Started my poctop D49c build!!!

[ln76d]

Looks good, but if atomic weight  will be too much boring, try to find something similar to this.

 

[achase4u]

So far I am enjoying the explanation of what atoms, electrons are etc.  It starts talking about tubes and diode tubes, with a heater, cathode and plate.  Thermionic emission is used to stir up the electrons so they break the surface barrier and leave the emitter and shoot over to the plate.  Interesting...... who knew all these tiny things were happening!

So I kind of understand what a heater is and why it needs the voltage.  It is what allows a tube to function!

8)

 

[Marc HENRY]

i have here interesting measuring of a bunch of 15 AC701 M49c (most of them where M49 or M49b modified for M49c)
i noticed some differences in high frenquencies. Ok, some are with 600p, others with 150p for C6
You can see differences in bass roll-off and in level for some of them. All have the 5M (R3) connected, and same value for C9, C1, C2...
output transformers are not all the same, but the difference is not here...strange...

 

[bremusound]

Did they all have the same type of capsule?

 

[Marc HENRY]

Did they all have the same type of capsule?

i made the measures of those preamps without the capsules. One problem at a time :-D The test signal is direct from the output of a Macbook air, lowest level, through a 1n cap. i use fuzz measure. On the screen shot you can see that there is two "families " of curves. looks like a Negative feed back connected or not, but it is connected on every mike