Help identify this tubes...

[ODwan]

Hi all!
Here's one for you tube experts out there:
I happened upon this two old tubes and like to have some more info on them.
the first is pretty easy: a Mullard ECC83
but what type exactly and when was it made?
On the back is printed a code:
163
B7J5


the second only says USA 7025 on it. So it's a 7025 but of what make?
There are traces of a gold label, but nothing legible.

I hope someone can shed some light!
Thanx,
Timo

[David Root]

The Mullard is a 1967, the 7 in the date code is the year, and a 4-digit date code is '60s or '70s but the label looks like '60s to me with BVA on it. In the code B is Blackburn, the factory where it was made in England. J is the month. Looks like a standard '60s Mullard ECC83.

The 7025 would be RCA or Tung-Sol, based on the octagon around the 7025. Looks like a gray plate, so likely early '60s. These would have had a date code like 61-25 or MH if RCA, or 3226125 if Tung-Sol (for example) but these rub off easily, unlike the etched Mullard codes.
I looked again at the octagon, it has the characteristic breaks in the lines that RCA used as date codes too. Also this appears to be a short plate and '60s gray plate Tung-Sols had long (17mm) plates, so I think it's an RCA. The gold label traces may be from an RCA made for someone else, either an OEM or another tube seller.

Both great ECC83s!

[Phil_S]

On the 7025, the letters USA look very RCA to my eye.

[ODwan]

Thanx!
That was very helpfull!
I never really bought into that NOS tube hype, but did not have the opportunity to try some out myself.
But, dammit, they sound better!!!
These are pulls from a beat-to-death silverface Fender combo, the only tubes left intact
I tryed them in a Marshall JCM800 build and a Dumble HRM build in V1 position.
The Mullard really makes the Marshall come alive, much more authentic sounding. The 7025 sounds good though does not really cut it.
The HRM likes both tubes: the Mullard is in your face and very big sounding. The 7025 is quieter, politer and sonehow more detailed.
Both outshine all current production tubes I have tried. Hard to describe, they just sound more like tubes if that makes sense....
Cheers,
Timo

[David Root]

Welcome to the Old Tubes Appreciation Society!!

[JR88]

Right one a RCA grey plate maybe? hard to tell.

[johnny riff]

id check for shorts.. if ok .plug them in! hear how they sound.. you may have a gift from the gods..

[ODwan]

Both seem ok, holding up for 10 playhours now.
I don't have a tube tester, but mu factor seems right on par with new tubes.
I measure all corresponding voltages every hour or so: all ok with no drift.
David: yeah, I think I'm hooked Since I don't have the money to shell out 100 bucks for one tube, I'll have to haunt the flea markets some more...

Cheers,

Timo