Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Cowwe on October 14, 2023, 01:12:20 PM
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On my stock crack I have recently had this issue where the right channel makes some loud static and crackling noises. It may go away if I remove and reinsert the power tube or switch it with a different one, but every tube gives me this problem now (even the stock 6080 that used to work fine).
Moving the tube around while the amp is on changes this noise for the better or worse. It doesn't always happen, but when it does it's so loud that I have to turn my Crack off.
Is it safe to assume that I might need to reheat some joints in the power tube side?
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Yes, I would reflow the joints in the amp (other than those where the LEDs attach and the power switch).
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As a general suggestion, if the noise does change a lot, coming and going when I move the power tube, is it an indication that the problem might be in that tube's socket? Or it could also be any other solder joint?
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I have tried reheating the joints in the tube socket that might have been less than ideal but it hasn't fixed my issue. I keep having loud static and crackling only in the right channel, no matter what tube I try on.
I have checked voltages and everything measures within the standards.
Before yesterday I have had this problem occasionally, but removing/switching power tubes usually made it go away.
Yesterday I have installed the 2 diodes as ground break to shield from usb noise, and it did work perfectly at first.
Later in the night and today the noise does not go away no matter what I do, and it's so loud that the amplifier is unusable.
I know it has to be a mistake I made somewhere, but it feels so disheartening to keep having so many problems with my kit after putting in all the effort that I could..
I have tried messing with the cables but that did not do anything.
I am going to post some pictures. Please let me know if you have any idea what else I can do.
https://imgur.com/a/z68PjJd (https://imgur.com/a/z68PjJd)
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Here is the modification with the diodes. To me the joints look well covered in solder and pretty clean. Plus, I used the amp for a couple hours right after installing them and everything worked perfectly.
https://imgur.com/a/7aKU7dQ (https://imgur.com/a/7aKU7dQ)
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I have been testing things out a little more:
Just now I could hear the same static coming and going a bit more quietly, but then this happened:
After a minute it looked like the tubes' glow got a little fainter but quickly regained strength.
One more minute after that my Crack just turned off and won't turn on again.
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I have switched the first tube with a second and now the amp turns on again, with the noise in the right channel remaining.
Switched second and first around again and it lights up again. I really don't understand anymore.
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One more report: I have tried the chopstick test and tapped every solder joint in my amp, and couldn't notice any reaction in the intermittent buzzing.
Tapping the chassis or the tubes also doesn't seem to bring any reaction.
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You are either using lead free solder or a cold iron. If you're using lead free solder, get some leaded solder. If you're using leaded solder, turn the iron all the way up.
The solder joints back by the power switch would be of very minimal concern if you are rocking the 6080 and that's making noise. Perhaps you could take some more build photos of the rest of the amp and post them.
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I am using 60% leaded solder, as was reccommended. I also tried keeping my iron set to maximum, or close to it, during most of the process.
Here are some pictures. Please let me know if you want to see anything more closely.
https://imgur.com/a/4gpyDsY (https://imgur.com/a/4gpyDsY)
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10L could use more solder. It would also be good to see the octal socket itself.
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Here are some close ups on the socket. https://imgur.com/a/tR906FF (https://imgur.com/a/tR906FF)
I'm going to look into 10L.
Looking closer I'm thinking 21L might need some solder too (the last picture).
I'm going to take a break for today (damn you timezones), but thank you for the support until now. Earlier today I was really despairing.
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No despair necessary. Bottlehead support ranks right up there with the very best you will find anywhere. QFT.
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What you can do is to plug the cheapest headphones you have into the Crack (they can be low impedance headphones, that's OK), then poke around the circuit with a wooden chopstick while the amp is running to see if you can set the noise off. This is what I do when I have a noise issue that I'm having a hard time tracking down.
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Unfortunately as I reported yesterday I have already tried tapping away with a chopstick while listening for reactions in the sound, but I couldn't tell if there was any change.
