Harbeth HL P3 mk1 distortion

[Ian7633]

My brother's mk1 P3's are around 22 years old and have given great service but recently he had noticed some distortion from one speaker. As I used to work for Harbeth and actually built his speakers I said I'd take a look. Immediately it became clear that one of the the Seas mid/bass drivers was the culprit. There was a very slight roughness to the cone movement, not enough to point to the coil burning out, more like a fragment of dirt rubbing. I stripped the unit down and after carefully moving the cone back and forth beyond it's normal range of movement the roughness seems to have gone.
I'm really hoping this has done the trick as Seas no longer makes these drivers and the current version used in the P3 ES3 is different. I'd still like to replace both drivers but can't find a suitable replacement. Any ideas would be welcome.
The photos are of the dodgy unit. https://uploads.tapatalk-cdn.com/20171031/fb3dc1a4070b80e70a6329f12b63219c.jpghttps://uploads.tapatalk-cdn.com/20171031/0e8a34b41c07df74a6f655ac6ccde39f.jpghttps://uploads.tapatalk-cdn.com/20171031/c993b5adc028e5316bcf4ea34f8bfb40.jpghttps://uploads.tapatalk-cdn.com/20171031/e5987601992eba0cdd1018f024cc9fd0.jpg

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[RothwellAudio]

I've heard people say that the voice coil can droop after several years and become off center causing the coil to rub. Simply turning the driver upside down can cure it. However, I've never tried it myself.
Or if you can remove the dust cap safely you might be able to clean the gap around the voice coil by probing it with sticky tape to pull out any debris. Possibly :scratch:

[Pharos]

One really difficult problem is that the very strong magnetic field is ideal for attracting small particles of steel, and when made speakers are often in an industrial environment where such is abundant.

I have seen small particles of magnetic material on BBC LS 3/4 tweeters and heard it effects, as I have also on new ATC 50 tweeters. This is easier to remove than any problems in the gap itself.

If they are really failing you could go to the extreme of actually removing the magnet assembly and cleaning all if particles are the problem, but IMO as stated gravity causing a slight droop id more likely, especially if the 'grating' is consistent in nature with respect to movement. All dynamic speakers are susceptible to this problem.

If you contact Alan Shaw he may well give you advice on what to do, and if you dismantle, which adhesives to use to re-attach, having centred the coils in the gaps.

[Ian7633]

I've heard people say that the voice coil can droop after several years and become off center causing the coil to rub. Simply turning the driver upside down can cure it. However, I've never tried it myself.
Or if you can remove the dust cap safely you might be able to clean the gap around the voice coil by probing it with sticky tape to pull out any debris. Possibly :scratch:
Thanks Andrew, at the moment the distortion hasn't came back so maybe I did manage to dislodge a dirt particle. If it does return I'll definitely try turning the driver upside down, failing that there's nothing to lose carefully removing the dust cap and cleaning the coil and magnet. There is a video of this being done on Youtube so well worth trying.

[Ian7633]

One really difficult problem is that the very strong magnetic field is ideal for attracting small particles of steel, and when made speakers are often in an industrial environment where such is abundant.

I have seen small particles of magnetic material on BBC LS 3/4 tweeters and heard it effects, as I have also on new ATC 50 tweeters. This is easier to remove than any problems in the gap itself.

If they are really failing you could go to the extreme of actually removing the magnet assembly and cleaning all if particles are the problem, but IMO as stated gravity causing a slight droop id more likely, especially if the 'grating' is consistent in nature with respect to movement. All dynamic speakers are susceptible to this problem.

If you contact Alan Shaw he may well give you advice on what to do, and if you dismantle, which adhesives to use to re-attach, having centred the coils in the gaps.
As you and Andrew suggest a sagging suspension is very likely what is going on. I need to extend the feed wires but other than that a very straight forward procedure. I really hope to keep the original drivers as they are matched to the crossovers, and they do sound lovely.

[YNWaN]

I’m afraid I think a sagging suspension is unlikely to be the problem here. This problem is more likely to occur when the cone is large relative to the rear suspension and/or the driver has a soft roll surround (foam for example). In this case the weight of the cone looks to be pretty minor compared to its support.

[Ian7633]

I’m afraid I think a sagging suspension is unlikely to be the problem here. This problem is more likely to occur when the cone is large relative to the rear suspension and/or the driver has a soft roll surround (foam for example). In this case the weight of the cone looks to be pretty minor compared to its support.

I've only heard of the sagging in larger speakers too, like you say the weight of the cone being relative to the suspension material. The surrounds on my Signifers 12 bass drivers were replaced because of this very issue.

[walpurgis]

Anybody experiencing problems with a suspected speech coil misalignment could do worse than look here: http://theartofsound.net/forum/showthread.php?51367-The-walpurgis-fix-for-buzzing-and-rubbing-speakers!

[Ian7633]

Anybody experiencing problems with a suspected speech coil misalignment could do worse than look here: http://theartofsound.net/forum/showthread.php?51367-The-walpurgis-fix-for-buzzing-and-rubbing-speakers!

I will try anything to sort it out, been using them all day and no problems so hopefully it's cured.