Question For Other NOS Tube Junkies

[Zer09]

Do you have a very specific favorite tube you like to run in your amps? I'm asking because I'm running low on my 6l6 of choice in blackface amps. It's the GE 6L6GC made at their Owensboro, KY plant in 1959. Yes that specific. I've had several quads of them over the years and the only tube that ever came close were original Tung Sol's from around the same vintage. Something very special was going on down there that year IMHO. I sold a quad a couple years back (I now regret it) and had a brand new pair roll of my bench and shatter just about the time I first started using them. I've tried plenty from the 60's-80's but none have measured up. Anyone have a similar tube? Just wondering if I'm alone in my freakish specificity.

[Chuck H]

People get freakish about guitar strings, battery brand in effects... Why not power tubes. I'm sure there are nuances specific to that tube that give you what you want. Now... If you can't find or afford them your only option is to go with another tube. Sooo many 6L6's are considered good now. It might be an idea to look at commercial designs that use roughly the same Vp as your amp. What are these using. A proper bias on a tube that is endorsed by a major MFG should give good results. If not EXACTLY the same. And the cost savings over trying different tube types or buying NOS or some special brand should be significant. Believe it or not, major MFG's DO try to use tubes that sound good. Even if they are lowballing the price.

[ken]

Don't get me started...

I collect tubes like other people collect stamps, and yes there are tonal differences between tube manufacturers and rev levels.
However, I'm not as bad as the OP. Not yet, anyways.
My fave? RCA 6L6GA for tweeds, and GE's in later amps.
Now, preamp tubes are a whole 'nother story...

ken

[Zer09]

When I first started buying them I was paying $100-125 for a quad. I see pairs going for that price and higher now. I no longer consider them an option at this point. I have plenty of others to choose from so I just can't see myself paying that price. I have a bunch of othe GE's, Sylvania's, and RCA's The GE's have a very big, open, airy sound. As audio guys would describe them, a huge sound stage. The thing I love about those 1959 tubes was how smooth the breakup is. Otherwise I think they are just like other GE's from the same era. A great, great tube.

I do use some modern production tubes but I buy them mostly for comparison purposes. I have more NOS tubes than I'll use in a lifetime so I try to stick with what I already have. I do agree that there are some very good 6l6's out there. I really like the Tung Sol's and if I didn't have so many NOS options those and the Winged C would be my tubes of choice. My problem with these tubes is quality/consistency/reliability/longevity. But if I were to get that combined with great tone in a new tube I'd probably be paying more than NOS go for.

[Zer09]

Don't get me started...

I collect tubes like other people collect stamps, and yes there are tonal differences between tube manufacturers and rev levels.
However, I'm not as bad as the OP. Not yet, anyways.
My fave? RCA 6L6GA for tweeds, and GE's in later amps.
Now, preamp tubes are a whole 'nother story...

ken

Ken,
I'm sure it's my own conservatism that has kept me stuck on that specific tube. I'm sure I can find some from 1960, 61 etc.. that sound just as good to me but I have not come across any (though I haven't looked for a good 10 years, until now). My first experience with these tubes way back when just blew me away. They were Harman Kardon labelled. I soon bought more and some from other years but they weren't quite the same and neither was the structure of the tubes. The bottles got bigger and the mica spacers got smaller. i have to wonder if that is all that changed. However, to be honest, I haven't met a GE that I haven't liked. They are the absolute best 6l6 to me. I know many people love the RCA blackplate but I never thought they stood out above other US tubes. I have to admit though I had no tweed era amps at the times I was trying them and I think that's where a lot of their hype came from.

[ken]

You know you're obsessing about tubes when... you just finished recording a song and in the back of your mind you're thinking "I shoulda used the Mullards instead of the Bugle Boys on that lead... should I overdub?"

Keep an open mind, and try lots of tubes. Some of the lesser known tubes can sound really cool. GE tubes are still reasonably easy to find, especially if you look at 'offbrand' tubes.

ken

[RitzRed]

is there some kind of chart that tells what each tubes does I am trying to learn how to make old tube amps out of different type old record players or what ever into harp amps or small guitar amps I would like to learn witch amp to use by what tubes it has is there a chart or something I can get that will tell me like what a 12AX7 tubes does or a 6L6,or 6V6 or 35W5 12AU6 like what is the difference or what function is different like say between a 12AU6 and a 12AV6 I guess what I am asking is there a way to learn what each tube does using the digits numbers

[Jazz P Bass]

Consult the datasheets?
Here is an awesome link: electron Tube Data sheets - Search
When it comes to oddball tubes like the 35W5, 12AV6, Google that number. Go up top & click on images. Sometimes a schematic will be shown.
Be aware that a lot of these older pieces of equipment are very unsafe.
The line voltage may or may not be present on the metal chassis. (ie: Widow Maker)
To make them safe, a line isolation transformer should be hooked up between the line & the equipment.

