Så har även jag tagit mig tid att få ihop min Nutube. Kul projekt att experimentera med. Genom att justera gallerspänningen(?) reglerar man hur mycket "Second harmonic distortion" man får, från inget alls till så mycket 2:a tons karaktär på ljudet man önskar, eller som konstruktören Nelson Pass uttryckte saken:
"Routinely people describe negative phase second harmonic distortion as having a deeper sound stage and a magnified illusion of placement of instruments in that depth. Positive phase second harmonic distortion is often described as more up close, intimate and perhaps more detailed. Let's be clear. To the extent that it works, it's just a psycho-acoustic trick. It doesn't work for everyone, and is not as good on complicated music, where IM distortion is more of a problem. IMHO it's also trick that doesn't like to be over-done. Some people like to sweeten up their analytical sounding amplifiers with a tube preamp, but you might find that this circuit plus a SET (or even a SIT) amplifier is too much of a good thing."
Referens:
https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf Jag är inte övertygad att det blev så mycket bättre, men det blev lite annorlunda, med olika mycket karaktär på olika musik. Rekommenderas för er som tycker om o experimentera!