Mozztronics | HA-1 Headphone Amplifier

Now in new orange even tougher sheetmetal enclosure !

I was disappointed by the headphone output on my Digital Audio Workstation (DAW) interface. While there is enough volume for recording instruments, it doesn’t quite cut it when recording a loud vocalist as there is not quite enough volume in the cans.

Quite often, in order to save money, a standard op amp or low voltage chip is used to drive the headphones directly. This is ok for the majority of use, but this type of circuit has a limitation when it comes to maximum volume available, and transients, which are a vital component to audio definition, become limited.

So i made a headphone amplifier. I used the same 15VAC plug-pack i use for my TD-1 tube driver pedal, i use internal 15V positive and negative regulated power supplies for low noise, and i use a class AB transistor output circuit, so as to get capacity to pump transient energy quickly into the speaker (something an op amp based headphone amp cannot do as well).

Listening tests resulted in a clearer sound, tighter and more defined bass, a bigger sound-stage, and it was easier to pick the position of instruments across the stereo mix. Vocals were also clearer and there was an improvement in the depth of field.

This unit also works well with media players, just connect the line out, or headphone out into the HA-1 headphone amp and adjust the volume.

Input is via a stereo TRS 1/4″ jack socket and there are two stereo TRS 1/4″ jack sockets to plug the headphones into. Two pairs of headphones can be run at the same time. These should both be of similar impedance. I recommend 32 ohm headphones (or higher impedance).

Mozztronics uses the industry standard 2.1mm socket for the power supply connection. Power is from an external 15VAC 0.4A plugpack.