Thd Flexi 50 Head
Thd Flexi 50 Head

Flexi 50 Head, Tube Guitar Amp Head from Thd.

content in English
loudfunk 31/01/2012

Thd Flexi 50 Head : Recensione di loudfunk (content in English)

"Finally a production amp that feels like a vintage amp and isn't a Fender or Marshall clone"

  • Like
  • Tweet
  • +1
  • Mail
All tube 50 watt head.
3 12AX7 pre-amp tubes, 2 EL34 power tubes.
Volume, bass, mid, treble, boost volume, boost tone, master and cut controls.
Switches for input sensitivity, bright, boost on/off, master on/off, 20/50 watt mode, stand-by and power.
On the back you get passive line level effects loop send and return jacks, 2 speaker jacks and the 2/4 ohm-8/16 ohm impedance selector, transformer driven live out with line/instrument level switch and control. As well as the "link input to boost switch" with that you can foot switch the amp so when you turn the boost on the amp uses the high sensitivity input and off it uses low sensitivity.
There are also bias points and controls so you can bias the quickly for your power tubes of choice.


As with all THD amps super easy to get a good tone out of. With the same caveat as for the UniValve or BiValve it needs to be dialed with the ear not the eyes.


That's what I love about this amp. It sounds and feels like an old amp. Without loosing its identity. That in itself is quite the feat. I use it mostly set to a crunch sound so i can use the guitar's volume to clean it up. This is actually one of the few amps where the clean sounds amazing when used like this. And for over the top stuff I hit it with a pedal. Usually something like a Maxon SD9 or a Demeter Fat Boost.


Great amp in a small package. I really like to use it different than intended. It shipped with 2 12AX7 and a 12AT7 and replacing the AT for another AX type type in the pre-amp it opened up. Then using the bias controls to run the bias at 33 mA instead of the factory setting of 25 mA made crunch chords overall frequencies much more cohesive. Switching to running a EL34 and 6550 together gave me the best of both worlds. The nice midrange :fur" of the 34 with the bottom and "glass" of the 6550.