Here's a great little headphone amp that I designed last year. It has a bass input, plus a stereo line input. There are controls for bass preamp gain, line in volume, headphone gain, and a filter for the bass channel. The filter is simply a broadband notch of about 12dB at around 500Hz. After some experimenting, I settled on this because it really seems to make the electric bass sound more natural through the various headphones that I have. I can switch it in and out. The headphone gain switch is to accomodate various headphone sensitivities. This prototype has two settings, but I have since designed a new three way switch for more flexibility. With the notch switched out, and the headphone sensitivity switch set for high output, the amp can be used as a handy portable line driver. However I think opamps don't do a great job of this - especially with only 9v around them. I chose an opamp design in the interests of portability and low current consumption as a headphone amp first and foremost. The amp was designed on two specially cut PCB's that are installed one above the other. Also, the edges of the two boards and the side of the bass input jack serve to hold the battery in place. The device switches itself on when a guitar lead is plugged in - similar to many effect pedals and onboard preamps. Since building this, I have made many improvements, and hope to build a new version soon. |
Play-Along Heaphone Amp |
Play-Along |
Headphone Amp |
Here's a great little headphone amp that I designed last year. It has a bass input, plus a stereo line input. There are controls for bass preamp gain, line in volume, headphone gain, and a filter for the bass channel. The filter is simply a broadband notch of about 12dB at around 500Hz. After some experimenting, I settled on this because it really seems to make the electric bass sound more natural through the various headphones that I have. I can switch it in and out. The headphone gain switch is to accomodate various headphone sensitivities. This prototype has two settings, but I have since designed a new three way switch for more flexibility. With the notch switched out, and the headphone sensitivity switch set for high output, the amp can be used as a handy portable line driver. However I think opamps don't do a great job of this - especially with only 9v around them. I chose an opamp design in the interests of portability and low current consumption as a headphone amp first and foremost. The amp was designed on two specially cut PCB's that are installed one above the other. Also, the edges of the two boards and the side of the bass input jack serve to hold the battery in place. The device switches itself on when a guitar lead is plugged in - similar to many effect pedals and onboard preamps. Since building this, I have made many improvements, and hope to build a new version soon. |
