"Castanet" Headphone Amplifier (discontinued)
The Castanet is an all-tube headphone amp using a parafeed 6H30 SET with impedance matching output transformer. No skimping on this design, this circuit really delivers. Vibrant, punchy and clean sonics, with well controlled deep bass, even driving the 32 ohm Grados. Listen for hours on end with no fatigue. No scrimping on this design, it is maximal topology, very good quality parts.
There are two output jacks, one for low impedance (Grado) and another for high impedance (Sennheiser) headphones. They are wired to separate taps on the output transformers for optimal signal matching. In fact, you can run both at the same time. The only controls are the volume knob and power switch (on back).
The DIY half-kit comes with a blank circuit board, assembly manual, and all of the various screw, nuts, washers, fuse clips, and rubber bumpers needed to properly complete it.
For the truly adventurous, the Castanet can be used as a linestage (buffered volume control) to add a little SET magic into your system. As a power amplifier it will deliver 0.5W into an efficient 8-ohm loudspeaker.
A complete DIY project will run you roughly $550. The breakdown is $129 Hagerman Technology + $76 DigiKey + $171 AES + $61 Mouser + $36 New Sensor + $64 Front Panel Express. This is no ordinary headphone amplifier, and will appear entirely professional inside and out when you are done.
|Output Impedance||9 ohms|
|Bandwidth (-3dB)||12Hz to 75kHz|
|SNR||98dB ref 1V A-weighted|
|Size||10" x 10" x 4"|
This wideband design has superbly controlled transient response. Here is the 10kHz square wave, no ripples or glitches.