Blue flash from speaker and all kaput..Help!!

[gisgillen]

I am feeling terrible. I wrote a few days ago asking if the B&W XT4 speakers would work with my 80 watts RMS per channel receiver. I got a good reply from `The Master´ who said `they could work well´ but suggested some more powerful amplifiers. Tonight I went for a listen at the sellers house...luckily not too far away...loved `em, and to my delight he suggested I take them home for a listen. Worked really well. Then after about two hours and listening at a high volume to the end of the Firebird Suite there was a sudden blue flash from the right speaker and the sound just stopped? Now my old speakers which I plugged back in don`t work either so I suppose it must be the amplifier...or what? I am not a technical person. Have I done something wrong? Used wrong leads or something...my leads are pretty simple and were (are!) connected to my old B&W speakers which are from the 70`s. As I say, for two hours just perfect..and not loud the whole time, a variety of stuff, then this. I feel absolutely terrible as the speakers are as it were on trial. What now??? Many thanks. I certainly wont sleep tonight.

 

[Al ears]

I am feeling terrible. I wrote a few days ago asking if the B&W XT4 speakers would work with my 80 watts RMS per channel receiver. I got a good reply from `The Master´ who said `they could work well´ but suggested some more powerful amplifiers. Tonight I went for a listen at the sellers house...luckily not too far away...loved `em, and to my delight he suggested I take them home for a listen. Worked really well. Then after about two hours and listening at a high volume to the end of the Firebird Suite there was a sudden blue flash from the right speaker and the sound just stopped? Now my old speakers which I plugged back in don`t work either so I suppose it must be the amplifier...or what? I am not a technical person. Have I done something wrong? Used wrong leads or something...my leads are pretty simple and were (are!) connected to my old B&W speakers which are from the 70`s. As I say, for two hours just perfect..and not loud the whole time, a variety of stuff, then this. I feel absolutely terrible as the speakers are as it were on trial. What now??? Many thanks. I certainly wont sleep tonight.

Curious. Your receiver is 105 wpc by the way. However those speakers should handle up to 150 watts.

 

[Vladimir]

Sounds like the amp blew the fuses on the outputs. Best to have a professional check it up.

 

[gisgillen]

Referring to yesterdays `blue flash´ problem. Vladimir suggested maybe the amp had blown a fuse. The situation now is, I just woke, (couldn`t sleep) my old speakers are connected but no sound. However the amplifier works normally using headphones. And what was the blue flash which came from the bottom of the speaker? I am so worried as as yet I haven`t bought them. Are the speakers broken?? Many thanks

 

[MajorFubar]

You need to try the borrowed speakers with a different amp to rule-out whether they've been damaged or not. I'm with Vlad, sounds like your own amp has blown the output fuses. If you really have fried the speakers, expect the seller to make you pay for them. Sorry. Big blue flashes are never a good sign. Good ;uck.

 

[the_master66]

Hi Gisgillen,

Not good.....sorry I suggested giving them a go...

This sounds like a component failed in the crossover of the XT4 and caused a short which has blown the protection fuses in the amp - the input terminals in the XT4 are low down which means it's likely that the crossover is low down too (hence the blue flash from speaker an amp at high volumes will be pushing a fair amount of current)

This is all likely to be repairable - speaker crossovers are not usually very complicated and it'll probably be pretty obvoius what component has failed, the amp will need a professional eye over it.......but hopefully be an easy repair.

You can only be honest with the speaker seller and write it off as a unfortunate incidient.....each owner fixing their own faults.

Thanks

The_Master66

 

[The_Lhc]

B and I are your friend...

Referring to yesterdays `blue flash´ problem. Vladimir suggested maybe the amp had blown a fuse. The situation now is, I just woke, (couldn`t sleep) my old speakers are connected but no sound. However the amplifier works normally using headphones.

Yes it would do, the output fuses cover the amplifier stages, the headphone output is taken BEFORE the amp stage, so it won't be affected. It's not a particularly big deal, these fuses are designed to be replaceable, I blew the fuses on my amp not long after I got it (sent the dust cap on one of the surround speakers flying across the room!), sent it back under warranty, Sony fixed it and I've been using it every day ever since, that was 15 years ago!

 

[gisgillen]

Thank you all for your suggestions. I will try the XT4`s later today with a different amp. I am praying they are ok. It is obvious the amplifier has broken (blown fuse probably) but hopefully not an expensive repair. I asked today the opinion of a local B&W dealer who thinks the speakers will be ok, but this blue flash does scare me! He looked up my amp (the Denon DRA-700AE), and said that maybe the power is not enough for these complex designs, so if played with the ampflifier at too high a volume this is what can happen. Does this mean if I get everything repaired I would always have to worry about the same thing happening again??? Therefore would it be wise if the speakers are ok to return them to the owner? (and think of an alternative) Who by the way was a lovely older chap, it was his idea for me to bring them home to try and he said `if you don`t like them then just return them´!! Amazing. But obviously if they are broken I cannot do that. So does it really mean 80 watts RMS per channel is too little if I want to listen loud? And a much more powerful amplifier would be needed. Many, many thanks to you all. I will let you know if they are still ok.

 

[the_master66]

Hi Gisgillen,

Be very careful using a different amp as there may be a fault in the speakers which may damage the other amplifier, I don't think the B&W dealer is correct as the blue flash was from the speakers - if the speaker design was too much for the amp to drive it just wouldn't get the best out of the speakers they would work OK, if the XT4 was extremely difficult to drive (which i doubt) the amp would probably got too hot and shutdown gracefully....this sounds much more like a short which usually manifests itself dramatically - are you sure that a stray wire didn't touch + to - on the back of the speakers - best to carefully check?

