Tube Advertising

Vintage Vacuum Tube Advertising

One of my favorite glimpses into the golden-age of vacuum tube electronics is the advertising for the tubes themselves. Even though only a few factories actually manufactured ‘receiving’ tubes, various ‘brand names’ all tried to lure you over to their quality and reliability. However, by reading ‘between the lines’ of sample advertising, we can derive at a few interesting observations. Let’s begin, shall we?


Here is a classic example of the ‘My tube is better than your tube’ advertising that went on in the early years of vacuum tube manufacturing. This RCA ad promises that no tube even dreams about leaving their factory (wait a minute, didn’t GE make RCA tubes?) until it passes a myriad of ‘tough tube’ contests. No mention is made of drug testing after though. Other RCA ad slogans of the late 1940’s/early 1950’s include… “9999/100% pure… yet we threw it away!” “Take a look at quality being born.” (With a few factory pictures showing the ‘RCA’ tube plant) and “Quality control by feedback… the secret of RCA tube performance.” (Supposedly RCA engineers listened to service technicians and audiophiles about how to make tube ‘improvements’.) A very interesting website has the history of many tube companies, including RCA. This website also has a factory tour, showing how an RCA tube is manufactured. Check it out HERE.

CBS bravado claimed that their tubes were ‘more dependable’ and would ‘cut callbacks’.

At the same time, CBS claimed they alone put their tubes through rigorous cycled tests, at low (105VAC) and high (140VAC) line voltage conditions, to ‘weed out’ problematic tubes. They also tested for ‘gradual deterioration of electrical characteristics’, in order to cut ‘callbacks’ (there’s that phrase again). Later on these ‘super-tubes’ somehow became ‘super-duper tubes’ when matched. There were many CBS tube advertisements, and they usually told you more in their advertising than most other ‘manufacturers’. To check out a very informative advertisement explaining why a CBS rectifier tube is ‘better’ than the competition, HERE.  The ads will absolutely give you something to consider when shopping for a rectifier tube.

 Mullard7025     AmperexECC83     Sonotone_7025


When Philips caught on that the original 12AX7 (developed in 1948) wasn’t a very good audio tube, they introduced the much better ECC83. Of course Philips manufactured tubes under many other brand names, including Amperex and Mullard. The advertisement for the Amperex ECC83 can be seen above left. It had all of the features that Sonotone tried to lure you with over to their 12AX7 replacement, the 7025. The Sontone advertisement for their 7025 can be seen above center. The Mullard ECC83/7025 advertisement can be seen above right. Strange that a tube originally ‘conceived’ as a high gain audio voltage amplifier should be ‘born’ with so many ‘birth defects’. Stranger yet is the blatant omission that anybody’s 7025 sounds better than the ‘old’ 12AX7, or has better linearity and less distortion. They are simply advertised as being more reliable, have less noise, be less microphonic and have less filament hum. Any tube labeled 12AX7 after the mid 1950’s is probably a 7025 anyway, with the improved construction. This includes the many tubes labeled 12AX7/7025, done in hopes of striking a familiar ‘name’ with old-timers out tube shopping.


Another RCA ad campaign started out with this header. Most capacitor ads as well mentioned that the ‘callbacks’ could have been avoided if only the technician had used ‘Brand X’ tube/capacitor. Later on, ‘tube matching’ was a shtick dreamed up to dissuade customers from buying surplus tubes from electronic ‘discount shops’ that had proliferated after WWII.

Take THAT, you dirty ol’ UNMATCHED tube!

