flatline comp with 1n4001?

[davepedals]

i have a vero layout for flatline that states 1n34a, another says 1n4001.   are there big differences?  if so - what would you say they are?
i hope the 4001's are ok because i just got a great deal on them!  also picked up four VTL5C2's for $10 bucks including shipping!
oh yeah... what difference does substituting the 220k for a 390k make?

- sorry for combining questions!

many thanks!

[CynicalMan]

The original circuit used 1n34s. Using silicon diodes would increase the threshold, and it might give the envelope detector a harder knee. Using a 390k resistor would increase the ratio by increasing the gain of the stage when the led's off. I don't know what the extent of these changes would be, but I think you should just breadboard them and find out.

[Hides-His-Eyes]

Schottky diodes will still have a silicon knee, but the same lower threshold.

[petemoore]

  Any old leaky germanium transistors B/E junction diode is exactly that.
  Otherwise the circuit is designed around the ge diode threshold.
  And probably for good reasons, it's worth it to try it with the Ge like threshold. Diodes of various shapes and colors can be found lurking in crud on old circuit boards, pull some and apply DMM to read the thresholds.
 

[davepedals]

thanks for the replies. i'll certainly try out different components.  i just wish the 1n34s were cheaper and less fragile!
i have a bit of time on my hands so i'm going to play around with this comp quite a bit.  Thanks again!