static/crackling in left channel

[atom631]

After getting the voltages sorted, Ive been using the amp for quite a few hours between yesterday and today. Sounds absolutely amazing, but I noticed that there is a slight static and crackling sound coming from the left channel. Its very faint and only audible when there is dead silence. Almost sounds like turntable static. I have tried a different  6080 and 12AU7 tubes and that didnt make a difference. I then was going to unplug the RCAs and swap them to see if the noise happened in right channel. But when I unplugged the RCAs, there was still the static/crackle coming from the left channel without the cables being plugged in. I tried re-soldering all the contacts on the headphone jack and that didnt seem to make a difference either. I also tried different headphones and a different cable. No change.

Here is a pic for reference, any ideas?

 

[Paul Birkeland]

What wattage is your soldering iron?  What kind of solder are you using?

This is either a cold iron, lead free solder, or just not enough dwell time with the iron to get the solder to flow out properly. 

Do note that the LEDs and power switch are sensitive to being overheated, so I do not recommend reflowing those joints unless you are able to spot a specific issue.

 

[atom631]

What wattage is your soldering iron?  What kind of solder are you using?

This is either a cold iron, lead free solder, or just not enough dwell time with the iron to get the solder to flow out properly. 

Do note that the LEDs and power switch are sensitive to being overheated, so I do not recommend reflowing those joints unless you are able to spot a specific issue.

I used a Hakko FX888D-23BY iron @ 750 degrees. I believe this unit is 70w. I used Cardas Audio Quad Eutectic Solder.

Is there specific terminals I should reflow?

 

[Paul Birkeland]

I would go into the manual for the FX888 and examine the instructions for raising the temperature vs. the instructions for calibrating the probe.  It's so easy to think you're cranking up the temperature on the iron when instead you are calibrating the probe and telling the iron it's hotter than it actually is. Once armed with this information, I would set it to 899 degrees for reflowing your joints.

 

[atom631]

I would go into the manual for the FX888 and examine the instructions for raising the temperature vs. the instructions for calibrating the probe.  It's so easy to think you're cranking up the temperature on the iron when instead you are calibrating the probe and telling the iron it's hotter than it actually is. Once armed with this information, I would set it to 899 degrees for reflowing your joints.

ok, ill do that. do you recommend i reflow every joint (with the exception of the power switch and LEDs) or just the joints for the left channel?

also - should i add solder, or just reflow with whats on there already?

 

[atom631]

I tried to reflow and add solder to joints that looked like they could've used a little more and Im still hearing the crackle.

here are some more detailed pics.

 

[Paul Birkeland]

I see at least one black wire on the volume pot that doesn't look like solder has flowed around it.  The same goes for at least one of the white wires on the pot.  Were you able to turn the iron up to 899?

5U and 5L could use a little more heat to really flow out all the way.

 

[atom631]

I see at least one black wire on the volume pot that doesn't look like solder has flowed around it.  The same goes for at least one of the white wires on the pot.  Were you able to turn the iron up to 899?

5U and 5L could use a little more heat to really flow out all the way.

Yes, I got the iron up to 899. I reflowed and add a little solder to 5U/5L and the black leads on the volume pot. Still have the static.

here are the after pics.

 

[Paul Birkeland]

The other test you can do is to put an inexpensive set of headphones on and plug them into the amp, then poke around with a wooden chopstick to see if you can poke anything in particular to make the noise start or stop.

 

[atom631]

The other test you can do is to put an inexpensive set of headphones on and plug them into the amp, then poke around with a wooden chopstick to see if you can poke anything in particular to make the noise start or stop.

spent the better part of an hour doing this. poking, proding, tapping, moving to no avail. I did find a wire that looks like I touched with the iron and burned off some of the jacket, I was thinking maybe that was it, but i replaced it and no dice.

I tried gently wiggling the tubes, power cord, RCAs, volume knob and headphone jack and it didnt make a difference.

if i lower the volume knob all the way down to 0, I still hear it. Raising it all the way up doesnt change the level of the static.

i tried re-seating the fuse and flipping it around.

i tried a thicker power cable and moving entirely away from any  other electronics.

is this the point where i start replacing parts? or could it be one of the tube sockets may dirty? if so, what can I try cleaning them with?

 

[Paul Birkeland]

Yes, you can clean the tube pins just in case.  The sockets are brand new, so definitely leave them alone.  Also refrain from introducing deoxit into this equation.  To clean the tube pins, you can plug in and remove each tube 4-5 times and that will generally burnish the contacts nicely.  Also if you have a really specific description of the noise, some things that people consider to be static can be interference from nearby wireless devices.

 

[atom631]

Yes, you can clean the tube pins just in case.  The sockets are brand new, so definitely leave them alone.  Also refrain from introducing deoxit into this equation.  To clean the tube pins, you can plug in and remove each tube 4-5 times and that will generally burnish the contacts nicely.  Also if you have a really specific description of the noise, some things that people consider to be static can be interference from nearby wireless devices.

with the amount of times I plugged and unplugged the tubes yesterday, they should definitely be clean.

i moved the amp as far away from any wifi devices and tried and it didnt change. I would say the closest wifi device was at least 10’ away.

the best I can describe the noise im hearing is almost like the static you hear when you put the needle down on a record on a cheap turntable, just before the music starts. its a bit of static with a little crackle.

the thing is, its not constant. sometimes it disappears for a few seconds. sometimes it will get a little louder. when it gets a little louder it can sound almost like a faint wind gust. like someone blowing into a microphone. but keep in mind its very faint. once the music starts, i cant hear it until there is a quiet dip in the track. I would chalk it up to some sort of distortion, but its only occurring in the left channel.

 

[Mucker]

I have built 4 Bottlehead products and concur it's most likely a solder issue. I would reflow all of them especially the black wires but be extra careful with the led's and power switch as they are less tolerant to high heat. I'm sure you will track it down.

Do you have a different headphone to try?

 

[atom631]

I have built 4 Bottlehead products and concur it's most likely a solder issue. I would reflow all of them especially the black wires but be extra careful with the led's and power switch as they are less tolerant to high heat. I'm sure you will track it down.

Do you have a different headphone to try?

Ive tried 2 different headphones. same thing.

i will try to reflow the black wires again. perhaps i will buy more LEDs and a switch in case i fry them.

no chance this an issue with the jack itself?

 

[Mucker]

It's entirely possible it has to do with the jack. Usually the black wires there are normally the culprit. Maybe try moving them around, adjusting them while the heat is on. Plus make sure all the wires at terminal 3 are secured well.

 

[atom631]

It's entirely possible it has to do with the jack. Usually the black wires there are normally the culprit. Maybe try moving them around, adjusting them while the heat is on. Plus make sure all the wires at terminal 3 are secured well.

i reflowed all the black wires, including the LEDs and the switch. no change. also had my wife take a listen to make sure im not losing my mind and she hears it too.

here are some pics. i tried to get as close as possible and capture every joint.

part 1

 

[atom631]

part 2

 

[atom631]

part 3

 

[atom631]

part 4

 

[Paul Birkeland]

The left RCA jack ground lug and the chassis earth lug by the power entry module do not look adequately soldered, just as an example.