Most tube manufacturers, who earned a small fortune selling overpriced tubes to the government and military sectors during the war years, now had to deal with their ‘full price’ retailers that were feeling the pinch of the surplus tube market after the war was over. To make matters worse, every corner drug store and hardware store had a tube tester, and the frugal customer could test his own tubes, and then purchase a surplus replacement, saving twice (no service call charges, and a cheaper tube). To see a vintage Canadian tube price list from RAD-TEL tubes, HERE. But was all this ‘competition’ really healthy for the retail tube industry? Consider that even the business of testing tubes was gaining momentum! Many outfits sold/rented tube testing equipment, targeting the usual outlets; anywhere Mom and Pop may have wandered when they hit the big city on a Saturday afternoon. An article appeared in the December 1957 issue of Electronic Technician telling the ‘legitimate’ TV repair shop that they should also look into renting a tube tester to place in the corner Drug Store! Below is a scan of the first page to the article.

By simply placing your ‘Self-Serve’ tube tester in a busy locale, you too can profit from tube sales!

The article mentions that since the ‘business’ of testing tubes is booming, so why shouldn’t the ‘legitimate’ TV shop get in on the action? Apparently, a conservative estimate has it that there are between 20,000 and 25,000 ‘Self-Serve’ tube testers in the US alone in 1955. A further estimate has it that this is worth between $20,000,000 and $30,000,000 in tube sales yearly. To test the tubes was always a ‘freebie’, and if needed, the replacement tubes were purchased right on the spot. The ‘owner’ of the machine typically split the profit of the tube sales 50-50 with the Drug Store or Hardware store that allowed the tester to be placed in their establishment. So of course it is no surprise that ‘Self-Serve’ tube tester advertising picked up quite nicely during the 1950’s. Below are a few sample ads from various magazines of this era.

Equipment_Leasing     Shell     U_Check_Em
If there’s a Dollar to be made, you can be sure there will be competition.

These advertisements all point out that the machines can either be purchased outright or rented. Also mentioned are some ‘facts’ about how much money can be made simply by leaving such a machine in your local Convenience Store. As an example, it is claimed that $50 worth of tube sales per week is not unreasonable. Even in ‘poor’ locations, tube sales of $20 to $25 per week is ‘normal’. So how do the tube manufacturers and retail sector fight back? Placards were sent to all retailers, offering ‘Free, Professional Tube Testing, On the Latest Equipment’ (big deal; ‘Self-Serve’ testers are also free to use), but the service shops were encouraged to take as much time as necessary to make the customer feel like his problems were being handled with sympathy and a technical understanding that the corner druggist simply didn’t have. Then a definite ‘bright idea’ of the decade came along; those tubes at the drug store weren’t ‘matched’ (Gasp)!

CBS_matched_ad1    Philco_tube_ad    CBS_matched_ad2

Although these same tubes only left the factory after meeting… ‘exacting quality standards’ and being… ‘thoroughly tested and inspected’ on Monday, they somehow sounded ‘better’ and offered fidelity that was a little higher when… ‘Their critical audio characteristics are matched’… into pairs on Tuesday. Of course, those millions of government surplus tubes made last Sunday weren’t ‘matched’, and shouldn’t be purchased from your local surplus electronics retailer. Always buy the freshest batch and only from the manufacturer or licensed full price retailer, OK? To be fair, today’s tubes have a poorer quality control standard, which makes matching (or more like weeding out the really bad ones) a necessary evil. The CBS ad above throws in the statement that their matched tubes allow for… ‘reduced distortion even below that attainable by controls for balancing plate currents.’ In other words, pay more for two tubes that already have similar current draw characteristics than waste time fiddling around with controls and two ‘unmatched’ tubes. In a stereo amplifier this may be warranted, but in a guitar amplifier it may not be desirable to have perfectly matched output tubes. This of course assumes that the phase inverter and output transformer are perfectly balanced as well.

I don’t believe Fisher made their own tubes, but Damn, those EL37’s look cool!

Fisher promised to select their tubes individually, and chose only those tubes that exhibited… ‘maximum gain, low noise, exact tolerances, long life and… absolutely identical performance characteristics.’ Yet they were available as single units or in matched pairs. So, again, how are they ‘better’ when ‘matched’? Shouldn’t two ‘singles’ be the best possible tubes? Fisher also states that ‘Only The Best Goes Into Every Box!’, yet somehow their ‘best’ got ‘better’ when shipped in pairs. Perhaps Fisher felt it was really only better for their cash register.

