NOS Tubes

[drgordonfreeman]

Where can someone take a deep dive into new old stock (NOS) tubes? I've had a growing interest in them over the last several years, but I've never purchased one, mostly because I don't fully understand what I'd be purchasing.

Looking at NOS 12ax7 preamps tubes, I've seen tubes out there like the Mullard 12ax7-W, the RCA 7025 BP, the GE 12ax7-NP, and Telefunken ECC83-V.

Is there a resource listing what all of those "-ABC's" mean? For example, what's the differences between a 12ax7-W, a 12ax7-A, and a 12ax7-NP? Is there a difference between Telefunken tubes labeled as ECC83 versus ECC83-"ABC"? Can a 7025 BP be used in the same place as a 12ax7-"ABC"?

I'm looking to learn about those sorts of things, so I can become more informed.

Are there any websites out there where a guy can learn about these different sort of tubes?

 

[FleshOnGear]

There's a lot to unpack here. I found an FAQ at the Tung-Sol website that gives an overview of tube designations - http://tungsol.com/html/faqs15.html . It doesn't explain the tonal differences between tubes, but explains some of the suffixes.

I have yet to find a great website for teaching about various old production tubes that isn't ultimately trying to sell NOS tubes (usually at premium prices).

Looking at NOS 12ax7 preamps tubes, I've seen tubes out there like the Mullard 12ax7-W, the RCA 7025 BP, the GE 12ax7-NP, and Telefunken ECC83-V.

Is there a resource listing what all of those "-ABC's" mean? For example, what's the differences between a 12ax7-W, a 12ax7-A, and a 12ax7-NP? Is there a difference between Telefunken tubes labeled as ECC83 versus ECC83-"ABC"? Can a 7025 BP be used in the same place as a 12ax7-"ABC"?

The tube names you've listed I have never seen before. I'm hardly an NOS tube expert, but I have a decent stash. A lot of the important differences between NOS tubes is related more to the manufacturer and the particular construction each manufacturer used during specific time periods. For instance, over many years the Mullard ECC83 was built in 3 different long plate versions (the mC1, the f91, and the f92) and two different short plate versions (the I61 and the I63) - to the best of my knowledge. Those codes are manufacturer codes used by Mullard, and aren't related to the naming convention used to create the ECC83 designation.

Different suffixes to the tube name can have a meaning, as indicated in the website above. A, B, or C is supposed to mean a new version of a tube with improved electrical specs; but, in the case of the 12AX7/ECC83/7025, I think the spec has always been the same. So I suppose that leaves the probability that manufacturers or tube resellers are using suffixes to indicate their own different versions of construction rather than a different electrical spec.

With vintage tubes I'm more used to seeing that kind of difference indicated by a production code, like the Mullards. Or, there might be no change in the name or a visible code, and you're left visually identifying the physical construction within the tube. Suffixes are used liberally by the sellers of current production tubes, though.

Anyway, I'm rambling a bit. My humble suggestion is to first familiarize yourself with different manufacturers (like RCA, GE, Sylvania, Raytheon, Mullard, Brimar, Telefunken, Siemens, Amperex, etc.), then research different versions they've built (like black plate vs. gray plate, long plate vs. short plate, ribbed plate vs. smooth plate, different getter construction). You will pick up some descriptions of the differences in tone along the way. Good luck!

 

[Trelwheen]

Tube King's tube tasters guide :

specs-tube-ecc83-12ax7-470053.pdf

Identifying NOS tubes :

https://www.vivatubes.com/identifying-vintage-nos-vacuum-tubes-by-brand-country-and-eia-code/

Those are a good start for two different aspects of the pursuit of elderly thermionics.

A few important points to keep in mind:

Learn how to identify tubes by the appearance of plates, getters, the glass itself and other characteristics. The etched codes tell the real story, but sometimes even they can be vague or missing

A painted or silk screened label is not a reliable means of identification. Many manufacturers would make tubes for one another and many would supply the same customers.

Long plate 12ax7s can be very noisy in some amps, particularly in the first gain stage.

