Short plate vs long plate. Common cathode vs common anode

[fatboy135]

Ok there is no questions about the short and long plates produces different tones, too very diferent tones.
I´m researching some information about this matter, could anyone helps me???

Ok another question, does anybody knows any tubes that works fine on a common cathode and on common anode topology???

 

[Timbre Wolf]

Ok there is no questions about the short and long plates produces different tones, too very diferent tones.
I´m researching some information about this matter, could anyone helps me???

Are you inquiring about any particular brand? I'll assume you're referring to the 12AX7 types, and generalize as I can from NOS experience: long-plates have a more articulate character, which is often accompanied by a greater range of frequencies and dynamic nature, when compared with short-plate 12AX7s.

If you want to talk tonal differences, we'll have to start naming brands. In fact, to have any sort of meaningful discussion, its best to be as specific as possible. Even within brands, the difference between long-plate versions and short-plate versions is not necessarily accounted for by the plate length alone (examples: Mullard f91 ECC83 vs. Mullard I63 12AX7A, or RCA long gray-plate 12AX7 vs. RCA short gray-plate 12AX7A = all very different tube characters).

- T

 

[fatboy135]

ok why about brands??? I think that their are two principal kind of construction short vs long and the long have some advantages and some handicaps, and the short have some advanteges and some disadvantages.
What about starting with general diferences, and sounds between these types of construction. And then we go into specific features in brands????

 

[Timbre Wolf]

I've kind of gone into detail about brand differences here, though that is not a complete discussion on this broader topic. There are many variations available, and what may seem like subtle distinctions in construction/brand, are not so subtle in performance.

Is there some particular character you're seeking? The more detail you provide regarding your needs, the more I (or others) may be able to help.

Again, it is difficult to simply generalize about long-plate tubes vs. short-plate. But another potential difference is that some long-plate preamp tubes may be more prone to microphonics, especially when confronted with heavy vibrations in a combo. Of course, there are exceptions to this generalization, which is why I like to be as specific as possible.

- T

 

[fatboy135]

Is there some particular character you're seeking? The more detail you provide regarding your needs, the more I (or others) may be able to help.

I want to do a good topic maybe with a few post over general opinions and the getting into the real matter with the brands and its particulars

there are exceptions to this generalization, which is why I like to be as specific as possible.

That is maybe a couple of features and then the particular features of every brand.
I had used regular tubes all my live, I never used N.O.S tubes.
Maybe I think that it is better to post about tubes manufacturers, because in reflector factory are made the sovtek and the eh, and doing a discussion about the sovtek and another discussion about eh maybe it will be a waste of time because they are quite similar aren´t them???

 

[fatboy135]

I forget it: I have append your link about retubing a triaxis to my favorites folder. But I think that I will not use NOS tubes for the moment.
one question sir: did you ever broken a tube in the triaxis V3 position???
on phat mod triaxis the second stage of V3 is a cathode follower.
I just speak with mesa today and they recomend to me to put in this position a chinese tube.

 

[Timbre Wolf]

one question sir: did you ever broken a tube in the triaxis V3 position???
on phat mod triaxis the second stage of V3 is a cathode follower.
I just speak with mesa today and they recomend to me to put in this position a chinese tube.

I'm not sure I understand the question precisely. Broken tube in V3? If you're asking about whether the glass or pins have broken, then - no, I have not. If you're wondering if I've had a tube "go bad" there, then - yes, I have "worn out" tubes in that and other positions. I've used 12AX7, 5751, and 12AT7 types in V3, all with enough success to be able to say that they all can potentially be useful in that position.

- T

 

[fatboy135]

yes I was refering to go bad in that position, sorry for my spanish-english.
So I go bad a tube in that position due the cathode follower topology, then I´m looking for a tube that supports all the current that amplifies that kind of topology

 

[Timbre Wolf]

yes I was refering to go bad in that position, sorry for my spanish-english.

No problem. I hope you will not be offended when I ask for clarification.

I´m looking for a tube that supports all the current that amplifies that kind of topology

We're talking about Triaxis V3 here, which is designed for a 12AX7. Any 12AX7 should be fine here, in terms of current handling. 5751 and 12AT7 also work fine. There is the concern of not overloading the op amp that follows V3, so a lower-mu tube may be advisable.

