staticy low level noise on one channel of Clarinet

david62 · « **on:** 3 Apr 2010, 09:28 pm »

My Clarinet is a couple of months old and started having a very low level staticy hiss noise that comes and goes in the right channel.I pushed components with a dowel and wiggled wires but could not induce more static.I switched the 12aU7 tubes between their sockets,but the noise stayed in the same channel.I don't have two new tubes to switch out.I re-crimped all of the transformer wires,checked for ground loops with the chassis mounted RCA's,and disconnected the Russian Teflon bypass caps from the C303 positions.I reflowed the solder joints to the PC board connections to the RCA's for the output.The noise is there no matter where the selector switch is.Can anybody think of anything else to try before I take the whole PC board out and reflow the solder joints in that channel?Can it still be a tube even though I switched them between sockets?Thanks,
Dave

hotrod · « **Reply #1 on:** 3 Apr 2010, 10:21 pm »

David,
I could be wrong on this but switching the tubes the noisy half of the tube will still be in the same channel.I found the Clarinet to be more picky than the Cornet when it comes to noisy tubes.I can pull the noisy tube out of the Clarinet and put in in the Cornet where it is silent.
A noisy tube could very well be the problem,before you tear into the Clarinet again I would replace the tubes,could save you a large headach.As far as what tubes, maybe someone will chime in.I have little experience with new production tubes,your best bet would be to talk with Jim McShane,he's a very knowlegable tube seller and could point you in the right direction.
I've always had the best luck with 60's Amperex/Philips 12AU7's,most I have purchased have been very quiet,and I love their sonics.

http://pages.prodigy.net/jimmcshane/tubes.htm#order

david62 · « **Reply #2 on:** 4 Apr 2010, 02:03 am »

It certainly would be good news to me if it could be a tube.I plan to buy a couple of RCA clear tops and can try them.I wasn't too thrilled to tear back into it to say the least.If I do have to take the PC board out of the case,It would be nice to put some kind of pin connectors on the PC board that could make it easier to connect,and re-connect the wires to the chassis mounted RCA's since it is difficult access to make those solder connections.There must be some male/female small connectors...

soewhatman · « **Reply #3 on:** 4 Apr 2010, 02:49 am »

I'll second that the Clarinet is sensitive to tubes. I was getting quite a bit of hiss from mine and replaced the tubes yesterday with some of the new production JJ tubes. Back to dead silence for now. I had the original set in for about a year before they got really noisy (also JJ new production tubes).

Rick.

david62 · « **Reply #4 on:** 4 Apr 2010, 12:03 pm »

Rick,

Was the tube noise that you had staticy that would come and go?I'm currently running new production JJ tubes.
Dave

david62 · « **Reply #5 on:** 5 Apr 2010, 03:14 pm »

Any other suggestions would be appreciated!

soewhatman · « **Reply #6 on:** 5 Apr 2010, 03:32 pm »

The noise was staticy, and would occasionally pop. The static noise was pretty consistent, other than slowly growing in volume over the last couple of months.

Rick.

david62 · « **Reply #7 on:** 5 Apr 2010, 05:34 pm »

That is good news,because it opens up the possibility that it is a tube.I will hopefully have different tubes to try next week.
Dave

GBB · « **Reply #8 on:** 5 Apr 2010, 06:45 pm »

If it isn't the tubes then you should think about going into the unit and reflowing more of the solder joints. A "cold" solder joint can get noisy.
I had this happen in a tube power amp and it turned out that one of the solder connections that provided power to the input tubes had gotten noisy. That noise was coupling into the circuit and causing loud noises that would scare me to death. It took a long time to figure out the problem. I replaced quite a few parts before someone suggested that it could be a soldering issue.

---Gary

david62 · « **Reply #9 on:** 5 Apr 2010, 07:10 pm »

It still could be a solder joint.The noise is very soft and comes and goes.Hissy static is the best way that I can describe it.I was not able to induce it by pushing components with a dowel while listening.I almost thought that wiggling transformer wires increased it,but I could not be sure that I was causing it....

WGH · « **Reply #10 on:** 5 Apr 2010, 07:44 pm »

I had the same problem with a Cornet2, the noise started soft with the occasional pop. All the joints looked great so I re-flowed the connections around the tube sockets. I found the cold joint at a resistor one connection away from the tube socket.

