today is 2-21-2023. Western Electric makes 1 model tube (300b) in the USA. Internationally, Reflektor/New Sensor in Russia makes all the EH brands. JJ In the Slovak Republic makes their brand. Shuguang plant in China closed, but Psvane is producing tubes in China. If Russia would stop fighting, hopefully the EH brands of tubes will become more affordable again.

[@holywells]

What a lot of people do not realize is that almost every home in America has vacuum tubes that are used every day. Some people say that tubes are useless and outdated, and yet, they still use their microwave ovens to cook their food. LOL.

[@deadfreightwest5956]

Yup, that's probably the last place a vacuum tube will forever hold court. All rise for the august magnetron!

[@MrRusty-fm4gb]

I’ve taken apart several microwaves when I was on one and I didn’t see any vacuum tubes. The only vacuum tube I saw was the vacuum hose I used to clean up the mess of broken plastic, beryllium dust, broken glass…. You’re not talking about the display are you? I believe that is a glass chamber filled with gas…. Like a Nixie tube, but a 6 sided box and a glass nipple that is closed off..(that part is always black and carbonized from the heat when they seal it up)… I have my eye on this JVC RX 6008V AV receiver… but there is a classic Ford Mustang dashboard-style record player ontop with a bunch of garbage ontop of that. I think there might be come vacuum tubes in that. Edit: I just learned from this video that the carbon or heat damaged area on the glass is “getter flash”… 😎

[@stevethetoolman2435]

Great video! The factory information was great. I grew up in a tube world. Ty

[@paulkielt9301]

Very instructive! NOS preamp tubes are the best you can find nowadays. I use Tesla's, Brimar's and Mullard's. Unfortunately, I've never tested NOS power tubes because they cost an arm and a leg!

[@zacharydoering313]

I think you forgot the KR tube factory in Czech Republic. They make a lot of tubes that are oddball large glass tubes like the KR845 and 300b, but they do exist and are not in Russia or China.

[@ryanacree]

I think he means for audio amplification purposes. For guitar amps and such.

[@zacharydoering313]

@@ryanacree so am I, JJ is Czech based as well. KR makes audio tubes 845 and 300b are used in high end audio amps.

[@bytesysed]

I love tubes

[@MAINTMAN73]

Eimac still makes a lot of commercial tubes in the USA. But nothing for HiFi amps

[@flyintime6320]

Awesome video! Tubes & tester reminded me of my days in the metrology lab. Got a few tubes iin a ham set here at home, but will have to look for NOS I (might) have hanging around. Great stuff guys - glad I found you!

[@amplifiedparts]

Thanks!

[@randalltufts3321]

I need a bid list guys. Great video. Glad to see these getting life.

[@amplifiedparts]

send an email to [e-mail] and we will get one over to you!

[@suzukiyesteryear]

Great Tee Shirt!!!!!! Gotta' get a couple of those. Thanks for a great video!!!

[@amplifiedparts]

Hey thanks! Here is the link for the shirt! www.amplifiedparts.com/products/t-shirt-black-12ax7-tube-diagram

[@bill-2018]

Brimar are making a comeback. The people doing it are getting the equipment and getting it working again. See, The Great British Valve Project.

[@joey_bonin]

Should be good. I had some 6BR7 audio pentodes that were beautiful -- rugged, quiet, excellent.

[@carlc2597]

Very interesting and informative - plus fun to watch!

[@georgeswanson7937]

A-yup, those are the three tube factories... except for Emission Labs, KR, Euro Audio Team, Takatsuki and now Elrog.

[@sparkplug964]

This is bay far the best video I have watched on tubes, thanks for the info, great video.

[@halbertking2683]

I had a customer come in with JJ power tubes that were branded Telefunken . I don't deal in TAD tubes but people who have brought them in for me to install and bias have had high failure rates.

[@antoniograncino3506]

I purchased a "matched" quad set of Russian Mullard EL34's The transconductance specification for the EL34 is 6000 micromhos (or microSiemens). This set measured, on my calibrated Hickok 6000A tester, from 5200 to 5400. I purchased subsequently a matched quad of JJ (Tesla) EL34's that measured 6000 on one pair and 6020 on the other pair. The "Mullards" measure about what all my used EL34's measure.

