K4700 (speaker protection) testing and connecting questions

Hi all

So, I´ve assembled the K4700 kit and want to see if it´s working (fingers crossed). In the manual it says:
“Connect a net-cord to the MAINS, connect the module to the net and check …”
Does this mean I should connect pin N (Neutral?) and L (Live?) of the MAINS directly to the live (brown?) and neutral (blue?) leads of a normal power cable? Ground (yellow/green?) not used? Does it matter if N is connected to live and vice versa?

Assuming the module works, I naturally want to install it to the amp (a Behringer A500). The manual states: “MASS: this point has to be connected to the mass of the amplifier.” “MASS”; is that the earth ground, chassis ground or something else?

As you can tell; I´m a complete noob at this stuff (and I wouldn’t do all this unless I had to get these amp to work with my speaker project), so please assume I know nothing (absolutely nothing!) when answering. Thanks in advance!

Yes, the two dangerous wires of the mains lead to the points N and L on the print.
No, you can interchange N and L (so N of mains to L on print and vice versa).
Mass = the ground of your amplifier. Is normally a point in which many wires come togeter (star topology). Sometimes the same as chassis ground but not always.

Thanks again Laserguy, truly appreciated!

I´ll try and post a pic (within the hour) of the point I assume the MASS should be connected to just to be safe.

Again; thank you for answering my silly questions!

So; “MASS” connects here:


I´ve tested the modules and they are working; god!

Now I need to connect them to the amp (not used in bridge mode) but I´m slightly confused about the speaker connection. The manual illustrates a single connection from each channel of the amp to the K4700. Which lead (+ or -) is supposed to be connected to the K4700’s “PA” connection and what about the other lead?

I would love quick reply since this needs to be finished today.

Ok, so I´m pretty confident that it´s the positive speaker lead that is supposed to be connected to the “PA” point of the K4700, but what about the negative speaker lead in the amp? Should I just let it be connected as it is or should I connect it somewhere else or should I cut it? I guess it doesn’t matter since it’s probably also connected to ground, but I would like to be sure about this so I don’t mess up the brand new amp.

Edit: What cable area is recommended for the mains connections (inside the amp)? I have 1,5 and 2,5 mm2 at hand.

Before I kill myself and/or the amp; is this how it should be done (se pic above, twisted red/black and blue/yellow is the speaker outputs, L +/- and R +/- ):

  1. “MASS” (earth ground, right?) from K4700 to the earth ground of the amp (as indicated on the pic).
  2. L + and R + from the amp to the “PA” L & R of the K4700.
  3. “LS” L & R from the K4700 to the positive L & R speaker terminals of the amp.
  4. The negative speaker terminals (L & R) summed and connected to earth ground (as indicated on the pic).*
  • I can see (measured) that these are already connected to earth ground. Does this mean that I only need make sure that the “MASS” of the K4700 is connected to earth ground of the amp and all is done in regards to the negative speaker outputs?

I would really welcome any response since I would like to get this system running by tonight. Thanks in advance!

A couple of remarks:

First: We have the impression that your knowledge is limited. There is no problem with that, but if you make a mistake, it could lead to problems such as destruction of the amp, destruction of the K4700 kit or both. There might even be a fire hazard!

We can give hints, but in no way we can be held responsible for damage, injury or other problems resulting from the use of our hints.
If you are not sure, please seek local professional help.

Without a schematic diagram, we cannot judge 100% correctly how to wire the kit. We have to assume certain things.

The indicated wire on the picture is most likely not the GND but the earth connection. It is strange, but we cannot spot the GND on the picture. If there is zero ohms resistance between this earth and each speaker (-), then we must assume it is also the GND.

In that case, wire the GND of the amp to the GND (reverse ‘T’) of the K4700 kit. Make sure the kit is configured for ‘symmetric’ power supply.
Wire the L and R (+) of the amp to L and R (PA) of the kit.
Wire L and R (LS) of the kit to the L and R (+) speaker connections of the amp
(please see manual page 12, fig. 5.0)

Yes, absolutely; I have very limited knowledge about these things as stated previously (and my nick gives a hint also :wink: and I´m completely aware that you cannot guarantee anything.

The resistance between the negative speaker terminals of the amp and the earth ground (or whatever it is that is illustrated in the pic above) is less than 1 ohm, so I assume it´s low enough to consider this the point to connect MASS to. I´ll then leave the connection between the negative side of the amps and the terminals as is?

Yes; I´ve built the K4700 without the extra resistors (for symmetrical operation).

Thank you for your reply. Now I can finish this thing!

Like Velleman said: it is strange that there is no real mass point, only an earthing point. In lots of amplifiers the mass is indeed connected to the earth but as this can give earth loops (hum), this is not always the case: mostly the mass is connected to the earth by means of a capacitor.
But as you measured lower than 1 Ohms, you can be pretty sure that you’ve done it right.

Thanks again Laserguy, you´ve been very helpful. I´m sure you’re a great asset to this forum!

Oh thanks :stuck_out_tongue: