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Help me ID this 7025

Iceman63

Member
Messages
654
Please help me with this guys. I cannot for the life of me figure out how to post my pics.
You tube experts...I can send you a pic of the 7025 tube in question.
 

DaveKS

Member
Messages
16,704
You need to put pics on a photo hosting sight like photobucket then use image link to post.

If they have the flat sided top and bottom mica spacers, then their RCA, the best.



This here even though it says Sylvania on glass is actually a CBS/Hytron, the little code dots under the 7025 etch give it away. GE also have little dots under etch.
 

Iceman63

Member
Messages
654
I have pics on photobucket. I tried the image thing, put the url stuff in there...to no avail. Beats me. The tube only says 7025 and above that in small lettering says U.S.A.
I'll try again to post pics.
 

DaveKS

Member
Messages
16,704
I have pics on photobucket. I tried the image thing, put the url stuff in there...to no avail. Beats me. The tube only says 7025 and above that in small lettering says U.S.A.
I'll try again to post pics.
You need to find the image link and then paste in post it will already have the image tags.

Or just post a direct link to you photobucket
 

zzmoore

Member
Messages
7,158
You need to find the image link and then paste in post it will already have the image tags.

Or just post a direct link to you photobucket
Yes...bring up the pic in photobucket.
To the right of the pic (its been a while) there should be some options...4-5 of them.
Click on "direct" then you should be able to (right click) and paste it direct into your post.
Christ.....I hope that made sense.
good luck
 

DaveKS

Member
Messages
16,704
If their flat sided they are RCA, they're only ones who built them like that.

Hint photos of tubes, use good strong room lighting but don't use flash, the glare on glass and washing out of internals makes it very hard to see anything.
 

Iceman63

Member
Messages
654
I'm going to try to take better pics. If it's an RCA, approx. how old would it be?
Where would this tube be best used? V1 a good slot?
 

Jeff West

Member
Messages
1,055
From that photo, appears to be RCA 7025 made at their Cincinnati factory 1958-60. Probably closer to '60 because I think they didn't have "USA" on the earliest ones. Nice tube, IMO.
 
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DaveKS

Member
Messages
16,704
Assuming it's not dead, yes one of the best v1 you could ever want. RCA 7025 are a holly grail type tube to many, it's pretty much my fav tube especially for fender'ish amps.

And they last forever, my 1st experience with them was probably 9yrs ago with some I dug out of milk cartons from a TV/Ham radio repairmans estate, they looked like yours pretty much, all the ink worn off. My jaw hit floor when popped them in v1, there was that sound I had been searching for. Had local tech with tester check them, he said they tested around 95% of what a new tube should. I'm still running that pair in my amps 9yrs later with constant use and they still test out at about 93-94%.

If you look online you'll see they go for $100 and up if their brand new NOS.

Jeff West knows more about the origins/history of tubes than anybody else on here I'd think, so consider the ID part settled
 
Messages
1,657
From that photo, appears to be RCA 7025 made at their Cincinnati factory 1958-60. Probably closer to '60 because I think they didn't have "USA" on the earliest ones. Nice tube, IMO.
I say no way. I've never seen a 1950's short-plate RCA 12AX7. The earliest I've seen for them is 1961.
 

Jeff West

Member
Messages
1,055
You're certainly right about that for short plate. When I looked at it on my phone awhile ago it looked like a long plate!

There was a different RCA 7025 version briefly in between long grey and short grey, too.
 

Iceman63

Member
Messages
654
This tube was in a Badger 30 I picked up used about 4 yrs ago. Someone had re-tubed it....whether or not for a different tone search or what, I don't know. I ended up going all stock tubes in that amp for a baseline, especially since I use it mostly as a pedal platform.
Right now I'm playing around with the first couple of slots in my PRS Custom 50. Tried a Tung-sol 12ax7 in V1 and a Penta in V2. Brightened it up, but was a bit too open sounding for me with single coils. Suited me ok w/humbuckers. I put the JJ back in V2(also the CF), and will try this 7025 in V1, along with the Tung-sol, a Sovtek 5751, or a Gold Lion 12ax7, and see which one I like best in V1. Gold lion in V1 right now is not much brighter than the JJ.
 

