Hello, I’m trying to identify this 12ax7 tube brand. Does this photo provide enough info for someone to be able to figure it out?
Thanks.
Thanks.
Tube I.D.
- Thread starter playittwice
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Thanks!
I see “USA”, so had a hunch that could be a possibility. (RCA). Good to know the symbol designation also, learning still. How do they rank? Good, average, etc.
I see “USA”, so had a hunch that could be a possibility. (RCA). Good to know the symbol designation also, learning still. How do they rank? Good, average, etc.
After further researching, I read these tubes get pretty good reviews from end-users. (RCA’s) If I did my research correctly, they are Black Plates.
On another note, I purchased a pre-amp a while ago, an Eico HF-85, I sent to a fellow AK’r to have restored, (excellent results BTW, if you’re reading this). As a newbie to tubes, he had informed me the tubes were some excellent vintage tubes, Amperex Bugle Boy 12ax7’s. Circa 1958 “Delta” 8H is the etching on the tube.
Being the creatures of habit we are it seems, always fiddling, I decided to roll these tubes into my Scott 222b. Wow these tubes took this amp to another level. It sounds absolutely stunning! I had no idea rolling tubes can make that much difference, I’m sure these BB’s make it a bit more special, but I was definitely not expecting this much of a surprise. The tubes I had in were no slouch either, I think. (Tele’s).
I’m learning a lot just from experimenting and some testing, to hear what sounds best/better. Just wanted to share my experience in case someone is wanting to tube roll, but hasn’t given it a try. Good stuff for sure.
Also a big shoutout to the people here on AK for taking the time to help answer questions and giving advice to myself and the learning community.
Thanks.
On another note, I purchased a pre-amp a while ago, an Eico HF-85, I sent to a fellow AK’r to have restored, (excellent results BTW, if you’re reading this). As a newbie to tubes, he had informed me the tubes were some excellent vintage tubes, Amperex Bugle Boy 12ax7’s. Circa 1958 “Delta” 8H is the etching on the tube.
Being the creatures of habit we are it seems, always fiddling, I decided to roll these tubes into my Scott 222b. Wow these tubes took this amp to another level. It sounds absolutely stunning! I had no idea rolling tubes can make that much difference, I’m sure these BB’s make it a bit more special, but I was definitely not expecting this much of a surprise. The tubes I had in were no slouch either, I think. (Tele’s).
I’m learning a lot just from experimenting and some testing, to hear what sounds best/better. Just wanted to share my experience in case someone is wanting to tube roll, but hasn’t given it a try. Good stuff for sure.
Also a big shoutout to the people here on AK for taking the time to help answer questions and giving advice to myself and the learning community.
Thanks.
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I have occasionally thought that some Euro tubes were over-hyped, or at least not as good as the money they command would imply. Plenty of "boring" US tubes from the major makers are perfectly fine.
the worst old production 12ax7 I own happen to be Amperex. Horribly noisy things, sounds like a windy day at the beach when they are in anything. I think I stuck them in an MPX decoder where their noise doesn't actually cause any problems.
the worst old production 12ax7 I own happen to be Amperex. Horribly noisy things, sounds like a windy day at the beach when they are in anything. I think I stuck them in an MPX decoder where their noise doesn't actually cause any problems.
Dswankey
Lunatic Member
Blasphemy!
If you like that breezy day at the beach effect, I'd be happy to trade you for some "crappy" US old production jobs. I'm really not kidding, these are the noisiest 12ax7 tubes I've ever come across. The EF86 that came out of the same amps are the most microphonic tubes I've ever had. All Amperex, all out of my Hoffman console. Not sure if they were getting Amperex's seconds or what but they aren't good. The EF86 are so bad I had to wrap them in solder and triode-wire them to keep the console from howling like a mic placed next to a PA speaker.
Well, that is not the same experience im having w/these BB tubes. Not sure what’s happening in your case, I am not a roller by any stretch, I’m just sharing my experience, and it happens to be a good one.
BTW, I do value your opinion and experience, you’ve been around this stuff a lot longer than myself. 
I've run across the same issue with Amperex Bugle Boy tubes. Once I was blessed with several from a pair of old scrap Tektronix scopes found while clearing out a trashed shed. Took them home and all measured good on the Hickok. Surprisingly, two from that set were very noisy on my tube amp. The others were no improvement over the RCA and Sylvania tubes they replaced, so those USA tubes went back in. I sold those Amperex tubes with full disclosure and still made a pretty penny.
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So my takeaway from this is;
I’m a lucky chap to have snagged some good ones!
I’m a lucky chap to have snagged some good ones!
I’m assuming the ones I have are what you show. Bummer there isn’t any more info on the tubes. So they are a 7025 rather than a 12ax7, the 7025 is a low-noise-low hum version of the 12ax7. Good to know.
My research shows there is a long plate and a short plate version. The ones I have are short plate I believe. Doesn’t matter, except for my own knowledge/research. As I said above, I’m trying to figure out all the variables and options there are available and what is desirable and favorable.
Thanks.
My research shows there is a long plate and a short plate version. The ones I have are short plate I believe. Doesn’t matter, except for my own knowledge/research. As I said above, I’m trying to figure out all the variables and options there are available and what is desirable and favorable.
Thanks.
The tube you pictured in post #1 shows what appears to be the top of the letter "X" and number "7" within the stop sign, which lends it as being a 12AX7.
Some 12AX7 (and 12AX7A) are built the same as a 7025. Same tube other than a slight change to the heater construction. It was probably cheaper to just make one tube and label them appropriately rather than build 2 or 3 slightly different tubes that perform identically.
the 7025 heater is spiral wound, the regular one is just a zig-zag of heater folded up inside the cathode tube. Sometimes you can see the construction at the top or bottom of the cathode.
The 12AX7A is a variation allowing for controlled warmup in series string applications. Subs just fine for a regular 12AX7.
the 7025 heater is spiral wound, the regular one is just a zig-zag of heater folded up inside the cathode tube. Sometimes you can see the construction at the top or bottom of the cathode.
The 12AX7A is a variation allowing for controlled warmup in series string applications. Subs just fine for a regular 12AX7.
No. Sorry for the confusion. I referenced the wrong post. {I hate when I do that!)
I was trying to state that the RCA black plate 7025 are premium tubes. They are as good as any European ECC83.
Now... RCA 12AX7A tubes are 7025 with spiral-wound, low-noise heater filaments.
In any event, the RCA 12AX7 (and all the variants) are excellent tubes. High testing, quiet ones will sound sweet and last.
No worries Mr. B! I’m probably overthinking this anyway.
My thought is; if they sound good, they are good, but when I need to buy/replace them it’s nice to know what to get.
Thanks for the help and clarification.
My thought is; if they sound good, they are good, but when I need to buy/replace them it’s nice to know what to get.
Thanks for the help and clarification.