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I am going to give the chopstick test another try once I get home from work. For the meantime, could the fact that my issue is only on the right channel highlight some possibilities as to where the problem could lie? The left channel is completely fine.
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You can also rock the tube with those headphones in and look for two components moving differently that would otherwise be soldered together.
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I have an update (I'm afraid it might be a pretty bad one).
I once again closely inspected my kit looking for any loose wires and poorly soldered joints, but couldn't find anything that caught my eye so I decided to move on to the chopstick test.
I had just my 12au7 in its socket while the 6080 wasn't inserted, and the power switch was off. I plugged the amp in, intending to then insert the 6080 and turn the crack on, but before I could I got shocked through (I'm positive but not 100% sure) the chassis.
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The chassis is earthed, so it's unlikely that you'd be shocked by the chassis, but it is possible that you were touching part of the IEC power entry module when you plugged the power cord in. I would plug the cord into the Crack first, then the wall.
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Today I went through testing everything once again.
Resistances measured correctly. The amp turned on correctly and the voltage check is within the limits:
1) 84 2) 170 3) 0 4)170 5)80
6) 0 7)104 8)0 9)106 10)0
I went on to plug a pair of old headphones. The crackling was still there so I tried tapping on each solder joint with a chopstick. Nothing made any notable difference in the noise.
The one thing that made the difference was rocking the 6080 tube until the noise went away.
Tonight I'm going to try to listen with different tubes and see whether it really was just the tube pins not making contact all along.
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Fit. Check for noise. Clean pins. Check for noise. Do this for all of your 6080's. Lots of wiggling can sometimes distort individual pin sockets. If so. contact can be improved if you give them a very gentle squeeze.
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Yeah, it's definitely the pins not making good contact or some parts being dirty. Depending on how I insert the tube (depth or slight angle differences) my Crack either works perfectly, makes some background noise or won't start at all.
I've had the amp turn itself off a couple times while listening, and slightly moving the power tube turns it on again.
How would you suggest to clean the pins and socket? Is using alcool okay?
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Deoxit is the best thing I have found for cleaning contacts.
If that doesn't do I use a cutting torch tip cleaner. Which is basically a tiny hole file.
I would also check your volume pot connections again. I had a similar problem years back when I first built mine that ended up being a bad joint on the volume pot. Messing around with the tube was flexing the top plate enough to flex the wire braid to the pot and make/break contact.
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My kit is officially making me go insane.
It had worked flawlessly for 2 days, then as I was listening it turned itself off. Now it's back to the same issue, where for some reason the amp turns itself off and if I wiggle the tube ever so slightly it turns itself on again (until it happens again).
I thought maybe vibrations from me moving at my desk might be moving the tube and breaking some contact, but it has happened even while I wasn't touching anything.
I went and reflowed a solder joint at terminal 13 since the red wire didn't look well covered, closely inspected every joint once mroe and tested the voltage as usual: everything is within standard values.
Setting the Crack to stand vertically, I went with the chopstick test again and tapped on all joints, cautiously moved the octagonal socket pins left and right and lightly pulled/pushed on wires: no changes at all in the sound and the amp kept sounding perfect for a good 10-15 minutes.
I put the kit back to its place and within 5 minutes of listening it turned itself off once again.
I have wiped the inside of the socket a bit and it looks clean enough to me. The pins themselves also feel pretty tight, and I'm not sure how I would go about messing with them to make a better contact.
Once more, please let me know if you have any ideas what else I can try. If you would like, I'm willing to send a close up picture of every single joint you'd like to see.
This amp is such a joy when it works, but this situation is so very frustrating.
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Socket looks clean. As it is new it should be. You could try and bend the contacts in a fraction with a tiny screwdriver. Cleaning the pins by pushing the through a sheet of Scotchbrite soaked in DeOxit worth doing. Wiser heads might be able to say why the unit actually switches off and which pin might be the cause. If it is safe to do so, have a poke around with the chop stick when it is this "off" state.
