System Problems

[Conchis]

My equipment is only seven years' old, so by no means 'ancient'. I don't play music at ear-splitting volumes. However, after returning home after a fortnight away, I've noticed that when I play music at a 'reasonable' volume (i.e., with the volume control at the 'ten to twelve' position, I'm getting terrible crackling come from the right hand speaker when the music features low bass notes or heavy percussion. Does this mean my speakers (or, at least one of them) are done for? Or can I take some form of remedial action. Speakers are Mordaunt Shorts, Amp is Cambridge Audio Azur 640a.

Another strange issue: when I have the DVD player plugged in, even if I'm not using it, I get a terrible droning sound on the audio channel and the volume control on the amplifier gradually goes down to zero (as by magic). This problem ceases when I unplug the DVD player. It's never happened before and has occurred very suddenly. Any ideas?

[umslopogaas]

The drone sounds like an earthing failure: maybe an earth wire has come loose somewhere?

For the crackle, try swapping the speakers over. If it now happens on the left speaker, its the speaker at fault. If its still on the right, the problem is in the amp.

[Dave2002]

Also try turning the problem speaker upside down. Do this after checking other things which fail to correct the problem. The cone suspension might be faulty. It is possible to get that fixed, or the drive replaced - at a cost.

[Ferretfancy]

Also try turning the problem speaker upside down. Do this after checking other things which fail to correct the problem. The cone suspension might be faulty. It is possible to get that fixed, or the drive replaced - at a cost.

If the speaker drive unit is fixed with bolts to the front panel, it's often possible to loosen the screws and rotate the unit by 60 degrees, taking care that the wires behind the unit still reach. I've done this successfully in the past and it might avoid an expensive repacement.

[jayne lee wilson]

First thing is as above - switch the speakers (they weigh much? watch your back, bend the knees now...) to see if it's in the speaker or the amp/electronics.

So all this was the case soon as you started to listen, as if it had changed while you were away, yeah?
Assuming no teenage or adult headbangers were at home (or broke in ) to rock out and overload your system, did you leave the system on standby/powered up while you were away? A mains spike or surge could have caused damage to the amp or DVD player. It would be unusual for this to cause speaker damage (unless you left it all on and the volume up and there was a serious disturbance at the local power station ) .
I always leave my system powered up (usually best for longevity & sound), and mains disturbances have happened to me overnight once or twice, but luckily any affected components just switch to standby. (The system runs off isolation transformers which do offer some protection).

With the DVD player, it sounds like a grounding issue - try separating any of the DVD's cables (mains or interconnect) that touch other cables to see if the hum reduces or stops. No joy? Switch the player off, wait a few minutes, switch on. Still po-faced? Try connection into different mains or or amp inputs. If none of this works unplug the DVD player from everything and wait a few minutes before trying again. Amazing how many problems can be cured by doing this.
The amp's behaviour seems strange, unless it has some electronic auto-protection active against overload and is responding to the hum by reducing volume....(time to rtbm***)

Various components respond oddly to the mains, volume etc.: my Mum's Denon integrated shuts down completely if the volume is left at zero overnight! She has to keep a whisper of music going in off the tuner to keep things running. It's in her bedroom so we call it the snooze setting...

(***read the bloody manual. Oh the stories I could tell......)

[Dave2002]

First thing is as above - switch the speakers (they weigh much? watch your back, bend the knees now...) to see if it's in the speaker or the amp/electronics.

For testing just swap the wires over. No point in moving the speakers if there's no need to.

[Conchis]

Hello, everyone


Thanks for the very helpful advice above. I did switch the speakers around and the same speaker is still at fault. So, it would appear the amplifier is still OK, but the speaker itself needs attention.

I'm guessing this is probably a job for an engineer, then, unless someone can suggest a 'home-made' remedy based on experience?

Jane - I was also puzzled by the way the problem seemed to 'arise' after my absence. No-one was in the house while I was away, so the system hasn't been used. I did leave it on standby, though, so a power surge can't be discounted.

Will have a go at what you suggest with the DVD player. When I remove the plug from the DVD player while playing a CD, the problem ceases, so it may not be a 'major' issue, anyway.

[Dave2002]

Hello, everyone


Thanks for the very helpful advice above. I did switch the speakers around and the same speaker is still at fault. So, it would appear the amplifier is still OK, but the speaker itself needs attention.

Re my msg 6 - did you just switch the cable at the amplifier end? That's enabled you to home in a bit further, but one thing occurred to me is that the problem could be with the cable itself. If there's a cable fault, then it's possible for a form of microphony to occur, if the vibrations at the speaker end are causing a problem - for example say, in the connections. Then, as you also suggest, it could be a fault within the speaker, though again it could be something "simple" like a wire which needs to be reconnected, or something more difficult, such as a faulty voice coil, or a cone suspension issue.

You could presumably rule out the cable microphony possibility by swapping the cables over - though that might cause the problem to disappear simply because sometimes changing things "does that", without actually "curing" an underlying fault.

How much are the speakers worth to you? Are you very fond of them? How much are new equivalents?

I was once strongly recommended a speaker repair company - I think it was this one in Wembley - http://wembleyloudspeaker.com/
I did discuss problems with them, and I was quite surprised when they said they could completely remake the drive unit if I wanted (seemingly including rewinding the voice coiils), though they did suggest that I only sent the drive unit - and they told me how to get it out. I didn't actually bother, though I did obtain some "new" drivers second hand which I've still not got round to fitting.

If you really like the speakers, then it is probably worth exploring some form of repair option, or else look for the same models again, perhaps on eBay or ask for help on a hi-fi enthusiast web site - there are a few. I don't think that speakers that old should normally fail - some of mine are about 40 years old and still work.

[Conchis]

Re my msg 6 - did you just switch the cable at the amplifier end? That's enabled you to home in a bit further, but one thing occurred to me is that the problem could be with the cable itself. If there's a cable fault, then it's possible for a form of microphony to occur, if the vibrations at the speaker end are causing a problem - for example say, in the connections. Then, as you also suggest, it could be a fault within the speaker, though again it could be something "simple" like a wire which needs to be reconnected, or something more difficult, such as a faulty voice coil, or a cone suspension issue.

You could presumably rule out the cable microphony possibility by swapping the cables over - though that might cause the problem to disappear simply because sometimes changing things "does that", without actually "curing" an underlying fault.

How much are the speakers worth to you? Are you very fond of them? How much are new equivalents?

I was once strongly recommended a speaker repair company - I think it was this one in Wembley - http://wembleyloudspeaker.com/
I did discuss problems with them, and I was quite surprised when they said they could completely remake the drive unit if I wanted (seemingly including rewinding the voice coiils), though they did suggest that I only sent the drive unit - and they told me how to get it out. I didn't actually bother, though I did obtain some "new" drivers second hand which I've still not got round to fitting.

If you really like the speakers, then it is probably worth exploring some form of repair option, or else look for the same models again, perhaps on eBay or ask for help on a hi-fi enthusiast web site - there are a few. I don't think that speakers that old should normally fail - some of mine are about 40 years old and still work.

I do like the speakers, which have been excellent up to now. Can you recommend me some hifi self-help websites I can check out?

Thanks. :)

[Conchis]

Slight update.

When removing the cover from the 'problem' speaker, I noticed that the plastic around the lower woofer was loose, not held on with adhesive like that one the other one. I think this might be what is causing the rattle. Could it just be a case of putting more adhesive round the rubber to secure the woofer? If so, what adhesive is advisable?

[soileduk]

http://www.mordaunt-short.com/

Have a word with the manufacturer. They should be able to help.

[Dave2002]

Slight update.

When removing the cover from the 'problem' speaker, I noticed that the plastic around the lower woofer was loose, not held on with adhesive like that one the other one. I think this might be what is causing the rattle. Could it just be a case of putting more adhesive round the rubber to secure the woofer? If so, what adhesive is advisable?

That could be causing the rattle I suppose, possibly for more than one reason. Firstly, the loose plastic may be vibrating. Secondly, it's possible that the seal into the cabinet has gone, allowing air to move round the speaker. This could upset the resonances and other factors, such as the suspension.

The suggestion to contact the manufacturer does make some sense. Assuming that adhesive might provide a solution, you may need to know whether it should be a hard setting one, or one with a bit of give.

Good luck with that.

[David-G]

I would support the idea of contacting the manufacturer. I once had a similar problem with one of my Spendor BC3s. I contacted Spendor, who suggested I bring the problem speaker down to them. They repaired it.

I have another thought, which I slightly hesitate to suggest... I once had a fault with an amplifier. I took the amplifier for a little drive of a few miles. When home again it worked fine. It's an easy thing to try...

Incidentally, the BC3s are now 44 years old and working as well as ever. I find the longevity of speakers quite amazing.

[Dave2002]

I have another thought, which I slightly hesitate to suggest... I once had a fault with an amplifier. I took the amplifier for a little drive of a few miles. When home again it worked fine. It's an easy thing to try...

A variant of a solution used by many engineers. If it doesn't work, hit it with something hard.

Rubber mallet first, I'd suggest, before reaching for the sledge hammer!

Also, shaking, and turning around and upside down sometimes works.

It might not have been the drive though, which fixed the amplifier. Perhaps unplugging all the connections and then plugging them back in was what really effected the cure.

Whatever.....

[Ferretfancy]

A variant of a solution used by many engineers. If it doesn't work, hit it with something hard.

Rubber mallet first, I'd suggest, before reaching for the sledge hammer!

Also, shaking, and turning around and upside down sometimes works.

It might not have been the drive though, which fixed the amplifier. Perhaps unplugging all the connections and then plugging them back in was what really effected the cure.

Whatever.....

When I first joined the Beeb I was sent to the old Camden Theatre as a back room operator on a live broadcast of Friday Night is Music Night, relieving an experienced operator in a change of shift. As he left, he pointed to one of the steel grey equipment bays, and said-- "If you go off air, kick it just there" I spent the whole evening staring at the spot petrified!