Wayne

david62 · « **Reply #11 on:** 5 Apr 2010, 08:10 pm »

I still do suspect a solder joint.I bad tube would be too easy.The worst thing about taking the PC board out will be re-making te RCA

david62 · « **Reply #12 on:** 5 Apr 2010, 08:13 pm »

I still do suspect a solder joint.I bad tube would be too easy.The worst thing about taking the PC board out will be re-making the RCA connections.Has anybody used lugs or other connectors to make disconnecting and re-connecting the PCB any easier?

harryf · « **Reply #13 on:** 7 Apr 2010, 03:05 am »

I have always had a small hiss on my clarinet.I would bet a tube.I had a set of jj's that were so bad i had to pull them 5 min after start up.The same two tubes sound fine in everything else.
I also bought some eh tubes.The same but at lower level's in sound.
I would buy a good set of nos tubes and see if that fix's it or buy a known matched set from a big vendor like aes.
I wonder is the resistor change that was talked awhile back about might not fix it.
I would rather have some his than hum any day.I can turn mine up to 11 o'clock before it's too bad but a 12 o'clock i can hear the hiss at idel

david62 · « **Reply #14 on:** 7 Apr 2010, 12:22 pm »

I agree that a low level hiss is better than a hum problem.The Clarinet has been very good as far as hum goes.I am currently running JJ tubes and as soon as I get my hands on some NOS tubes to try I can see if the intermittent staticy hiss in one channel is a tube before I take the board out and re-heat solder joints. The worst part of taking the board out will be re-doing the PCB wire connections to the chassis mounted RCA's,I hopefully it's a tube!
Dave

Bill Epstein · « **Reply #15 on:** 7 Apr 2010, 10:33 pm »

Bite the bullet, fix the board. You'll get good at re-wiring the RCAs.

Noise in one channel eliminates the power supply until after it branches to the tubes. Check the schematic, is it R14? Then re-flow all the board holes on the right channel. See if you can't wiggle a resistor or cap lead in it's hole as you go. Don't make blobs. If there ia already a blob of solder on the hole, wick or suck it out, then re-solder. Noise loves to hide in blobs.

The Clarinet with the new resistor spec is a phantom at full volume; hiss, hum or crackle don't live there. I'm re-building my Aikido in a new case. The work is going slow because after every listening session with the Clarinet and my re-tipped Clearaudio, I ask myself why I'm bothering.

david62 · « **Reply #16 on:** 8 Apr 2010, 01:18 am »

Bill,

I will most likely have to re-heat the solder joints in the right channel.I tried the wiggle test with a dowel while listening with head phones,but could not induce any noise above the random.I switched the 12au7 tubes between the sockets and the noise stayed in the rt.channel,but I was told that it could still be a tube.I used silver thin wires to the RCA's and it is easily fractured at the board /solder joint moving it,so perhaps I should use another type of wire.
Dave

poty · « **Reply #17 on:** 8 Apr 2010, 07:51 am »

Switching the tubes couldn't eliminate noise (as soon as each halves stays in the same channel), but if the problem is only with one tube it SHOULD change someting in its (noise) structure (volume, tone and so on). So if the switching brought nope in the noise it can't be tubes' fault. If you feel good with safe practice you can make a simple adapter from a spare tube soket and some wires and switch halves of your existing tube to check whether the problem is in it or not.
Looking at the wires layout I suspect problems with proper grounding (maybe soldering too, but I do not believe in that bogeyman of DIY).

david62 · « **Reply #18 on:** 8 Apr 2010, 02:05 pm »

As soon as I can make the time,I will be re-heating solder joints.I used Cardas solder and lightly scraped the leads and lugs of all components to be soldered,I even lightly scraped the PCB where the joints were to go.It's possible that I didn't heat a joint enough some place.Thanks for all of the advice.
Dave

harryf · « **Reply #19 on:** 8 Apr 2010, 05:07 pm »

I also used thin silver wire to wire up my rca's.I always wondered if that might be part of my hiss problem.I don't know if that info might help.I do think if you pulled a tube and swaped them then you don't have a tube problem.I myself use a few different soldering iron's.When i want to reheat a joint i use my 80 watt one.If it's hot just a quick touch does the trick.My 25 watt one sometimes takes awhile and need's to have sloder added to flow.
I do agree suck any excess solder out.No blob's.
I also wonder about those caps.They are quite large do they touch?Probably not the problem but i would want then not touching another cap.If i could.