NBL's sound muffled, any ideas?

Not sure what happened but all of a sudden both of my NBL’s started to sound very muffled like someone had a drape over the top of each of them. I tried trouble shooting by first turning off everything and letting it sit, turned it back on same thing. Tried a different source, same thing. Finally brought up an old pair of speakers and no muffled sound. Any thoughts? I thought maybe the passive crossovers, but would it make sense for both to go out at once? Seems really odd. Any help or ideas would be much appreciated! Been thinking hard about new speakers anyway but didn’t want this to happen. Thank you!

Were you playing music loudly at the time ?

1 Like

I wasn’t playing it loud at all actually. We have music going all the time in the house at a volume that we can have a conversation. Turned it up a little and noticed it.

Very strange. As you say, unusual for this to happen to both speakers simultaneously but from your description, it sounds like something related to the treble units and / or crossover. Any electrical storms or power cuts you’ve been aware of ?

No electrical storms or cuts recently. My house has actually been hit by lightning before and they survived that a few years back. Seems like some sort of power surge to it though. Everything else is working fine still with the speakers I put in place of the NBLs

Sounds like it’s time to get your dealer involved - I’ll be interested in what they find. Good luck.

It would be very odd indeed for a fault simultaneously with both speakers, so I’d look elsewhere first. But to start, are you sure it’s not your ears? Sound changes can happen, sometimes suddenly - and can reverse again equally suddenly. Are you the only person who listens and has noticed a change

That’s an interesting idea that did not cross my mind. My wife had just walked in when I started playing music and even she thought it sounded very muffled. Once we switched out speakers to an old pair we had, the muffling was gone. In hindsight now it may have been more prevalent in the right speaker but both were off. See what my dealer thinks if i can reach him tomorrow.

Anything still coming out of the tweeters? It doesn’t sound much in isolation but there’s still enough to tell if it’s working.

There wasn’t.

I would order a new pair of tweeters while you still can. There’s a seperate thread with the details. (Buy 2 pairs)

Reflecting, whilst both tweeters failing simultaneously seems unlikely unless there was clear reason such as a loud switch-on thump from incorrect start up or mains-borne impulse, or during very loud playing it might not be that both failed simultaneously: If one speaker had lost output at the top end with mid fine and other speaker OK, it might not necessarily be obvious if listening casually, but the second one failing would then stand out. Maybe this is what has happened, with tweeters at fault.

Did anyone accidentally unplug and then re-plug something like a SNAIC? This is often a sure-fire Tweeter killer. Otherwise maybe a mains spike?

It could just be that one tweeter had failed or was failing but because the other was still working it wasn’t so noticeable. Then when the second one failed, it suddenly became obvious.


If I remember correctly, the tweeters of the NBL’s are the middle driver, not the one at the top.
I only say this so that you don’t listen to the upper-most driver and accidentally think the tweeters aren’t working…

With external crossovers it’s easy to test the drivers.

When I lost one tweeter the effect on the soundstage was blatant.

@Richard.Dane hit the nail on the head. This is exactly what happened on Friday while connecting the superline to the 552. It was loose so I unattached and plugged it back in. I did hear some crackling then but things sounded (or so I thought) until yesterday. Didn’t happen right away on Friday but something between then and yesterday just triggered it some more for the tweeters to fail. Wonder if the crossovers were affected as well. Lesson learned for powering down always! Thank you everyone, see what I can source for tweeters and/or crossover work.

1 Like

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.