What is the HeadRoom Crossfeed?

Imagine you are listening to a pair of speakers. If you turn off the left speaker, both ears hear the sound from the right speaker. But because the left ear is slight farther away than the right ear, it hears the speaker’s sound slightly after the right ear; about 300 microSeconds. This time difference is called the “inter-aural time difference” and it is the main thing your brain listens for in order to tell where to place sound left-to-right.

But in headphones if you turn off the left channel, only the right ear hears the sound. In headphones, if there is any sound that is only in the left channel, or only in the right channel, then only that ear hears the sound. This is not natu- ral, and you brain becomes fatigued trying to figure out where sound is com- ing from when only one ear is hearing it. This tends to create an audio image that is a blob on the left, blob on the right and a blob in the middle.

HeadRoom amplifiers cure the problem by allowing you to cross-feed a little of the left and right channels across to each other through a short time de- lay using the crossfeed switch. The usefulness of the circuit varies depending on what type of recording you are listening to; mono and binaural recordings need no processor at all. Old studio recordings that have instruments panned hard left or right, benefit greatly from the processor. Live and classical record- ings miked from a distance benefit somewhat less, and can often be listened to without the processor quite comfortably.

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Electronics Modules for your Micro Amp

The Micro Module

This little red module contains all the electronics for a Micro Headphone Amp. There are two 4-layer circuit boards (one each for the left and right channel) that are connected with a series of header pins used to solder the module to the main circuit board. This module is designed to sound great but must provide at least 20 hours of play time on two 9-Volt batteries in the Micro Amp. It uses AD822 op-amps for the internal input buffer, crossfeed, sum- mer, and power amp voltage gain stage. The output current amplifier is our version of the highly regarded Diamond Buffer discrete transistor design by Walt Jung. Resistors are 1% metal thin film, and caps in the signal chain are polyphenylenesulfide (poly film); these are MUCH higher quality parts than you’d ever find in a typical consumer electronics product. The Micro Amp can be upgraded to the Desktop Module. The result will be an approximate halving of play time and moderate improvement in sound quality. If you will be using this amp largely in a portable mode, we suggest sticking with the stock micro module as its better sounding by far than any portable source (accept maybe the Micro DAC) and saving batteries is a good thing.

Micro electronics module

Desktop electronics module

The crossfeed switch in HeadRoom amplifiers al- low you to cross-feed a little of the left and right channels across to eacho- ther through a short time delay.

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Desktop Electronics Module Upgrade

The Micro Amp can be upgraded to the Desktop Module. This little green mod- ule contains all the electronics for a Desktop Headphone Amp. There are two 4-layer circuit boards (one each for the left and right channel) that are con- nected with a series of header pins used to solder the module to the main cir- cuit board. This module is designed to sound great but must provide at least 20 hours of play time on four D-cells in the Desktop Portable Amp. It uses Burr- Brown (Okay, now TI) 2134 op-amps for the internal input buffer, crossfeed, summer, and power amp voltage gain stage. The output current amplifier is

Plain

With

Far ear

Near ear

hears

hears sound

Headphones

HeadRoom

slight delay.

first.

our version of the highly regarded Diamond Buffer discrete transistor design by Walt Jung. Resistors are 1% metal thin film, and caps in the signal chain are polyphenylenesulfide (poly film); these are MUCH higher quality parts than you’d ever find in a typical consumer electronics product.

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HeadRoom Headphone Amplifier & Digital-Analog Converter owner manual What is the HeadRoom Crossfeed?, Micro Module
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Headphone Amplifier & Digital-Analog Converter specifications

The HeadRoom Headphone Amplifier & Digital-Analog Converter (DAC) represents a pinnacle in audio technology, delivering exceptional sound quality and an immersive listening experience. This innovative device caters to audiophiles and casual listeners alike by providing an array of features that enhance sound reproduction, ensuring that every note is rendered with precision and clarity.

At the heart of the HeadRoom unit is its advanced digital-analog conversion technology. The high-resolution DAC converts digital audio signals into analog sound waves more accurately than traditional converters. This leads to reduced distortion, improved dynamic range, and a more faithful representation of the original recording. Users benefit from the ability to playback high-definition audio files, making the most of their music collection, whether it be lossless formats or high sample rates.

One of the standout features of the HeadRoom headphone amplifier is its robust amplification capabilities. Designed to drive a wide range of headphones, from standard models to high-impedance audiophile options, the amplifier provides ample power without introducing noise or distortion. This ensures that users experience rich bass, clear mids, and sparkling highs, making every genre of music come alive.

The device boasts multiple connectivity options, allowing it to seamlessly integrate with various audio sources. USB, optical, and coaxial inputs mean that it can easily connect to computers, digital music players, and even televisions. This versatility makes the HeadRoom an ideal choice for home studios, living rooms, or on-the-go listening.

Another remarkable characteristic of the HeadRoom headphone amplifier and DAC is its user-friendly interface. With intuitive controls, users can adjust volume levels and switch between inputs with ease. The compact and stylish design also ensures that it fits seamlessly into any audio setup, making it as aesthetically pleasing as it is functional.

In conclusion, the HeadRoom Headphone Amplifier & Digital-Analog Converter is a must-have for anyone seeking to elevate their listening experience. Featuring high-resolution DAC technology, robust amplification, versatile connectivity, and an elegant design, this device stands out as a premier choice for music lovers who demand the best in sound quality. By harnessing cutting-edge technology, the HeadRoom ensures that every listening session is not just heard, but profoundly felt.
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