In fact, I found I prefer a 5751 for V3, and recently re-confirmed this by testing some 12AX7s in that position. Every once in a while I test out my preferences by swapping in different preamp tubes - this keeps me honest. I found that any 12AX7 in V3 made for increased compression in all my Triaxis modes, when compared to the 5751. The 5751 allows for more clarity and dynamic range - like opening a window and breathing fresh air. I should note that older black-plate 5751 are tangibly more dynamically responsive than the common JAN-GE gray-plate 5751 (and forget about the Sovtek 5751 - save a few more $ for a tube that matters).

- T

 

[fatboy135]

There is the concern of not overloading the op amp that follows V3, so a lower-mu tube may be advisable.

You could manage the input into the IC3 ( dynamic voice IC ) by the master parameter.

which is designed for a 12AX7. Any 12AX7 should be fine here, in terms of current handling

Sorry to be disapointed but it is known that sovtek lps and eh becomes wrong after playing these tubes in that position. After a couple of hours the second stage of tube becomes bad and the led1red doesn´t sounds, after replacing that tube with another the led1red works so fine.

12AT7 also work fine

The issue is not as easy as potatoes, if you want tune the work point of the tube with a 12at7 you must to recalculate the resistors over the cathode and anode. Usually you will need lower values of resistors but it must been calculate.

I prefer a 5751 for V3

Ok I´m interested on learn more about this tubes, please explain to me

 

[Guitarzan]

The 5751 tube was made in conjunction with the Army/Navy/Nasa for a robust tube they could use for military purposes. Hence when you find them called JAN it stands for Joint Army Navy. The 5751 has approximatley 70% the power of a standard 12AX7. It's gain is right between the 12AT7 and the 12AX7. Stevie Ray Vaughan and alot of blues players use them for their very usable distortion. Hope that explains it. Go Here and read about it.

 

[fatboy135]

yes I read it but I´m a bit lost into the 5751,7025 and other names, where could I find a table with tube equivalents or with all tubes models and features?

 

[Guitarzan]

Try readingthis page. Go to the very bottom there is a chart.

 

[fatboy135]

ohhhhhhhh then the numbers of 5751 7025 are for military purposes????
I must to read more literature about tubes

 

[Guitarzan]

The number designations are used for military purposes, but... they each have different qualities. Note the mu for each...Do you get it?

 

[fatboy135]

yes I saw it, I´m searching on google some info about the 5751

 

[Timbre Wolf]

Guitarzan - thanks for links to pages I had not read before. There was some useful information there. Not to dwell on it, but some information was laughably pointless (Sovetek 5751 is the "SRV" tube? :lol: It didn't help me cop his chops! And the quote from the Rivera page "American made tubes are known for their scooped voicing and round uncolored "white" tone." - bound to confuse everyone). I'll try not to throw out the good with the bad, though, and appreciate some different points of view.

Here's another couple of references: Brent Jesse and SND Tubes

By the way, fatboy135, the 12AT7 will work in V3 - just plug one in and play. No need to change resistors, no need to think with such effort, truly "easy as potatoes" - trust me, I've done it many times. I used to run a Mullard CV4024 there (also known as a 12AT7WA, M8162, or ECC81).

Its lots of fun to swap tubes, but its even more fun if you can let go of what it is "supposed" to sound like, and just take note of what it does sound like. Play and have fun!

- T

 

[fatboy135]

By the way, fatboy135, the 12AT7 will work in V3 - just plug one in and play. No need to change resistors, no need to think with such effort, truly "easy as potatoes" - trust me, I've done it many times

you could put any tube with 9 pines into that socket, but believe me that getting a perfect match is needed because 12ax7 is only able to move 1 watt and the 12at7 is able to get 2.5 watts.
Download the 12ax7, 12at7 datasheet and compare the curves.
The current and voltage that are needed to good work of a 12ax7 and 12at7 are different, so a re-resistors design is needed.
If you want to try the 12at7 on this position it will works but if you want to place this tube for the rest of your life on a 12ax7 position I recommend to you to redesign the resistor values.

Play and have fun!

:lol: of course man I do it

I have one question more. I´m thinking to get a tube tester because I buy oem tubes very cheap in dozens quantities. Has anybody got this kind of machines????

 

[fatboy135]

ooopsss I forget. I´m looking to get the 5751 on a triaxis, then which is the better position de V3 or the V5???

 

[Timbre Wolf]

I use a 5751 ('50s RCA black-plate) in V3, a 12BZ7 (RCA black-plate) in V5, and a 12AT7 in V2 (Mullard CV4024). But what do I know??

- T