National Incoming NOS Tube Stash Day - With A Nice Backstory.

[ViperDoc]

WOW. Grab a tube tester and see how they look before fragging your transformers.

The EF93 is a 7-pin hi-fi pentode. I bet those would be a stellar Ebay post. Enjoy those tubes!

I understand NOS tubes from the 60s were built to handle much higher voltages, are better made, and sound great, just so long as they're not damaged.

 

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WOW. Grab a tube tester and see how they look before fragging your transformers.

Excellent idea!

The EF93 is a 7-pin hi-fi pentode. I bet those would be a stellar Ebay post. Enjoy those tubes!

They aren't worth much, apparently. I might hang onto them in case a friend needs one.

I understand NOS tubes from the 60s were built to handle much higher voltages, are better made, and sound great, just so long as they're not damaged.

They are definitely better built; you can see it in the build of the tube. These are pics taken of two of my tubes, first an NOS GE:

NOS GE

The parts are straight, instead of crooked; the supports are perpendicular to the base; cleaner wiring, etc. Look at the top of the tube for a clean build quality. Note also that the mica spacers are parallel, and that the "fingers" that serve to keep a minimum contact with the glass so the parts don't rattle are evenly spaced.

NOS Mullard:

As with the GE, the construction inside the tube is about perfect. The angle on this shot is different, but the tube is built well inside. Any bend on the pins on the bottom straighten, of course, when the tube is inserted into the socket.

New Production Labeled Mesa

New production, copying box plate like GE, taken from my Mesa amp when it was new; the supports are cockeyed tilting left, it's hard to see from the angle of the picture but the parts, especially at the top of the tube are also a mess, Wires coming up from the pins are messy and bent. The mica spacers are not parallel, the top one tilts vertically. The mica spacers also have irregular "fingers" so the parts are more likely to rattle against the glass.

The new production tube tends to ring even at low volume and and rattle at high volume as well. The poor assembly quality contributes to this. I find this typical of newer tubes, not the exception.

It's my understanding that this is a Chinese-made tube. The new production Russian and JJ tubes are closer to NOS in terms of evident build quality, though not quite as perfect.

Apologies for the grainy photo.

 

[ViperDoc]

Excellent idea!

They aren't worth much, apparently. I might hang onto them in case a friend needs one.

They are definitely better built; you can see it in the build of the tube. These are pics taken of two of my tubes, first an NOS GE:

NOS GE

The parts are straight, instead of crooked; the supports are perpendicular to the base; cleaner wiring, etc. Look at the top of the tube for a clean build quality. Note also that the mica spacers are parallel, and that the "fingers" that serve to keep a minimum contact with the glass so the parts don't rattle are evenly spaced.

NOS Mullard:

As with the GE, the construction inside the tube is about perfect. The angle on this shot is different, but the tube is built well inside. Any bend on the pins on the bottom straighten, of course, when the tube is inserted into the socket.

New Production Labeled Mesa

New production, copying box plate like GE, taken from my Mesa amp when it was new; the supports are cockeyed tilting left, it's hard to see from the angle of the picture but the parts, especially at the top of the tube are also a mess, Wires coming up from the pins are messy and bent. The mica spacers are not parallel, the top one tilts vertically. The mica spacers also have irregular "fingers" so the parts are more likely to rattle against the glass.

The new production tube tends to ring even at low volume and and rattle at high volume as well. The poor assembly quality contributes to this. I find this typical of newer tubes, not the exception.

It's my understanding that this is a Chinese-made tube. The new production Russian and JJ tubes are closer to NOS in terms of evident build quality, though not quite as perfect.

Apologies for the grainy photo.

The 12AX7WA is a ruggedised valve (“W”) for reduced microphonics, often yielding smoother breakup and higher treble response than the “WB” version, which tends to be darker. Note also the difference in plate length from those to your WD tube in the other picture.

 

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The 12AX7WA is a ruggedised valve (“W”) for reduced microphonics, often yielding smoother breakup and higher treble response than the “WB” version, which tends to be darker. Note also the difference in plate length from those to your WD tube in the other picture.

The WD is a Blackburn Mullard NOS, but it’s not my tube, which is a CV 4004 British Military.

Sorry for any confusion. The picture is just to show construction quality.

 

[László]

O fellow tube people (if any yet there be), feast thine eyes!

Apparently my friend decided to hang onto the other RCA 7025 and GE 12AX7, and I don't blame him one bit! But this is quite the haul.

I don't believe the EF93 or 6AN8A are guitar amp tubes. But they're nice artifacts of a bygone era!

 

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Mysteries Solved, and Interesting Discoveries.

Other than the DuMont/Mullard EL34s, the date of manufacture was pretty simple to discover, and I've covered that for each tube. I still don't have enough data on the EL34s, except it's clear they're Mullard UK manufacture. The rest are clearly early '70s NOS tubes.

If the EL34s work I can use them, and can also use the RCA 7025 if it works. I probably can't install the 6L6s in my amps as they're metal tube versions and might not be able to handle the plate voltage of newer amps. The 6550s probably won't work in my amps either. The amps aren't designed for them. But maybe down the road I can use both sets if I happen to get the right amps.

The GE 6L6 pair:

This first GE tube pair is interesting, though may not be appropriate for my amps; it's an all metal, vintage 6L6 type that might not survive modern plate voltages.

Modern amps use the 6L6 GC, which is glass. The GE tubes I got are the original 6L6s, with metal envelopes. These GE 6L6 have date code EI (Feb 1973) and 188-5 (Kentucky plant). They are NOS and in perfect condition, but not yet tested.

The Mystery of the DuMont EL34/5CA7s solved!

These are in fact Blackburn Mullard EL34/6CA7s! Very, very desirable unobtainium. One of them had a clearly visible Mullard label that I accidentally partly rubbed off when cleaning the dust off the tube. The old ink on UK tubes rubs off very easily. That was dumb of me! But you can see the halo getter and 'Great Britain' printing. I'm trying to check the date codes that partially rubbed off.

These tubes appear to be used. There's a ring from the tube retainers around the bases, and they were dusty. They may test great, they may not, but they're the real deal.

The RCA is a correct RCA, US-made 7025. 'EW' indicates the August, 1974 date of manufacture.

Here's the biggest surprise:

Westinghouse 6550s are Tung-Sol triple getters, manufactured by Westinghouse USA per 337 in date code. The additional numbers in the code say the date of manufacture is 1973.

 

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That RCA is going into one of my amps, I already have Mullard preamp stuff in the HXDA, and Brimar in the DG30, so either the Fillmore or the Lone Star. Coin flip, I suppose.