I’ve had my RM30Ms for five years and in the last year I have been having an odd problem. Some of the nuts which are in pairs at the bottom of each mid range panel have come slightly loose. These nuts each hold a cable on the inside of the speaker.
The symptoms of a loose nut were occasional ‘crackling’ and a loss of dB, in my case 5dB.
Why do these nuts come loose and is there anything that can be done about it?
Does anyone else have this problem?
The background was that earlier this year I was listening away when I thought I heard the crackling sound from the right speaker. It occurred whilst playing a new CD which had a female singer with a particularly high pitched voice. Now I use a digital equaliser so I thought that perhaps I had over done it for some frequencies, even though I’d had no problems with other music up to that point. I was able to identify what I thought was the problem area and lower the dBs for that. It seemed to solve the problem for a bit but later it returned. I therefore tried all sorts of tests to try and isolate the problem, swapping cables, taking out the equaliser and so on, until I was convinced the problem was the right speaker’s mid range panels.
Was a panel damaged? Brian suggested I could replace it if I could find which one it was. I tried but couldn’t locate it so I decided to swap each speakers panels one at a time to see if I could find it that way. I started to remove a panel from the right speaker, undoing the four screws. This revealed that the two nuts held two cables, but they seemed secure. I put the panel back and decided to tighten the nuts slightly. They were hand tight but using a spanner I tightened one of them slightly - the other seemed tight enough. This was enough to correct the problem (yes, all this grief for one eighth of a turn of one nut). It also added about five dBs to that speaker (I could detect that by re-centering using the equaliser).
Over the last few weeks the centre of the image seems to have moved about a bit and occasionally would move to the right by 4dBs. Stupidly it did not occur to me that this was a mid range panel nut problem again but today I heard some crackling from the left speaker and, sure enough, I found a loose nut which has solved both problems.
