He was cleaning his attic a while back and found a box of old tubes. We had talked many times about tube amps vs solid state and he knew I was a bit of a tube amp junkie.

So... he boxed all that stuff up and sent it to me. There must be about 50 to 60 tubes of various sizes and types. I would say that all of these probably date from the 60's when he fooled around with radios and such.

I've started going through them and found a few that I recognized, a couple of rectifier tubes commonly used in Fender amps, and quite a few 12AX7, 12AT7, ...that sort of thing.

My question concerns how to identify a lot of tubes that I don't recognize. In particular I have a handful of Telefunken tubes that are about the same physical package as a 12Ax7 type tube, but have numbers I don't recognize. Besides the Telefunkens, there are quite a few Sylvania, GE, and Raytheon, plus some other names that I didn't recognize.

I've done a fairly lengthy web search without much success, can anybody suggest some sort of tube x-ref that might be useful? I expect a lot of these tubes are probably for some RF applications and not useful for audio, but I think it's possible I may have some fairly desirable tubes in this lot....

Tell 'em BAMA sent ya.

Amp Workshop Forum

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Prevent Juvenile delinquecy...teach children to STEEL

1976 MSA D-10 8+4, G&L Skyhawk, 1920 Gibson A Mandolin, Fender DPC750 w/Tubefex, 70's Fender Super Reverb, Takamine 6-String

[This message was edited by Bryan Knox on 28 September 2006 at 02:40 PM.]

Brad

Brad, thanks so much for the generous offer

BTW, did I mention there is one (1) KT66 that's opaque gray??? (Unfortunately, no matching tube) is that some milspec thing or something????

and a bunch of Mullards too..

FYI, I advertised them on Ebay and sold them very easily for quite a good price. I also had a box about a foot square of oldies, 01A's and the like, sold them on Ebay too to a collector in Korea for a very nice price. I wrapped them individually in bubble-wrap and put them in a 1/2" plywood box, they got there safe and he was happy to pay the shipping even with the extra weight of the plywood box.

You might consider selling them on Ebay yourself, but you'll need to inventory the ones you can identify, and specify whether or not you've tested them and then list for example "12 mini unidentifiables not tested" or whatever.

[This message was edited by Jim Phelps on 28 September 2006 at 04:08 PM.]

Thanks for the offers and help guys, I'm gonna put a list together of everything I've got. I may just post it here.

[This message was edited by Bill Terry on 29 September 2006 at 07:12 AM.]

If you find any 80 tubes, save 'em...

ECC83 = 12AX7
ECC82 = 12AU7
ECC81 = 12AT7

They may also be the MillSpec/Special quality versions :
ECC803 or E83CC = ECC83 (12AX7)
ECC802 or E82CC = ECC82 (12AU7)
ECC801 or E81CC = ECC81 (12AT7)

Hope that helps !

50L6
50C5
35Z5
35W4

Those are normally used in cheapo "transformerless" amps where one side of the chassis is hot. They are a great way to get electrocuted. Basically, any amp where the sum total of the first numbers of the tubes adds up to 110-120 means line voltage is used for the heaters and there's no power transformer. You can use them safely with a GFCI, but it's still chancy. I've thrown those amps...and tubes...in the trash. Unsafe.

And Gene, a properly maintained tube amp will tonally bury any solid state amp you find, unless your only aim is squeaky-clean tones with no warmth. I have about 20 tube amps, all completely reliable - because I take care of them. Solid state amps are lighter and cheaper, but there's a reason tube amps are still made and used - tone and ease of service.

BTW, I have hundreds of tubes inherited from my father-in-law. And those are guitar amp tubes - I weeded out a couple thousand radio/TV tubes and gave most of them to radio clubs. If anyone needs 6V6's, let me know - I have tons of matched pairs....

[This message was edited by Jim Sliff on 29 September 2006 at 11:12 AM.]

The European tube designations are actually quite informative in that the letters actually tell you something about the tubes function !

E means 6.3 Volts, parallel heating
C means Small Signal Triode
F means Small Signal Pentode
L means High Power Pentode

So an
ECCxx is a 6.3 Volt, parallel heated, small signal dual-triode
EFxx is a 6.3 Volt, parallel heated, small signal pentode
ELxx is a 6.3 Volt, parallel heated, high power pentode

The specific purpose of the tube is given by the actual type-number (xx) but just by looking at it, you know a lot about it already. There are a lot more combinations of letters of course.

Jim, can I ask if you are playing through a tube amp, and what type? I'm presently using a
Rivera for gigs and and older Carvin for practice stuff. Both have the true "tone" you
speak of.

Others I'll use are an Ampeg V4 (two power tubes removed); a '55 tweed Deluxe; '66 Bassman modified to '64 specs with slightly more gain on channel 2; various other small tweed Champs and such; and a 1/4watt all-tube Zvex Nano with a 12" Greenback - that sucker screams at low volume! Oh - and a '62 brown Princeton, which has the best low-volume clean tone of any amp ever made IMO. Probably the one I'll use when I get the guts to start recording some of my hopeless playing...

John

I also found a great website database some time ago when I was trying to identify my own box of tubes. I'll try to find that too.

