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Soft Start / DC Filter 230V

Soft Start Circuit + DC Filter and power control Combo 230V AC Model 2018


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A soft start circuit to switch on big transformers on the mains grid.

NewClassD Soft Start circuit prevents high inrush currents from big mains transformers, that will normally blow fuses, overload switches and stress the rectifiers and capacitors. With this soft start circuit, the mains is connected slowly and smoothly to the power supply preventing any problems.

The DC Filter conditions the mains power, and removes the DC component. This will stop your transformer from humming. (Mechanical Hum).

This 2011 model includes also an offline power controller, which can also function as mains switch. You can connect a pushbutton and an LED to a set of terminals, and use them to switch the amplifier on and off. These are offline, with isolation class 1 (2kV isolation) so the GND terminal must be connected to earth, see the Earthing Instruction.
The middle terminal of the mains should be left unused.

Do i need a soft start module?
If your transformer is 400 VA or less, then you probably don't need a soft start circuit. At 500 VA you should start thinking about it, and by 800 VA it's pretty much a necessity. If you connect an 800 VA transformer directly to the mains, chances are your mains fuse will blow due to inrush current. If you have two 400 VA running on the same mains line, the same goes. If you have a 500 VA transformer, and a huge capacitor bank, say 100.000uF total, you need a soft start. If you only have say 44.000 uF behind a 500 VA transformer, you might just get by without a soft start. So that's pretty much the way you can tell.

Can i connect two transformers to one soft start board?
Yes you can, there are even 3 sets of terminals for up to 3 transformers. If you have more transformers, you can put two primary wires in each terminal, so you can safely connect up to 6 mains transformers into one soft start module. Just as long as you remember the max. load is 2300 VA.

Safety Notification.
This module is a Safety Class 1 circuit with isolation voltage of 2kV and creepage distance of >3mm. This means you can only use it in an amplifier that is connected to safety earth in your mains outlet, for safety reasons. We will offer a safety class 2 version and a free upgrade from this version, by May 1st. 2018.

NewClassD ApS | DK7500 Holstebro | Denmark | tel +45 32130963 | E-Mail: |126