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You used the phrases "turned itself off" and "turned itself on" - does this happen instantly, or does it fade in and out? Is there a loud click, or a thump, or does it just go silent? Have you measured voltages while it is silent (yes that's hard to do!)?
It iis likely to be a thermal expansion that causes a disconnect. These details might help locate the intermittent connection.
It may be a broken wire, where it was nicked when the insulation was removed and the insulation crept back to cver the which then broke in subsequent handling. A little gentle yanking of wires can reveal this kind of problem.
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When I say it "turns itself off/on" I mean it happens as if I would be removing the plug or flipping the power switch. The tubes start glowing fainter until they go dark, while the volume gets lower until it's silent (in the span of about 5 or 10 seconds). There are no clicks or noises, aside from two quiet thumps at the very end (one per ear), which I'm positive the amp does normally whenever you would turn it off.
From what I have noticed it's not fading in and out, but rather it fades out and stays like that until I mess with it. I haven't tried leaving it alone after it fades out to see if it fades back in, though.
My amp has been unplugged for a couple hours now so it's completely cool, but it isn't turning on if I plug it in (I would need to go and move the tube).
I'm going to try and measure the voltages right now as long as it's in this state.
Thank you again for your patience in assisting me, Paul.
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Here are the measurements while the amp is plugged in, but the tubes and LED's are not lighting up.
terminal 1 - 242V
terminal 2 - 248V
terminal 3 - 0V
terminal 4 - 248V
terminal 5 - 242V
terminal 6 - 0V
terminal 7 - 0V
terminal 8 - 0V
terminal 9 - 0V
terminal 10 - 0V
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Those conditions would be neither tube conducting. Can you see the orange glow from either tube under these conditions? This hypothesis doesn't fit the "instant off" condition you describe though.
This is very much not an issue with tube socket pin fitment, as both the 12AU7 and 6080 are unable to operate under these conditions.
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No, in these conditions neither of the tubes, nor LED's, glows.
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OK, there are wires going from B7/B8 to the power transformer. If both tubes are not glowing but the high voltage remains, then one of those wires is not well connected or broken.
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Right, that makes sense. I am going to reflow B7 and B8, since it's pretty tricky to tell whether the joints look good.
I will check voltages again afterwards and report back.
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Don't ignore that it may well be the wires at the power transformer that feed B7/B8 that are loose.
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Yes, of course.
After reflowing B7 and B8 the voltages measure within good ranges and the amp is working.
I'm going to let it run like this for some time and see whether that fixed the issue.
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I have a brief update, bringing both good and bad news about my situation.
The good news is that reflowing B7 and B8 seems to have fixed the issue with my amp dying and coming back alive. I have kept it on for a number of hours and the amp stays on.
The bad news is that I am back to fighting with the the crackling noise in the right channel.
Last night I went through the usual chopstick test, and I have found that lightly pushing on the black wire to terminal 3 sends static noise on both channels. I don't know whether this could be the culprit for my issue, but I will be starting from reflowing there.
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I would carefully examine the black wires that meet at the headphone jack. It's extremely common for builders to not capture both of them with solder adequately, and this can cause a lot of issues.
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I went and soldered terminal 3. Now the joint looks nice and well connected and doesn't react when I try to mess with it with a chopstick.
Unfortunately this didn't solve the noise issue.
The joint at the jack terminal with two black wires connecting honestly looks very good to me. The two wires seem to be covered in solder and they don't make any static or crackling when I mess with them.
I have spent a long time trying to find the joint that's causing the noise but I haven't been able to get anything out of it. I can't even tell whether the noise changes by rocking the tube anymore.
My voltage readings are the following:
1) 79,6 2)172,5 3)0 4)172,6 5)79,7
6)0 7)105,4 8)0 9)106,8 10)0
I have noticed that there is a 1,4v difference between terminal 7 and 9. Could this be an hint?
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For what it's worth, I have tried recording the crackling. https://voca.ro/1j7PsZyGOoYt
Please try to ignore the loud clock sound in the background and the quiet static, which comes from the microphone itself.
