Type: Hybrid Tube Headphone Amp & Preamp
Budget: around $100 using stock parts, $150 if using TKD pot
PSU: External, 24V, 1A (switching)
Really easy, unexpensive and safe project, powerful amp with low, euphonic distortion and sweet tube Single Ended sound w/o cloying nor breaking the bank, or having to hunt unobtanium NOS tubes to get it “right”.
It’s unexpensive because thanks to Pete Millett DIY spirit you basically get the PCB for free, the NuTube is worth $50 alone.
Been following Pete Millett designs since early 2000… since then I have a crush with his designs, have to try them, budget allowing, of course.
When saw this new design, I had to try it!
Uses the Korg developed, Vacuum Fluorescent Display (opposed to classic Thermoionic Effect used by traditional tubes) technology based NuTube 6P1
NuTube provides the gain (6x) stage (A1), relaying the heavy lifting to OPA551 opamps at the output.
The NuHybrid… was assembled in a couple hours, was my Xmas project. I wholeheartedly advice this project for anyone wanting to step into DIY tube sound safely and unexpensively.
I just upgraded the BOM to WIMA MKP caps (+$2, fit perfect) and the TKD pot, as the weak link on most amps is the potentiometer. Only mod done was grounding the TKD metal case to the PCB ground.
Use a typical POE brick (24V 2A) from a mikrotik router to power it. Tried a linear PSU, saw zero enhancement, so back to the switched one.
Its sound (HD6XX)… it’s incredibly transparent, while adding just the proper amount of euphony, keeping pace and decay without losing slam… I was more blasted after hearing the NuHybrid than after my last OTL White Cathode Follower monster iteration using almost 6A in heaters.