Re-tension Your Tube Sockets, Resolder Output Sockets

The main symptom is noise–crackling, static, pops, or hum when you wiggle the tubes. The noise is independent of the volume and tone controls. The spring contacts in tube sockets lose tension over time, and the solder joints can crack from expansion and contraction.

This is a particular problem with the output tubes because they run so hot. The heat conducted through the pins is enough to anneal the contacts, so they lose their grip. It occasionally happens to the other tubes, but less frequently. The output tube sockets are also prone to cracked solder joints because of the continual heating and cooling, expansion and contraction.To fix cracked solder joints, just reheat them with a soldering iron and apply a small amount of fresh solder. Take care not to melt the ribbon cables.

Re-tensioning tube sockets is easy. Make sure that the amp is discharged. If you turn it off while the tubes are warm enough so you can play through it, the amp will self-discharge through the tubes. See Removing the Circuit Board for more information.


You’ll need a small jeweler’s screwdriver, typically the smallest that comes in a set. Here you can see the size relative to the tube socket. The socket has a pair of springs in each position. The top of each spring is flared to guide the pin into the socket.


To re-tension the socket, gently insert the screwdriver between the socket wall and one of the springs. It doesn’t matter which spring, but one may have more room than the other. Choose the easiest one. Insert the blade far enough so that the tip is below the flare. Give the screwdriver a small twist, about 1/8 turn. This will bend the body of the spring inwards so it gets a better grip on the tube pin. You want to bend the portion below the flare, not the flare. Bending the flare will not help the tension and will make it difficult to insert the tube later.

You should probably clean the socket and tube pins at the same time. Use a nonlubricating contact cleaner such as DeoxIT 5. Do not use “tuner lube” or a lubricating contact cleaner. The oily residue will oxidize from the heat and cause poor contact. To clean the sockets, just spray the tube pins and insert/remove the tube a few times.

Cracked Solder Joints

The constant heating and cooling, expansion and contraction can also cause cracked solder joints on the output tube sockets. Reseating the tubes might have pushed the cracked areas together, but the expansion and contraction might have loosened them up again. The solution is to resolder the sockets, but be careful. Apply only as much heat as you need and a tiny amount of fresh solder to help things flow.

Don’t overheat the “dots,” the solder pads with no trace. Otherwise, they’ll lift and you’ll lose a bit of the support on the socket. Approach the other pads from the trace side, with most of the heat on the pin, so you don’t lift the pad.

Don’t melt the ribbon cables!

Don’t overheat the “dots,” the solder pads with no trace. Otherwise, they’ll lift and you’ll lose a bit of the support on the socket. Approach the other pads from the trace side, with most of the heat on the pin, so you don’t lift the pad.

Don’t melt the ribbon cables!


  1. Avent Lane says:

    Great Website and really appreciate the dissemination of great (and correct) infomation. (I know I know, buy something aready!!!!!!;) Believe me I will………..Oh if I might suggest adding info to the “retensioning of tube socket is to also check the solder joints in the pcb to the sockets for cracks, “cold solder joints”. I’ve repaired a couple of these amps with this problem by reheating and adding more solder for better mechanical strenght. People like to “wiggle” the tubes to get a better connection and sometimes are little too robust in their excercise and contribute to a failure of the connection…………You gotta love that DeoxIT, best tool in my kit.

  2. Jonny Orange says:

    Thanks for all your info Bill! My BJ was making some awful noise and cooking one of my power tubes. I re-tensioned the socket and everything works great! you save me a ton of money.

  3. Paul says:

    I’m about to purchase a BJ with your mods already done. It does have the black sockets which I understand can be problematic. Antique Electronics Supply has some ceramic sockets that will probably work. If you were swapping out sockets, which would you recommend?

  4. S. Riley says:

    Bill, I hear a rattle coming from the 12AX7 tubes when the tone is thick with low-mids and bass. It is more of a physical rattle rather than an electrical hum/hiss. It’s very annoying when recording. If I touch the tubes, the rattle subsides. Could this still be a socket issue in that the tube isn’t held firmly and is vibrating? Or could it be the tube guts vibrating?

    • bill says:

      That’s filament rattle or a loose grid. Your speaker is vibrating the tube; it’s a common failure for tubes in combo amps. You might be able to overcome it for a while with some silicone O-rings to damp the tube, but ultimately, you’ll have to replace it.

  5. Jeff says:

    I am having the problem mentioned above. I have a Marshall jcm 900 running Groovetubes and the socket is loose. It runs about 10 minutes and goes quiet. If I press down the sound goes up again so I know its a loose socket. My question is should I re-tension the socket while it is “warm”. I see you should do this after the amp discharges, so I’m wondering if thats what you mean. Basically work on it while its warm?
    Thanks and great forum.