[@joey_bonin]

When the empire fell they took with them all the proprietary design elements, including the rare earth information. That's why these new Russian tubes are not quite what they were. The same applies to Svetlana tubes.

[@FretBuzzGuitar]

Justin. I have 5 Westinghouse 7951A tubes that look great and appear to be NOS. I don't have a tube tester so I don't know for sure. Inside the boxes (not the tubes) there is a fine white powder. I've read some comments saying this means the tubes have lost vacuum but also seen other comments saying this is not the case. How can I get in touch to see if you want to buy the tubes? I have some others as well.

[@ramirobenavidez7871]

Jeff Horn -Hi my name is Ramiro from San Antonio TX.I have 4 old things that use vacuum tubes.I was like u.I had no tubes tester.and the old TV repair shop will tell me that they don't have one no more..will it took me 3 years to find one for sale in a flea-market 4 $35.00 dollars.. u can find one too..they are out there..

[@gregdolecki8530]

NOS JAN12AX7WA Sylvania (deep bass, smooth highs) and GE (brilliant without being harsh). Wonderful tubes and wicked rugged. JAN12AT7WC Philips for your phase inverter. Super.

[@boballard6040]

Great video and well explained ! Digging the box art as well.. thanks !

[@timw.9466]

Rossville works in Rossville Georgia has retooled the factory from Kansas to reproduce the origional Western Electric 300b class A tube. Dont know if this qualifies as a US factory but theyre very coveted by audiophiles. I believe theyre 1500 US $ a pair and well worth it if you have a amplifier that can benefit . I have a Cary cad 300 sei its a single ended integrated and a Lampizator tube dac that utilises the 300b , 101d, 2a3 and 45 pure class A amplifier tubes in a dht set dsd dac. The worlds only SET dac from Poland

[@bill-2018]

I bought five 4 pin valves at a radio rally a few years ago to make a one valve radio and the most interesting one is marked D.E.R. with the B.B.C. logo, it has a pip on top where it was sealed. The logo dates it between 1924 and 1927. It has a tungsten filament and lights up like a light bulb and it amazingly still works.

[@missmygamergirl445]

you can't beat a tt filament for reliability they just don't like cold starts or vibration. Anyone using a tt tube without a remote power supply shouldn't be using them.hifi guy you know who you are. And don't be buying and hoarding them. one pair of ten y has lasted me for 15 years 18 hours a day and still nos test. remote power choke input soft start supplies starving them.Yes better to starve a little.

[@9ernie9]

I have a 4 valve set I'm trying to restore. Uses 3 x DE6 and 1 x DER valve. Not easy finding information on stuff that's almost 100 years old!

[@bill-2018]

@@9ernie9 Great stuff. I use The Valve Museum and the German Radiomuseum online. I also have the Babani Valve Books.

[@RickJando]

Very educational video, thank you.

[@jas20per]

Tubes what we on the other side of the pond call valves, just to move things on Transistors and other early semiconductors especially Germanium NOS versions are now commanding big money. I do hope you are moving in that direction.

[@amplifiedparts]

Hi jas20per, we are definitely working on building up stock of some good NOS germanium (and a few silicon) transistors. We have some NPN Philips OC141 in stock right now, but we are going to see what we can do about tracking down some of the really in-demand types.

[@tonyturtle5805]

tubes are a wonderfull thing to behold

[@marcofacen9564]

Please don't forget KR (Kron Audio)! I know that your approach is coming from the guitar amplifier side. But KR is still handcrafting the best tubes available in Prag, Czech Republic.

[@VintageGearMan]

I wish I had this clean of a job.

[@richardmcleod5967]

The decoration on the Arcturus tubes had some very interesting designs on the boxes, but there were so many made in the United States with decorative designs on the boxes.

[@Rebel9668]

My Pappy used to repair old tv's and radios and we had literally thousands of tubes that 4 of us spent nearly a month sorting out to their individual numbers back in the late '70's. By about 1988 there just wasn't any call for tubes anymore and hadn't been in several years, not locally anyhow and with no such thing as internet back then there simply wasn't a market for them and we hauled them all off to a landfill. Had I known that late in life I'd develop an interest in old radios you bet I would have saved them and nowadays everytime I think about dumping all those I could just kick myself.

