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Alto Professional ACL4 is a 1U four-channel analog compressor and limiter, new and factory sealed. It uses a low-distortion THAT Corporation VCA, adds side-chain, Smart Knee Control and a peak limiter on every channel, and runs as four mono channels or two true-stereo pairs with balanced XLR and 1/4 inch TRS I/O.
Four channels of clean compression in one rack space.
The ACL4 is a four-channel compressor and limiter from Alto's dynamics line. A very low-distortion VCA from THAT Corporation keeps operation quiet and transparent, so it can sit on vocals, drums or a bus without coloring them.
Two Couple switches link the channels into two true-stereo pairs, or all four run as independent mono processors. Smart Knee Control works soft-knee at lower thresholds and hard-knee at higher ones, a Smart Gain Control peak limiter catches overs, and a side-chain on each channel handles ducking and external loops. Seventeen LEDs per channel show gain reduction and level.
This unit is new old stock: brand new, factory sealed, in the original box.
At a Glance
| Type | 4-channel compressor and limiter |
| Channels | 4 mono or 2 stereo pairs |
| VCA | THAT Corporation, low distortion |
| Threshold | -40 dBu to +20 dBu |
| Make-up gain | Plus or minus 20 dB |
| I/O | Balanced XLR and 1/4 in TRS per channel |
| Format | 1U rackmount |
| Condition | Brand new, factory sealed, original box. Discontinued model, no manufacturer warranty. Guaranteed working on arrival |
What Is the ACL4 Used For?
Drum bus compression, multi-channel live sound, broadcast, and studios that need several channels of compression in one rack space.
Who Is the ACL4 For?
Live engineers running several vocal or instrument channels, churches, and project studios that need channel count over a single premium compressor.
Connections
| Inputs | 4, balanced XLR and 1/4 in TRS |
| Outputs | 4, balanced XLR and 1/4 in TRS |
| Side-chain | Per channel |
| Metering | 17 LEDs per channel |
Specifications
| Channels | 4 |
| Stereo linking | 2 Couple switches |
| VCA | THAT Corporation |
| Knee | Smart Knee Control |
| Limiter | Smart Gain Control peak limiter |
| Threshold range | -40 dBu to +20 dBu |
| Output gain | Plus or minus 20 dB |
| Format | 1U, 19 in rackmount |
Why Alto Professional?
Alto Professional built affordable live sound and studio processors for working engineers, churches and project studios. Its rack processor line was discontinued years ago, so units still sealed in the original box are hard to find.
Frequently Asked Questions
Is this a genuine Alto Professional product?
Yes. Victory is a veteran owned dealer in Miami and this unit is new, factory sealed in its original packaging.
Can it run in stereo?
Yes. Two Couple switches link the four channels into two true-stereo pairs, or all four run as mono channels.
Does it come with a warranty?
It is a discontinued model, so there is no manufacturer warranty. Victory guarantees it working on arrival.