Preamp popping!


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?

 You should always turn the preamp on first and then the amp. You should turn them off in the reverse order. I leave my preamp on mute until everything including sources are turned on. 

I understand. But none the less.. If there's something faulty, I want to fix it. Ideas?
Also, the popping occurs independent of the volume control. Your comment on muting the pre made me think of that, so thanks!
It's been discussed here gazilion of times!
Preamp first once it came up COMPLETELY than and only THAN amp.
The LOUD pop will be regardless of regardless of the preamp or amp you're using UNLESS you follow procedure RIGHT WAY.
So, in a very indirect and too much coffe way you're saying that it's normal. There's nothing wrong.

I'm curious as to why it only is happening now... Ah, back to searching. 
If you’re saying that the popping has only started recently and you’ve been following the same turn-on sequence as before: Yes- It’s probably a tube issue. If it’s affecting both channels, check the rectifier. If only one channel, the signal tubes.  Those can be eliminated by swapping them from channel to channel and seeing if the pop follows the swap.
Does your pre-amp have a built in muting system that automatically engages on turn on? If so, perhaps it is failing. 
@newbee and @rodman99999 thank you.  that's the kind of input i was hoping for..

it turns out my 6V6 tube is starting to go.  i turned on the preamp and watched the tubes.  a huge arc shot from the top of the tube to the base.
i'm thinking that's not good.

so i put in the original junky one and will buy a new one.  odd, i had my pre serviced for a hum issue and since i've had it back this is the second of these tubes to go.  the tech gave me a new tube the first time it went.  this may point to a bigger issue.  or not.  i'm assuming the second until proven otherwise.

and thanks everyone, i've been on forums forever, i know how to search.. there was nothing i found specifically for my situation.  and guess what? now there is.  so the next time someone searches, this thread is another possible resource.  it's not like this forum is choked with traffic about whiners who have no idea how to basic troubleshoot.  i understand the startup procedure.  but some times i break the rules.  and when i had in the past there was never popping before.. 
i'm glad i found the source.
after service or tube(s) replacement, turn on preamp first. once it's completely up, you can turn on amp.

Ha! Thanks. I'm going to stick with the PROPER procedure for system turn on now. I've never seen a tube arc like that. Exciting!
Didn't see a reference to your power amp's make or bias system.  If possible, check your bias adjustment.   Personally, I can't think of a way for your pre to cause output tube failures.
Sorry, the 6v6 that died is on my preamp.

I have a class D power amp.. A Crown xls1500. 

@lowrider57 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..!
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?

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..
I agree with randy11, although I think the unit should be properly serviced to be sure.


Yet another member is using Crown XLS series! They are great and very clean sounding amps for super cheap!
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!
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.
@escritorjuan -  Don't know who gave you that advice(amp on first/off last), BUT-  Don't ever take any advice from them again!
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. 
@minorl right? I knew something was wrong because it didn’t pop like that normally and everyone is telling me I’m turning things on in the wrong order... I'm glad you caught that. I was wondering if I’d lost my ability to communicate

10-30 seconds was the kicker.... That and no tube preamp I have ever owned popped at start up.

2,875 posts
01-19-2017 2:23pm
@escritorjuan - Don’t know who gave you that advice(amp on first/off last), BUT- Don’t ever take any advice from them again!


I was borrowing my mentors mobile DJ rig and talking on the phone with him as I powered up his amp (the mixer/preamp and dual CD player were already on). A loud POP burst over the speakers. Needless to say, he was not happy! That’s when he gave me his advice.

Now, this was a powerful pro Crown amp. With that gear (and my DJ gear, with its 550 watt Crown PB-3 amp), this was the correct approach.

Its funny. I used to think the amp was before the preamp in the power up sequence during the entire 25+ years I owned my Adcom separates and never heard a pop or had any issues, not even a blown fuse. The first time I heard about the "correct" power up sequence was from reading it in this forum.
@toddverrone Thanks for confirming my suspicion! If I recall rightly the RCAs are the 6V6s to be looking for.
In my case, the advise to turn on the amp on first and off last came from a mobile DJ in regards to his pro audio gear.  I was working for him at the time and had turned on his Crown amp last, creating a big "POP"!  He was not happy. 

With my LampizatOr Lite 7 DAC (which acts like a preamp in my system, as I use a passive preamp), I was advised to turn it on first, and then the amp, etc.  


That's what I've mostly been doing lately: turn on pre, turn on amp, then the opposite for turn off: first the amps, then the pre.
I still think it’s funny, reading this thread again, how much I was shouted at in the beginning about not following the right power on/off sequence. It goes to show you how we often form an opinion before we’ve heard all the facts. And I speak from experience.. lots of experience. ;-)