My 6SL7/6AS7 Tube amplifier

PIANOLYDIA · 3631

0 Members and 1 Guest are viewing this topic.

Offline PIANOLYDIA

  • Newbie
  • *
    • Posts: 2
on: April 02, 2014, 06:59:59 AM
Hi everyone,
    I am building a Compression driver high 100 Spl tweeter amp to be used for a bi-amped setup. I choose the 6SL7 but thought I could use a 6AS7G as the output tubes. I also thought about power output as in SE Cad by John Broskie, it says my output would be about 6-watts, but the Mu of the the tube is 1.41 So does that mean a ratio output? how many watts would I expect, and would it be able to swing that 6AS7G to Full output? I am using john's Constant current grounded cathode design to improve the driver stage and gives me a Mu of 32. I am also driving this amplifier with a 1626 darling Pre-amp, So that will only add to the gain! any thoughts? pianolydia... 
« Last Edit: April 04, 2014, 12:17:32 AM by PIANOLYDIA »



Offline Paul Joppa

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 5822
Reply #1 on: April 03, 2014, 06:08:06 AM
You are misreading the schematic notes. The tube will dissipate 6 watts as heat; the power output will be much less. The driver operating point is inconsistent with the specifications of the 6sl7, so it's hard to tell whether it can provide the necessary +/-6v to drive the 6as7 to full power, but if it were capable you would get no more than about 1.5 watts power output.

Paul Joppa


Offline PIANOLYDIA

  • Newbie
  • *
    • Posts: 2
Reply #2 on: April 04, 2014, 12:01:05 AM
Hi everyone,
    I am building a Compression driver high 100 Spl tweeter amp to be used for a bi-amped setup. I choose the 6SL7 but thought I could use a 6AS7G as the output tubes. I also thought about power output as in SE Cad by John Broskie, it says my output would be about 6-watts, but the Mu of the the tube is 1.41 So does that mean a ratio output? how many watts would I expect, and would it be able to swing that 6AS7G to Full output? I am using john's Constant current grounded cathode design to improve the driver stage and gives me a Mu of 32. I am also driving this amplifier with a 1626 darling Pre-amp, So that will only add to the gain! any thoughts? pianolydia...



Okay, One point that will have to be addressed with this amp is the -30 PSRR from the new Compound amp Plate follower input stage, I know at this gain of 59db will drive the 6AS7 to full output, Now, taking notice of the Vout Swing of -35/+56V shows that the match up to the coupling of the stages will match the Peak input of the Output stage at full power. Keep in mind DC FILAMENTS WILL BE A MUST! as well as Possible choke or double chokes in the PSU to overcome some of that high PSRR figure, Electronics, always a trade off! But I know this will have high distortion at full swing and would be at 3.04 watts per channel, But, I would not run this amp at full volume anyway! I did the best I could and I hope this is right.as it looked good in all the Curves, noticing though that this amp is going to run on the HOT SIDE as it will be pushing it somewhere around 85% of idle and that's Hot! 10.7 watts dissipation! in the output stage. Any comments I will appreciate. PSU is my next concern to deal with that 6SL7 input stage without having to do a interstage transformer..... Pianolydia
« Last Edit: April 04, 2014, 11:01:01 PM by PIANOLYDIA »