Jeff West

Member
Messages
1,055
On the etched octagon, if there's a little tab (I think RCA called them "nibs" in their standardizing notice) protruding on the lower right corner (like under the "5" in 7025), that indicates Cincinnati factory manufacture. Better look again on the one above, though, I might just have seen what I was expecting to see! I think all the early RCA-made 7025s were Cincinnati. There were other factory designators; if the tab is in the lower left corner, or the top right corner, for example, both of those designate specific factories in the giant Harrison, NJ plant complex. The early '70s 7025 shown near the top of the thread likely will show one of those. RCA Cincinnati factory shut down production of these in very early '60s, IIRC, ca. 1962. Harrison lasted until mid 1976.

The short-lived long blackplate RCA 7025s were distinctive; they apparently came well after bp RCA 12AX7s had stopped, and I've never seen one labelled as "12AX7". The ones I have or have seen are usually dated ca. 1960 or '61. The bottom mica is straight sided, but the top is a "sandwich" of a straight sided mica under a fully round one, so looks round (with teeth) from the top. They have rectangular getter arrangement, not halo. I'll look to see if there's a handy photo online, but if not I can shoot one. I'm looking at one here and it has the Cincinnati tab on the octagon.

Hard to date the short grey plate RCA 7025s across the early '60s thru mid '70s if they don't have markings, but I've seen a few early ones with D getters instead of halos.

Jeff

https://cdn3.volusion.com/gm5yp.bd2vt/v/vspfiles/photos/RCA-7025-BP-3.jpg

https://cdn3.volusion.com/gm5yp.bd2vt/v/vspfiles/photos/RCA-7025-BP-2.jpg

http://tubeaudio.netfirms.com/7025rca.jpg

https://cdn3.volusion.com/gm5yp.bd2vt/v/vspfiles/photos/RCA-7025-BP-4.jpg
(Cincinnati)

http://www.ebay.com/itm/Matched-Pair-RCA-7025-12ax7-ECC83-short-plates-tubes-Test-NOS-/171830247314 ("EW" = 8/74 labelling; octagon = Harrison, Factory #1)
 
Last edited:

Tone Meister

Member
Messages
3,266
Mind blowing historical knowledge of tubes by Jeff West, The Dirty Tube, Timbre Wolf, et al. The TGP community should count itself very lucky to have these true experts to run our silly tube questions by.

:beer

Carry on ...
 

lousyatit

Silver Supporting Member
Messages
2,339
On the etched octagon, if there's a little tab (I think RCA called them "nibs" in their standardizing notice) protruding on the lower right corner (like under the "5" in 7025), that indicates Cincinnati factory manufacture. Better look again on the one above, though, I might just have seen what I was expecting to see! I think all the early RCA-made 7025s were Cincinnati. There were other factory designators; if the tab is in the lower left corner, or the top right corner, for example, both of those designate specific factories in the giant Harrison, NJ plant complex. The early '70s 7025 shown near the top of the thread likely will show one of those. RCA Cincinnati factory shut down production of these in very early '60s, IIRC, ca. 1962. Harrison lasted until mid 1976.

The short-lived long blackplate RCA 7025s were distinctive; they apparently came well after bp RCA 12AX7s had stopped, and I've never seen one labelled as "12AX7". The ones I have or have seen are usually dated ca. 1960 or '61. The bottom mica is straight sided, but the top is a "sandwich" of a straight sided mica under a fully round one, so looks round (with teeth) from the top. They have rectangular getter arrangement, not halo. I'll look to see if there's a handy photo online, but if not I can shoot one. I'm looking at one here and it has the Cincinnati tab on the octagon.

Hard to date the short grey plate RCA 7025s across the early '60s thru mid '70s if they don't have markings, but I've seen a few early ones with D getters instead of halos.

Jeff

https://cdn3.volusion.com/gm5yp.bd2vt/v/vspfiles/photos/RCA-7025-BP-3.jpg

https://cdn3.volusion.com/gm5yp.bd2vt/v/vspfiles/photos/RCA-7025-BP-2.jpg
Jeff, Hudson R. and I both urge you to write a book....PLEASE!
 

Jeff West

Member
Messages
1,055
Hey, is that K.O.? We should talk sometime! And I wanna play Hudson's '58 LP Jr. again!

If a book were to be written, as Tone Meister indicates, there could be many good collaborators here!

As I've said before, the real credit for a lot of the arcane RCA coding and other stuff as repeated here goes to Ludwell Sibley and his associates who researched it from a wealth of original RCA internal production printed material, also to Bro. Patrick Dowd who had saved that material from certain fate in a landfill at the time of the Harrison plant closing in '76, and to those who maintained and organized it since.
 




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