2. amps-preamps
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"Crack" sound in left speaker tube amp

Hi everyone,
I'll try to be as precise as I can be, but I'm not a native english speaker.

First of all, here are the specs :
Power tube Amp - PrimaLuna Prologue Five
Tube Preamp - Shanling MC30
Scandyna "The Drop" Speaker + "The Ball" Subwoofer

Since a few weeks, I can hear a "craking" sound on my left speaker everytime I switch on the Power Amp. I know the problem comes from there because if I connect the speakers to the Shanling MC30 only, the problem doesn't appear.

What does it sound like ? Well, it's like if you unplug a jack from a switched on amp, you know ? This harsh sound that feels like something is tearing apart... When it happens, the speaker seems to shrink in, then out, following this noise, and the sound gets a little lower, mushy.

The noise often occurs some 5-10 minutes after the Power Amp is on, as if it came only after it had heated up. Then it happens every 5 seconds perhaps. And everytime it sounds really scary..

I've tried everything so far : I unplugged everything but it's still the same...

I don't know what to do, I didn't come accross anything like this on any forum. Is it a known issue ?

I hope someone here will have a magical answer ; I always receives great help from you guys !

All the best.
Franz
abalem

Showing 1 response by steveaustin

steveaustin
57 posts
 
Did you switch the tubes in the left channel with the right channel tubes to eliminate the possibility of the tubes being the problem?

I think a "crack" or "clack" -type sound can also indicate an A/C 'leak' within the amp, though I'm not sure if that would present itself in only one channel.

I had a Jolida 502A years ago that developed that exact problem - that same "clack!" followed by the volume-fading-out-then-fading-back-in phenomenon. I took it back to the dealer, and, of course, they couldn't get it to reproduce the problem there in the store (even leaving it on for days at a time). I really loved the sound of that Jolida otherwise (it was my first foray into the world of tubes), but had to get rid of it when I was unable to get to the bottom of what was causing that noise.
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