• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

new build SE to EL 508

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hello ,

I prepare the manufacturing d an ampli new on the basis of EL 508 to copy the assembly(editing) d EL84, with similar parts, of whom think you of the joined plan?

J put the plan with EL508 and 12 AT 7.

so use 2 way for build 😉
 

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  • Ampli 12 AT 7 - EL 508 -.jpg
    Ampli 12 AT 7 - EL 508 -.jpg
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You do realize that an EL508/PL508 is intended for the field deflection output stage of a color TV and as such may not be the most linear tube available. The datasheet doesn't even show I(a)/V(g) graph, whereas the EL84 does. Maybe better use an EL503 if you can get it. Compare with PL504 (line output) which does have this graph.

But then again, why not give it a go...
 
I built a SE whit the PL508, Better use Screen drive for it. the first grid is very un-lineair . yet if you manipulate the potential on G2 it shows quite a lineair relation between vg2 and IA

If you are serious about building this amp. I could wire up my test setup and give you some curves VG2/IA whit G1 tied to cathode.

V4lve.
 
hello ,

sur la doc de base , il est mis qu a 190 V= anode , on as 60 mA , ca équivaut a 11.5 W PA .

j ai donc calculer un TRS pour cette valeur :

190 Va / 60 mA = 3166.66 soit 3.2 Kohms pour un TRS en SE ; un TRS de 5 Kohms me semble bien si je reste dans cette plage de tension !

j ai pas trouver la doc des 6p41s , elle doit surment afficher des valeurs intéressantes .

désoler , j ai pas traduit en mode anglais !

merci bien 😉
 
hello ,

J use l English partially, I am not tres hardly meme in radio...

J like the assemblies exotic because tres few to use and so too easy for assemblies normalized(standardized) in audio, as a result, j uses with my stock of recovery(recycling).

Thank you for your help

😉
 
I'm having issues measuring this tube on my valve meter due to excessive HF oscillations .

So I connected an old rats nest experiment on my bench. It works very well , but needs some NFB to clean up the Bass. Witch isn't all to loud.

p1260230.jpg


I found out about 80-100 volt swing is needed to fully drive the tube. at 300 volt anode voltage.

The tube conducts 5mA whit VG2=0 volt and 100mA @ 60 volt VG2

Im thinking of using an Opamp Class A shunt element whit a BJT to drive this tube. that way you could drive the amp directly from A CD player. but most of you would disagree.

By the way, this tube seems to cope very well whit 30Watt PD 😀


V4lve
 
Here I am again, j have so much to go(take) up d antenna(office) with a lot of plan diverse, whom j have to forget full of things which j liked and in particular, tubes BF and HF, as a result, I go(take) up little n matter what, I am almost crazy...

me old call is FA1PZN , me new call is F4PZN , only qrv to 12 meter , 10 meter and 2 meter , so 6 meter is stopped for not antenna .

😛
 
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