Can we learn anything from this Strauss amp? Heaps!

You may not have heard of the Strauss amplifiers, a once well-respected Aussie amplifier maker. Your initial thought is that this is not relevant to me …. but wait.
There are some good techniques for you here, particularly as we had no access to schematics. Luckily this is a relatively simple circuit.
You have to ask yourself, "do you feel lucky? Well, do you punk? Do you know how to tell if your amp is FIXED BIAS or CATHODE BIAS with only one measurement?" If not, today is your lucky day. (This was in the original Dirty Harry script ... really.)
Q1. When the bias is good, how else can you cool down an amp that is cooking EL84s for dinner?
Q2. Do you know how to calculate the idle dissipation? Are you measuring plate current or cathode current? They’re not the same.

Please…if you have picked up anything from this video, can you honour me with a LIKE?

Video Index,
00:00 Introduction
09:32 How to tell I an amp is Fixed Bias or Cathode Biased with no schematic
14:34 How to Bias if you can only measure Cathode Current instead of Plate current
16:21 Let's calculate the power dissipation at idle
24:40 What’s the cause of the crackling noise in the preamp tube?
27:00 The culprit in the cathode
32:00 Increasing the Screen Grid resistor will cool down the tube
35:50 Replacing 100 ohm screen grids resistors with 470 ohm
40:20 Paul McCartney “Got Back” rant
45:10 Can you hear a bit of Vox tone?
47:25 The Sound Test of the Strauss SRT15
50:00 The End