Samson co1 mod question...

Hello
In one of the oldest topics in this forum dealt with the
modification of the microphone Samson 01.
http://www.audiomastersforum.net/synforum/10/topic-10663.htm
I replaced the FET on k170bl (less noisy) and it is a little improved the situation.
But, unfortunately, I did not understand what was done next:
"So now I have an impedance converter with a higher value capsule load (more voltage output from the mic) and a quieter FET. So the tradeoff between higher noise from the load resistor and the quieter FET sort-of balances out, but we have more output from the capsule (there's plenty of headroom, so no problems with this), and there is now a quieter, smoother BG, sound from the mic. "
Huge request to all to Steve G personally explain, please, if you remember it.
P.S.
I did not understand English, sorry.
  Regards, Eugen

If I recall correctly, I changed the 1/2 gigohm load resistor on the input for one that was at least 1 gigohm. This is definitely a compromise, but I thought it was worth it.

Thank you very much, Steve.
I'll try to do it

I am personally interested in modifying/rebuilding condenser microphones. A basic problem in this respect is to find suitable resistors in the range of 100 .... 1000 Megohms. The common supplies end at 22 Megohms. Can anyone tell me a source ?

I am personally interested in modifying/rebuilding condenser microphones. A basic problem in this respect is to find suitable resistors in the range of 100 .... 1000 Megohms. The common supplies end at 22 Megohms. Can anyone tell me a source ?

Almost the only easily obtainable source of these is from a Vishay distributor. In the UK, Farnell stock values at least up to 1Gohm. There's a data sheet here. And you don't want to buy too many - they aren't exactly the cheapest devices in the world!

There's a data sheet here. And you don't want to buy too many - they aren't exactly the cheapest devices in the world!

Thanks a lot Steve. So far I could only get devices in glass moulded that took up half of the space of the microphone itself.. With respect to price: Sometimes it's simply a matter of to have or not to have .....

You do have to watch out with them, whatever you do. Generally they are better in terms of moisture susceptibility when they've had a conformal coating of some sort applied to them, and it has thoroughly dried out. It's quite normal to mount them in mid-air because of this.

[reduced]

I am well aware of the problems of high valued resistors, especially with respect to handling. Apart from high voltage applications, they are almost only common in impedance converters as needed for condenser microphones, therefore they are rare and expensive. The strange outcome of a pertinent noise analysis is that the noise density within the audible range is reduced by using a very high value resistor for polarizing the capsule. At the same time such a choice improves the low frequency cutoff.