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I just went ahead and reflowed most of the joints in the amp, basically only leaving alone the 9 pin socket and the connection around the power switch. I made sure to pay particular attention to the octagonal socket and the part where the black wires meet at the jack. Nonetheless, this did not solve anything. Right now I am at a loss on what to do, as the amp is still unusable as it is.
One thing that keeps puzzling me, is that a couple of weeks ago the noise did react to moving the 6080, and that after messing with it for a bit the amp did work flawlessly for a period of time. It only came back after I reflowed the bad joints at B7/B8, which fixed my issue with the amp turning itself off.
Hoping that you won't mind the wall of text, I'm going to reorganize the main results from my testings so to have the situation as clear as possible:
-The crackling noise appears soon after the amp is on. I would say after about 15 seconds, whereas when the problem first appeared it only started after a longer period of warm-up.
-The noise is exclusively in the right channel. If I just barely unplug my headphone jack I can hear it in both (since that's when the headphones normally play in mono).
-The noise does not depend on whether I have the RCA's connected or not, and it does not change depending on which wall outlet I plug it in (not even a different house).
-I have tried multiple driver and power tubes and all of them have the same issue. Wiggling either tube does not have an audible effect, and the socket and tube pins look rather clean.
-The noise doesn't change depending on volume. It's always there at the same volume.
-The chopstick test did not reveal any weak connection. Even lightly pulling/pushing on wires I couldn't notice any audible reaction.
-Applying pressure on the chassis in several different positions did not reveal any audible changes either.
-I have reflowed the majority of joints, including those that looked alright to my eyes, and the voltages always measure within the standard values. The one thing I noticed, as I mentioned in a previous message, is that there is always a discrepancy of about 1.5V between terminals 7 and 9, whereas the other terminals (for example 1 and 5) mirror each other much more closely.
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I would try this: https://forum.bottlehead.com/index.php?topic=11676.0 (https://forum.bottlehead.com/index.php?topic=11676.0)
The 1.5V difference between 7 and 9 is not anything concerning.
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I have already applied the modification with the diodes and it served its purpose in eliminating the noise coming from my pc, as I posted in the beginning of this thread here are a couple of pictures. https://imgur.com/a/7aKU7dQ
My problem is present even if no RCA's are connected.
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That sounds more like an interference issue, like some WiFi enabled device that's too close to the Crack. This is a similar noise to the USB computer noise, but if it's present with no cables attached, then it may well be coming through the air.
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I honestly find that very unlikely though. I have used the amp for around two months with no noise outside of those coming from my source, which was fixed with the diode modification as a breaker. I haven't added any new device to my setup, and even moving to a completely different house kilometers away from my place the noise was the same.
Plus, a couple of weeks ago I could actually interact with this noise through wiggling the 6080 tube, and had two days where it was completely gone.
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I am most likely grasping at straws right now since I am running out of ideas, but I have noticed that my wirewound resistors are not turned the same way they are in the manual's pictures.
Could this make a difference of some sort?
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If you could make the noise stop by wiggling a tube in the socket it would seem prudent to clean the tube pins and socket. Try Caig Deoxit.
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I appreciate the input, Doc.
The idea that it might be either dirty tube pins or a dirty socket occurred to me too, so I went and cleaned them both several times (the last time being yesterday). I don't have Caig Deoxit in Italy, so for the time being I used another product, but as of now cleaning contacts hasn't had any impact on the noise.
Most importantly I cannot seem to interact with the noise in any way anymore, neither wiggling the tube nor applying pressure to the chassis or messing with wires seems to be changing the noise. It might also be a bit hard to tell since the noise is very randomic: at times it's quiet for several seconds and sometimes it's unbearably persistent. It really puzzles me that a couple of weeks ago I was actually able to make the noise change by moving the tube now I can't anymore.
One aspect that came to my mind recently and that might be a useful detail, is that I remembered when I heard this noise for the first time: I was listening to some music and suddenly, only in the right driver, I heard a very loud noise that would be comparable to having an aluminum foil crumpled up into a ball close to your ear. At the time I got pretty scared and quickly turned off the amp, but for a period of time after that event the amp kept working normally.
Tonight I am going to try cleaning the contacts better and I will keep looking for the source of the noise as I have been doing every day these past weeks, but I am really at a loss right now.
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As unfortunately expected, cleaning the pins and the socket did not make a change in the noise I keep hearing, and spending more time looking for bad solder joints and faulty cables with a chopstick still hasn't revealed anything.
I have tried changing power chord, wall outlet, turning off anything that might create interference and taken my kit elsewhere, and nothing changed.
My Crack is still unusable and I think I have run out of ideas.
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The next step would be to try a different 6080 tube.
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I have already tried all of my tubes, both 6080's and 12au7's that used to sound perfect. All of them showcase the same exact noise
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I just went back and listened to the sound file again. This week I returned a Gates limiter to a friend who brought it in saying made a similar sound and was unusable for recording. I had replaced all the tubes and replaced the film coupling caps but the faint crackle persisted. Bear in mind this is a 60 or more year old piece of equipment. I went through and chopstick tested the connections and found that a string of terminals in the middle of the chassis were causing the problem. Perhaps the old solder flux had degraded the joints over time, which caused less than perfect conductivity. Reflowing those terminals and adding just a bit of fresh solder completely solved the problem. I know you have already gone through reflowing the joints, but it could be that one has just not quite reflowed well enough. Beyond that my suggestion would be very unlikely things like a slightly leaky capacitor somewhere. Since it is only in one channel it would have to be some component on that side of the amp. Unless some part has been physically damaged the odds of this being the issue are quite low.
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In the last couple of weeks I haven't updated my thread, I have done some more testing and inspecting to no avail, which brought me to biting the bullet and bringing my kit to a local hifi repairman.
I have explained to them in detail every piece of information I had gathered on my issue and finally got my "fixed" amp back yesterday (the man was rather vague about what he did to solve the issue, and was also very vague at describing the noise itself).
Naturally, the combination of my newfound ineptitude at electronics and my bad luck meant that when I plugged my headphones into the Crack the noise was still there and I most likely got scammed.
As suggested, I have made one last attempt at reflowing every single joint in the amp, adding just a slight touch of new solder, paying very close attention that (from what I have learned) the joints all look good and have the right amount of solder to them. It didn't work.
As it is still not clear to me, could you please specify which terminals are responsible for the right channel?
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It's a pity you had your wallet squeezed to no effect with this repair. I don't know where you are but those funds would have been better used for sending your Crack back to BH HQ for repair. That is something to consider as an alternative to chasing your tail at home.
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Thankfully the wasted money wasn't a lot. The real disappointment came from thinking I could finally listen to my amp again and having my expectations betrayed by a supposed professional.
Still, I have thought about the possibility of sending it back to BH, but that has to be my last resort. I live in Italy and the money and time that it would take would probably be comparable to getting a new amp altogether. Plus I don't know how the built amp would hold while traveling across the sea.
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This has been a bit of a long thread and I'm not sure that I see it in here, but you didn't use any additional flux right? There have been some occasions where the wrong soldering products were used and conductive residues were left (which could usually be cleaned off).
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I have made 100% sure to only ever use the suggested 60/40 solder, nothing else.
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Since I'm still not sure about it, could I ask you to point out which sequence of terminals is responsible for the right channel in the crack?
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The red wire going from the red RCA to the pot, the red wire leaving the pot, the red wire leaving A6, the red wire leaving terminal 2 and going to B1, the red wire leaving B3 going to terminal 7, the red wire leaving terminal 6, and all the black ground wires.
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Hello again. I hope everyone spent some nice holidays.
I would love to announce that in my month and a half of absence from this thread I found a solution to my noise issue, but it unfortunately isn't so.
I do have a rather bizarre update though:
I had, as usual, double, triple and quadruple checked every and each solder joint inside my amplifier at length and couldn't for the life of me find anything wrong that could be the source of my problem.
