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finding tubes...

is not a problem thanks to the guitar amp market, which is about 80% of world tube production: 12ax7, el34, el84, 6v6gt, 6l6gc etc are all readily available as new production. Yes, any amp over 20 yrs old should be recapped as a matter of course, they are either failed or about to. The superiority of tubes over any solid state is due to the difference in prevalence of odd vs. even order harmonic overtones, vacuum tubes are natural high frequency producers even at very high power, which is why in Radar and radio transmission they are still used... bit of a science lecture here, but there it is, the reason most high end studios doing mixing & production and virtually all top guitar players have gone back to tube amplification. The fact that most tube amps and radio receivers have discrete components and point-to-point wiring is sheer icing on the cake, making them easy to repair. You can still get vintage Fisher, Scott et all for $3-600 range, if new they would be more like $3000 in today's mooolah. A McIntosh tube amp (made right here in Binghamton NY, and I've had almost every amp they ever made over the 40 years I've been into this stuff) sells for 5 to 10 times what their SS stuff does... there is a reason!
 
No doubt there has been a resurgence in vacuum tube audio which has made all the components easier to find, tubes, transformers and high voltage capacitors etc. I first started dabbling with tubes in the mid 80's and there was a time there where even common tubes were scarce!

No doubt there is truth about the harmonic distortions raised by tubes, generally they are musically related and more pleasing to the ear. But provided the transistor design is run in a linear condition the argument is muted to a degree. I do TRULY love my Marshall 2204 guitar amp though as the EL34's sound so good when they start to saturate the output transformer. I have a handful of tube amplifiers I use in my hifi that I enjoy a lot, but most of the time I run some form of solid state power amp. The tube amps do have some warm and fuzzy agreeable distortions though if I am in the mood for that. To each their own and the only thing that matters in the end is to enjoy your music!

The use of vacuum tubes in radio or TV applications is actually becoming rare in new transmitters below 1000Mhz. LDMOS transistors have become so rugged and linear that they have replaced tubes in most all applications over the past few years. For a long time I have stated that anything over 100w RF needs a filament, but that just isn't true today. Efficiency, linearity and ruggedness are on a par and there is no need for a high voltage supply and its inherent problems. Note I still use a 1.5kw HF amp based around a pair of 3-500Z tubes though. The tube amps are a bit cheaper per watt still for ham radio use.

I'd gladly help anyone wishing to enter into vacuum tube hifi nirvana, but I have to stop short of recommending them as daily drivers to people that don't want the hassles. I have mentored a few friends into becoming their own tube technicians, but a lot of us just want a hifi that works without the need os a soldering iron and a DMM.
 
Tubes for transmission----Still used today-esp in Short Wave broadcast transmitters.The driver stages in them are solid state-but the power amplifiers are still tubes-VERY large ones at that.These tubes can dissapate up to 1MW!!Some digital TV transmitters still use tubes,too-Klystrode tubes-these have both the advantages of klystrons and tetrode tubes.They can handle the digital peak pulses best.For the short wave transmitters-modulator stages are solid state pulse step--you have 32-48 of these stages in series to develop both the plate voltage for the power tube in the final PA and the modulation for it.One of our transnmitters has the first pulse step modulator built.They can work great if all is well-but DIFFICULT to service-Ours has been doing well now-all of the modules have been rebuilt.A module in this is time consuming to replace-they are water cooled-new PSM's have air cooled modulator modules-this is easier.The traditional tubed push pull modulator is still easiest to service.A modulator tube can be replaced only in a matter of minutes-even having to use the tube puller cranes.
The agency I work in has solid state MW tranmsitters overseas that are up to 1 Mw.They do take up a lot of space-actually more than the tubed transmitter of equal power.Its just as we put it--You can have a lot of ants pulling the load or say two elephants pulling the load.The tubes are still much easier to service in the high power stuff.
For Hi-Fi some folks insist on the tubes just as the muscians do.If you have a good vintage name brand amp such as Dynaco,MiIntosh,Scott,Marantz,Fisher,Magnavox and so on you really won't have difficulties if you just understand that tubes have to be replaced so often as light bulbs are---remember a tube is still a light bulb with the extra electrodes in it around the filament! And for those vintage amps-caps will need to be replaced-so you will need to weild the soldering iron.Some caps may be hard to find-I am still looking for electrolytic caps over 525V rating for my MI 60 monoblock amps.So want to recap them.Tubes for audio-for G-amps or Hi-Fi-there is a market still for them are they will be around--more are actually made TODAY than 50 yrs ago!!Most are built in China or Russia.The Russian ones are best.A few tube factories are still in use in the US.Esp Burl Electronics(used to make tubes for RCA) that makes transmitting tubes as Eimac does and Econco(Rebuilt transmtter tubes)Large tubes can be green-when old they can be rebuilt and work like new!
 
new tubes...