[@WarinPartita6]

Interesting​ video.​ Thanks, man.

[@Rebel9668]

I wish a company would start re-making things like 6U5 magic eye tubes. A lot of us in the antique radio community would probably buy those as a NOS one the last time I checked was upwards of about $75.00 . I have a friend that restores and even scratch builds tube amplifiers along with restoring old radios and communications receivers (Hallicrafters, Hammarlund, National, etc.) that I'll have to share this video with :) He has a yt channel as well called Ron's Vintage Electronics. I'm pretty sure the only amplifier tubes I've bought were 6v6 but I don't even remember for which radio. Oddly enough most old radios the tubes are perfectly fine. It's everything else that degrades like caps, resistors, wiring, etc.

[@joey_bonin]

If you have 12.6 volts available you can sub a 1629 tube. They're cheaper.

[@gtartrek9453]

Very informative, thanks.

[@davidstein9129]

Great video. Thanks

[@scrummasterinblack]

Does new old stock mean that at one point in the future it will run out and no longer available?

[@joey_bonin]

It means it is no longer made by any US company, so yes, inventories are dwindling.

[@technicalmasternadimji9008]

Great information

[@technicalmasternadimji9008]

🤝🤲

[@wdmm94]

Tungsol WAS an American maker of bulbs and tubes.

[@chrollo7102]

This is a great video, learned a lot

[@cryptout]

Awesome video, thanks!

[@nothingelse1520]

Do you use dielectric grease on any tube connections?

[@WitchidWitchid]

I still use tubes in some of my vintage ham radio equipment. Whenever I can I try and get New Old Stock tubes, particularly when it comes to tubes for a transmitters final amplifier. I have had better luck with old US made tubes in that particular application in particular old new military spec. tubes.

[@paullesho]

I really love the American made tube electronics, Hallicrafters philco's, ECT, I have restored several and still learning. I hope that there will be a tube manufacturer some where to help keep these alive. thank you for this info.

[@joey_bonin]

Really, the only ones being made are mostly audio tubes, for guitar and high fidelity amplifiers.

[@petroldevo9934]

Hell, the f-4 phantom my dad flew had tube equipment in it... but the tubes were hardened for aviation.

[@DucNguyen-pl8zg]

I heard Russian use tubes too since tubes are much less susceptible to EMI.

[@MuscleDad420]

Those would have been JAN (Joint Army Navy) tubes. The holy grail of tubes are those used for medical devices. Super long life, super rugged.

[@spider02540]

@@MuscleDad420 hmm. I have a pair of JAN Phillips ECG 6922s, do you think the ECG stands for Electrocardiogram?

[@joey_bonin]

@@DucNguyen-pl8zg All tubes are impervious to EMF. That's why the Russian military used them well into the 80s.

[@slam854]

Shuguang had a fire in in their factory (neighbors factory) that damaged about 75% of the manufacturing area. This closed their plant with a long & slow rebuild ahead PS Vane was starting production about same time. They hired many Shuguang workers and managers. I have 12) Siemens copy EL-34's labeled TAD and use them in my PrimaLuna Dialog Premium HP amp. It uses 8. Another pair of monoblocs is Atma-Sphere M60's. They use 8) 6AS7G tubes / chassis in OTL design.

[@phillipbainbridge9107]

So what's YOUR honest opinion of Shuguang quality?

[@amplifiedparts]

The Valve Art screened tubes and the TAD tubes from that factory are excellent.

[@LateNightYinzer]

Everything, and I mean EVERYTHING, used to run on tubes. I remember talking to an old timer about elevators..they even had elevators that literally ran off 6L6's. To add to the getter flash bit..there are top getters, side getters, I've even seen bottom-ish getters. So long as it is shiny and silver, it's good. If it looks white and chalky, that's the immediate tell tale sign of a failing vacuum and the tube is bad.

[@hesmellslikerome]

What about western electric? And ELROG Vacuum Tubes?

[@adailyllama4786]

Western Electric in Rossville, Georgia is producing vacuum tubes.

[@michaelhelgeland4588]

TheMightyB58 only one tube though, the 300b and they cost a few limbs and a testicle

[@TheSoundtec]

Can you suggest a good data base for my large collection. Better a premade list included? Thanks for your time!

