MARQUETTE AUDIO LABS

* Since 1994 *

Buzz Audio Stereo Optical Compressor

Buzz Audio SOC front view
Modern music styles generally require the bass tracks to be compressed and nothing can sound sweeter in this application than a good optical compressor - say hello to the Buzz Audio SOC-1.1. Considerable design effort has been placed on how the SOC responds to low frequency content resulting in a totally new and unique "Differential Drive Side Chain" (DDSC) topology. The DDSC design also has spin offs for mix buss and vocal tracking applications plus the soft knee "sound" of the SOC has won favour with recordists of acoustic and classical music styles where gentle levelling without artifacts and "pumping" are important.

The SOC is based on the Light Dependant Resistor (LDR) technology as used in many classic compressors, but the DDSC topology plus our own Opto Gain Reduction Module design create a more adjustable, predictable and coherent compression characteristic. Gain reduction is totally passive, there are no distortions introduced from semiconductor elements and the signal path is kept to a minimum. LDR selection and matching within a stereo unit ensures accurate tracking compared to vintage optical designs.

A common problem with older opto compressor designs (and many modern ones) is the inherent slow attack time of the LDR elements, which is not so desireable for modern mix buss applications. A unique "speed up" circuit in the DDSC circuit of the SOC effectively reduces the attack time to less than 1mS (in fast attack mode). We believe this is the fastest attack time of any LDR based compressor on the market today and finally makes the LDR technology suitable for stereo mixdown (2 buss) compression tasks.

All the features available on the SOC allows users to create many different flavours of compression, from full on squash to just gentle levelling. A very useful piece of kit destined to become a classic.

Controls for:- Attack(3) Release (6) Ratio (4) Drive and Out Levels.
Big knobs, large back-lit VU meters, conductive plastic pots and reliable switches.
Separate power supply regulators for audio/sidechain sections.
Each channel individually power regulated.
Auto bypass/mute relay when power lost.
Electronically balanced inputs and outputs on XLR.
Gain reduction metering that doesn't drift !!
New generation opamps utilized in the audio path.
Unique Differential Sidechain circuit design.
Performance comparable to many tube compressors costing alot more !!

Max Input/Output Level = +23.5dBu.
Measured with 2k ohm load and 0dB output gain makeup.

Frequency Response = 4Hz to 250kHz.
-3dB points with no gain reduction.

Harmonic Distortion = less than 0.008%.
Measured 100Hz to 10kHz with no gain reduction.

Harmonic Distortion = less than 0.03%.
Measured 100Hz to 10kHz with 20dB gain reduction, Attack-AUTO, Release-16

Residual Output Noise = typically -90dBu, -100dBu A wtg.
No gain reduction, 0dB output gain makeup, 150R input source impedance.

Channel to Channel Crosstalk = below noise.
150R source Z on measured CH-A, +20dBu applied to CH-B, 100Hz to 10kHz.

Standard Operating Level = +4dBu = 0 VU meter display.
Other sensitivities can be supplied from the factory.

Size = 2 Unit rack mount, (482Wx88Hx250D).
Power requirements = 230V/115V selectable, IEC detachable power cable.

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


Please call Dave at (510) 581-3817 for your price.