• 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.

Trying to achieve 25-30 watts... help please!

diaz028

Member
2007-06-26 7:30 pm
How much power can I get from 400V B+?

My OT is rated at 35 watts.

So I am just wondering what tubes I can use to achieve about 25-30 watts of audio power, other than cathode biased 4xEL84?

1. Cathode biased 4 x 6V6 ?
2. Cathode Biased 2 x 6L6 ?

Just wondering. All specs for the 6V6 and 6L6 show wattage ratings with B+ of 360V and 450V, but nothing in between, and not always with cathode bias.

Thank you!
 
How much power can I get from 400V B+?

Lots!

Is this for geeetar or hifi?

Where is your 400V coming from and how many mA can it deliver? What heater current can it deliver?

My OT is rated at 35 watts.

OK - what is its primary and secondary impedance?

So I am just wondering what tubes I can use to achieve about 25-30 watts of audio power, other than cathode biased 4xEL84?

1. Cathode biased 4 x 6V6 ?
2. Cathode Biased 2 x 6L6 ?

Just wondering. All specs for the 6V6 and 6L6 show wattage ratings with B+ of 360V and 450V, but nothing in between, and not always with cathode bias.

aaaaaaahhhh you get to enter the magic realm of load lines.....

Easy entry level learning stuff here
 
Last edited:

diaz028

Member
2007-06-26 7:30 pm
Class = A or AB Push Pull (whatever works)

PT = 300 0 300 @ +150mA
OT = 35watts @ 4000cct
Filter = SS rectifier, 44u input cap, 10h choke, 44u grid cap.

Depending on the tubes, B+ should end up around 350-400V. Amp is not built yet, still in the design phase.
 
Using KT88's with 400V B+ & fixed bias with 4KA-A should get around 40W walkover and a very long life. Perhaps a luxury overkill.
The 6L6 was the standard workhorse for the popular 30W-1960's guitar amps. The number of circuits around is vast.

I often run output trannies well-over their ratings. Sofar without failure. A 100W from a 50W tranny is fine solong deep bass isn't required. The trick is not to disconnect the output under load.

richy
 

artosalo

Member
2010-02-16 9:00 am
With a PP-pair of 6L6, 807, 6P3S-E etc. you can get some 25 to 35 W depending on bias system. With fixed bias you will get more power with better efficiency.

Here is one of my amplifiers I built few years ago with Edcor transformer and 6P3S-E tubes.

[IMGDEAD]http://kuva.termiitti.com/image/13764.jpg[/IMGDEAD]

[IMGDEAD]http://kuva.termiitti.com/image/13765.JPG[/IMGDEAD]

It has the preamplifier, tone controls and balance, but can be easily simplified.