[RitzRed]

ok thanks I will take a look. Where do I buy a line isolation transformer and exactly where do I wire it in? do you know how to tell what a tube does by the number or letter number combination like I have a little Magnavox amp with just 3 tubes 2 are 50EH5,s and one is a 9 pin tube but the numbers on the tube are gone.So do you know what that 9 pin tube would be? I am assuming it is like a 12AX7 tube but I am new to all this! A,lso I have another little amp with 3 tubes they are 12SJ7, 50L6,and 35Z5 do you know what each of these tubes do,? and can they be changed or upgraded to make the amp sound better or more power?

[Jazz P Bass]

The 50EH5 amp is a stereo amp.
2 channels.
The 50L6 is an output tube.
The 35Z5 is a rectifier.
The 12SJ7 is a preamp tube.
Typically these amps need an isolation transformer. (Transformer - Hammond, Line Isolation, 90 VA | Antique Electronic Supply LLC) to be operated safely.
The 50EH5 is good for about 5 watts output.
The 50L6 is good for about 10 watts output.
Google each of the tubes for circuits that use them.

[RitzRed]

ok I will do that thanks

[Mr Johnny Birchwood]

Here's a hint, GE 12v6 NOS can be had for about 10 bux a pair. That's a 6v6 with a 12v fil. I design and build amps around tubes with funky fil voltages because they are widely available and cheap. There are millions of these odd filament tubes out there that can be had for next to nothing. Any tech worth his bench fee can make a voltage doubler or retrofit an amp to use a different fil voltage in his sleep. There are probly some 6L6 equivs with odd fil voltages, maybe from the same plant and era, I don't know for sure. Better hurry before I buy em all up...

[Chuck H]

Any tech worth his bench fee can make a voltage doubler or retrofit an amp to use a different fil voltage in his sleep.

I'll agree that it's not THAT hard to do. But it IS expensive. Anyone who can do it knows why. Tell me... Have you had good luck voltage doubling filament supplies??? Then there's the issue of the preamp wiring being designed for 6.3V!!! I detest wiring filament supplies. If you wan't it on the cheap, don't ask ME to do it. I don't see this as an economical solution in the long run anyway. Tube availability for any NOS type is a crap shoot. I suppose it's fine to rewire for a cheaper tube, if you can get 'em. But then you have to undo th modification to run the normal stuff if/when it comes up. Like selling the amp or the alternate tube becomes scarce. I'm glad it works for YOU. But I might not endorse it.

[Mr Johnny Birchwood]

I'll agree that it's not THAT hard to do. But it IS expensive. Anyone who can do it knows why. Tell me... Have you had good luck voltage doubling filament supplies??? Then there's the issue of the preamp wiring being designed for 6.3V!!! I detest wiring filament supplies. If you wan't it on the cheap, don't ask ME to do it. I don't see this as an economical solution in the long run anyway. Tube availability for any NOS type is a crap shoot. I suppose it's fine to rewire for a cheaper tube, if you can get 'em. But then you have to undo th modification to run the normal stuff if/when it comes up. Like selling the amp or the alternate tube becomes scarce. I'm glad it works for YOU. But I might not endorse it.

I've had good luck with voltage doublers, but the easier solution is to get a separate dc supply for the fils. Easily reversible. Recycling centers have garbage cans full of wall warts. A 12v 1a dc wall wart will easily run a pair of 12v6 and cost you 3 bux. Easily reversible and puts less wear on the mains power tranny. Mostly I use the funky filament voltages for custom builds where I can design around different fil voltages. For 10 bux a pair, NOS 12v6's are a steal compared to a desirable pair of 6v6's. Especially after the NOS tube ravers inflate the prices of these old tubes. I like US made NOS and GOS tubes for a couple reasons: Reliability, and close mfg tolerances. I can solder a 10cent VCR capacitor into an amp and change the tone WAY more than any magic tubes ever will. What the tube ravers are hearing is likely just the effect of different conduction changing op points. Just like a slight adjustment on the volume knob. Oh well, if it makes em happy...

[Chuck H]

I agree for the most part with your observations. But I don't think I'd ever run my power tube filaments off a common, salvage, DC wall wart transformer rated at 1A. Not for a customer or a help suggestion anyway. Home brew personal amps not withstading. No holds barred there.