A while back I had been playing with the el-cheapo 6J1 china preamp.
Even after fixing up some of the many flaws, I was never really satisfied with how it sounded.
After some reading around I came across this build by Ratti3: 6J1\EF95 Hybrid Tube Preamp.
I had a box of NOS GE 5654W's that needed a suitable home, so down the rabbit hole I went.
Adapting the scheme from Ratti3's creation, I came up with the following, running off a simple 12v Wall-Wart:
The HV power supply comes from this cheap boost module:
This HV supply is filtered sufficiently to not impose much noise into the system.
The main amplification is done by a single 5532 which although is sufficient, a future iteration could benefit by having either another in parallel or a simple BJT stage.
The board design:
PCB (Don't have any pics of it populated to hand):
And in a finished case:
Measurements:
As can be seen, the THD is at 0.8%, but this amp has heaps of H2 making it lovely and warm:
All in all, a simple headphone amp with that nice warm 'tube' sound.
Thanks to @Ratti3 for posting his design that I used as a launch point.
Even after fixing up some of the many flaws, I was never really satisfied with how it sounded.
After some reading around I came across this build by Ratti3: 6J1\EF95 Hybrid Tube Preamp.
I had a box of NOS GE 5654W's that needed a suitable home, so down the rabbit hole I went.
Adapting the scheme from Ratti3's creation, I came up with the following, running off a simple 12v Wall-Wart:
The HV power supply comes from this cheap boost module:
This HV supply is filtered sufficiently to not impose much noise into the system.
The main amplification is done by a single 5532 which although is sufficient, a future iteration could benefit by having either another in parallel or a simple BJT stage.
The board design:
PCB (Don't have any pics of it populated to hand):
And in a finished case:
Measurements:
As can be seen, the THD is at 0.8%, but this amp has heaps of H2 making it lovely and warm:
All in all, a simple headphone amp with that nice warm 'tube' sound.
Thanks to @Ratti3 for posting his design that I used as a launch point.