    • bill says:

      Your problem may be bad solder joints on the sockets, not loose springs in the socket.

      To discharge the amp, just turn it off after you’ve been playing it. Leave the standby in “play” position and the amp will discharge itself. Unplug it. After that, you can work on it warm or cold.

  6. Glenn says:

    Hi Bill. Just finishing up my mods, retentioning my tube sockets and inspecting solder joints. Sure enough V5 had a number of loose connections so I resoldered them. BUT… I noticed the pad of pin 6 raised from the board when the solder melted and figured I’d have to fix this one. Upon inspection it seems that pin 6 does not have a trace connected to it? I’ve been looking at Schematics on line but have not found a lay-out to check for use of this pin. V4 looks the same. Am I correct that it is not in use and I’m good to go? Thanks for all your help.

  7. Rob Weathers says:

    Hey Bill,

    I ordered the basic kit and T020 last week. I can’t wait for them to arrive. I put in a nice set of NOS Sylvania JAN power tubes dated 1970 (green ink/ gray plate), for the 6BQ5 outputs and NOS Sylvania 12AX7 pre-amp tubes dated 1961,(green ink/ gray plate), the other night in anticipation of the mods and transformer. I turned on the amp and …nothing. One of the 12AX7s felt really loose. Did a little reading on this website, re-tensioned all 5 sockets and voila, I’m back in business. Thank you so much for the tips! You taught me something and saved me some money. Thank you!

    I noticed that I can get pc board-mountable 9 pin sockets in ceramic on the web. Is there any value to this if one of the sockets eventually fails? The plastic base subjected to all of that heat has to be problematic over time. Also, they have octals in pc board-mountable ceramic as well. Can these be soldered into the tube board if you clearance the chassis metal instead of your new wires to board approach? Reason being that I think I would like to try 6V6s at some point. Thanks in advance.

    Best regards,
    Rob Weathers

    • bill says:

      I really don’t know if the socket springs in the ceramic sockets are any better than the standard sockets. And some of the ceramic sockets don’t allow you to reach in with a screwdriver to retension the springs.

  8. John says:


    Tip: if you remove the chassis completely, take the tubes out first! As the last bottom chassis screw comes out, the speaker magnet grabs the chassis and slams the tubes against the speaker, if you’re lucky, as I was, just bending the pins and loosening the tube sockets. All OK now!

    Another thing to look for with snap crackle and pop (and hum) is those pesky springs that hold on the aluminum heat sink/retainer for the power tubes. When I first bought the amp it hummed like crazy. There was a nice purple glow between one of the springs and the wall of the tube it was touching (couldn’t really tell if the glow was inside or outside the tube). Replaced the output tubes and ‘dressed’ the spring, and now all is well, even with fat-bottle EH tubes.

  9. Kurt says:

    Hi Bill,

    fantastic site with lots of useful info! Got a BJr myself now. I read all your posts to shorten the time until it arrived. 🙂

    It was pretty obvious for me to do at least the bias mod. Everything worked well, no copper traces harmed.

    I set the bias to about 80%. Still, the tubes get very hot. I measured the temperature and both are about 160°C – which is about 320°F – after having played for about an hour at a very moderate volume.

    You wrote in one of your articles that you measured the temperature by yourself before and after a bias mod. What is the expected temperature on the EL84s? I couldn’t find any info on that on the internets.

    Thanks a lot!

  10. Wil says:

    My BJ is making annoying noises… I already post something somewhere (accurate description !) on your site concerning it. I finally found what it is ! It’s the two EL84 ! When I tap them, they’re making some “spring noises”, so when I play mainly lows or at high volume, you hear it quite distinctively ! I can put the EL84s on every socket (even on the 12AX7 sockets), they’re always making that annoying buzz. The 12AX7 don’t, even on the EL84s’ sockets. I re-tension everything but I tend to think it’s the EL84s themselves. As they go easier than the 12AX7 in the sockets, there might be some looseness (is that the right word ?). So I order some JJ EL84, i’ll report if it works !
    Post-scriptum : My current tubes are stock GT EL84

    • bill says:


      You will burn a resistor in the power supply at the very least. You may also get arcing that destroys the circuit board


      You are hearing filament rattle. Get new EL84s.

      Update: He emailed to say that he hadn’t turned on the power, that he was testing the rattle relative to the tightness of the sockets. Whew!

