This is similar to the circuit shown in Project 01 (except that this version provides a useful reduction of noise). The gain control pot must be a dual-gang linear type, as the circuit configuration provides the logarithmic law required. One channel only is shown, so two units are required for stereo.
The gain control being used to pre-set the gain so that the pre-amp's gain control is normally used for setting the listening level. The relay is a high quality, sealed, gold plated contact, TQ signal switching type, reputedly with a very long life expectancy. The relay contact arrangement enabling it (the headphone amp) to be left switched off when normally not in use.
The input relay is operated by auxiliary contacts on the headphone sockets through a transistor driver (with a small delay) so as to mute the power amp input when listening on headphones. The intention is to permanently insert the headphone amp between pre and power amps, although it can be used as a stand-alone item.
the active gain stage is, almost, perfectly logarithmic and.low output impedance to drive several pairs of phones.Baxandall), both published in Electronics and Wireless World in recent years. It is based on designs for a headphone amplifier by John Linsley-Hood, and an active volume control, using a linear pot, by Doug Self (the 'pot' circuit was originally designed by P.J. This design for a headphone amplifier arose after the purchase of commercial equipment with separate pre and power amplifiers without a headphone output. The input switching shown here can be used with the P113 as well, but note that the PCB does not include the relay or switching circuitry. There are hundreds of very satisfied customers who have built the P113. While it is similar to the version described here, it has higher performance, excellent sound quality and can even drive a small loudspeaker (not that this is especially useful). Maximum output power: 2 x 2W (1kHz/300Ohm)ĭynamic range: 133.62dB (HP), 134.Please see Project 113 for the ESP version of the headphone amp, and a PCB is available for it.
Volume remotely adjustable (learns any IR remote control) Laterality control: super-fine balance control Innovative Phonitor Matrix: speaker-equivalent listening on headphones Even our creative team got even more creative and came up with a fascinating name: "Phonitor 2".ġ20V Rail headphone amplifier, preamplifier and monitor controllerįor all headphones with impedances >10Ohms (>40Ohms for balanced headphones)* Likewise, we revised the 120V Rail Technology in order for it to perform better, which resulted in our measurement gear being outclassed. We have kept all proven features while incorporating some major improvements - as such, the new Phonitor can be used as the ultimate monitor controller and preamp for three different sources. We are uber-happy to introduce the successor of our legendary Phonitor 2 headphone preamp. The Phonitor 2 corrects this problem, providing an idealized mix room using headphones. Trying to mix or master with headphones is an issue since the normal sound of speakers is lost by 100% separation of left and right channels. This is truly a reference level headphone amp.