Home Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

RE: any one know what this circuit call ? it is driving a pair of EL34pp

The input (front end) circuit shown is called a singly-driven differential amplifier. In order to give symmetry to the output waveform (since the tube not driver by its grid is actually driven through its cathode), it was historically usually attached at its common cathode point to a large negative voltage through a very large resistance, to minimize voltage-divider signal loss to the second tube. This is the 'long tail' of the long tailed pair.

The circuit you have shown is very poorly designed, both because the long tail is omitted, and thus drive to the output EL34s will be quite asymmetric, and because the output pair are cathode biased, which raises the devil's choice of either having lowish output and very high output impedence, or having a very large electroytic capicitor paralleling the cathode resistor, which is in the signal path.

Here's a little more optimum solution:





If you wish to use other types in the front end positions, knock yerself out, but the 6GK5 is really optimum for this application.

And cheep!

Poinz


This post is made possible by the generous support of people like you and our sponsors:
  Sonic Craft  


Follow Ups Full Thread
Follow Ups
  • RE: any one know what this circuit call ? it is driving a pair of EL34pp - Poindexter 22:45:44 03/16/12 (0)

FAQ

Post a Message!

Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.