Richardson still makes quite a few audio as well as Eimac, think they bought the name and prod equip for them quite a few years ago, they make the majority of the tubes for commercial & Military in the US. They even made a special run for McIntosh a few years ago for the KT-88s in the Mc275 re-issue.

My uncle here (ex- IBM EE) built the first prototype MacKit MK-30 when his EE buddy over at Mc asked him to put it together and tell him how it went, he still has it in a closet along with a regular MC30 and a C-20.

The Mc MI-series amps were mostly silver-painted commercial versions of the Mc30, Mc60, Mc75 etc, but I once had a MI-200 2 chassis 200 watt tube monster that was mainly built for lab and research use in vibration analysis, shaker tables and the like, however a few were sold as mega-Hi-Fi amps by places like Harvey Radio in NYC. It used 2 x 8005 big transmitting tubes in the output stage, and that thing was just amazing, talk about headroom! With the right speakers like big Altec VOTs or Acoustat Electrostatics the sound-stage was galactic in proportion! The Grateful Dead used MI-200s for their first 15 years of live concertizing. That's one of the few amps I wish I'd hung onto. The Marantz M2, M5 & C-7 are the only others.

Good SS amps/receivers are for sure less work to maintain, but certain blown output transistors can be harder to find than some tubes!
 
Oh and...

yes, most new production tubes are made in Russia and China, along with some Eastern Europeans like JJ (formerly Tesla), and there's Westrex in the US who still makes a few of the classic Western Electric tubes under license like the 300B (pricey!. The Russian/Chinese tubes have improved hugely in recent years, but due to lack of some rare-earth metal alloys and specialized production equipment no longer made, they have yet to reach the quality of some of the best vintage tubes circa 1940s-70s.
 
weighing in late...

Michaelman2(Mike): audiokarma.org is a good resource..people there are helpful, knowledgeable, and you can get an idea on anything you're looking at or haven't considered. Thrifting, I found a Kenwood KR-4070 and Sherwood S-7250. While not high end, these are respectful systems that have very good build quality.

I like your now r.i.p. Marantz -so who knows, you might find one again, if that's your interest. Yogitunes mentioned the old stereo consoles; worth considering, too, even if not components - if you have room!

PS -not really related to the thread, but with firedome, tolivac and kb0nes talking about tubes, I thought I'd present my biggest tube...given to me my buddy/neighbor via his dad ...when a Detroit TV station, I think, was upgrading their transmitters in the mid 1960's. If I could just get it to power some speakers. :-) it weighs a ton. Specs: http://www.rossrevenge.co.uk/tx/5762.jpg

ovrphil++12-28-2013-20-28-28.jpg.png
 
The system i put together in the early 90's

Here's the system i put together in the early 90's and it's still going strong after THOUSANDS of hours.

All this stuff is getable on ebay...

KENWOOD Basic C1 Pre-Amp the C1 has tons of tone settings, a great phono section with settings for cartriges and etc.

ADCOM GFA-535 strong yet compact amp.

TECHNICS SH-GE70 GRAPHIC EQUALIZER between the pre-amp and the equalizer you can make almost anything sound great.

Originally i had Boston Acoustics towers but in the mid 90's i got a deal on a pair of ADS M9 towers which i still have and they are just better.

I love classic 60's tube gear but at this point when that stuff is 50 years old there always is something needing repair and no one to repair it.
 
