2. amps-preamps
  3. 155723-118910

all tube phono preamp creating a crackling, fire-like sound

Hello
I just purchased an all tube phono preamp from an Audiogon seller. the preamp uses the following tubes:
5u4gb, Ob2, 6v6, and 5 12ax7. My problem is that one channel sounds totally awesome but the other channel is unlistenable with a crackling, fire like sound which a friend of mine said sounds like frying bacon. I have changed all of the tubes except for the 0b2. I have also tried a multitude of various interconnect cables, none of this has made any difference. The sound will go away for a couple of seconds and then it comes back, it also comes in waves, starting off low and then getting louder. I also ruled out it being a speaker problem by switching  speakers and their channel. 
Does anybody out there have any experience with an issue like this, and if so, what was the problem and how did you resolve it? I love this unit and I'm about to send it back the manufacturer, where hopefully the problem will be resolved.
thank you
dpoud
10 responses Add your response
jetter
3,033 posts
 
If you have a new tube try it.

If you do not have a new tube very gently nudge the top of the suspect tube gently just a millimeter or two, barely moving it carefully with the eraser end of a pencil. I have had the exact situation you are describing and just nudging the tube a millimeter or so "seated" it properly. I still have the preamp and it works perfectly.  If you do not do this as gently as I mention please know I warned you as you can cause further damage to the unit.

If the two suggestions above do not work I would follow ebm's good advice ASAP.
atmasphere's avatar
atmasphere
11,793 posts
 
@dpoud

Given this is a phono preamp, its running through a line stage or may be driving the amplifier directly.


Either way, did you swap the interconnects at the output of the phono section left for right? If no, you need to do that, if yes, what happened?
ebm
9,311 posts
 
You got ripped off get your money back as unit has bad capacitors or resistors or both.
br3098
994 posts
 
Sounds like a tube is going t*ts up. Do you have access to a good tube tester?

pops
2,273 posts
 
That is exactly what a tube sounds like as it begins to crap out.  It can last a long time like that but eventually it will wear out and quit.
Ag insider logo xs@2x
dudleyy
1 posts
 
I had the same problem that you reference in your post.  I went through a process of elimination that felt like eternity.  It turned out that there was a bad tube.  Double check your tubes....  Good luck!
yogiboy's avatar
yogiboy
5,656 posts
 
Return it to the seller and get a refund!
roberjerman
4,319 posts
 
Bad interstage coupling cap. Send unit back for repair!
superwhite50's avatar
superwhite50
6 posts
 
That sizzling sound is something Ive heard many times I was using a Schitt Freya and had to replace tubes often I was paying extra for the higher rated hand picked tubes and still the sound would return .Ill say one thing you get what you pay for .I recently got fed up and spent some cash for a Mcintosh c2600  Absolutely night and day My system is a Mcintosh 452 into a C2600 wilson sophia 3 speakers audioquest water xlr and a Mcintosh sacd player I have also just purchased a Pro-ject rpm 5 carbon turntable .Im in NYC so we are under a super quarantine right now .I have no regrets on my setup and now have plenty of time to sit and listen.Spend as much as you can afford to on components.Your ears will thank you .I often purchase used on this site.
rsf507
2,313 posts
 
Did you change interconnects, L to R and does crackling sound stay in bad channel or more to other side? Because it's only one side probably not but try grounding to different items in system or leave completely ungrounded.
What all tubed phono unit is it?
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