Smoking speaker!!

For a while now my DPA Power amp has been making a loud buzzing sound when switched on. One speaker works and one is silent (when cd playing) apart from the buzz and a few pops. After about 5 mins the buzzing speaker emits a very loud bang/crack (best way I can describe it). Until tonight when I saw light smoke coming from behind the woofer. I turned everything off and tried again, same result. Is this an amp problem and have I trashed the speaker? Only had the speakers for a week! (2nd hand AVI Bigga trons). Any info would be helpful. Thanks, Steve.

 

Just wondering why you left the amp on if it was not playing sound from one speaker and the other was buzzing? I'd say its an amp issue and they speakers may well be fooked. Sorry.

 

Hopefully you've only damaged a crossover component in the speaker as a drive unit will probably be more expensive to replace.

The amp, however, sounds f*cked. Sounds like it's maybe outputting high dc voltage to the speaker through some fault?

Is it still in warranty?

 

Hi Tenson - the silent speaker (no music, only buzz), after the loud bang worked fine and all buzzing stopped. Other speaker had no buzz and worked.
Hi Andy - the amp is over 10 years old and DPA are no more! Pos a dead transformer? Any idea how to assess the damage to the speaker? Only way I can see to get in is removing the woofer. I've never done repairs before but looks like I'm about to start!
Thanks for the replies.

 

check for a short on the speaker cables .....as a starting point

 

Steve - which DPA is it? I can usually fix them (have 2 x 50S myself). It'll be a dead driver stage, probably caused by the bias controler failing, this causes the output stage to go to one rail. £30 worth of transistors, tops.

Unfortunately though your affected speaker will need a new driver though, sorry. The woofer's voice coil will have been toasted by the DC current the amps dumped into it!

 

Hi zanash, speaker cables seem ok, thanks for reply.

Felix - amps are 200S (pre and power). Would you be prepared to do the repair? Would be great if you could. Please email if you're interested with approx cost for everything. What would be the probability of this happening again after repair? Also, do you think the pre amp will be affected in any way?
Speaker - I've had a quick look around for parts/repairs but haven't found anywhere yet, any links or part numbers/prices?
Thanks for the info, Steve.

 

I guess its a good idea to try the speakers with another amp and see if they are even broken. If it was just a tiny bit of smoke something may have got het up but be alright.

 

It should be a straightforward subsitution of replacement parts, followed by re-bias and a run overnight watching the DC offset. I've PMed my contact details

 

Tenson - I tried the speaker with another amp and it didn't sound good! Thinking of taking it to Audio Excellence as I'd rather not post it, anyone have experience of them?
Thanks, Steve.

 

Give Colin a ring at Chevin Audio, he knows all about DPA gear and is very helpfull.

 

Thanks Muzzer but I've taken up an offer by Felix to fix the amp.