The OST-4 is a 500 Series enclosure in a “square box” format, able to accommodate up to 4 modules. As the rest of the new Heritage Audio line of 500 Series enclosures, it features “ON SLOT” Technology (OTS).

“ON SLOT TECHNOLOGY” takes advantage of last generation power electronics to handle power supply on a “per slot” basis. Each slot has its own power supply linear regulation stages; therefore modules are isolated from the rest. They just share the metal enclosure.

With literally hundreds of brands making 500 series modules, we at Heritage Audio think this is the professional way of handling this reliably, eliminating issues often associated with sharing power between different modules of different brands and natures.

Each slot features test LEDs for checking correct power operation (red for +16v, green for -16v), located aside of the slot connector.

Thanks to the use of OST, the power capability of the OST-10 is 400mA per rail per slot maximum, with an overall of 700mA per rail, whichever is reached first. Each slot has its own red (+16v) and green (-16v) LEDs for easy testing of the power status.

Phantom power available is 80mA total.

The RAF Blue Gray enclosure is made out of heavy gauge steel.

Connections are by means of gold plated XLR Input and Outputs.

• On Slot Technology
• Maximum audio rails current: 700mA per rail, or 400mA per rail per slot, whatever is reached first.
• Maximum phantom power current: 70mA.
• Operating voltage: 100-240 VAC


I toyed with the idea of owning a lunchbox for some time and finally pulled the trigger on this guy. It’s perfect and simple and its small enough to fit on a crowded desk. Perfect for a first lunchbox. Did I really need 8 slots to fill to start out with? Nope. I have everything I need for years here and it’s good clean power. I want just a few really special modules so this is perfect for me. And it fits in my small space as the power supply is separate and doesn’t take up much room on a desk. Gold plated Neutrik connectors as well.

James from Phoenix, AZ on March 14, 2016
 Excellent all around

This little guy is awesome. very sturdy, and straight to the point. The only downsides of this unit that I can think of are no power switch, and it would be cool to have trs outs on the back. I knew it didn’t have these features when I purchased it, so it isn’t a disappointment at all. For the price its unbeatable.

Anonymous on December 30, 2015

300 bucks, Solid, compact but powerful, very cool green lights……. you can’t beat this deal…….. used it with Neve 1073LB and TG2 500.

Jay from Los angeles on November 11, 2015Music background: Pop, gospel


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