Ovrphil:The tube you have is an RCA 5762/7C24 power triode.During the fifties and 60's even into the 70's these tubes were WORKHORSES in the broadcast industry.The 5762 is a realitivly low gain forced air cooled triode with 3Kw plate disapation.I have encountered these tubes in mostly RCA transmitters-AM,Older FM and RCA VHF TV transmitters both high band and Lo band analog.For the TV transmitters these were used in the Visual driver stages-and several in parallel-in what was called the "Afterburner"-"Incinerator"25Kw and 50Kw linear power amp stages.7 were used in the 25Kw-for 50Kw (High band) two 25Kw power amps were used feeding a hybrid combiner.Tuning these things was a real challange-for TV--phase shifts in the tuning caused "ghosting" in the visual image-and color shifts for color programs-once the amps and combiner was tuned-it was pretty stable and fine.For AM transmitters-these tubes were used in RCA 5Kw and 10Kw AM tranmsitters in both the RF power amp and the modulator-for modulator duty-two were used in push-pull.Since it was low gain stage-high drive power was needed-this was commonly done by triode connected 813 tubes as cathode followers feeding a special 4winding primary driver transformer.These are now unobtanium!!!if you have an RCA AM transmitter whose mod driver transformer is blown-you can get one from a junker transmitter.The mod transformers are still available thru Peter Dahl and other rebuilders.The mod transformer is push pull primary-and often two secondary windings-one for the RF driver stage-the other for the PA-they are capacitance coupled by oil filled blocker caps-if these are old-you can pep up an old transmitter by replacing them-Just like a NEW transmitter-esp if the mod chain tubes are replaced,too-same with blocker caps in low level audio stages-these often use 807 tubes or common audio tubes like 6L6,6V6,EL34,KT88,6550 and so one.Those mentioned tubes can even drive the grids of tetrode modulator tubes that have high gain-some later triodes,too.
Those Westrex tubes are loved by the high end Hi-Fi folks who can afford the GROSSLY overpriced SA amps for them and the GROSSLY overpricved 300 tubes-remember at a surplus store years ago-they had BINS full of JAN 300's at something like 50 cents each--now I am kicking myself for not buying some of them-they were WE tubes,too.Just made to mil Joint Army-Navy specs.Bet these would go for more than 50 cents each today!!!
Anothwer tube maker I haven't heard from was "Action-TUNGSEGRAM!!" as stated on the tube package-they made a lot of 5762/7C24 tubes as shown in OverPhils picture.Have several of the Tungsegram ones in my collection-problem-when they burnt out-rebuilders such as Econco could not accept them for rebuild.So off to the trash they went-didn't save the stations money after all-NO DUD VALUE!!The RCA and other maker 5762 tubes could get you up to $50 each for dud value.
Oh sorry-on my Amp designation meant to say MC60-the non industrial version-yet these often showed up in some radio stations and recording studios as monitor amps.Just wish I was around when they replaced them-and got the old "MACS"These aren't that hard for the electronics guy to redo.You jst have to be able to get electrolytics for the rectifier section that are rated at 525V and above.And for older amps--the bias rectifier diode will need replacing,too-these were selenium diodes and get weak as they age-bias voltage can't be set for the output stage and the output tubes overheat--GLOWING PLATES--NOT GOOD!!!And the blocker caps from the driver-phase inverter get leaky-causing false positive bias on the output stage tubes-and more stress on the bias diode-I just replace them with 1N4006 silicone rect diodes-then just fine-same with the bias cap the diode is connnected to-then get set for YEARS of operation!Then doesn't matter what brand amp it is.
Yes,agree on the SS parts-most are "house" numbers or ones made for that applicationyears after the amp was made--these are Unobtanium!!!So you have to try to find subs-and these don't always work-esp for Sony parts-esp in their TV sets.Thats what I like about tubes-you can get them and subs can be made without problems for the most part.And the circuits are easier to work on-more straightforward.I do have some McIntosh MI75 amps-these new recapping,too.I would like to build a full wave rectifier stage to replace the voltage doubler stage these have-the voltage doublers are CRAP compared to a full wave 5U4,5AR4,5R4 and so on.Replace the voltage doubler power supply and the amp takes on a NEW and BETTER sound personality!
 