How would “Tube to Tube Uniformity” improve with matched pairs?

Even Mullard was known to exhibit a bit of bravado about the quality of their tubes. This 1962 Electronics World advertisement mentions….. ‘Tube-to-Tube Uniformity and Section-to-Section Uniformity’ and that ‘Each tube (is) Individually Laboratory-Tested’. Surely this could foreshadow an embarrassing case of hoof-in-mouth disease if they jumped on the matched tube shtick.


By using Sylvania tubes, you are guaranteed that these tubes met ‘exacting standards’, and all were pre-tested to ensure that each and every tube delivered ‘exceptional performance’ (doesn’t everybody make this claim?). Could they be even better if they were sold in selected, matched pairs? Apparently not, as Sylvania didn’t jump on the matching bandwagon. Perhaps the military (pictured above as the primary recipient of this outstanding performance and dependability) didn’t need matched 5881’s in their B52’s.


Not to sound like a broken record, but these late 30’s/early 40’s ads from RCA state that their precision construction techniques will guarantee a very consistent performance from quality tube to quality tube. Most other tube manufacturers(?) had similar claims, with catchy slogans like… “Only Our Very Best Goes Into EVERY Box!” To their benefit, RCA never really jumped on the tube matching shtick that started in the late 1950’s, although the above ad implies that every RCA tube is ‘matched’ right from the beginning (I’ve highlighted the point #1, which should be a dandy conversation starter). FYI; The 2A5 shown above is a 2.5-volt filament pentode, and is electrically identical to the 6.3-volt heater 6F6 (Very similar to the 6V6. The lesson here is that just as Chrysler built many models on a ‘K-Car’ chassis, Many tube types are built on only a few different structures). It was possible to achieve 19 watts output with a pair of push/pull 2A5’s.


Why not let even the tube testers get in on the act? This is the ‘My tube tester can pick out bad tubes your tube tester says are good’ type of advertising common when ‘mutual conductance testers’ became the buzzword. This is an ‘oddball’ though, as the Sencore Mighty Mite is an emission tester! It does have the advantage over simpler emission testers in that it tests tubes at ‘rated load’, which is a fancy way of saying higher test currents. Cheaper emission testers used cheaper power transformers, which cannot handle high current demands (the tubes emission could ‘sag’ under heavier load). Testing at lower currents may miss problematic tubes, as the above advertisement mentions. Emission testers as a whole are inferior, as they connect all tubes as virtual diodes, by shorting any grids to the plate. The plate current is measured as an AC voltage is applied. The ‘upgraded’ emission testers used beefier power transformers and higher voltages to try and weed out the borderline weak tubes. Nonetheless, emission testers lost favor with the service technician besieged with callbacks because they only indicated the condition of the cathode coating. Since most tubes other than diodes rely on the ability of the control grid to regulate the flow of electrons, the actual number of electrons flowing seems less important. Having said that, I still do own and operate a number of vintage/later model service-type tube testers, both emission and mutual conductance types. I just let my ears and eyes do the final ‘testing’. For a complete idiot’s guide to understanding the basics of tube tester function, see HERE.

The only honest tube advertisement I have ever found.

And, finally, this Amperex advertisement. It is the only ‘honest’ tube advertisement I have found to date. Every statement made is factually correct. However, what is omitted is the proviso that these statements are only true compared to a 5U4 and similar rectifiers. Other rectifier tubes (like the 83-v, or the 84/6Z4) available before the 5AR4/GZ34, or the 5V4, available during the same time would offer equal ‘improvements’. With a tube manual or a tube theory book in your hands, read about the differences between a directly heated cathode and an indirectly heated cathode. What differences do each type yield in our amplifiers? Which has more ‘sag’? Which type actually helps our output tubes last longer?

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