Vintage EL84 SE Amplifier
Accidentaly I found the chassis of what must have been a vintage stereo tube receiver.
All that was left worth re-using were the output and mains transformers. Luckily these
measured well with no hint of a defect. I decided to build an EL84 SE amp. with them.
Not high-end but rather a small amp for occasional use with a hopefully pleasant sound.
The circuit of the output stage is close to Mizushima's inspired former version of
EL84 SE Amplifier yet with a different driver stage. Out of curiosity I tried the triode
section of the venerable ECH81.
The mains transformer gives around 230V AC so I opted for a silicon bridge rectifier
followed by a split (per channel) RC filter.
Build with humble expectations, the result has been very rewarding.
After playing a bit with the driver's operating point, the sound of this amp
-in my system- is very exiting.
One could argue the bass could be stronger, but the rest makes up for it. The light "up-tilt"
in the frequency response is surely due to the vintage OPTs. Modern OPTs will provide different results.
The very mild feedback from power stage anode to driver anode via 1Meg Ohm calms down a little this
"wild joung mustang". With other OPTs this may not be required at all.
A matter of taste...