Tubes that everyone should own, or at least hear

There’s a lot of tubes out there, from the usual suspects to the unique and rare.

What are the mainstream tubes you feel are necessary to a tube user, and what tubes do you think are out of the ordinary and worthy of discussion?

The ubiquitous 12AU7 and 6SN7 are used in numerous applications and are the backbone for many designs.

And we all are familiar with the EL34 power tube- perhaps most popular because of the best selling and absolutely charming and personable Dynaco ST70, and it’s less popular but equally capable twin brothers, the Dynaco Mark IV (this last statement is open for discussion and differences of opinions and/or facts).

But here’s a tube I’ve talked about in the past- and enjoyed immensely in a Dennis Had designed SET amplifier- the 807.

The 807, a beam tetrode popular among ham radio and broadcast (RF transmitter) use, was heavily purchased and used within the military, and the famed D.T.N. Williamson designed a circuit for a high-fidelity audio amplifier[pdf] initially I believe for the KT66 but very quickly a version followed which used the 807 tube. Of course the Williamson circuit became widespread for use among other tubes as well.

Just a lovely tube aesthetic, but what impressed me most was the sound that sweet Dennis Had amplifier produced.

Bonus- the 807 is not an expensive tube, and seems readily available, both used and new old stock.

So- I know of many, many more tubes beloved by us bottleheads- I’ll forgo mentioning any more for now and see what our illustrious members have to say.

So- what are your “must have” and “should have” (or at least should listen to) tube types?

9285166C-905F-4825-9998-62B24FB27A3C.jpeg
 

Fran604g

Just Call Me Junior
Site Supporter
Since 2011 I've owned my get*SET*go amp, so I have to bring up the 6B4G. Many go crazy for it's progenitor, the 2A3, but I can't image the 2 versions sounding much different in the right circuits. Although, I'd someday like to experience them both side by side to know for certain.
 

Wntrmute2

Not So Mediocre Member
Site Supporter
2C22 - one half of a 6SN7. Dual top-caps. Lovely sound!
2C22_RCA_049.jpg
 
Since 2011 I've owned my get*SET*go amp, so I have to bring up the 6B4G. Many go crazy for it's progenitor, the 2A3, but I can't image the 2 versions sounding much different in the right circuits. Although, I'd someday like to experience them both side by side to know for certain.
Can the 2A3 be substituted for the 6B4G?

If so, would it require an adaptor?
 
Can the 2A3 be substituted for the 6B4G?

If so, would it require an adaptor?
Filament voltages are different - 2.5v @ 2.5A for the 2A3 vs. 6.3v @ 1A for the 6B4. Their bases are different - 4 pins for the 2A3 vs. 8 pins for the 6B4. You can swap a 6B4 for a 2A3 if you correct for these two things. In other words you need to change the filament supply to 6.3v and you need an adaptor or a new tube socket.
 
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Thermionics

Post Whore In Training
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Filament voltages are different - 2.5v @ 2.5A for the 2A3 vs. 6.3v @ 1A for the 6B4. Their bases are different - 4 pins for the 2A3 for 8 pins for the 6B4. You can swap a 6B4 for a 2A3 if you correct for these two things. In other words you need to change the filament supply to 6.3v and you need an adapter or a new tube socket.
There was also the 6A3 which was a 4-pin 6V version of the 2A3 (and there are 6A3 to 6B4G adapters out there).
 

Thermionics

Post Whore In Training
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Boy - someone already grabbed the 6B4G out from under me...so I guess I'd say EL84 (either SE or PP), or 7591 (really, you should hear a PP 7591 amp as it is a fantastic tube, all things being equal).

For signal tubes, I'd throw the 6GM8 as it is a twin-triode designed to run at 24V B+ (sounds amazingly good in John Broskie's Aikido LV circuit).
 
Boy - someone already grabbed the 6B4G out from under me...so I guess I'd say EL84 (either SE or PP), or 7591 (really, you should hear a PP 7591 amp as it is a fantastic tube, all things being equal).

For signal tubes, I'd throw the 6GM8 as it is a twin-triode designed to run at 24V B+ (sounds amazingly good in John Broskie's Aikido LV circuit).
I just sent member @Tlarwa some 6BQ5/EL84s and 7591s. He said the 6BQ5/EL84s were nice but the 7591s were exceptional.

Folk frequently talk about the Dynaco ST70 followed by the MKIIIs but everyone says the truly magical amp from Dynaco is the ST35. Which is 6BQ5/EL84 based.
 

Thermionics

Post Whore In Training
Site Supporter
I just sent member @Tlarwa some 6BQ5/EL84s and 7591s. He said the 6BQ5/EL84s were nice but the 7591s were exceptional.

Folk frequently talk about the Dynaco ST70 followed by the MKIIIs but everyone says the truly magical amp from Dynaco is the ST35. Which is 6BQ5/EL84 based.
Yeah, the two amps I have which are very much lunchpail push-pull amps (but eminently listenable) are a Dynaco Stereo35 clone (using SCA35 iron and EFB(tm) biasing) and a Fisher 660A 7591 amp. Those are not going anywhere, even though they only get occasional use now and then.
 

Thermionics

Post Whore In Training
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I have a couple of boxes of tubes from my father's ratio days back in the late 40s. I should pull them out and see if there is anything useful in there.
Provided they aren't series-string radio tubes, there could be some interesting finds...
 

fiddlefye

Senior Member
Site Supporter
First box.

VR99 10E/277
6SG7
6SQ7
6CM7
3AU6
3CB6
4BS8
1X2B
12AU6
50C5
35W4
2 x 866A/866 transmitting tubes (big beasts).
 

mhardy6647

Señor Member
Site Supporter
Yeah -- the 6V6 is kind of the... I dunno... Mazda 323 of output tubes.
Gets no respect, but it's absolutely competent and it gets the job done with great aplomb.



There've been a couple of PP and SE 6V6 amps here (past & present, come to think of it) & they're perfectly dandy.






... and what is a 6AQ5, Grasshopper, but a 6V6 in a miniature envelope with a 7-pin base?

:smoke
 
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mhardy6647

Señor Member
Site Supporter
I've been wanting to build a 6V6 amp fir while just get a sampling.

The nice thing about 6V6s is they're like coat hangers. Put a couple of em in a dark closet for a year or so and next time you look, there'll be a passel of 'em in there.

EDIT:
Oh, this bad boy :confused: uses PP 7408 outputs -- the 7408 being yet another 6V6 morph.

 
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