      • Wil says:

        Put some new JJ’s in my Bj, still making this annoying noise !! I don’t understand… These tubes don’t make noise when I tap them, but when I play, it’s like the stock Groove Tubes. Maybe the sockets are guilty…

  11. Jasonblanchard says:

    I just recently purchased a used BJr and love it, but I’ve noticed a couple of troublesome things about it. At first I noticed a sweet type of burning aroma while playing. I put the guitar down to quench my thirst and noticed a power tube EL84 in an orange glow! It released itself and pretty much went back to normal, I suppose. The other thing I noticed was while in use after some time the brightness/sharpness becomes muddied with saturating distortion. It seems to be a gradual progression. The smell is no longer evident. I plan to change the tubes, install a standby switch, and do the basic mods in the future. I greatly appreciate your insight. Oh, I was looking at a matched set of Electro Harmonix EL84s and was given the option of Hard, Medium, and Soft. Can you help me narrow my choice down? Thanks for your time.

    • bill says:

      One of the EL84s was glowing orange because it lost bias voltage, which caused it to overheat. The amp was running on one output tube. The loss of bias voltage was caused by a weak spring in the tube socket, a cracked solder joint on the socket, or oxidation or corrosion on the tube pins… or all three.

      Here is the fix:

      The tone is probably degrading because of the above issues. I would resolder both output tube sockets, retension them, and clean the pins. And it’s probably time for fresh EL84s.

      I’d go for the medium tubes.

  12. livingwater says:

    My 2011 blues Jr3 has a (tube stabalizer) metal bracket with two springs holding the output tubes in place.
    Is there a better mouse trap for this?

  13. Jasonblanchard says:

    Cool, I’m on the right track. Soon after I sent the email I did just that; of course, after reading the wealth of information concerning the Blues Jr. in your site. Last time I played in a group setting I used an attenuator/pre amp booster to get a little more clean headroom out of the amp, but I still felt it pushing. I just ordered a matched set of EL84’s and a 12AY7 for V1 {Electro Harmonix} from Tube Depot to squeeze out the best sound possible thus far, but waiting on those to come in. These are really temporary solutions until I can start modding it up. Taking care of some ground work first.

    Thanks for your help

  14. Bill T says:

    Great article! I was experiencing some static, buzzing and signal dropouts with a cream board BJr, this was happening before I did any of your mods. I recently re-tubed my Tweed green board (which is a tone monster thanks to your modification kits!) and I decided to see if I could figure out where the noise in the cream board was coming from. One EL84 would glow bright red when I moved it a little, sound dropping in and out. Turned the amp off, discharged the caps and removed the tube socket board and found broken solder joints on both EL84s and also on one of the 12AXY sockets. Repaired those and all static is now gone.
    With the basic mods and a few other of your tone tweaks, the cream board is sounding better than before. I still favor my Tweed since I replaced the OT and added your Presence / Boost mod, but the cream board still has potential. Thanks for sharing your tone tweaks!

  15. bigalex says:

    Hi Bill,

    I got a Blues Jr for several years. It has been my main gigging amp although I don’t gig so much anymore. Got JJ’s on it. Gorgeous sound!

    2 weeks ago I went to a recording session. Once the amp was set in the recording room I started to warm up a little. After 30 min, a loud BUZZ started (PAWWWWWWWWWWWWWWWWWW) that wouldn’t go away reducing both master and volume knobs and even plugging out the cable. Turned the amp off waited a little, powered it on again and after a few chords PAWWWWWWWWWWWWW again. I Looked at the tubes and they were glowing normally. No red plating, etc.

    Then I sent the amp to a very nice local tech. We managed to reproduce the problem and while the Buzz was on he touched the power tubes, move them a bit on the sockets and the buzz went away. he said I got a possible problem in the sockets solder joints or even in the tubes. He played for a while after this and the buzz didn’t come back. He did a resoldering job on all sockets pins, and sprayed some contact cleaner. Then we played for about an hour with no issues. I went home certain that my Blues Jr was back on the road again.

    Yesterday I decided to test it at home. Played for 3 hours with no problems. I decided to take a break and put the guitar on the stand while keeping the amp on.

    I was in Kitchen when all of a sudden I heard it again PAWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW

    I didn’t believe!! The buzz was back! Turned it off, then turned it on again and the bus went away as for magic.

    Played a little more this morning with no buzz coming back. It seems that now the amp in not as sensitive as it was before but I can’t rely on it to record or gig anymore.

    I heard somewhere that a bad speaker connection could possibly cause this. I compared the the plug pressure on the speaker jack against the footswitch jack and it seems the footswicht has a tigher connection.

    Other than this, could it be simply a bad tube?

    Thanks in advance for reading this long post and I hope you can shed some light on this issue.

    • bill says:

      It’s not a bad speaker connection. The jack is loose-feeling, but it’s probably fine, unless it crackles when you move it. Your tech did the right things, but you probably should have replaced the output tubes, too.

      Other possibilities: a failing first filter cap, bad ground on the speaker jack or a broken solder joint on the speaker jack. If the jack loses ground, the amp buzzes loudly.

