Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: benzxc on August 09, 2019, 09:45:58 AM
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Hi all,
I just built my crack w/ speedball upgrade. Works perfectly and sounds great. There is absolutely zero background noise/hum/hiss when I connect to my phone, even when I max out the volume (when not playing music).
However, when I connect my crack to my laptop, there is a very audible noise/hiss/hum once the potentiometer is about 25% of the way, and gets progressively louder.
I know that this is probably an issue with my laptop and not the crack as it is silent when connected to my phone.
Anybody have any experience with getting rid of the noise when connecting the crack to a laptop? As I mainly use my laptop for listening, it would be nice if there is a solution to this issue. :)
Thanks!
Ben
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Are you using the same cable with the phone that you are with the laptop? If not, try that. If so, you might want to try a DAC to connect to the laptop.
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Oh also - what do you have the volume on the laptop set at? I'd recommend setting it to the highest possible and then using the Crack potentiometer to control the volume.
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Hi Jameson,
Thanks. Yes I am using the same cables. I also am using a DAC with the laptop. The dragonfly red. And yes I have recently started to Max out the volume on my computer as well.
Thanks!
Ben
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It's possible the laptop fans influence the PS of the DAC.
External USB dacs with a separate PS like some Schiit or DACS with optical input solve this issue.
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https://forum.bottlehead.com/index.php?topic=11676.0 (https://forum.bottlehead.com/index.php?topic=11676.0)
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Thanks!
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So I spent the whole day tinkering with the crack. Trimmed excesses and resoldered some bad joints. The hissing is gone now and I had an enjoyable few hours.
However, I did notice this really strange high frequency hissing when I turn the volume to 0%. It sounds kind of like what I imagine tinnitus to sound like. Although it is barely audible, it is unignorable once I notice it. It is not there all the time but rather comes and goes, stays for maybe 25 to 30 seconds and then disappears.
At first I thought it might be my wifi, electronics and the like, so I brought the crack into my bedroom away from all those applicances but it still seems to be present sometimes. It doesn't go away if I play with the volume, or if I plug/unplug the RCA inputs. It seems to be only with the headphone jack and power.
Has anyone had any experience with this? Could this be a tube problem? I'd be most grateful for any assistance!
Thanks to all!
Ben
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Oh - I might mention that this afternoon after I trimmed some excess I plugged in my headphones for a listen and somehow there was a loud pop in my right channel, and I saw a spark in the larger tube. I thought I might have ruined my headphones so I turned it off and plugged my headphones into my phone and it worked fine. I did the voltage tests (all fine) before I started using my crack again - all was fine after that. Not sure what might have caused that.
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Also, the high freq hiss appears to be from the right ear. Although this hiss happened before the pop happened...
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It might help to post some build photos.
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Thanks, Paul. Here are a few photos.
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You have a little more trimming to do. It might help to get a good set of side cutters as opposed to wire cutters.
I also do not see the connection that I've circled in red in this photo. Not having this connection could cause the pop and flash.
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Thanks, Paul! Is this the connection that you are referring to? Might have been the angle of the last photo.
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Indeed. In that photo it looks like the inboard side of the lower 2.49K resistor might've been cut.
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So I went ahead and trimmed some remaining excesses and tightened a few screws here and there.
The weird very very low volume hiss (I almost have to "look" for it) is still there - although it is not there all the time. I find that I can get rid of it simply by unplugging the headphone jack and replugging it. It is a little weird, because it is independent of the RCA jacks and independent of volume control. Anyone has similar issues? Maybe I might have to try a few other tubes?
Apart from this little issue, the crack w/speedball upgrade works beautifully and it has been a great few days working on this.
Thanks,
Ben
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Have you checked the pointed out resistor by PB?
This could explain your issue and destroy headphones when not properly solved.
Edit: the fact that mechanical influence at the headphone jack changes the sound point to a mechanical problem.
I suspect a solder joint or the resistor mentioned before.
You could try tubes, but that wouldn't explain the influence when fiddling at the headphone jack.
Edit 2: What he says. (points down)
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Also if you have a noise that changes when you plug and unplug the headphone cable, that is indicative of a loose connection, not a bad tube.
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Thanks, Paul, Tom,
Can you point out again which resistor connection I am missing? I attach a new photo again. I was a little unsure of which one in PBs previous post.
