2. amps-preamps
  3. 127980-84541

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?
128x128toddverrone
czarivey
5,740 posts
 
Yet another member is using Crown XLS series! They are great and very clean sounding amps for super cheap!
atmasphere's avatar
atmasphere
11,633 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!
escritorjuan's avatar
escritorjuan
120 posts
 
I guess the sequencing depends on the equipment you have.  When I was a mobile DJ, I was told to "always, always, always" turn the amp on first before anything else and, when I'm powering down, turn it off last.  

But, with my LampizatOr Lite 7 DAC, it's the amp first, then the DAC for the same stated reason -- powering it up with the amp turned on can create a possibly damaging popping noise.  

My guess is that your preamp would fall into the similar sequence as my DAC.
rodman99999
6,032 posts
 
@escritorjuan -  Don't know who gave you that advice(amp on first/off last), BUT-  Don't ever take any advice from them again!
minorl
1,015 posts
 
The advice to turn the pre on first is sound. However, many new pre amps like Audio Research have an auto mute feature. It allows the ore to stabilize first. It also forces the owner to physically inmate the pre before using it. 

Its is funny to to see that the initially responded ignored the OP's concerns regarding if a real problem exist.

amps on last. But, if a real problem exist with the pre, it may still have D.C. On the output when you turn the amp on. So in general if all things are working correctly amp on last, pre on first is sound, but if the pre is faulty, it would not have mattered. 
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