The RH84 Experiment

This was my attempt at building an RH84 Version 2  type amplifier that was first presented on Audio Asylum Tube DIY forum back in September 2016. 

I reported on making some circuit changes to designer Alec Kitic's schematic to adjust for a lower B+ of 300VDC compared to the recommended value of 315VDC.

I recall reporting on not achieving the same sort of THD performance benchmarks that were reported by the designer.   

My efforts were rewarded by Alex ranting about "circuit butchers"  deviating from his schematic values and using cheap tube console grade SE OPT's.  

Here is some measurement data regarding distortion performance vs. power output:

THD = .66% @ 1W,   1.12% @ 2W,   1.58% @ 3W  and   2.37% at 4W.   THD measurements taken at 1KHz.

Not bad performance for using value-minded  AES SE 5K/8 OPT's. 

Subjectively, the circuit played reasonably well on my Altec horn system .

DEATHTUBE 667