Thanks,
Ben
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That black wire going to the headphone jack looks like it has a good bit that's bare wire (the jacket was stripped kind of far back), and that could be hitting the top plate or interacting with something. Might want to wrap some electrical tape or insulating material around it.
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Thanks, Jameson. Will do.
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Thanks, Paul, Tom,
Can you point out again which resistor connection I am missing? I attach a new photo again. I was a little unsure of which one in PBs previous post.
Thanks,
Ben
Look at the more proximal (left) part of the bottom 2.49k resistor, it shows a weird / sharp angle, a possible break.
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Thanks, Tom.
I attach a photo from another angle. It doesn't appear cut to me.
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I still suspect a bad solder joint somewhere. First, go over all ground connections (trace back all black wires, look for loose or flaky connections) and see that all screws with a ground connection are properly tightened.
When not succesfull.
Get some cheap headphones out. Plug them in. Plug in a source without any sound. Flip crack over on some stands (and put the power switch to on). Plug the powercord in. Get out a wooden (non conductive) chop-stick and start poking at the joints (start around the jack) untill you reproduce the hissing sound, that's your bad joint. Be very careful when doing this.
Edit: forgot to say. Indeed that resistor looks good in this picture (unlike in the one on the previous page)
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Thanks, Tom. Will do.
Going to get some shut eye now. It is 3:40 AM in the part of the world where I am located... been the third night I've stayed up this late since I started building the crack.
Thanks for all the help.
Ben
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That other photo you provided shows that the resistor lead is bent a little bit, not cut. It looked suspicious at the alternate angle, but not so much now.
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So I went back and resoldered all accessible joints and tightened all screws again to no avail. Then, I did the chopstick test and didn't hear any joints that made the hiss/hum. The hiss/hum just seemed to be there all the time.
I also noticed the hiss doesn't start immediately after I turn the amp on. Rather, it starts a few minutes after the amp is turned on.
I ordered a set of new tubes just to rule that out as a source of issue. Otherwise, I'm kind of at a loss now and am thinking of maybe sending it back to bottlehead for repair.
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Hi all,
Happy to report that having left the newly built crack w/ speedball upgrade on and playing music for 10 plus hours, the right channel hiss seems to have gone away. I have checked many times over the past 2 hours and it has not resurfaced. Needless to say that I am a happy camper now! :D Will keep monitoring to see if the hiss comes back.
Thanks again,
Ben
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Oh no! It has come back......... :(
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Not sure if you've cleaned the tube pins, but I have exorcised various gremlins by doing so.
Bernie
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Thanks, Bernie! Will do so right now to see if it makes a difference.
Any suggested/proper way to clean the pins?
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Is this noise still there with nothing plugged into the inputs?
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Hi Paul, yes the noise is present when the RCA inputs are not connected.
Thanks,
Ben
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Do you happen to have an ethernet over powerline kit in your home?
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Hi Paul, I don't have that, unfortunately.
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I just noticed that one of my heatsinks is not entirely in the socket. Attached photo. Could this be the cause of the weird low volume hissing sound, or is this unrelated?
Even if unrelated, is this something that could cause serious issues that I should fix now? I ask because I am a little hesitant to make any big and unnecessary moves on my crack at this point for fear of messing something else up. Of course, if this is necessary to fix I will do it.
Thanks!
Ben
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Oops, photo here.
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That shouldn't cause a problem.
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Phew, good to know. Thanks for your help as always, Paul.
The noise occurs sporadically. It is low enough in volume that I can live with it if I can't fix it.
However, once I get those new tubes I will report back to see if anything changes.
Thanks to everyone for all the help so far!
Ben
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I would also suggest doing the modification I posted earlier on this thread, as you may have a polluting device somewhere in your house, and that will give you some extra isolation.
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Thanks, Paul!
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So I did some experimenting at home today and I think I isolated the source of the noise.
I unplugged all electronic appliances around the home but the noise persisted. Knocking around the crack, I noticed that if I tap at the 6080 power tube in a certain location, the noise decreased, and in one instance even disappeared. (I'm not sure if it actually disappeared entirely since the volume was small to begin with but it decreased noticeably. )
Does this mean that the noise comes from a noisy tube?