I'm sure you don't mean it that way and you know the tube itself is not going to electricute anyone! I think throwing these tubes away because they have been included in some dangerous circuitry is silly, there are radio collectors who need these tubes and are aware of the dangers of their old radios or whatever.

Besides, they are also used in many old table A.M. radios that didn't have that problem. Before moving here and selling everything I collected and repaired old radios and many of them had these tubes and didn't have hot chassis.

Better throw away our old Fender amps too, you can get a nasty shock or even be electrocuted if the ground switch is in the wrong position. There's nothing wrong with selling or giving away those tubes if that's his plan.

You can't get rid of everything because someone might hurt themself with it... that's the government's job...

[This message was edited by Jim Phelps on 29 September 2006 at 07:20 PM.]

Regarding topic drift, personally I don't care so much. Tube amps, tubes, it's all the same, I enjoy reading this stuff. I see it as just like a face to face conversation, sometimes the topic wanders. How bout those Dixie Chicks huh?

The Fenders with ground switches are easily modified for safety. Not the transformerless amps.

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www.home.earthlink.net/~johnd37

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“Back then, everything was different, and you only saw it once; now everything’s the same and you see it over and over again"
-Peter Case

Emission testers simply heat the tube up and measure the flow of electrons from the hot cathode. They are only slightly better than checking the heater resistance with an ohmmeter for an open circuit. Most of the old "drugstore" tube testers were emission testers. In fact, they had a hidden pot so that they could be set to whatever the owner wished the meter to show.

Dynamic conductance testers actually place regulated voltages on the various components within the tube and supply a small signal to the tube's grid. The gain of the tube is then measured in a manner very similar to what the tube would see in an actual amplifier circuit. They require a setup chart because there are so many combinations of pin connections and internal components to test for.

There were many dynamic conductance tube testers made in the vacuum tube era (40's to 70's) which are quite accurate and reliable. If you decide to try to find one for purchase, the most sought-after units are made by B&K and Hickok. The Heathkit TT-1 is also a very good tester using the Weston 981 design.

I have a couple nice old Hickoks, and they are great testers - but all of the garden-variety tube testers max out at about 180 volts on the plates. you can't match tubes...or even test for durability...with those testers. they are nice to have if you own a lot of tubes and need to weed out duds, but the only way to really do final tests and match them is in a specialty tester built for the purpose, or in an amp with a bias tester (BiasRite, BiasKing etc.). The transconductance testers ARE far better than the emmision types - but still extremely limited, and most people are better off NOThaving one so they don't get overconfident about old tubes....and blow an output transformer in a vintage amp.

One other major issue is calibration - ALL transconductance testers must be calibrated every 5 years or so or they are useless. 90% of the tube testers you find on eBay or at garage sales have not ben calibrated - and that little job runs about $100-150 plus shipping. Forget price shopping, there are only a few shops that calibrate them.

So while the unit ARE accurate and reliable, that is true only when calibrated, and only within a rather limited scope.

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Tube Characteristics and substitutions
Some quick and dirty subs and some tube data such as recommended bias current and appx voltages. These subs are all taken from the Tube Substitution Handbook sold by Antique Electronics Supply. or provided from the net.

A (short) catalog of tubes you are likely to see in a guitar amp:

12AX7[A, WA] and substitutes - preamp and driver tubes
12AT7, 12AU7 and subs, preamp and driver tubes
12AY7 - driver tubes
6EU7 - dual triode used in some older amps for preamp tube
6L6 types - power output tubes, up to 50 watts/pair, a mainstay of Fender
EL34 - Euro power pentodes, up to 50 watts/pair, many Marshalls
6V6 - smaller, lower power cousin of the 6L6, 10-14 watts per pair; used in smaller Fenders
EL84 - fits a 9 pin socket like a 12AX7 but twice as tall; miniature power pentode, good for 12-18 watts per pair; used in smaller Vox amps, and a quad of these drives the Vox AC-30 for 30 watts.
Substitutions:
* means appropriate for parallel filament circuits
# means may not work in all circuits
Preamp and driver tube substitutions:

12AX7 (high gain dual triodes with pinout 9A)
12AD7* 12DT7 7729
12AU7# 5751* B339
12AU7A# 5751WA* B759
12AX7 6057 CV4004
12AX7A 6681 E83CC
12AX7WA 6L13 ECC803
12BZ7* 7025 ECC83
12DF7 7025A M8137
12DM7* 7494
12AU7 (moderately high gain dual triodes with pinout 9A)
12AU7[A,AW,] 6189 7730
12AX7* and subs 6670 ECC186
5814[A,AW]* 6680 ECC802
5963 7316 ECC82
6067 7489 M8136
12AT7 (medium gain dual triodes with pinout 9A)
12AT7[many suffixes] 7492 E81CC
6201 7728 ECC801
6679 A2900 M8162
ECC81 B152 QA2406
12AZ7[A]* B309 QB309
6060 B739
6671 CV4024
12AY7 (low gain dual triodes with pinout 9A)
12AY7(and suffixes) 6072
2082
Power tube substitutions: