B&W DM640 - is there anything wrong?

The 640 is a great speaker. Have had mine for 14 yrs and they still sound great. looking to replace them with the 683 just because of age. I figure 14 yrs is a long time and the 683's sound every bit as good and maybe even better in the mids and highs. Any way, they really need to be about 2.5 feet from the rear wall and that is the minimum reccomended from B&W. I know sometimes that is tough but when they are too close and being rear ported they start to get a little muddy. Not having the ports doesnt help either as they can really be fine tuned with them. I also wouldnt put them right on the floor. The base's with the spikes are there for a reason. There is definately a big difference when not using them. Well hope you find your problem because they are great speakers.

These speakers do sound great now.

I did make a couple of additional changes since my post above.

I cut the long port tube to make it the short size to get more bass.

Also, I noticed that the midrange is out of phase with the woofers (same on both speakers), can't really tell if the tweeter is out of phase. So I'm bi-wiring to the amp, and fixing the phase issue at the speaker posts. Eventually I want to open the speaker and find the cause of this, probably a wire is connected backwards. This made the biggest improvement of all for obvious reasons.

About raising them off the floor, I may try the plinth / spikes again, now that the polarity is fixed. A friend of mine has 802s and he also likes them right on the floor, without the plinth / spikes. Maybe it has to do with the concrete / tile floors here in S FL.

Hi, I know this is an old post, hope you're still on the forum!  I've got a pair of these speakers, but didn't get the different bass port tubes or block.  I do have the 150mm port tubes, but I can't find anywhere online or in the manuals if these are the long or shorter tubes that were originally included.

I'm thinking about cutting mine down also, what length did you shorten yours to?