If you are hunting tubes for a particular type of amp, let us know and maybe we can make some suggestions.

Happy hunting

 

[Dogs of Doom]

Tube King's tube tasters guide :

specs-tube-ecc83-12ax7-470053.pdf

https://medias.audiofanzine.com/files/specs-tube-ecc83-12ax7-470053.pdf

 

[Trelwheen]

https://medias.audiofanzine.com/files/specs-tube-ecc83-12ax7-470053.pdf

¡Gracias!

 

[drgordonfreeman]

I knew this was the right place to ask. You guys are a awesome, and thank you so much for the informative posts and pointing me in the right direction!

 

[Dogs of Doom]

for me, the thing is finding an honest broker...

I mean, we used to have a couple on here that were selling them all the time. They had their testers, & were honest about the state of their tubes.

They'd price them fairly, accordingly.

They could tell you all about the tube they had. They might have a tube measuring 60%, but, they'd sell it as such & you could get it for the same price as a CP tube. Chances are that 60% rated tube would outlive a new CP tube at 100%.

I'm fine w/ that, as long as I know what I'm buying into...

But, when you go on, say, ebay, every tube by a seller measures 100% NOS, it makes me question if they are an honest broker, especially, when the tube looks like it's been beaten to death...

Then, there are the ones w/ their newly screen printed tubes...

Be wary...

It pays to do research on certain tubes that you are looking at, to make sure that someone's not counterfeiting them to rip you off.

Then you have to realize that some people rate things generously, so, they might not rate so well in the real world. I've had that w/ some of the well known online shops... even w/ current production tubes...

 

[drgordonfreeman]

for me, the thing is finding an honest broker...

I mean, we used to have a couple on here that were selling them all the time. They had their testers, & were honest about the state of their tubes.

They'd price them fairly, accordingly.

They could tell you all about the tube they had. They might have a tube measuring 60%, but, they'd sell it as such & you could get it for the same price as a CP tube. Chances are that 60% rated tube would outlive a new CP tube at 100%.

I'm fine w/ that, as long as I know what I'm buying into...

But, when you go on, say, ebay, every tube by a seller measures 100% NOS, it makes me question if they are an honest broker, especially, when the tube looks like it's been beaten to death...

Then, there are the ones w/ their newly screen printed tubes...

Be wary...

It pays to do research on certain tubes that you are looking at, to make sure that someone's not counterfeiting them to rip you off.

Then you have to realize that some people rate things generously, so, they might not rate so well in the real world. I've had that w/ some of the well known online shops... even w/ current production tubes...

This is great insight. Speaking of which, whatever happened to Marty? He was a mod here at one point. Didn't he sell NOS?

@Dogs of Doom do you have any recommendations for users on here whom you've had good experiences with?

 

[drgordonfreeman]

There's a lot to unpack here. I found an FAQ at the Tung-Sol website that gives an overview of tube designations - http://tungsol.com/html/faqs15.html . It doesn't explain the tonal differences between tubes, but explains some of the suffixes.

I have yet to find a great website for teaching about various old production tubes that isn't ultimately trying to sell NOS tubes (usually at premium prices).


The tube names you've listed I have never seen before. I'm hardly an NOS tube expert, but I have a decent stash. A lot of the important differences between NOS tubes is related more to the manufacturer and the particular construction each manufacturer used during specific time periods. For instance, over many years the Mullard ECC83 was built in 3 different long plate versions (the mC1, the f91, and the f92) and two different short plate versions (the I61 and the I63) - to the best of my knowledge. Those codes are manufacturer codes used by Mullard, and aren't related to the naming convention used to create the ECC83 designation.

Different suffixes to the tube name can have a meaning, as indicated in the website above. A, B, or C is supposed to mean a new version of a tube with improved electrical specs; but, in the case of the 12AX7/ECC83/7025, I think the spec has always been the same. So I suppose that leaves the probability that manufacturers or tube resellers are using suffixes to indicate their own different versions of construction rather than a different electrical spec.

With vintage tubes I'm more used to seeing that kind of difference indicated by a production code, like the Mullards. Or, there might be no change in the name or a visible code, and you're left visually identifying the physical construction within the tube. Suffixes are used liberally by the sellers of current production tubes, though.

Anyway, I'm rambling a bit. My humble suggestion is to first familiarize yourself with different manufacturers (like RCA, GE, Sylvania, Raytheon, Mullard, Brimar, Telefunken, Siemens, Amperex, etc.), then research different versions they've built (like black plate vs. gray plate, long plate vs. short plate, ribbed plate vs. smooth plate, different getter construction). You will pick up some descriptions of the differences in tone along the way. Good luck!

I found this while reading:


12AX7A - This version can be used in series or parallel filament circuits. These usually date to the 1960s and have greyplates. Vintage versions of these are about the most sought after tubes of any type today. Often RCA and GE made these for electronic organ manufacturers, and have the organ brand name on the label. These are usually specially selected tubes, and are a great buy---when available! Sometimes, 12AX7A tubes made for the US Military are labeled 12AX7WA, and I have seen WB and WC versions. The W is the military type code, A,B, and C are progressively later productions. These are nice military spec tubes. DO NOT confuse these with current production Russian or Chinese crap with the suffix WX, WB, or WC! These are not military tubes and are not NOS tubes at all!

12AX7WA - Premium military and industrial versions of the ECC83/12AX7.

 

[Dogs of Doom]

This is great insight. Speaking of which, whatever happened to Marty? He was a mod here at one point. Didn't he sell NOS?

@Dogs of Doom do you have any recommendations for users on here whom you've had good experiences with?

Marty got tired of the tube business. He finally had a couple big sales on here (& elsewhere), then he sold the rest of his supply bulk to a big store (tubestore?) He also sold various grades of used tubes.

I don't know of anyone really selling them on here. Used to be @RiverRatt was selling tubes of various states all the time & you could get some good deals from him, but he pretty much got out of it at the same time as Marty. You might see him do a post here & there, selling a few...

I stocked up when they were selling, so I have quite a few & haven't been really looking. I've bought a few things off ebay, but, I know that can be a crapshoot.

I really can't vouch for anyone on here currently, from personal experience, except those two...

 

[RiverRatt]

Hey Dogs, I haven’t been buying and selling at all for the last 10 years or so. I’m friends with Marty and he doesn’t appear to be selling tubes either - he just has his personal stash.

It used to be pretty easy to monitor eBay and find good deals flying under the radar, but that source dried up quickly once people caught on.

eBay soured me on selling. I had people filing a complaint with eBay, who would promptly freeze my PayPal account until they reached a decision and they ALWAYS sided with the buyer.

I still have a few tubes that I would sell. None are NOS but they all test great. I went a little crazy buying stuff from zZounds on their no-interest financing - it’s too easy. Now I need to pay off a thing or two.

 

[Maggot Brain]

If you are interested in vintage tubes at good prices I highly suggest hunting thrift stores, antique stores, estate sales and swap meets. I became determined to find some vintage tubes in the wild and over the past year found 6 vintage pre amp tube locally.

I've found:
RCA 12AT7
GE 12AT7wa
GE 12AT7
GE 12AU7
Amperex Bugle Boy 12AX7
Amperex Bugle boy 12AX7

My holy grail being the Bugle Boys which I must proudly repeat I got for $1.00.

The online prices have gone crazy and as mentioned before that a lot of sellers stretch the truth on the condition of the tubes. These Bugle Boys were in a bowl of radio parts in a antique/thrift store, assuming they were parted out. I could easily find some empty Amperex boxes, which Ironically a local store has, and pass them off as NOS to the ill informed. I would never do that but I'm guessing majority of "NOS" tubes are just old used tubes thrown in a box.

 

[FleshOnGear]

I would love to find some long plate Mullard ECC83s in the wild - mC1 or f91. Those are my holy grail, for sure.

