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Why does unplugging/replugging TT leads from tube phono pre-amp reset dead channel?

I have a BAT VK P-10SE with Superpak.  Tubed phono preamp.  When one of the channels drops out (it actually is out when the system powers up), I used to go nuts trying to figure out which tube needed replacing.  I have learned, after much frustration, that simply unplugging the lead from the Turntable - and plugging it back in - solves the problem.  Sometimes it's the left channel.  Sometimes the right.  And if I leave the system on with no music playing for a while, on occasion a channel will drop out.  I have asked at several stereo shops...no one know why this works.  Or what the real underlying cause of the problem is.  When it works...it sounds great.  No indication of a tube issue.  And the cartridge - Shelter 901 - sounds great, too.  Any advice is welcome.  Thanks.

Joe
jmfawdofile

Showing 5 responses by lewm

lewm
13,543 posts
 
None of the glitches you discovered leads to an easy explanation for what you experienced, in my opinion, but it's good that you found them.  And it's even better that you are now able to listen for longer periods without that aggravating problem, no matter what the cause.  I don't think that, because your unit was at BAT a year ago, we can rule out a cold solder joint that is intermittent.  If the unit functioned flawlessly at BAT on the workbench, they would never have had cause to look for such a problem.  And such problems can be near to invisible by inspection.  Sometimes you just have to bite the bullet and re-solder everything, in order to get rid of an intermittent solder fault.  (I don't suggest you need to do that, since you are doing fine as is.) Happy New Year.
lewm
13,543 posts
 
Or by the way, have you ever unscrewed the protective barrels of the male RCAs at the ends of the ICs, to see whether there is an intermittent or cold solder joint to the hot pin?
lewm
13,543 posts
 
You really don't need to upgrade the cable so much as you need to try a different pair of male RCA plugs at the ends of the cables coming from your Linn. If you have soldering skills, you can buy any pair of aftermarket male RCAs and do it yourself.  I recommend Cardas, for ease of use or WBT. (I am guessing that you have one continuous set of wires from the cartridge all the way to the phono stage, so it would be a big job to change out the wires.  If you are using a traditional pair of ICs with RCA connections at each end, then of course you need to attend to the connectors at the turntable end, as well. Or maybe the wires terminate in a DIN plug at the tonearm end.  DIN plugs can be maddening too.)
lewm
13,543 posts
 
Al, I did see that.  Perhaps the male pins in question are just thinner than most. Thus, they are not only a misfit for the BAT but also for the adaptors.  You could have a snug ground fitting and never know whether the hot pin is also snug, just due to the nature of an RCA connector.
lewm
13,543 posts
 
There is no explanation.
You have entered..... The Twilight Zone.

I am thinking of a mismatch between the male RCA plugs at the ends of the ICs coming from the Linn and the female RCA jacks on the BAT, such that the hot contact is intermittent. This can happen if the male RCA pin is not long enough quite to reach the contact point inside the female or the male is too thin in diameter. I apologize for the myriad of sexual connotations. 
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