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What is DC offset and why did I blow my speakers

So I have a Krell integrated and typically play CD's with out problem. I added a turntable and a BAT tubed phono stage and it sounds great for about five minutes, then my sound starts to drop off and two minutes later I've got two blown woofers. I talk to a few people who say that I probably had a DC offset problem and to check the DC voltage at the output capcitors on the phono stage.

In laymen's terms (not an expert here), can someone describe to me what might have happened and what a DC offset is, how it is corrected, etc. I don't want to go through another set of speakers.

And what else might have caused something like this. I replaced the speakers and back to just the CD now without any problems. I really want to get this phono back up and running so what should I do next.

Thanks in advance!
jspownell
sean
6,229 posts
 
My thoughts are that the phono stage either has a DC offset problem and / or you were pumping a ton of subsonic info into a vented speaker. This can cause excessive woofer excursion, resulting in their demise. If you're speakers are vented and you want to play vinyl, i would HIGHLY suggest using a subsonic filter. Record warps can produce GOBS of energy, especially if the arm / cartridge are not properly set-up / matched. Other than that, you may have to send your phono section back to the manufacturer for an inspection.

Outside of the problems at hand, it sure seems like BAT gear is mentioned in more than a few threads of this nature. It makes me wonder how good QA is over there ?? Sean
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ivanj
640 posts
 
How close is the turntable to the speakers? Probaly have it in between the speakers? What kind of TT and cartridge is it? What kind of speakers are they?
jspownell OP
4 posts
 
The turntable was in between the speakers with approximately three feet on both sides. They were good quality bookshelf speakers running from an Aries with a Clear Audio Sigma Wood.
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