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The SE UL 6P41S USSR

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Hello all ,

i build the SE UL 6P41S drived 6N2P .

the pics ;) , and the 6P41S is good for small SE :D

good day for all ;)
 

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I have lately experimented with some SE amplifiers applying the distortion cancelling. Below is one of the test circuits using soviet 6P41S TV-power pentode.
The output stage can deliver 4.5 W with some 3 % THD with 50 % UL and optimized bias.
When the properly adjusted/biased voltage amplifier is added, the overall THD drops to 1.1 % due to distortion cancelling.
The optimum anode voltage of 6N9S is relatively high, 178 V. Then the THD at the anode of 6N9S is 3.3 %.
At 2 W out the THD is 0.6 % at the output and 2.1 % at the 6N9S anode.

Sensitivity for 4.5 W is 0.54 Vrms and Zout = 3.3 ohms.
 

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  • 6P41S_6N9S_SE.JPG
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Well, I'm finally back to working on an amp and I'm going to build a second 6P41S for my daughter and SIL who currently have my prototype amp which is switchable from UL to Triode mode, and Mu stagee or Current source loaded 6J9P in triode mode as a driver.

I've got the output tube wired on a breadboard and was playing around wiht plate dissipation. The datasheet calls for 14W max, however they are driving two tubes in class B with 60W out, so I suspected the actual dissipation was higher.

I started cranking up the power knob until I finally got the fins to start showing very faint red (very even spread of color which is nice).

Dude! 33W dissipation!

Figuring 85% safety margin that means it should hold up to 28W dissipation and near 7W out SE mode with reasonable tube life.

Has anyone else pushed this tube to see what it is capable of?

I'll take this back to my original thread so as not to hijack this one.
 
hello ,

for the moment , i ajust de the build for 5 W and looking possible up 6 W !

i joint the calcul for possible up the good build to +/- 5 W extanded 6 W , G1 is ajusted to +/- -38V , so possible up -50 V +/- 6 W or 7 W ;)

many think Thegimp for the info
 

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  • Calcul 6P41S --.jpg
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artosolo, have you looked at the harmonic distribution of the amp? I suspect you are canceling mostly 2nd harmonic distortion.

Without an attempt to cancel harmoinics, I get apporximately 2.4%thd at 1W out using a 5K 40% UL transformer.

My harmonics are roughly
2nd -32dB
3rd -60dB
4th -68dB
5th -76dB

I am running 90mA anode current, and see about twice the distortionat 60mA, with most of the increase in 2nd harmonic value.
 
Hello all ,

Very interesting but i have small one concerns with the regulation of my triodes 6N2P, the resistances d anodes make 100 K, a put a potentiometer of 100 K Log x 2, i use Led Red ( 1.5 V ) for cathodes , a condenser of 22 nF in decoupling but me n arrives not has to limit the gain behind my préampli, the resistance of leak made 330 K, she is certainly too high!

:(
 
artosolo, have you looked at the harmonic distribution of the amp? I suspect you are canceling mostly 2nd harmonic distortion.

I am running 90mA anode current, and see about twice the distortionat 60mA, with most of the increase in 2nd harmonic value.

I have not made harmonic analysis, but it is obvious that the 2nd harmonic is dominant and the cancellation of this is the greatest. It can even be seen with an oscilloscope.

What are your +Ub and Rl (OPT) ?
 
hello ,

i change schéma , so good performance , the Led Red is replace to 1 résistor 1.4 K , bécause , the G1 to 6N2P is up -1.5 V , so good to -1.4 V ;)

i up new upgrad later , the 6P41S is possible up +/- 6.5 W to SE UL to OPT 5 K / 8 Ohms .

thank for me help

:xmasman: happy day for all
 

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  • Ampli SE UL 6P41S - 6N2P-ev - EZ81 .JPG
    Ampli SE UL 6P41S - 6N2P-ev - EZ81 .JPG
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This model seems pretty close except for screen current, and grid voltage is too high.


*
* $
* LAZAROIU
*
*--------------------------------------------------
.SUBCKT 6P41S-E 1 2 3 4 ; A G2 G1 C (Beam Tetrode)
X1 1 2 3 4 PENTODE MU=18.368 EX=0.602 KG1=230.00 KP=160.8 KG2=600 KVB=25.8 CCG=3.0P CPG1=2.9P CCP=1.9P RGI=2K
.ENDS 6P41S-E
 
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