Should I grab any of these valves? (tubes)...

[Earthscum]

I have seen a box of tubes sitting in my local lectro shop for awhile, and asked how much they were... cheap enough (no, seriously... $2 each).

Anyways, this is a partial list of the tubes in the box... would any of these be suitable for stompbox use, or even pre-amp use?

6J6A
6RP22
6J4
18FY6A
11BM8
12T10
12SF5

and a couple power tubes I wrote down:
17GW6 (Raytheon, x2)
12W6GT (x2)

There were some other small tubes as well... a couple that started with 16, 17, and maybe a couple 11's. There were about 10 different larger tubes, also.

So, any of these worth picking up to play with? I'm still a total noob with tubes, although I actually understand them better now (12xx7's and standard dual-triodes). I figure, like transistors, the more variants I have, the more I learn and understand.

I looked up all of these, and the ones I decided I'll grab are the 6J6A and the 6RP22, just because I saw typical use schematics for both. The 6J6A datasheet had me confused, though, so I better ask first.

[pazuzu]

at 2$ a piece i would buy them all. put them in your toolbox and hold on to them. or send them to me.

[CynicalMan]

I did a quick check and you can get most of those for $2-5 on ebay, so I wouldn't worry too much about picking them up. Personally, I'd pick 1 or 2 that you think would be useful and pick them up, because getting these means that you'll have to design a project for them, design a power supply, get weird parts such as sockets, transformers, power resistors, etc. So, while they may look like a good deal now, you might get them all home and just end up with a box of weird tubes tucked away because making something out of them would be too fiddly.

Still, if you find something to do with a 6J6A, please post it, because I have one for this exact reason  (Active Surplus FTW)

[Earthscum]

I agree about having a box full of tubes I'll never use.

I think I'm definitely grabbing the 6J6A... it has a common cathode, should be good for fender style preamp... or maybe something from AX84.
Maybe the 6RP22... there's a Japanese site that used one in a hi-fi amp HERE.

Ha! Sweet... datasheets...

So, the 6J4 is looking like another one I'm grabbing... "The 6J4 is a high-mu triode designed for use as a grounded-grid amplifier at frequencies up to approximately 500megacycles.... 12000 uMho's..." Could be fun. Maybe use it for a tone stack.

[PRR]

Pass.

You'll buy them, never use them.

6J6 is a great tube. And VERY cheap. I've thought of many ways to use it in audio. None really make sense, even at 50 cents each. If you were on a desert island with a crate of 6J6, you could make a guitar-amp or FM radio or even a RADAR (the early tail-radars were stuffed with 6J6). Any place with eBay and UPS, you can get handier audio tubes at negligible cost.

6J4 is a cookin' little UHF triode, way-fat for most audio purposes.

> at frequencies up to approximately 500megacycles....

How often do you play 500 megacycles??

18FY6 is a half a 12AX7 except with VERY odd heater voltage.

12SF5 is another half-12AX7 on a funny base with an odd heater voltage.

12T10 would be mildly interesting to a very experienced pentode-geek. It has enuff bits inside to be a (poor) "one bottle guitar amp". But that little-side is a very odd pentode intended for quad-detection, may be hard to bias-up as a linear amp.

12W6 is a 25L6 low-volt high-current power pentode. Very good for a 2W-4W 110V-200V power amp, but nobody builds those since everything is scaled for 300V 6V6 or EL84.

6RP22 is another small power pentode, yawn.

17GW6 is a very handsome bottle, will work in smaller 6L6 amps, except that odd heater voltage and awkward (and dangerous) plate-cap.

And for any of these.... if you DID build something around their quirks, and it failed, you'd have to buy another. Some of these are a glut on the market, others may be getting scarce. None will be handy on a rainy night with a gig in an hour. Whereas with 12A_7 6V6 EL84 and friends, there's tons of known-good plans, you can buy a replacement on Saturday evening, your friends may have spare.

> design a project for them, design a power supply, get weird parts such as sockets, transformers

Indeed, indeed.

There's none of these I'd want for $2.

> a total noob with tubes

Then you can find enough "fun" (and aggravation) using common tubes. Learn your craft before you play with oddballs. Don't worry, there will ALWAYS be oddball tubes around.

[Earthscum]

Thanks a bunch, Paul. I was kind of expecting a response somewhere around those lines. That's why I didn't get any of them today.

"Learn your craft before you play with oddballs. Don't worry, there will ALWAYS be oddball tubes around."

True... but I'm typically a "gotta break it before I'll buy it" kind of person (if that makes sense). I couldn't grasp how transistors worked until I went back to the first "transistor" I learned about, the SCR. I started playing with some sensitive gate SCR's and all of a sudden everything about transistors clicked and now I have no problems biasing them and making them do backflips of sorts. Apparently I had to have the transistor and diode action in the same package for me to understand, or "see" how everything was working.

It was fun, and I was hoping a couple of these tubes would be a bit more common, but oh well. Guess I'll keep hoping my lectro guy gets some more of the sub-mini's in... I missed out on a round of those (can't remember the number, 68xx or something... was same ones Rick was using about 2 years ago in his amps. They were gone before I figured that out).

Thanks for the info, guys. Guess I'm back to my LPS (I'm loving the sound of those on my bass... a bit fatter sound, and more clear than the WS's I tried).

[PRR]

> 6J6A... it has a common cathode, should be good for

Twin triodes with internal common-cathode connection are NOT handy for audio.

We say the most usual amp stage is "common cathode", but we really want an individual small cathode R-C network for EACH triode. There are exceptions: the long-tail driver often has both cathode strapped together. But generally we stock individual-cathode twins and strap for the few situations where we want cathodes directly coupled.

> playing with some sensitive gate SCR's and all of a sudden everything about transistors clicked and now I have no problems biasing

Truly an odd path. Classic SCR teaching path is to learn one BJT, learn other-polarity BJT, combine to a 2-stage amplifier, then combine again in a perverse 2-BJT PNPN loop: the SCR. Yes, "same" in that you tickle a base/gate to a point and it conducts. However an SCR, once conducting, never stops conducting.

Yeah, get a 12V tube, 12V 0.3A supply, a 50V-100V supply (can be a stack of 9V batts), and re-build the classic triode stage. It may be handy to rig two AA cells and a 100K pot to give variable +1V/-1V DC signal to tickle the grid while you watch the plate.

[Earthscum]

"We say the most usual amp stage is "common cathode", but we really want an individual small cathode R-C network for EACH triode. There are exceptions: the long-tail driver often has both cathode strapped together. But generally we stock individual-cathode twins and strap for the few situations where we want cathodes directly coupled."

Aye, gotcha. This is the preamp stage that made me think that 6j6 might be useful in:
http://www.ax84.com/static/corepreamps/Crunch/AX84_Crunch_Preamp_Schematic.pdf

Right now I actually have a McTube power supply. It's really quiet, and sits a solid 104V, right on with others reports using the same RS transformers. The main tranny is 12V CT 450mA Standard Chassis-Mount Transformer with Leads and the step-up tranny is 12.6V 300mA PCB-Mount Miniature Transformer.

I forget about using batteries to bias. Leave it to you old schoolers to remind me. I should build a real battery powered pedal, lol... I just find amusement in odd things, like imagining a way over-sized pedal with a bank of 10-15x9V batteries and a single tube sticking out the top. Mmm... half rusty, hacked together, totally archaic... that's alot of battery. Wish RS still did the battery a month club. That was our free supply of 9V's all the way through Jr. High and high school.

[petemoore]

  Bags of tubes !
  For sale. 4 sale again...
1  Calculate the market and make investment according to increased value asessment. Look at it from strictly investment standpoint.
2  Have a use for them already ready [or at least very near].  Determine whether the data sheets will 'allow' usage for your purposes.
  Among 'various tube' #'s you will find radio, and other purpose tubes, some may be suitable for amplification or other common audio tasks. Of those...decided if they fit your platform, or, based on projected future availablity and desire for their performance characteristics..whether you actually want a platform that will accomodate them.
  Straying off the beaten path [12ax7 etc. common tube types] may be possible, but most of those who've done it learned the beaten path first, plotted a destination [as well as a load line], and had a route planned out.
  What defines "Amp" ? How many tubes ? How many features ? What is the power supply like ? Which speaker may matter more than...
  Epi Valve Jr. is one suggestion, a kit-amp is another.
  I would stray toward the Jr. [or any other factory tube platform which is easily 'servicable'] unless the kit for some reason fits the definition more closely in some way, at least until the destination platform and all the route including all roadblock notations is in place, designing an amp from 'these tubes' from scratch...I'm just not sayin' it can't be done.
  As you can see, those tubes are a drip in the bucket of creating a working tube amp platform.