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pro-audio products

A-RACK 8+1
modular microphone preamps

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design features

The A-Rack 8+1 frame can house up to 9 of our MA-1.5 mic preamp modules. These modules contain pretty much the same circuitry as our True Class A MA-2.2 microphone amplifier except the output is electronically balanced. The A-Rack is designed for multi channel recording setups and the MA-1.5 preamp delivers a unique punchy and detailed sound for the discerning sound engineer. The non-reactive transformerless input stage of this design means the MA-1.5 preamp works well with all microphone types and there is plenty of low noise gain available. The A-Rack is in use by many broadcasters around the world including Radio New Zealand, the Canadian Broadcasting Corporation and the reknown production company Fogolabs where it has been used to record well known musicians and concerts.

Arack psuThe A-Rack includes a headphone monitoring system so that signals on each channel can be checked and the 20 segment meter displays peak channel level. The solo monitor system of 2 or more A-Racks can be linked together for ease of use. The solo buss is also available on a balanced output so it can be used as a mono mixer. As well as individual outputs on XLR, channels 1-8 are also wired to a rear DB-25 connector for easy interface to your recorder. Controls are provided for gain, 20dB input pad, output mode (balanced or unbalanced), high or low input impedance, 48V on/off and solo. The A-Rack power supply transformer is supplied in a separate enclosure to ensure lowest noise.

Please note the A-Rack system is not compatible with the 500 Series format.


ma-1.5 controls and functions

GAIN - 41 detent pot the sets gain from 22 to 70dB.
SOLO - sends the output signal to the solo mix buss.
MODE - changes the output from balanced to unbalanced if driving an unbalanced input.
MUTE - switches off the module ouput signal.
Phase - changes the polarity of the input signal.
-20dB - introduces 20dB of attenuation at the input for high level signals.
IN Z - changes the input impedance as seem by the connected microphone.
+48V - switches on the phantom power.

related products - MA-2.2 True Class A mic preamplifier

ma-1.5 module

user comments

Rob Heaney

My Name is Rob Heaney and I'm the audio engineer for the Cirque du Soleil recordings. I rented an 8 Channel A-RACK from a friend of mine at Fogo Labs in Montreal for a DVD recording of the Live Show Corteo fothe Cirque. I had API's, Neve 1073 and a variety of other mic preamps and of course the Buzz Audio A-Rack. A-B-ing troublesome sources with all the pre's, I came to the conclusion that the Buzz truly smoked all of them instantly and it wasn't subtle. My assistant and I freaked at the sonic happening and I have to say it was instant envy and love of these preamps.

I've been engineering for 22 years and it's the first time in the last 10 years that I've been truly impressed with a new piece of gear. I'm an analog pig and I have a vast collection of tube and Class A gear. Finally I can put a preamp on drums and it sounds like drums in the room, without any additional EQ. The mid presence is truly outrageous, the bass player couldn't believe the sound of his P-Bass and Ampeg B15. With double headed 1950's kick with massive punch, this pre does not fold down when it sees a transient and the harder you push it the fatter it gets (where did you hide the tubes?).

And last but not least, it makes a SM58 sound like a condenser mic. I surrender, I have found the Holy Grail of preamps, I'm sorry Mr Neve but you are now #2. This is truly no hipe, no bullshit, just serious headroom and truth. Finally somebody got it in a big way and you can quote me on that. My hat's off to you, I hope I'll purchase one someday soon. Congrats!
[October 2005]

specifications

MA-1.5 module specifications

Bal Mode Min Gain; +22dB (+2dB with pad in)
Bal Mode Max Gain; +70dB
Unbal Mode Min Gain; +16dB (-4dB with pad in)
Unbal Mode Max Gain; +64dB
Maximum Output Level; +32dBu in Bal Mode, +24dBu Unbal Mode.
Frequency Response; 2Hz to 250kHz @ 20dB gain (-3dB). 20Hz to 250kHz @ 65dB gain (-3dB).
Harmonic Distortion; less than 0.008%100Hz to 10kHz.
Slew Rate; typically 140 V/uS, @ +20dBu output level.
Equivalent Input Noise; -133.5dB A wtg, 150ohm source Z.
Signal to Noise Ratio; -74dB A wtg, input shorted.
Common Mode Noise Rejection; 100Hz-80dB, 1kHz -80dB, 10kHz-70dB internal trimmed.
Module to Module Crosstalk; below noise.
Input Impedance; 3k ohms/1k2 ohms switchable.
Connectors; In-XLR3F, Out-XLR3M.
Size; DIN 41612 standard 8 HP wide.
Power requirements; must be fitted into A-RACK module rack bin.

Specifications are typical of a production unit and are subject to change without notice.
0dBu reference = 0.775 volts RMS.


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