Zynsonix Link

March 1, 2014

Cavalli CTH Compact Tube Hybrid Headphone Amplifier

The Cavalli CTH Compact Tube Hybrid headphone amplifier is a very unique build. There were two design objectives for this unit, one was cfcubed's desire to make a tiny hybrid tube amplifier, the other was Cavall's desire to run the amp at a high plate voltage while running off of a 24V wall-wart (a wall-wart being the little black box transformer that plugs into a wall socket). The result was the CTH, which can fit in a compact Hammond chassis and has a plate voltage of 80V. Other special features include discrete output buffers, rail splitter, AMB's e12 muting delay and offset protection and a total build price of approximately $200.

The amplifier makes use of a single tube, either a 12AU7 or a 6922 (there's a switch for 6.3V / 12.6V tubes). Other tubes that users have found to work well are the 6F8G, 6CG7 and 6GU7. Either a Hammond 1455K1202 chassis (120mm) can be used, or a 1455K1602 (160mm) if one is using a larger potentiometer like an Alps Blue Velvet. I find that potentiometers can make a big difference in the sound, so I'll be using the larger Alps unit with the larger chassis.

Below is a photo of the board. As one can see, there is an extensive amount of items to be mounted in a very small space. Troubleshooting will be quite difficult if a part ends up in the wrong place, so it's important to pay extra-close attention when mounting each item.

The Cavalli CTH board

I decided on a black and red color scheme for this amplifier (black and red always go so well together). The chassis was powdercoated a nice candy apple red, and the aluminum tube surround (from VT4C) was spraypainted with black engine enamel. Since there are so many parts spaced so closely together, the CTH needs some ventilation holes to keep things cool, or at least cool enough. A number of holes were drilled in both the top plate and the bottom of the chassis.

Colorful chassis and tube surround

Tube surround mounted
More to come...

The Fine Print:
Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind. 


  1. Your builds are insane, I love them all. You have such eye for detail and finish.
    What kind of paint do you use, the white and the red?


  2. Hi Kenneth, the red is a powdercoat, it's candy apple red. The black is an enamel spray paint that is made by Rustoleum and can be purchased at Home Depot. I find the enamel holds up much better than other spray paint.

  3. daer sir,

    Do you still have this PCB, I so tired to find seller for this item