More things on 5762 tubes--the large radiator part is the plate terminal.The ring in the middle is grid.Since this tube has a direct heated cathode-the cathode return is the filament center tap.-In the transmitter thru the filament transformer center tap term.Filament is 12V AC or DC-DC is used for TV visual RF appliation to avoid filament hum bars in the picture.The plate vltage for these is 5Kv and up to 2A cathode current.Grid current is 200 Ma.When used in RCA TT25LB they have a real beauty-all of those 5762's running with their filaments glowing-the rectifier cabinet with all the mercury vapor rectifiers glowing light blue on light picture-dark picture-max modulation-they glow bright blue.The 5762 currents go up.In AM transmitters RCA 5H,10H the mercury vapor thyratron power-supply rect tubes flash to the modulation beleive they were 5563A mercury vapor thyratron-handles up to 10Kv 3A per tube.For its day this was a good system-the regulation was solid and if there is a fault-the thyratrons were bias off and the supply shut down.Faster than overload relays.The power transformer was 200-240V 3Ph and 2200V Scott connected 4 ph out going to four thyratron 5563.The Scott transformer was made by Mahoney Electric-they made a lot of transformers for RCA's transmitters.They were easily rebuilt when they went bad.These tubes were from the what radio guys called the "Chrome&Glass" era-transmitters had chrome framed veiwing windows so you could see the tubes and other parts.Very helpful!Transmtters today are just monolithic boxes-no beauty at all.In those early days transmitters were made to be seen as well as heard.They always fascinated me-and still do.Remember without transmitters--your radio just receives static!Same with digital things,too.
 
That IN4006 substtution

is commonly done on the zillions of Fisher 400/500/800 receivers, along with many many other '60s tube amps and receivers, that use selenium rectifiers for another important reason as well - selenium is HIGHLY poisonous and a rectifier that starts smoking in failure mode can be highly dangerous to one's health! We outlined the procedure along with dropping resistor mods required in our "Fisher Receiver" issue of Vacuum Tube Valley Magazine: "The Classic Electronics Reference Journal" published 1995-2004" RIP. Units with slow turn-on 5AR4/GZ34 rectifers seem to be the best functionally.

Tungsram of Hungary made some excellent audio tubes, their 12ax7s are now very sought after, I think I still have 4 somewhere. They also made light bulbs and that division was bought by GE in the 90s. The tube arm is defunct, afaik.

Tolivac if you need info on the caps needed to restore your MI-75s you may wish to consult "Audio Classics" here in Binghamton, you can Google them...they do all of McIntosh's service work on vintage units and are the largest Authorized McIntosh Service station in the world. I've had several MC-75s and several pairs of MC-60s, Mc225s, along with many others over the years, they are well built units and very easy to repair or restore, as long as the trannies ore OK...you don't want to know what it costs to rewind/rebuild one of those!
 
I have an old Fisher receiver that used to belong to my uncle. IIRC it's an 800c, hope to retrieve it from storage later this year and so will need to get on Audiokarma to find a vintage audio shop in SoCal who is experienced with old tube equipment. I'm a little leery of powering it up myself as I believe that's best done with a variac in the case of equipment that's not been used for years.
 
A Variac

should be used to power up anything not used for 5 yrs or so to slowly re-from the electrolytic caps as a leaking cap can cause damage in a number of ways. Variac is the trade name for variable a/c transformers made by General Radio, I use one for that purpose. You can also make a "poor man's variac" using an ordinary ceramic light bulb socket, some lamp cord and mount on a board, vary the bulb wattage to vary the amount of current limiting.

The Fisher 800 is a nice AM/FM receiver, used 7591 outputs iirc. Lots of tube repair places around LA, our magazine was based in the SF area, tons of places to get tube stuff fixed there also.
 
firedome . . .

Thanks for the advice. I've always had SS equipment from my first KLH Model 52 receiver to the Rotel amp and tuner/preamp I now have but it might be fun to mess with tubes if the 800 is serviceable. It's in good cosmetic shape though that means little electrically.

 

Hopefully whatever shop I find can deal with SS stuff too as the Rotel amp is getting a little scratchy in the left channel on occasion, but then again I bought it about '90 so can't complain. Luckily I found an identical amp on Ebay and just got it, haven't even powered it up but it should keep me going for awhile and later on give the option of using the pair as two bridged mono amps if I want.
 
