[sdiy] Tubes in Synths [ was : Harry's Nightmare! ]

[jhaible at t-online.de]

Ken Stone schrieb:
> >
> >> Has anyone ever built a tube based phaser? 
> >
> >It's not easy.
> >
> 
> There was an amplifier company that included phase shift 
> vibrato in their 
> designs. They used thermistors as their variable 
> elements, heating them by 
> putting DC across them (I think I've got my facts 
> straight). All one would 
> need to do is add a direct signal to the output, with 
> perhaps a little 
> feedback, and you would have a phaser.

Phase vibrato: easy. No precise flat gain required.
Phaser without feedback: *not* easy to get deep notches. You need
   *precisely* flat gain for the APF.
Phaser with feedback: easy again.

That's what I tried to say with "notch phaser" vs. "resonant phaser".

JH.