Short plate vs long plate. Common cathode vs common anode

[fatboy135]

a 12BZ7

This is quite similar to 12ax7, but why did you choose this tube and not a 12ax7¿??

 

[fatboy135]

http://forum.grailtone.com/viewtopic.php?t=749&postdays=0&postorder=asc&highlight=jan+5751&start=15
:wink:

 

[Timbre Wolf]

Exactly!

Here's an excerpt:

RCA 12BZ7 black plate – Yes, I did type that correctly! This has been my last great revelation. The 12BZ7 is a longer-bottle tube (nearly 1/2” taller, like the E180CC), but it fits fine in the Triaxis. And, although it has the same amplification factor as a 12AX7 (mu = 100), my rig sounds about 2dB louder with this tube. It reminds me of Nigel Tufnel, in Spinal Tap, pointing out that his Marshall volume goes to 11 (“One louder”). This is the “11” tube. This means that you can turn your amp “master” volume down to achieve the same volume, thus effectively dropping the noise floor about 2dB (take note, for when you’re recording), or keep the power amp volume the same, thus hitting the power tubes a little harder. It draws twice the current of the 12AX7, but, again, it works great with the Triaxis. I have tried a number of versions of the 12BZ7 (GE, CBS/Hytron, Sylvania, Philco), and they all have the tonal balance I like for this position. I prefer 12BZ7s with black plates for their proven dynamically-sensitive liveliness and articulate snappiness.

 

[fatboy135]

so I will configurate the triaxis with this tubes
v1 eh gold
v2 eh gold
v3 5751, are you agree?''
v4 eh gold
v5 don´t know maybe lps, svetlana jj 83s or 803, ei or maybe a 5751???
what do yo think???

 

[Timbre Wolf]

so I will configurate the triaxis with this tubes
v1 eh gold
v2 eh gold
v3 5751, are you agree?''
v4 eh gold
v5 don´t know maybe lps, svetlana jj 83s or 803, ei or maybe a 5751???
what do yo think???

I'm not crazy about EH tubes. I think that any of the other new production 12AX7 you named for V5 would sound/perform better than an EH 12AX7 in you input positions (V2 and V1). Well, I'd be cautious with Ei, as they're known to go microphonic rapidly. But if you like EH a lot, go ahead.

I'd also caution you against the 5751 in V5 - this is not the position where you want to lower gain at all. If you're into EH 12AX7s, I'd say put one here. I do recommend that you satisfy your own curiosity on this topic by purchasing a (NOS - really!) 5751 for V3, and first try it in V5 to see what I mean.

- T

 

[fatboy135]

yes I love eh, I purchase a good quantitie of tubes, then I will test them on my triaxis, and then I think that I will buy a 5751 to V3

 

[fatboy135]

After seeing the datasheets of 12ax7, 5751 and 12at7 I concluded that:
12ax7 curves and 5751 curves are perfect matched and could be substitute with no mods on the circuit, if you want to put a 12at7 you will need to recalculate the resistors.

Believe me I spend 4 years of my life with theoretical tubes, I´m not as practice as you with all kind of tubes, but I spent so great time solving equations and designing theorical tube circuits to be implemented by another crew.

For example on my spare time I moded the classical bottle rocket to have a more musical feeling with 12at7. Boogie gives me the original schematics and I recalculate it for use it with 12at7.

Here is my schematics:

This is not the entirely schematics it is only the amplification stages.
When you try to fit a 12at7 with a 12ax7 you must reduce the resistor value, the 12at7 is able to develop 2.5 watts, and the 12ax7 only 1 watt.
The 12at7 could reach the 20 mA but the 12ax7 only reach the 5 mA.
You must to recalculate resistors to fix a good work point that ables you to use the 12at7 as 12ax7. If you don´t do that you maybe will working the amp in not designed conditions.´
So I´m still interested in 5751

 

[fatboy135]

so I forget to say that these circuit where used in a line booster, not for guitar, but the bottle rocket works so fine as a tuber booster line if you mod it

 

[Timbre Wolf]

If you don´t do that you maybe will working the amp in not designed conditions.

I like to live dangerously 8)



It sounds like you're in the position to understand how to make a good thing sound better, and I look forward to the results of your hard work.

Meanwhile, I'm enjoing breaking the rules with my tube setup!!

- T

 

[Timbre Wolf]

Forgot to mention that I use 12AT7s as phase-inverters in my 20/20 power amp as well. And I use a 12BZ7 as the main input to that power amp. My 20/20 performs much more to my liking with these changes, though one could calculate that it's totally f-ed up! What can I say? :wink:

- T

 

[fatboy135]

I like to live dangerously

what car do you own???? :lol:

Forgot to mention that I use 12AT7s as phase-inverters in my 20/20 power amp as well

I´m using a 20/20 with the triaxis too

It sounds like you're in the position to understand how to make a good thing sound better, and I look forward to the results of your hard work.

I´m working so hard looking into jan 12ax7 substitutes, when I get a couple of models you will be the first person to know it

 

[fatboy135]

So....
After receiving and testing all that tubes, we can say that:
1) There is not needed to get NOS tubes for achieve a great tone
2) The best value quality price are the jj-ecc83s ( 7$ )
3) The tubes that can crunch your amp are the eh gold, svetlana 12ax7 and jj-ecc83s

My triaxis tube setup for the moment is:
V1-Eh gold
V2-Eh gold
V3-JJ-ecc83s
V4-JJ-ecc83s
V5-JJ-ecc83s//Svetlana 12ax7

So I´m waiting still for the 5751 and I´m trying to decided for the jj or the svetlana
:wink:

 

[Timbre Wolf]

So....
After receiving and testing all that tubes, we can say that:
1) There is not needed to get NOS tubes for achieve a great tone

Not for you, perhaps... :wink:

- T

 

[fatboy135]

not for regular workers
I think that there are another improvements to do better than waisting hundreds of dollars in those tubes, for example buying a better cable or maybe a buffer for your pedal chain

 

[fatboy135]

trust in me buy a couple of jj-ecc83s and try them, if you think that they are so bad for the 7$ that costs I will invite you some beers

 

[fatboy135]

ooops I forget it:
without any doubt I prefer short plate vs long plate

 

[Guitarzan]

I will invite you some beers

Cerveza!!!!!! I'm there!

 

[fatboy135]

cerveza??? are you from mexico???? :wink:

 

[Guitarzan]

Nuevo Mexico, Estados Unidos. Donde vive?

 

[fatboy135]

q pasa guey no me seas pinche frijolero :wink: