A/DA Microcab II User manual

Miked Guitar Cabinet Emulator for pre-amps
and power-amps
OWNER’S MANUAL Microcab II (version 1)
Originally written by ADA SIGNAL PROCESSORS, INC. Scanned and edited by Jur at 10th of august 2002.
Original ADA logo edited and rendered by Barend Onneweer of Raamw3rk.) The version of this manual is
copyrighted and may not be sold or placed on a website without permission of the editor.
Release No.1 for http://www.ada-mp1.com

Table of Contents
Introduction
Features
Precautions
Quick Set Up
Using the MicroCAB II
How to Get the Best Tone with Your MicroCAB II
What the MicroCAB II Docs
Glossary of Audio Terms
Specifications
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INTRODUCTION
Thank you for purchasing the ADA MlCROCAB II Miked Guitar Cabinet Emulator. The
MlCROCAB II is designed to deliver the distinct warmth and presence of a "close-miked"
guitar speaker cabinet to a mixing console for direct recording or for sound reinforcement.
The MlCROCAB II takes the signal from the output of a guitar preamp or poweramp. Your
new MlCROCAB II will preserve all the tone and fidelity from your guitar, preamp, and effects
units, while delivering the frequency response of various speaker cabinets, simulating difficult
and time-consuming miking techniques used in recording studios.
Please take a few moments to read this manual and familiarize yourself with your new
MlCROCAB II.
IMPORTANT: At this time, please complete and return the enclosed warranty card.
FEATURES
 Emulates any type or size of guitar cabinet.
 Stereo inputs and outputs.
 Stereo pass thru to poweramp or speaker load box.
 Variable THUMP control allows tuning the cabinet's low resonance.
 HI BALANCE control emulates mic placement and cabinet brightness.
 Lightweight design, in one rack space.
 One year parts and labor warranty
PRECAUTIONS
WARNING: To prevent fire or shock hazard, do not expose this appliance to rain or
moisture.
CAUTION: To prevent electric shock, do not remove cover. No user serviceable
parts inside. Refer servicing to qualified service personnel.
SET UP WARNING: WHEN CONNECTING THE MICROCAB TO THE OUTPUT OF A TUBE
POWER AMP OR AN ALL-TUBE HEAD, ALWAYS KEEP A LOAD CONNECTED TO THE
OUTPUT OF THE AMP. THE LOAD CAN BE EITHER A "LOAD BOX" OR THE SPEAKER
CABINET NORMALLY USED WITH THE AMP. USE THE EXTENSION JACK AT THE
SPEAKER CABINET TO CONNECT THE MICROCAB OR USE THE PASS THRU
CONNECTORS ON THE MICROCAB TO RECONNECT THE LOAD TO THE POWER AMP.
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QUICKSET UP
The MlCROCAB II Miked Guitar Cabinet Emulator is designed to accept preamp/effects
and poweramp output levels. DO NOT UNPLUG YOUR TUBE POWER AMPLIFIER
OUTPUTS from your speakers or load box when using the MlCROCAB II !
1. Connect stereo inputs (A & B) on rear panel of MlCROCAB II to (he outputs of your
preamp or effects device using shielded 1/4" phone cables. Or connect 1/4"
unshielded phone speaker cables to your power amplifier output(s).
2. Use your choice of the MlCROCAB II's 1/4" or XLR (balanced) outputs to connect
the MlCROCAB II to the inputs of your recording or sound reinforcement mixing
console. For stereo operation, connect outputs A & B to separate inputs on your
mixing console.
3. Use ground lift switch if necessary to eliminate any line noise or hum that may be
present from poorly-balanced power sources or ground loops in your system.
NOTE: YOU MUST HAVE A GOOD TONE FIRST! SET YOUR PREAMP AND EFFECTS
TO GET YOUR BEST TONE USING YOUR WHOLE RIG, INCLUDING THE GUITAR
CABINETS, BEFORE PATCHING IN THE MlCROCAB II.
USING THE MICROCAB II
The MlCROCAB II can be used in the recording studio to quickly capture "that right tone" just
as it sounds coming out of your guitar cabinets. The MlCROCAB II is also used for live sound
reinforcement to get the exact tone on stage into the house system, without much of the
hassle involved in lengthy sound checks and mike placement trial and error, while providing
absolute isolation from other instruments on-stage.
Since guitar speaker cabinet systems don't have a flat frequency response, some outboard
EQ is essential to simulate the characteristic tone and presence of a "live" speaker cabinet.
The ADA MlCROCAB II is designed to emulate the presence, tone and coloration found in a
variety of modern and vintage speaker cabinets. Further, since the signal at the speaker
cabinet is normally brought to your mixing console via a microphone, and not through a direct
box (this would sound terrible), the microphone's frequency response must be taken into
account. The MlCROCAB II emulates this characteristic, delivering the "feel" and tone that
has become an integral part of the sound of amplified guitar.
Additionally, the ADA MlCROCAB II is capable of emulating the close-miking characteristics
of the Shure SM57 microphone—the industry standard for guitar miking in the studio and live
sound reinforcement. The SM57 is well-noted for its "proximity effect," or low frequency boost
at 180 Hz when placed very near the sound source (see Huber, Microphone Manual, Focal
Press, 1988, p. 258), further enhancing the "thump" effect of the British-style 4x12 cabinet.
Also note, on the next page, that the high frequency response from the Shure SM57 when
placed off-axis is greatly attenuated. The shallow comb filter nodes across the mid-frequency
band, shown on page 8, is another "live miking" characteristic emulated by the MlCROCABII.
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HOW TO GET THE BEST TONE WITH YOUR MlCROCAB II
First, get your best tone using your whole regular rig, including your speaker cabinets!
Now, to capture that tone to tape, insert the MlCROCAB II between your preamp and your
power amp. Remember, you can listen to your regular speaker tone by using the MlCROCAB
II's pass-thru jacks on the rear panel. These are hardwired directly off the input jacks.
Alternately patch into your power amps outputs, remembering that vacuum tube power amps
always require a load (either the speaker cabinet or a "load box"). The MlCROCAB II does
not provide a speaker load for tube power amps.
Try the variety of cabinet configuration tone settings offered by the MlCROCAB II to obtain
the sound you want, starting with the exact speaker configuration that you are using. Use the
HI BALANCE tone control on the front panel to adjust the brightness, and the THUMP control
to boost or cut the amount of low-frequency resonance, especially if you are emulating a
sealed cabinet.
The MlCROCAB II offers emulations of 12-inch speakers in 1,2, and 4-speaker
configurations, in both open-back and sealed enclosures. You can also use the VINTAGE
settings for a darker-sounding tone coloration.
When using headphones with the MICROCAB II, you may want to adjust the HI
BALANCE downward to compensate for high frequency emphasis found in most
headphones.
WHAT THE MICROCAB II DOES
The ADA MICROCAB II is a tone-shaping device designed to emulate the complex physical
and psychoacoustic effects that make up the unique "live" sound of a close-miked guitar
cabinet. In the early days of recording, "distant" or "ambient" miking—often using a single
room microphone for the entire performance—was the standard; the distinctly modern
technique of close-miking adds more immediacy and control over the instrument voice.
There are some "competitive" products on the market, simple band pass filters, cutting highs
and some lows. Such speaker emulators can sound "muddy," that is, lacking in definition or
"presence." Only the ADA MICROCAB II offers true emulation of a classic "close-miked"
speaker cabinet. The MICROCAB II delivers improved voicing, brilliant presence, "in your
face" high-midrange sizzle (1.2 - 1.5 KHz), and the characteristic "thump" (low frequency
resonance) found in classic guitar cabinets. Moreover, the ADA MICROCAB II offers you the
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versatility of having a variety of speaker cabinet tones at your fingertips in one compact
single-space rack device.
The purpose of calling the ADA MICROCAB II a "miked" guitar cabinet emulator is to
distinguish it by features that account for the microphone in the audio path. As the number of
speakers is increased in a miked cabinet, the number of signal paths to the microphone
increases, adding a comb filter effect to the guitar sound on tape. The sound from these
"paths" travels different distances to the microphone element. Therefore, when combined,
cancellations and reinforcements are produced across the sound spectrum. This is the
source of the "complex" feel to the close-miked guitar cabinet.
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The "thump" or low frequency resonance in guitar cabinets mentioned above is perhaps the
most powerful characteristic in live amplified guitar performance. Most cabinets are like the
4x12 (an array of four 12" speakers as is used in British-style stack-type cabinets) with no
ports (holes as in hi-fi loudspeaker enclosures) and no open backs. The frequency produced
by such a speaker cabinet array is around 200 Hz (abbr. for Hertz or cycles per second). The
frequency is near the human chest cavity resonant frequency. The ADA MlCROCAB II is
unique it its ability to reproduce this power and "live" feel in a direct situation—again giving
"more tone to tape!"
GLOSSARY OF AUDIO TERMS
(From the CAMEO Dictionary of Creative Audio Terms, Gary Davis & Associates, 1979)
Coloration
Non-uniform frequency response resulting in distortion of the tonal quality of the
source.
Close Miking
A technique for recording or sound reinforcement whereby the microphones are
placed close to vocalists and to instruments or small groups of instruments. Close
miking provides a great deal of presence and detail for the nearby sound source(s),
while avoiding leakage from more distant sound sources. Most of today's popular
music recordings use close microphone techniques.
Comb filter
A comb filter has a series of very narrow, deep notches where signals are attenuated.
When the frequency response of such filters is graphed they resemble a hair comb.
Directivity factor
For a loudspeaker, this is a measurement of how much the speaker focuses the
sound in a given direction. Directivity is measured by taking the ratio of the average
sound level throughout 360 to the maximum sound level in front of the speaker (at a
given distance and frequency).
Distant miking
A microphone placement technique where one or more mics are located at a distance
of at least several feet from the performers. Distant microphone placement allows a
greater area to be covered using fewer microphones than close mic placement, and
is ideal for some types of recording. Distant mic placement usually will not provide the
presence and detail possible with close mic placement, although each technique has
its advantages.
Hass effect
Also known as the "precedence effect," this psychoacoustic phenomenon was first
described by Helmut Hass. The Hass effect describes our ability to perceive the
location of a sound source based on the relative level and arrival time of the sound in
each ear.
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Presence Range
Refers to that area of the audio frequency spectrum which affects the perceived
presence of the sound. Assuming there is no echo or reverb, presence or the feeling
of being "up front" will be determined by the relative balance of those frequencies
falling roughly in the 2 kHz to 5 kHz range.
Voicing
Refers to the careful equalization of a speaker/amplifier system as in a recording
studio monitor or sound reinforcement, system to achieve a particular sound or effect.
GRAPH A / Vintage 4x12 / Close/Far Miked
Above graph shows increasing tonal complexity of a 4x12 Vintage cabinet as the microphone
is moved closer to the speaker cabinet. At 5 meters, note fewer peaks, less low range
"thump," and less mid-hi range notches in the lower, dashed line. The greater the coloration
of the signal, the richer (and livelier) your tone will be.
GRAPH B / Close Miked 2x12 / Open Back/Sealed Back
Above graph compares response from an open back (solid line) vs. sealed back (dashed
line) 2x12 speaker cabinet. Note uneven and lower level response below 200 Hz in sealed
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cabinet, resulting in more complex and "darker" tone. The MlCROCAB II offers eight types of
open/sealed enclosures.
GRAPH C 4x12 / Sealed Cabinet / Off-Axis/On-Axis Miking
This graph compares on-axis (solid line) vs. off-axis (dashed line) response characteristics in
a close-miked 4x12 sealed cabinet. Note lower off-axis response above 2 kHz. resulting in
less "brightness." This response difference can be emulated in the MlCROCAB II by
adjusting the HI BALANCE tone control.
SPECIFICATIONS
Dimensions: 1 rack unit x 5" deep
Width 19"
Depth 5"
Height 1-3/4"
Weight: 2.5 Ibs., 4.5 Ibs., shipping
Maximum Input: +20 dBV
Maximum Output: +19 dBm
Input Impedance: 50k ohms
Power Consumption: 4 Watts,
117 VAC 60 Hz
220 VAC 50 Hz optional
100 VAC 60 Hz optional
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