EL34 PP New Design of newbie

[hien.t.nguyen]

Hi all.😀
I am Vietnamese,My English is not so good but I like to make a amplifier EL34,this is the schematic for me,I am use tube 6J1/6AK5 - 6H8C/6NS7-EL34.

 

[hien.t.nguyen]

6J1/6AK5 can use pentode or triod by SW1,I dont know do it have good for sound?

There are power supply and PCB for 2 chanel L+R+power supply

 

[hien.t.nguyen]

>>>

 

[hien.t.nguyen]

This is PCB of EL34 PP V1

 

[hien.t.nguyen]

PCB of EL34 PP V2.

 

[hien.t.nguyen]

Sch el34 pp-v1

 

[hien.t.nguyen]

Sch el34 pp-v2

 

[SY]

Mullard 5-20. One of the classics. Your phase splitter will be unbalanced, though. A CCS for the tail will fix that, otherwise you need to unbalance the plate resistors a bit (if memory serves, 28k and 33k, but I'd double-check that).

 

[hien.t.nguyen]

Mullard 5-20. One of the classics. Your phase splitter will be unbalanced, though. A CCS for the tail will fix that, otherwise you need to unbalance the plate resistors a bit (if memory serves, 28k and 33k, but I'd double-check that).

Thank mod.

That a good idea.

I not perfect my design, a VR adjust the balance current anode 6SN7,if dont so I must macthpair 6SN7

 

[danzup]

PCB of EL34 PP V2.

Nice PCB !
An estimate price for that ?

 

[hien.t.nguyen]

Thank danzup

It is only 10$ for one PCB.

24x21 cm for EL34 PP-V2

24x 24 cm for EL34 PP-V1

 

[Allen Wright]

You are using a pentode gain stage and a triode phase splitter, which is a lot of gain.

But you also are using pure pentod eoutput stage, and none of it with any loop negative feedback..

1/ I suspect you will have HUGE gain, far tooo much for any normal system

2/ You will have VERY high output impedance, which will not be good for 90% of speakers.

Regards, Allen

 

[hien.t.nguyen]

You are using a pentode gain stage and a triode phase splitter, which is a lot of gain.

But you also are using pure pentod eoutput stage, and none of it with any loop negative feedback..

1/ I suspect you will have HUGE gain, far tooo much for any normal system

2/ You will have VERY high output impedance, which will not be good for 90% of speakers.

Regards, Allen

Thank Allen.

I have using feedback by gain too much.

Can you see it ? R21 = 1.8K, R22 = 100 ohm.

 

[richwalters]

Check the screen grid resistors for the EL34 p-p. I read 1R; should read 400-1K ?

My charts give conflicting results; some mention common 800R-1K resistor and fixed bias supply. Other members could add.

richy

 

[hien.t.nguyen]

Check the screen grid resistors for the EL34 p-p. I read 1R; should read 400-1K ?

My charts give conflicting results; some mention common 800R-1K resistor and fixed bias supply. Other members could add.

richy

R for G2 can choice other values.

I am option for Ultralinear, not use R for G2.

Thank richwalters.

 

[Allen Wright]

OK, I can see the NFB resistors now I am shown.

I personally like all connections shown in an amp schematic, at least for the signal path, otherwise you can't get a conceptual understanding of it with a look, but have to hunt around findinding things marked FBR etc. Not intuitive.

Regards, Allen

 

[hien.t.nguyen]

OK, I can see the NFB resistors now I am shown.

I personally like all connections shown in an amp schematic, at least for the signal path, otherwise you can't get a conceptual understanding of it with a look, but have to hunt around findinding things marked FBR etc. Not intuitive.

Regards, Allen

OK.

Sorry Allen,I am not notice 😀