Can anybody tell me what this tube rating is?

[Leonard Neemoil]

I don't understand what the second digit is supposed to be. I'm referring to the hand written label that's on the tube base.

Thanks.

 

[Georgiatec]

I don't understand what the second digit is supposed to be. I'm referring to the hand written label that's on the tube base.

Thanks.


View attachment 104281

Could just be a batch number?

 

[fitz]

I don't understand what the second digit is supposed to be. I'm referring to the hand written label that's on the tube base.

Thanks.


View attachment 104281

Looks like a variation of a cursive letter F, possibly a lower case f, to me.
I have no clue if that means anything mathematically or electronically.

 

[nevermind]

I believe that is pico farads...

 

[Pete Farrington]

don't understand what the second digit is supposed to be.

There’s probably no reason that you need to understand it. It’s most likely an in house reference code made by whoever graded the valves.
All that matters to you is that they’re not too dissimilar.

 

[Old Punker]

 

[Leonard Neemoil]

There’s probably no reason that you need to understand it. It’s most likely an in house reference code made by whoever graded the valves.
All that matters to you is that they’re not too dissimilar.

Well I was just wondering the tube rating to compare to others I have laying around. I have some 45s I think and can't tell if these are 47 or what.

 

[Matthews Guitars]

4F. That means it'll never be drafted into military service.

 

[Pete Farrington]

Well I was just wondering the tube rating to compare to others I have laying around. I have some 45s I think and can't tell if these are 47 or what.

There’s no international / standard system for valve rating, these are probably internal references. ie only meaningful in regard of the people that wrote them.

 

[Leonard Neemoil]

There’s no international / standard system for valve rating, these are probably internal references. ie only meaningful in regard of the people that wrote them.

Well that makes absolutely zero sense. Especially considering that these are probably rebranded JJs and that's what I have laying around, JJs rated at 45.

 

[XTRXTR]

How is what Pete said not making sense? Or are you saying it makes no sense that these values are written on the tube base and they don't mean anything that anyone can decipher here?

Just cunundrummin

 

[fitz]

Well I was just wondering the tube rating to compare to others I have laying around. I have some 45s I think and can't tell if these are 47 or what.

Well, what if it IS a 47?
I've seen 7's written with the little slash through them - maybe a strange loopy top 7?
So now what, are you thinking of using one with one of your 45's?
The pair in a quad with the pair of 45's?
You've obviously got 2, and they a usually used and biased in pairs.
What amp are you using them in, and why would it matter?

these are probably rebranded JJs

They are Marshall branded JJ 's.
JJ logo is right next to the 4 something mystic rating.

 

[Leonard Neemoil]

How is what Pete said not making sense? Or are you saying it makes no sense that these values are written on the tube base and they don't mean anything that anyone can decipher here?

Just cunundrummin

Makes no sense to me that there isn't a standard for rating tubes considering we need matched pairs and quads. Also, since these are just rebranded JJs then they should imo be rated in the same manner as JJs.

Well, what if it IS a 47?
I've seen 7's written with the little slash through them - maybe a strange loopy top 7?
So now what, are you thinking of using one with one of your 45's?
The pair in a quad with the pair of 45's?
You've obviously got 2, and they a usually used and biased in pairs.
What amp are you using them in, and why would it matter?

They are Marshall branded JJ 's.
JJ logo is right next to the 4 something mystic rating.

If it is 47 then it's 47. But if it happened to be 45 then I could just swap them with my JJs and not really need to re bias right?

That's a pic of my DSL 100. My DSL 40 has 45s, and my spares are 45s. I just think it would be more convenient if both amps (meaning all of my tube amps) had tubes of the same rating.

 

[lespaul339]

Hmmmm that is confusing

 

[fitz]

then I could just swap them with my JJs and not really need to re bias right?

I've read here that even tubes sold as a "matched set" can measure and bias quite differently.
Just because your tubes are labeled the same, doesn't mean they actually are, or that your amp is set for them.
Probably best to check the bias after changing and adjust as necessary.
Might not need adjusting, but worth checking, nonetheless.