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アンプ Archangel X7のPDF クイック・スタート・マニュアルをオンラインで閲覧またはダウンロードできます。Archangel X7 6 ページ。 Acoustic instrument reference preamplifier / di

Isometric Equalizer ™

The EQ bands all have 26dB of boost and 15dB of cut, so go easy at first. The Isometric

Equalizer design allows for independent tuning of each band, and they are tuned precisely

for acoustic instruments.

The bass filter is tuned to 60Hz for tight and powerful bass response. 60Hz is tuned just

below the low B on a 7 string. When you boost the bass knob it will not cause the low E string to be

louder than the other strings like most EQ designs do. The tuning is still high enough to not cause

subwoofers to move violently, but low enough to really bring the house down when using modern

percussive fingerstyle playing techniques when boosted. It will also cut at 60 Hz to help acoustic

instruments to sit in the mix beautifully with bass and drums without needing excessive additional eq

from the mixer. Bass instruments and harp guitars will benefit greatly from the extended low filter

tuning.

The treble filter is tuned very high and designed as an upward expander. It increases the gain

exponentially as the frequencies get higher. It really allows your instrument to cut a through the mix with

amazing presence and clarity, without any of the shrill and ear piercing frequencies or harsh harmonics

that typical equalizers produce. The bright switch lowers the treble filters frequency by an octave, to

capture more high midrange frequencies that are sometimes needed for darker sounding instruments

and for instruments with laminated tops.

Harmonic Feedback Elimination (HFE)

The Isometric Equalizer's midrange filter is actually two filters in one. The tuning is

selectable with our Internal Mod Switches.

The first tuning is a conventional midrange filter tuned to 1.5kHz, which is the same

frequency that competes with vocals. The second tuning is our remarkable HFE setting.

It is tuned at 237Hz, which captures the first harmonic of the 95Hz to 110Hz fundamental that will

always feedback when acoustic guitars are amplified, especially when using piezo soundboard

transducers.

Acoustic instrument tops have several frequency modes that resonate differently. The fundamental is

the primary resonant frequency of the box. When we analyzed the typical acoustic guitar feedback, we

found that the fundamental frequency and the first harmonic were both excited at the same time at or

near the low G#. The harmonics that cause feedback, resonate primarily at (or close to) 106Hz and

212Hz, with the first harmonic being a little louder than the fundamental from the reinforcement of the

octaves and fifths in the top's upper bouts. We tuned the feedback elimination at 237Hz and it kills the

first harmonic's resonance, but still leaves the lower fundamental note perfectly intact. This stops the

feedback but leaves the bass response strong and powerful. And the frequencies that are cut are in the

typically much louder G string frequency range, and not the low E and A strings.

We don't use a notch filter in the X7 design and you can really hear the difference. The Isometric

Equalizer allows for fast and simple complete feedback elimination, and the bass response is still tight,

loud, and very low.

Features and specifications in this manual are subject to change without notice.

Current product information is available online at: