Tube Amp Archive

It works!! The problems were the bad cathode bias resistor and a bad solder on a ground.

A big thanks to you guys! 😉
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What about 400ohm cathode bias resitor so that i could low down my bias at about 45-49ma ? Instead of about 100ma!!! I didn t even notice that!
I don t know if it causes my weak and distorted sound, but a bias at about 100ma is a stupid mistake!! Shame on me! Lol

Thanks for help
I use an ez81 for dc voltage.
But it seems a bit high , can t explain why, but the 403v is real.

I really wonder if my bias is not wrong, really strange i m trying to calculate ...

30w is the plate dissipation sorry for my question

Thanks for your help
Yes i m using a se output transformer.
What is 30 in the p=vi ? Is it 30w?
If it is, how did you find that number, please?

Ok, strange indeed
I use a 220ohm resistor at the cathode as the schematic notice it ( but they note 314v on the plate instead of my 403v!).
I measured the -50v between pin5 and pin 8 .
I use a 6l6gc

Thanks for the answer!
Pin 3 is 403v
Pin4 is 400v
Pin 8 is 23v
Pin5 is -50v
12ax7 and ez81 are brand new. Not totally sure about the 6l6.

Hi everybody. I m building my third amp. A 6l6 single ended "Ax84 6l6 p1" type amp. The amp switch on, no problem. Without guitar plug in , all the command ( treble-medium-bass-volume) work normally. but when i plug the guitar there a weak volume which goes lower and lower and distorted. I checked a...

This schematic is quite easy...but i paid my lack of knowledges in amp built! Lol It won t be my last mistake ! Next time, i will build a single ended 6l6 type !! Building amp is really something great and when you find people who accept to teach you what they know and learn from their own mistake ,...

That s ok! Problem solved! It s a noob mistake! The input shielded wasn t well realized so that it was totally inefficient. Moreover, my v1 socket is quite bad ( oxyded at some place) . I ve made a good shield and corrected lead dress on v1 , now the little monster works perfectly well! Thanks men f...

I tend to try 2,7k resistor at v1 cathode and el84 grids 1k ?
But the deleted 470k before the gain/volume pot let me interrogative

Thanks a lot!
I ve seen they have deteled the 470k resistor between the gain volume pot and pin 7 on V1 and change el84's pin 9 10r resistor for 1k , and that 2,7k on v1 cathode. I won t ask explainations and give try instead lol

I have another possibility: the link between master volume and pin 2 of v2 , it should probably be shielded?
A guy had strictly same problem on his tmb and after hadding grid stopper everywhere he could without real effect he canceled hiss by shielding this pin.
It sounds totally realistic to me?

After googling a big part of the evening lol, my problem really looks like a lead dress adjmustment. I have been really careful about ironing but, i must confess that , for me, a wire is a simple conductor so it must have a good quality but i didn t figure how much lead dressing is important. Any ad...

Ok . I wasn t sure of what i had understood so , in fact those 100k are already in 1w actually.
Yes , i was suprised of those strange 820-1,5k cathode wiring?!

i know it s a minor problem...it drives me
Crazy !lol