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Old 30th December 2011, 08:51 PM   #1
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Join Date: Dec 2011
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Default NewBee PPEL84

Hi, EveryBody. I just find this forum at the good time for me. Indeed, I'm building my own PPEL84 Amp and I need some advice to continue. This Amp will be used to understand tube amplification and to improve my knowledge in this field.
Above, my schema build on spice.
I don't knnow how to simulate the output transfo so don't be careful to the 4 resistor at the right of EL84, it's in fact the place for the transformator.

If you have some advice or if you see some trouble ou my schema!! I'm interested in!
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Old 30th December 2011, 10:39 PM   #2
GloBug is offline GloBug  Canada
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Hi there, you just found this site now?

I can't see you pictures.

Upload your pictures using the "Manage Attachments" button just below where you were writing. Make sure your pictures are not too big, it will make for a faster upload.

Grab a chair you will be here for a while.

Salut à tous, vous venez de trouver ce site maintenant?

Je ne peux pas vous voir des photos.

Téléchargez vos photos en utilisant le "Gérer les pièces jointes"(Manage Attachments) bouton juste en dessous, où vous avez écrit. Assurez-vous que vos photos ne sont pas trop gros, il fera un rapide téléchargement.

Prenez une chaise, vous serez ici pendant un moment.
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Old 30th December 2011, 10:48 PM   #3
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Sorry, so the schema is below! Thank's !
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Old 30th December 2011, 10:51 PM   #4
kevinkr is offline kevinkr  United States
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Globug's advice to post pix directly here is excellent. If you do not see "Manage Attachments" you will see an option for "Go Advanced" click this and you will see "manage attachments."

Which version of spice are you using? Usually for a simple transformer model you calculate the inductance ratio between primary and secondary based on the square of the numerical ratio, select a reasonable primary inductance. Use the K directive K1 L1 L2 Lx 1 (coupling coefficient) to make a simple transformer where Lx is the last inductor to be combined into the transformer - should see the specifics under help. This will give you an ideal transformer which for most purposes is reasonable.

Welcome to the forum..
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
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Old 30th December 2011, 11:55 PM   #5
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Join Date: Dec 2011
Location: France
OK, thank's for the advice! I changed resistor by linear transformator. It seem's that's working. Fine.

What do you think about the volume Control and the impedance of the input?
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Old 1st January 2012, 08:55 AM   #6
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Location: France
How can I reduce the gain of the preamp stage without reducing the bandwith of this stage. With 2V peak to peak the gain is to much higher for the EL84 . I need a gain about 5 to 8.

I tried with resistors before the first tube but the bandwith reduce proportionally with the value of the resisor. I suppose that I need a high impedance input for CD player?

I hope you can help.
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Old 1st January 2012, 02:49 PM   #7
Fenris is offline Fenris  United States
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Use a tube with less gain like a 6n1p. Alternately, replace the 47K anode resistor of the first tube with two resistors that sum 47K and serve as a voltage divider. This way you can adjust the gain.
Listen to the music through the stereo, not the stereo through the music.
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