2. amps-preamps
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Preamp popping!

Salutations! 

I have a problem and was hoping to use our collective experience to solve it..

My preamp (dared mc-7p) produces a VERY loud pop through the speakers approximately 10-30 seconds after I power it up. I'm now concerned about blowing a tweeter. I can even see the 12" woofers move.

Obviously I can just turn the dared on first, then turn the amp on after a minute or so. But that's just hiding the problem. I'd like to solve it..

Ideas? I've tried nothing yet. My first inking is to try replacing tubes.. Good idea? If so, shall I start with the power or signal tubes? Again, my inkling is to start with power.

Assuming that doesn't work.. What else could it be? Some kind of capacitor gone bad?
toddverrone
lowrider57's avatar
lowrider57
5,418 posts
 
this pop was louder than the normal, quiet pop. This was super loud and did not sound 'healthy'. It turned out to be one of the power tubes on my preamp. When I turned the pre on, I actually saw a huge arc from the top of the tube to the bottom..!

OK, got it.  When tube was replaced did it return to normal operation?







toddverrone's avatar
toddverrone OP
840 posts
 
So far, yes. So, while I really should follow the rules, it's good I turned everything on at once. Otherwise I'd never have heard the popping and never would have noticed the tube getting ready to explode. 

What's odd is that it started popping a few months ago, but then stopped. I guess that's how these things go..
nutty
3,091 posts
 
I agree with randy11, although I think the unit should be properly serviced to be sure.

N

czarivey
5,946 posts
 
Yet another member is using Crown XLS series! They are great and very clean sounding amps for super cheap!
atmasphere's avatar
atmasphere
12,176 posts
 
You got it sorted- good work!

My recommendation, if not already offered, is to look for an NOS 6V6 on eBay or the like, made by RCA, Sylvania or the like, for use in this preamp.

A 6V6 arcing as you describe is a bit unusual but does suggest to me that it might have a construction problem, one that I've seen in modern-era tubes (being either Russian or Chinese). An older tube I suspect is far less likely to do something like this, even as it ages and eventually dies.

Happy Listening!
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