OvrPhil-Link is great-EXACTLY the tranmsitters I have worked on-WashDC and Baltimore.
Firedome--the GZ34/5AR4 was a good tube-you can use it in place of 5U4--But be sure to check the filter cap voltage ratings-there is less voltage drop across the 5AR4-so it can pop filter caps if not rated high enough. Do like its indirect cathode-matches the warm up time of other tubes.Some folks like to use 1N4006 to replace main rect tubes like 5U4 and 5AR4-advise them against that-the HV supply is then energized instantly-since no load(tubes not warm yet)that puts a stress on filter caps and tubes as they heat up.Prefer to use he tubed rectifiers in that case-use the diodes only to replace bias diodes.
NYCWriter-like those Kenwoods-the Kenwood tuner and intergrated amp shown-see those in Hi-Fi shops in the 70's 80's.Nice gear.Too bad the FM stations could not match the quality of that tuner-and yes,sometimes tuners like that or similar were used as monitors in radio station studio sites.You could listen to other stations to get an idea of the audio processing gear they are using.Too many FM's are processed to sound just as bad or worse than AM's.Have an HD-Digital FM tuner-only station that uses HD here is NPR.Sounds really good,though.
Oh yes,not only Hi-Fi encounter such likes as 12AU7,'X7 and6550,EL34,6L6 in many fender,Ampeg,and Marshall "G"fiddle amps.Some players are REAL particular on the tubes you put in their amps-often more so than the Hi-Fi guys.And for most G-amps-the output transmformers are designed deliberately to saturate so as to "crunch",Fuzz" or distort the sound.Totally unlike Hi-Fi.Marshall transformers were more like Hi-Fi-they didn't do that so much.Known folks that have these amps-to them 120-150 W loud from Mr. Marshall-FATHER OF LOUD!!!Just something about those amp heads on a stack of 4 12" speakers-you want to crank it up and FEEL it!Bass players especially love this.
 
Fisher 800

hydraulique, I have the feeling that if you begin listening to the Fisher 800, if properly restored, you won't want to go back to the SS units... at least that's been my experience with 98% of folks I've known who are willing to give them a try. They aren't as finicky as most will have you believe and with the proper speakers you may hear things in the music you've never before experienced.

Tolicvac, as you know the guitar guys have different desires as they like distortion and to be able to control it, but also have driven up demand for vintage tubes to the point many are absurdly expensive... if you had told an old radio guy 40 yrs ago that 2A3 or 45 tubes would be in the 100s of dollars, he'd had thought you should be committed. Now all the SE guys love them too. Not to mention WE 300Bs, priced in the 1000s! Luckily all the necessary tubes we still need for Hi-Fi are available new and the quality of them has improved drastically. .. btw where did you work in Baltimore, I was there 1950-1999.
 
For the Baltimore work-I helped out a contract man who helpted out various stations--Lots of work for the WEBB,and 860Khz-can't remember the call right now.WITH,WBAL,WCBM-and a few others. Same sort of thing at DC-employed by WPGCAM&FM,helpted several stations there-and toured sites in both towns.Great market for radio in the older days!Now its just "Mikey D" radio-stations sound the same anywhere becuase of common large owners.The radio industry sucks now-don't recommend it.Some of the transnmitters were in bad neighborhoods-esp DC so worked with my freind for safety.Also helpted out another guy in Richmond.Channel 8 and their 50Kw AM-can't remember the call or frequency right now.Rebuilt Ch#8 RCA TV transmitter.Took several midnight visits.But the pay was alright.
Yes,audio tubes I am as you can figure an older audio and even RF guy-over 45 yrs worth.Just think the prices on tubes and tube gear these days is criminal-remember most of it is old tech-even for the common power HI-FI- audio tetrode tubes the tech is coming 60Yrs!And older "SE" triodes--now about 100yrs!And keep in mind most of this circuitry is SIMPLE-so its pretty easy to deal with-And remember the tube circuits in the backs of RCA and GE tube handbooks-breadboarded many of these for fun!They worked pretty well,too!The audio tubes we know most-the 6V6,6L6 families were improved greatly during the war and just after-other tubes like 6550,7027,KT88,EL34,EL84 came out during the fifties.Then it always makes me think of those 300's at that surplus shop-and 45's common in older radios.Great output tube-300 and those were seen in the sound systems of the first "talkie" movies!Those WE amps from those days are now as valueable as gold!esp among the SE Hi-Fi fans.Most amps that are SE are built using that early WE design.The reentrent horn speakers for theaters then were incredibly efficient only a few watts needed to work them.Their response wasn't so good-mainly for voice-but they worked-and sad so many of them got thrown out.Collectors of old theater stuff loved them!
 

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