[@dimebagtribute]

For my taste Sylvania tubes, the old black plate 12ax7 or the 5751 3 micas, and the Raytheon 5751 windmill getter are the best tubes ever made for guitar and hi-fi preamps!! Nothing can beat these gems, hopefully I've got enough stock for 3 or 4 lifes...

[@pharmerdavid1432]

Or savings for old age, when they go WAY up in value...?

[@spl4028]

This was cool! Thanks

[@JinKwok]

Any new tubes brands or manufacturers worth mentioning in 2019?

[@docvolt5214]

In the hifi sector.. Nope.. They all suck compared to a cheap ass Philips NOS

[@paulbangash4317]

JinKwok brymar in the uk worth keeping an eye on

[@johnsimms3957]

I wish we could make them here again. Especially EL34s, 6L6s and 12AX7s.

[@DucNguyen-pl8zg]

They still make those.

[@joey_bonin]

I gave up on using EL34s years ago. They are Dodo bird eggs now.

[@chrissalisbury9193]

Hi I have a bag of old tubes not sure what they are for ! I found them in our loft when we moved in 20yrs ago

[@amplifiedparts]

Vacuum tubes were used in all sorts of antique electronic devices. Everything from televisions and radios to x-ray machines and calculators. These days, they are pretty much only used in guitar and hi-fi amplifiers. We buy tubes from the public, so if you wish to discuss selling your tubes, you can always shoot us an email! [e-mail]

[@VintageGearMan]

Nothing like tube audio.

[@gregj.gotham4402]

Im looking for quads of Sylvania 6v6gta black plate, if you have quads of them how can I get ahold of you about price

[@haythamchannel3553]

Thank you awesome video. My name is Haytham I'm from Lebanon my work is electronic maintenance especially old equipments

[@ryanacree]

You should clean the pins..that will not hurt, that will only help. And the flashing was not part of the vacuum process, it is part of the air purification process inside. The vacuum already was turned on, but then the flashing gets the impurities and floating items and puts them on the side of the glass instead of floating out inside the tube. It is the same process as making a mirror. There is a good video on tube manufacturing from the TV show "How It's Made".

[@joey_bonin]

I use D5.

[@cletusspuckler2243]

What are the best quality brands of NOS valves ? I restart old valves appliances, i want to have the best inside them !

[@holywells]

Depends on how much you want to spend on them. Most notably would be Telefunken, Mullard, Genelex, RCA, Sylvania, and some of the GE tubes. I have a VTL preamp that has NOS Telefunken 12AX7s in it. Super expensive, but nothing else can come close to sounding so fantastic, especially with moving coil cartridges. Good luck.

[@amoruzz]

"Send them our way, we may give you a little money for them?" 🤣

[@christianjimbomb8204]

Boxes last 100 years...and the NOS tubes longer...just treat them like they aren't cheap anymore

[@lazoom9748]

GREAT Video! ... I have NOS / Completely sealed set of Genalex KT77 still in their original boxes ...any idea what are they worth today?

[@Autojones]

A -LOT... Just look on E bay.

[@joey_bonin]

That tube is very rare, similar to a 7581A, GE's answer, except as with all Euro power tubes, can handle high screen voltages.

[@MadMax-cf9uu]

Great job, thanx

[@deadfreightwest5956]

Some octal tubes put the getter down in the base, where it's almost invisible. I've also seen tubes painted on the inside like an oscilloscope CRT. They have the getter in the base, too. But why the _paint?_

[@ghlscitel6714]

I wonder if all these old NOS tubes are still properly filled with vacuum. Thanks for explaining the short JAM - I never knew, and I'm 72 now, however non native English speaker.

[@hotpuppy1]

Getter turns white when vacuum is totally lost.

[@tomm7096]

Western Electric in Kansas City is still making vacuum tubes.

[@Autojones]

I just looked it up, I can't believe it, the famed 300B is back in production in the US. $700 for one and $1500 for a matched pair. the website says it's being produced in Georgia .

[@1959Berre]

I read about NOS tubes suffering from helium having infiltrated through the glass envelope over the years, compromising the vacuum. Is this a myth, or is there any reason for concern when using NOS tubes? Can this be ruled out by some test?