 

[drgordonfreeman]

@Dogs of Doom Thank you for the insight

@Maggot Brain I never even thought of searching for these things in old appliances…

 

[Maggot Brain]

@Dogs of Doom Thank you for the insight

@Maggot Brain I never even thought of searching for these things in old appliances…

Tube Radios, Reel to Reel machines, Organs with an amplifier inside, I'm sure there many more odds and ends but I believe these are the most common to come across thrifting etc.

 

[mickeydg5]

Where can someone take a deep dive into new old stock (NOS) tubes? I've had a growing interest in them over the last several years, but I've never purchased one, mostly because I don't fully understand what I'd be purchasing.

Looking at NOS 12ax7 preamps tubes, I've seen tubes out there like the Mullard 12ax7-W, the RCA 7025 BP, the GE 12ax7-NP, and Telefunken ECC83-V.

Is there a resource listing what all of those "-ABC's" mean? For example, what's the differences between a 12ax7-W, a 12ax7-A, and a 12ax7-NP? Is there a difference between Telefunken tubes labeled as ECC83 versus ECC83-"ABC"? Can a 7025 BP be used in the same place as a 12ax7-"ABC"?

I'm looking to learn about those sorts of things, so I can become more informed.

Are there any websites out there where a guy can learn about these different sort of tubes?

Marty is a wealth of knowledge.

I will add that the ABC's you mentioned mean nothing for real preamp tubes. Where did you get BP, NP and V? Post some links.

 

[Matthews Guitars]

I'm not going nuts for vintage/NOS tubes because I'm not claiming that I always hear a difference or am enough of a cork sniffer to really care. Most new manufactured tubes are good enough for me.

All I will say for sure about tubes from the "vintage days" vs. modern tubes is that vintage tubes were of more CONSISTENT high quality. Today, most tubes that are made (particularly if Russian) are subject to a simpler quality test: Is it a usable tube? If yes, ship it! Chinese quality controls may not be quite that high... although I will state in all honesty that I bought a set of Valve Art Chinese made KT-66s and put them in my '69 Plexi and I love the sound of that amp. I think they're very nice tubes. I would not hesitate to buy more. Until Brimar is making new KT-66s using the Mullard tooling, I'll be happy enough with the Valve Art KT-66s.

Back in the day, every tube maker would crush tubes that didn't perform to a high standard. Today we'd be thrilled to get our hands on some tubes that Mullard would have fed to the grinder.

 

[RiverRatt]

Tube Radios, Reel to Reel machines, Organs with an amplifier inside, I'm sure there many more odds and ends but I believe these are the most common to come across thrifting etc.

Just wanted to add, be careful with old radios and console stereos. Some don’t have a power transformer and run off wall voltage using series filaments. You’ll notice this by really strange tube numbers, like 35W4, 50C5, 25L6, etc. You might get lucky and find a single 12AX7 in some of those but if you’re planning on using one as the guitar amp, don't. They don’t call them widowmamers for nothing.

 

[yladrd61]

Take the red pill. Get a tube tester, even if it is not a top of the line tester. If you buy tubes online but from someone who has a lot of good feedback comments, only buy tubes with good high quality photos, and documented test data with numbers, and make sure you can return them if they are not exactly as described. Also it is much easier to find a matched pair than a matched quad of power tubes. Add tubes to your watch list on flea bay and Reverb and you will get a good many offers at a discount price. The rabbit hole is very deep, better pack a lunch.

 

[Maggot Brain]

Just wanted to add, be careful with old radios and console stereos. Some don’t have a power transformer and run off wall voltage using series filaments. You’ll notice this by really strange tube numbers, like 35W4, 50C5, 25L6, etc. You might get lucky and find a single 12AX7 in some of those but if you’re planning on using one as the guitar amp, don't. They don’t call them widowmamers for nothing.

I wouldn't use a radio for an amp, I'm talking about robbing compatible tubes ala 12AX7, 12AT7 and 12AU7. The radio tubes that add up to wall voltage aren't going to be compatible with the average guitar amp.

Definitely a good word of advice for anyone that might blindly experiment.