      • bigalex says:


        After playing several days at home with no issues I decided to give the Jr a real test at a friend´s jam.

        After about 30 min playing at moderated levels (volume 3 master 5) the problem came back. I unplug the guitar cable and squeezed the power tubes on the sockets (just like the tech did) with no success.

        Turn IT off and on (just like with Microsoft products) and the problem went away for a while.

        More 15 min of playing the PAWWWW came back.

        I Turned off the studio light and in complete darkness could inspect the power tubes. Both were red platting a little. The left one more than the right one.

        Blues Jr is known to run hot on power tubes. Is this at some level normal?

        Order a new set of power tubes?

        Thanks in advance

        • bill says:

          If you don’t have the basic mods kit with adjustable bias, you should ask for cool-running EL84s. If the tubes are OK, then you have a broken solder joint, oxidation, weak socket springs, or some other connection problem that’s causing oscillation. It’s also possible that your main filter cap is failing.

  16. snap says:

    Hi Bill,
    I purchased and performed most of your mods to my cream board Blues Jr around two years ago.
    Just the other day the amp started making intermittent crackling type noises. When I wiggled the power tubes it would incur more crackling and sometimes the problem temporarily went away, but the tone and volume would drop to about half and sound distorted.
    I also noticed that the V5 power tube was glowing much brighter than then V4 tube. I replaced the power tubes to no avail.

    These all seem like similar symptoms to problems you describe here (minus the one power tube glowing brighter than the others), but is there a way to test or troubleshoot where exactly the problem is?
    Or should I re-tension, resolder and use contact cleaner on everything all at once?
    And does the tube socket board need to be removed to perform these fixes?

    • bill says:

      It sounds like a cracked solder joint on one of the output tube sockets. The filament glow is not a reliable indicator, but if the entire plate gets red, that’s a sure sign that you have a bad connection at the pins or socket. You don’t have to remove the socket board.

  17. Haystack Calhoun says:

    I wonder if anyone has noticed, besides me, that the springs on the power tube retainer sound a slightly flat “A” when plucked? I suspect this causes the EL-84 tubes to become microphonic as mine did on “A” notes. What I did to try and correct this was simple: I stuck a small piece of electrical tape on each spring where is connects to the “C” retainer part to deaden it. Doing this might extend power tube life, I hope.

    Haystack Calhoun
    aka Agent Five

    • bill says:

      I don’t know if the resonating springs make any difference, but regarding your suggestion, I would say, “Right idea, wrong material.”

      Electrical tape has no place in an amplifier, and especially not that close to tubes. It gets hot, it melts, the glue gets all over everything. If you want to silence the springs, put a 1-inch piece of shrink tubing over them. The heat of the tubes will shrink it; you don’t even need to steal your wife’s hair dryer.

      Or you can slip a 3/4-inch or 1-inch piece of pipe cleaner into the spring. Either will damp the vibrations and won’t make a gooey mess.

  18. chadrocks777 says:

    Hey Bill (and fellow BJ modders)- I just completed the basic mod on my 3rd blues jr. This one, for some reason, is experiencing dropouts. It’s very strange, it will play fine for a few minutes, then suddenly drop out. If I turn the amp off, I can hear the sound coming back as it cools off.

    I was hoping it was cracked solder around the power tube sockets, but I’ve gone through and re-soldered them. I’ve also cleaned the sockets with electronic lubricant, and swapped tubes. No dice.

    The only other symptom I’m noticing is a slight “fizzle” sound at the end of a sustained chord.

    Is there anything in the basic mod kit that may be faulty (or installed improperly) that would cause these symptoms? Just so you know, I didn’t put the adjustable bias on this one. Any help would be much appreciated!

    • bill says:

      I think you’ve got a bad plate resistor or a bad solder joint in the signal path. You could build the audio tracer to follow the signal and see where it’s dropping out.

      • chadrocks777 says:

        Bill- thanks for taking the time to reply. I will definitely build an audio tracer….the only problem I’m having right now is that I can’t re-create the problem. I’ve been playing it for nearly 2 hours without a single drop out. I tried various volume settings, etc, but it seems to be working fine. I hate it when this happens, I’m way too nervous to take it to a gig…..any thoughts/suggestions? Again, thanks for any help!


        • bill says:

          Gig it and bring a backup!

          • chadrocks777 says:

            Hey Bill, dropouts are happening again- this time, I noticed that if I turn up the volume knob to 10 or so (master at 4), I can hear a little signal. Any thoughts? I’m planning on building an audio tracer, but the problem is so intermittent that it would be hard to trouble shoot with it.

            I’ll stop bothering you after this, and really, thanks again for this awesome website and all of your help.


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