Sub stopped working

I was hooking up some new sub cables from one of my stereo subs to the amp, I had everything off, but I couldn’t get the new rel Kimber spades to fit on the amp

So I pulled the amp out, unhooked everything, and when I unhooked the other subs cables I heard a low hum. I forgot to turn the other sub off.

Now, the sub appears to be on but no sound.

Did I blow it?

I unhooked everything and reconnected, still no sound from sub.

Check the fuse. If you shorted the cables, the fuse should’ve blown

1 Like

And this could happen to anyone…

I have never blown a fuse plugging in a trigger cable. Never not once. Twice, yes. Once, no.


If fuse was blown, wouldn’t the whole unit not turn on?

Power down and pull the plug out of it. Let it sit that way for 24 hours. Then plug it in and power it up. This should not help at all but it sure is easy to do.


I switched the cable and still no sound from the sub.

Now, I do have it currently set up with bare wire and a spade on the ground lug. Maybe it’s not getting good contact?

I could only afford one cable at a time.

Try disconnecting the ground lead. It won’t make sense to you but give it a try.

And float them?


Do I then also need an rca cable for ground?

It’s a class d amp

Good News.

I made the learned decision to switch the subs, and what I thought was a blown sub now does work when I switched it to the other channel. The other sub, when placed in the other channel now doesn’t work.

So, it seems to be a connection issue.


From the pic in your other post, it looks like it’s an NAD amp (blue negtive post)?
Here’s an interesting tidbit fro REL’s site: How to Connect a REL to Class D Gear - REL Acoustics

The Problem:

So, why does a Class D amp require a different connection than a traditional Class A/B amp? There is something done to the ground plane that is unique in our experience. See, ground should be exactly what it sounds like—a return path of energy back into Mother Earth. For every action, there is an equal and opposite reaction and for every outflow of electrical energy, there must be a proper, full return of that energy back to earth.

Here’s where Class D amps get weird (not all, but about 90% exhibit the anomaly I will describe next). The Black speaker terminals on the rear of your amp traditionally, and by electrical convention, mean Earth Ground. Zero ohms, zero Hz. Ground. But with most Class D amps, that Black-colored speaker terminal* is no longer ground. Worse, it actually references to a positive voltage that is significant. We consistently measure 10-15 volts ABOVE ground. In practical terms, if your REL were mistakenly connected to a Class D amp or receiver the input of the REL would eventually be burned out because it would be pulling 15 volts through a circuit designed to see zero voltage. Over some period of time—months or a few years, this unwelcome voltage will burn out the front end of your REL.

The Solution:

Fortunately, the solution turns out to be both easy and inexpensive—potentially no cost difference at all if your system is theater-based.

On the REL High Level cable go ahead and connect up the Red (R+) and the Yellow (L+) leads as usual. “Float” the Black wire (do not connect it to anything), in fact, snip off the portion that is pre-stripped and wrap it in electrical tape to avoid accidental shorting out later on.
Next, connect a long RCA-RCA interconnect from either an unused input on a preamp or receiver to the REL’s .1/LFE input. Do this even if you have no interest in theater, you are creating an audio ground, nothing more. This is true for 2-channel systems, we are not using the .1 LFE input for anything more than to produce ground.
If you are running this in a theater system, you’re done; run your usual .1/LFE cable and float the black wire and you’re done.

*One final call out, NAD recently introduced two new integrated amplifiers. We would like to commend them for specifically choosing Blue for their “Non-Hot” speaker terminal. Rather than Red/Black, the Red/Blue scheme gets people wondering why the color is different.

Along with our friends at Peachtree Audio, the NAD folks also added an old-fashioned knurled chassis ground bolt which makes it even easier than we described to obtain true ground on this style of amp. We salute these customer-centric companies.

1 Like


I’m aware of this.

I use the supplied ground lug.

Just an update-

I’m working with Kimber to get some bigger spades, while I wait to get them I put the lid ls cables back on and I still get sound from just one sub.

This situation has evolved.

I tried to get both subs back working. Switched the subs to just be sure it’s not the subs, and it’s not, the staid in same channel.

I put in a new cable with a different connection to see if it’s the connection on the cable, or something wrong with the amp, and still no sound from the sub. This connection previously worked in the other channel.

So it sounds like it’s actually the amp.

It get worse. I shut everything off, unplugged the amp, and tried one last time pulling it out and getting a really solid connection with the spades.

Tried turning amp back on, and nothing. It’s DEAD.


Did you check the fuse?

Wondering if one of your cables is shorted.

Maybe it’s the fuse but I don’t think the fuse is user serviceable on an nad…

It’s the whole amp that won’t even turn on now