Thanks

The_Master

 

[gisgillen]

Thank you `master66´ for your speedy reply. I have unti Friday. What would you suggest? I don`t believe there was a stray wire. How do I check if the speaker then is faulty or not if I don`t try with another amplifier? What is my best bet????? And obviously if it is faulty I will have to buy. I feel really bad.

 

[MajorFubar]

The Master makes a very fair point. You need to test the binding posts on the speakers with a multimeter to check there isn't a short in the xover, otherwise all you'll do is fry the other amp. The problem is, the fact you're posting here to start with, I'm making a shrewd guess you don't have one.

The fault could easily have been with the speakers to start with, but seeing they were given to you in working condition it's a sticky wicket unfortunately. Good luck.

 

[the_master66]

MajorFubar is correct - you will at some point need to to test the speakes with an amp, I was warning you just in case you used another prized amp - I have an old beat up Rotel amp covered in scratches and with knobs missing for this kind of thing, it has no real value and if it died during testing it wouldn't really matter....if you can't borrow an amp take a look in a cash converters or similar for an amp/receiver that was cosmetically rough but working and bid them down on it.......they'll probably be glad to get rid of it......anything will do to confirm speaker operation...

 

[gisgillen]

Thank you again Major Fubar and Master 66 for your latest replies. Seems there is no problem with the speakers...I am rather relieved!! My friend had an old Luxman LV-113 (65 watts RMS per channel) and despite telling him of the warning by you Master 66 he was happy to try. At first one speaker was dead but after a bit of research he discovered why. In connecting the cable to the speakers he wrapped it round not realising there was a hole in which to thread it through. And I have to admit I connected in this manner too, (didn`t realise) so could this have been the cause in some way? Anyway he also had some sort of tester (maybe a multimeter?) which when connected showed only zeros (when settled) on the first speaker, then the same on the second, which means the power is getting through or something (I`m out of my depth here). I was very relieved. I have now decided to keep the speakers as I had two very pleasurable hours listening last night, and it was only at the very end when I really wacked up the volume when the problem came. Presumably if one day I do get a better amplifier, more powerful, then they would be fine at this volume, they did sound good. Now I am happy if my Denon can be fixed (I get the impression from all my replies that it should not be a problem) and I can begining to listen to all my CD`s and LP`s. Many many thanks to you all for your expert help and advice, I am really chuffed.

 

[philpot1001]

general rule of thumb is not to take the amp passed 12 o'clock, maybe 1 o'clock position on the volume dial to avoid it clipping and distorting. If you need to go much passed that point i would suggest you need a more powerful amp.

 

[MajorFubar]

Well at least your conscience is clear which is good news. If you didn't wire them properly it's quite possible a stray strand caused a short and blew something in your amp.

 

[gisgillen]

Thank you philpot1001. So as a rule the amplifier not past the twelve or one o`clock position. My Denon is not like that, and anyway I use the remote. The dial on the amplifier goes round and round but the db level shows. On this model it goes from minus 70db (no sound!) to plus 10db. What would in your opinion be the maximum recommended level to avoid clipping and distorting? I think I`m usually in the minus 40`s or 30`s, but sometimes with my old B&W`s (70`s) even to almost zero with no problems. Thank you. I know these XT4`s are rather complex (apparently!).

 

[gisgillen]

Thanks again MajorFubar for all your input. Do you think my miswiring was what caused the blue flash? This flash still puzzles me as the speakers are ok? Anyway tomorrow I will buy them and spend a few days waiting for my amplifier to be repaired...painful!!! Hopefully it can be! Many thanks.

 

[philpot1001]

Thank you philpot1001. So as a rule the amplifier not past the twelve or one o`clock position. My Denon is not like that, and anyway I use the remote. The dial on the amplifier goes round and round but the db level shows. On this model it goes from minus 70db (no sound!) to plus 10db. What would in your opinion be the maximum recommended level to avoid clipping and distorting? I think I`m usually in the minus 40`s or 30`s, but sometimes with my old B&W`s (70`s) even to almost zero with no problems. Thank you. I know these XT4`s are rather complex (apparently!).

hmmm, this is a tricky one, ive not got any experience with this kind of set up, however it seems to me going to 0db, is probably pushing the amp. I know that db scale is exponential, so going to half the range will not equal half the power output, my guess would be -10db would be a safer limit - but thats purely an estimate- someone more educated on the matter here may be able to guide you.

 

[gisgillen]

First, thanks for all the help you`ve all given, fantastic. My XT4`s are ok and I `m now waiting for my Denon receiver to be repaired....the waiting is awful! In the meantime I have been looking at more amps and receivers. Having just forked out 1050 euros for the speakers (asking price 1200) I cannot afford one of these rather expensive amplifiers that have been suggested...Naim Supernait, Exposure3010s2 or Roksan Caspian..for example. I have found a new receiver which on paper looks ok for me...the Cambridge Audio Topaz SR20 which has a `class leading output of 100 watts per channel´....does that mean 100 watts RMS per channel? So would this be better than the Denon (DRA 700AE 80 watts RMS per channel) and a good match for the Bowers and Wilkins XT4`s. PS just noticed too a Cambridge Audio Azur 840A v2 second hand for 650 euros. The new Topaz would be 499 euros.