I read through the board and noticed others with similar issues and apparently some suggestions in these circumstances were, in addition to changing tubes, to leave the crack running for a few days to let the cathodes form. How many days should I do this for? Do I need to have music playing while I leave it on? And at what volume?
Thanks!
Ben
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Yes, you could certainly leave the Crack on for a few days. You don't need any music playing and the position of the volume control doesn't matter.
Physically tapping on a part of the amp and experience a difference in performance usually suggests a loose connection in the amp or possible just dirty pins on the 6080.
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Thanks, PB.
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Is it still suggestive of a loose connection in the amp if only tapping on the 6080 changes the noise, whereas tapping on the other tube does not change the sound at all.
I have checked my joints twice and reflowed them as well. Im afraid doing them again at this point might do more harm than good. Of course, I will do it if necessary. Just wanted to make sure before I go probing in again with my clumsy hands.
Thanks!
Ben
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It might help to post some pictures around the 6080 to see if there's anything people could spot. A lot of time those loose connections can be affected by tapping the chassis near where they exist. Someone had mentioned using a chopstick (non-conductive) to prod around those connections while listening to the amp with a crappy set of headphones to see if hitting any of them causes a pop. If so, that's where you focus.
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Prodding the connections with a chopstick and cheap headphones attached would be a good idea.
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Here is a photo of the 6080 socket. I just noticed there are two extremely loose tube sockets. Not the solder joints but the pin sockets connecting to the ceramic (?) base. Could these be it?
I tried the chopsticks and cheap headphone but no noise!
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All of the lower terminals on that terminal strip could use more heat and a tiny bit more solder.
The red wire going to B6 needs to be pulled through more and wrapped around the connection at the socket. The same goes for B3.
If the stripped bit of wire at B3 touches the stripped bit of wire at B2, you will start smoking parts in the power supply, so I would reheat those joints and pull the wire through a bit so the jacket is closer to the socket pins, then wrap the stripped wire up and over the socket pins and solder the bit of the wire that's wrapped over the pin. (Ditto for the joint at B1, but not B4. B4 is what you want to go for)
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Thanks, PB! Just did it, although the noise is still there. Guess I will just leave the crack on for a few days and see. In any event I will soon have a new tube to see if the issue is with the tube. BTW is there a suggested max continuous number of hours/days that I should keep the crack on for? Don't want to ruin it by doing this!
Thanks again,
Ben
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BTW is there a suggested max continuous number of hours/days that I should keep the crack on for?
My estimate would be about 3-5 years of constant operation before you'd probably burn up the tubes and 30-80 years for the caps to wear out.
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Whoa! Great to know, thanks PB! 8)
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Hopefully you'd have it fixed before that 80 years runs out!
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Hopefully you'd have it fixed before that 80 years runs out!
Fingers crossed! 8)
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Just an update to all who helped me and for all who have the same experience with the noise and is wondering:
Having left the Crack on for about 50 continuous hours, the weird low volume noise in the right channel has mostly disappeared. It resurfaces once in a while for a very short period of time, and the volume has noticeably decreased. (It was low volume to begin with, and has gotten even lower to the point it is unnoticeable unless I am consiously looking for it.)
I am going to leave the Crack on for a couple more days to see if the noise will disappear completely. Very very satisfied with the Crack! Excellent sound! Even if it doesn't disappear, I think I can live with it for now.
My new tubes haven't arrived yet but once they do, I will pop them in to see if it happens with the new tubes.
Thanks to all!
Ben
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70+ hours burn-in now and the sound has no re-appeared!
Although I do have a quick question: I just turned the Crack off and flipped it around to check on the wiring and I noticed this weird sound when I flipped it over. It sounded like there was a loose part in the Crack. I checked like crazy everywhere to see if there may be any loose parts but didn't find any. I could not pinpoint where the sound is coming from but the sound is not coming from the tubes themselves, and I tightened all screws as much as I could. I shook the Crack a few times and the sound reappeared.
Could the sound be coming from the tube sockets? I noticed that some of the sockets are very loose.
Is this something I should be concerned about, or should I just go ahead and use it and deal with it if an issue pops up? Like I said, the Crack is functioning perfectly now.
Thanks,
Ben
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If there are no tubes in the sockets, the pin contacts will move around a little bit when you shake the Crack. You want this though, those contacts need to move when you insert a tube.
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Thanks, PB. The noise occurred when the tubes were both in the socket.