[@amplifiedparts]

I think this is mainly an issue for CRT's and photosensitive tubes. Many tube testers have a gas test as well.

[@alexanderstefanov6474]

You forgot KR in the Czech republic, very high-end, super expensive, limited range, but they do a fantastic 300B and KT88

[@waynegram8907]

Amplifiedparts some preamps are large plate tubes and others are normal plate tube, what are the advantages of large plate tubes?

[@plainsabertooth7828]

Gotta buy some for my TV:3

[@JakeRegala]

can i replace a mictube 12AY7 to telefunken E88CC?

[@user-wy4mp9ts3u]

How on earth do you find the specks

[@BetamaxFlippy]

I believe most NOS valves still check out fine, but to support this resuscitated market I prefer to buy newly manifactured valves.

[@hi-fidude6670]

Is the Mullard reissue as good as the vintage ones?

[@chicowasp]

No.The older ones are much better.Can only talk about small signal tubes,12ax7 etc.Mullard m8137 is one mighty fine tube.

[@Pollys13a]

Interesting thanks.

[@billwilliams6338]

AMPLIFIED PARTS, what is the difference between a DC load line compared to a AC load line? The +Vcc voltage and output impedance sets the DC load line and AC load line? but what is a GOOD DC load line and AC load line and what is a BAD DC load line and AC load line?

[@locmanw1583]

Do you have any Mullard CV4003 for sale?

[@fluxxliveband]

Great informative video! Amplified Parts rules!!

[@michaklein1193]

I liked the Cetron box in 9:38, I wonder if its a 572b.

[@jonathanvanier]

Does anyone know where the Sophia Electric tubes are being manufactured? Thanks!

[@bertroost1675]

There is an old surplus place not too far from me that is loaded with tubes just like your warehouse. Most are pulls but they test them before you buy them. Great place.

[@Dave_____]

Where is it located?

[@bertroost1675]

@@Dave_____ Ohio

[@Dave_____]

@@bertroost1675 Thanks. Name of the place, if you do not mind sharing?

[@bertroost1675]

@@Dave_____ Are you a dealer or just a guy that wants to buy tubes for yourself?

[@Dave_____]

@@bertroost1675 Definitely not a dealer. Looking for a source of tubes other than the "normal" retailers.

[@2mikelim]

U left out brimar tubes which are still being produced in England as of now.

[@63stratoman]

I wonder what sort of killer amp you could build with the big ass tubes you showed us?!? Do you have a “matched quad” available? 😆

[@daytonasixty-eight1354]

Probably an amp far less capable than something with modern electronics. But what's the fun in that?

[@cletusspuckler2243]

@@daytonasixty-eight1354 Audiophile sound quality..... Nothing can beat valves !!

[@westelaudio943]

@@daytonasixty-eight1354 Building tube stuff is actually a lot of fun, and they also sound good even for HiFi, if you mean lower wattage, who cares, at home you won't be using much more than 10 watts anyways with decently efficient speakers. If you are one of the green party j*rks complaining about low efficiency, I don't think the 0.1% percent or so of the population using tube amp will have a grea environmental impact, LOL.

[@daytonasixty-eight1354]

@@westelaudio943 I don't give a fuck about the green party or the mothers of america crying about the gay baby whales

[@Thomasjcolbert82]

I like this video a lot!

[@33and1third]

doesn't western electric make tubes in USA too? nothing for guitar, just a couple like 300B hifi?

[@chilledoutpaul]

Awww I love your t-shirt but the $21 shipping to the UK is too much 😟

[@wiebl5266]

Hi, may I ask, hope somebody can help, is it safe to replace a preamp that uses 12ax7 tube with 12bz7?

[@NEEC1]

Very cool.

[@puciohenzap891]

I'd love to see a more technical breakdown on NOS vs new tubes, let's stay someone cracks the glass on 2 worn out power tubes, a current production Shuguang vs a GE from the 40's and look at the materials used, the bonding etc.

[@JohnMartin-vc5dj]

Did Mullard make 6DJ8 Tube in the 1950’s?

[@amplifiedparts]

It looks like it was originally developed by Amperex in 1958 so late 50s or early 60s would be my guess as to when the Mullards were first made.