1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Amp fries speakers - WHY??

Discussion in 'Amps and Cabs [BG]' started by lotusland9663, Jul 25, 2012.

  1. lotusland9663

    lotusland9663 Supporting Member

    Oct 15, 2009
    Vancouver BC Canada
    I connected my Ampeg SVT Pro 3 amp to my EA NL210 cab last night at rehearsal. I've been having trouble with this amp and thought I'd finally found somebody who had fixed it. The latest amp tech replaced the Tube Gain pot and things seemed to be OK.

    At rehearsal it played fine for a minute or two then there was a slight crackle and the output dropped a lot - then nothing. When I swapped in another amp there was no sound either- (that amp is works fine).

    I took my cab to a local speaker tech and he said the amp had delivered direct current to the speakers and totally destroyed them. They were stiff as a board and everything has to be replaced.

    Any thoughts as to what happened? Is the amp tech responsible for this? Thanks in advance
  2. Hard one to call. I always check for DC offset when a SS amp comes in and again when the amp leaves but I was taught that way. It was part of the shop check list as the owner bought 8 10" for one customer, he had no idea if the amp left the shop that way and customer service was job 1.
    Have no idea if the amp left the tech with high DC offset or if it was a new problem?
  3. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Can happen. For some reason, the 3PRO does NOT have the DC detector that all the other units do, which opens the relay if any DC is on the output.

    Have the technician check the amp for DC, checking especially the circuit that is supposed to drive the DC to zero (an op-amp connected to the output).

    A final check of the plus and minus 15V power supply should take care of the issues.

Share This Page