So I decided to bring my kit to a well respected hifi repairman that specializes in tube equipment (I had done this once before but the man couldn't find anything wrong in my amp). After hours of testing with my tubes and his, my power chord and his, and no source attached, my kit never made a noise. I have listened to it at his place with my own ears, and the amp is completely silent. So it turns out the previous repairman I had contacted most likely did not scam me.
I brought the amp back home and tried it anywhere I physically could, and in each of the 5 different houses I have tried it at the noise appears again and the Crack is unlistenable.
There should have been no difference between how we tested at this guy's place and mine, and yet my kit was perfect at his place.
He himself inspected the kit and found nothing wrong with the build. The only thing he recommended I replace is the tube sockets (in his experience those have caused him contact issues and noises), so I went ahead and replaced the octagonal socket but of course nothing changed.
At this point I am once again at a loss about how to proceed. While rewiring the octagonal socket I tried moving the right channel output to the left and viceversa, and the noise did indeed switch from right to left.
I have tested the grounding of my home outlets but they are fine, and my current measures 245V (hence the way I have wired my transformer according to the guide).
I don't know how useful this information could be.
If any idea comes to your mind about what I could test and what I could replace, please let me know.
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Off the wall but try to put a tin box over the whole Crack. Maybe a cooking foil dome would also work. It should show if it is suffering from EMF problems. Wrap your input leads in foil too.
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Off the wall but try to put a tin box over the whole Crack. Maybe a cooking foil dome would also work. It should show if it is suffering from EMF problems. Wrap your input leads in foil too.
I had thought about possible disturbance causes (even though it would be weird, having the same exact noise at many different places except for some that have no issues at all), so I recently tried using the amp while it was completely inside of a microwave, which should be shielding, but the noise was unbothered.
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After hours of testing with my tubes and his, my power chord and his, and no source attached, my kit never made a noise. I
What source was he using? What source are you using? What cables was he using? What cables are you using?
There's a whole lot ahead of the Crack that can make noises like these.
Do you happen to have ethernet over powerline converters where you're trying to use your Crack?
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What source was he using? What source are you using? What cables was he using? What cables are you using?
There's a whole lot ahead of the Crack that can make noises like these.
Do you happen to have ethernet over powerline converters where you're trying to use your Crack?
No source at all (simply plugging the amp to an outlet and headphones creates the noise). We have tested both my power cord and his. We have also used the same pair of headphones.
If you're referring to devices similar to wifi range extenders or repeaters then no, I don't have any at my place. I'm not sure what the term is, but I have my ethernet connected to my house's telephone line.
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Was the tech using your headphones when the Crack worked without any noise? If he was using different headphones and not hearing noise it might be that the plug on your headphones has some sort of contact issue with the Crack headphone jack. I apologize for not having read through the entire thread to see if you have tried different headphones.
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Was the tech using your headphones when the Crack worked without any noise? If he was using different headphones and not hearing noise it might be that the plug on your headphones has some sort of contact issue with the Crack headphone jack. I apologize for not having read through the entire thread to see if you have tried different headphones.
I have already tried a number of different headphones and cables, yeah.
And no need to apologize, doc. It's such a long (and probably confusing) thread that I was wondering if it wouldn't be better to just close it and open a new one with my issue laid out as clear as possible.
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Brief update: looking for a solution to my issue, I had been suggested that there would be a possibility of the volume potentiometer being the culprit to my noise. I thought that trying wouldn't hurt, so I went and replaced the stock potentiometer with an Alps Blue Velvet, but this didn't make the noise disappear.
I guess now I know for sure it's not the potentiometer, at least.
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Finally, I bring good news.
After replacing output capacitors and testing the 3k ohm wirewound resistors, it turns out what was producing the noise was the 22k ohm resistor on the right channel.
Replacing that completely got rid of the noise.
The problem has been solved. I am at peace.
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I have seen that once when a 22.1K resistor was installed very tightly against the terminal strip, which made an intermittent crack in the resistor.