Is 6J51P fit to drive a EL34SE?

[TonyTecson]

No, it really wants more voltage on anode than 6J49P.

Try 6P15P instead. If not microphonic, it may be a killer tube! ;-)

i used this tube to drive a 6c33 set years back...
and a 6p14p to drive the el34 set....

 

[artosalo]

I tried (just for fun) a 6J51P instead of the 6J49P with 10mA through it I thoght it sounded thinner..
(This is the EL34SE)
But maybe I shouldn´t judge it to hard it might be some other component that is the limmiting factor the IT trafo or the OPT.

The amount of THD, especially with SE-amplifiers, depends a lot on how the voltage amplifier is biased.
If you just swap 6J51P to 6J49P with no adjustments, the THD of the whole amplifier can be anything between 1%...6%.
This obviously has some effect to sound. And it is not caused by the tube itself but how it is "matched" with the output stage.

Good way to chase good sound is to have adjustable G2-voltage of the amplifier tube.

 

[Ryssen]

and a 6p14p to drive the el34 set....

Hmm that seems to be an output tube...
(maybe 6P15P is to...)

The amount of THD, especially with SE-amplifiers, depends a lot on how the voltage amplifier is biased.
If you just swap 6J51P to 6J49P with no adjustments, the THD of the whole amplifier can be anything between 1%...6%.
This obviously has some effect to sound. And it is not caused by the tube itself but how it is "matched" with the output stage.

Good way to chase good sound is to have adjustable G2-voltage of the amplifier tube.

What i did was I lowered the anoderesistor from 68Kohm (6J49P)
to about 17k.what I had on hand,for the 6J51P,with ledbias.
Anyway I started to rip appart the EL34 amp to (hopefully)use the chassie for an 807 amp,(no IT trafos) I am going to use CCS for the input tubes, might try 6P15P,what current should it run at?

 

[Wavebourn]

Hmm that seems to be an output tube...
(maybe 6P15P is to...)



What i did was I lowered the anoderesistor from 68Kohm (6J49P)
to about 17k.what I had on hand,for the 6J51P,with ledbias.
Anyway I started to rip appart the EL34 amp to (hopefully)use the chassie for an 807 amp,(no IT trafos) I am going to use CCS for the input tubes, might try 6P15P,what current should it run at?

EL34 is better than 807. 6P15P works like a charm on 10-15 mA.

http://www.wavebourn.com/forum/viewtopic.php?f=7&t=1187

 

[TonyTecson]

Hmm that seems to be an output tube...
(maybe 6P15P is to...)

they are....

 

[Ryssen]

6P15P works like a charm on 10-15 mA.

What voltage do you run them on with 15mA?Triodestrapped.
150-200v?

 

[Wavebourn]

What voltage do you run them on with 15mA?Triodestrapped.
150-200v?

The graph is above. Just draw your load line and see what kind of swing are you getting as the result.

 

[Ryssen]

I´m not really shure about loadline and CCS.
But if the bias point is 150V/10mA and I use a input signal of 3,5vP-P do I get about 100v p-p out?

Another question is this the formula to calculate the OPT impedans?
Z = Va^2 / Pa

 

[piano3]

probably more like 70V p-p

 

[Ryssen]

Thats right,I saw now that there are some possitive lines at the end to.. 🙂

 

[Ryssen]

A link I found:
se-output-trans-calc-1

 

[Ryssen]

Ok at 150v/10mA -4,5v I should be getting 98v p-p,then it should be able to run a 807 to fully out?
Or am I lost in this p-p RMS thing..😎
The 807 Tube

 

[Ryssen]

Is there sommething I should add or withdraw?
Unless I withdraw the 807 for a EL34...

 

[artosalo]

To me this seems to be OK.
How do you create the bias voltage ?

 

[Ryssen]

From a separate trafo or from a separate winding on the Main trafo.

Skickat från min SM-J510FN via Tapatalk

 

[Ryssen]

Been working on the PSU on the Schema above,and all voltages seems right.
trafo 312v ac x 1.41=439,92v at C1,428v at C2.Currentdraw 140mA.
Except one thing ..the secondary winding is 1ohm.
Could this be right??

 

[Ryssen]

I´ve made another one,with the same outputvoltage,but the secondary voltage is 338v and 35,7 ohm.
Wich one is right?? 😕