Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: dima424658 on November 22, 2021, 10:25:42 AM
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Hey there! Recently assembled the amp, and I have noise that comes mainly from the right channel. only new pot installed - ALPS RK27 Blue Velvet 250KOhm, everything else is standard. But there was the same noise with standard potentiometer installed :'(
The sound appears ten seconds after switching on and gradually increases regardless of rca jacks connected. Tolerable, but when nothing is playing, it's quite intrusive.
The soldering isn't perfect but i double-checked all the joints and it seems okay. Also i have no grounding in the house, but I use a Pilot XPro surge protector
Voltage check:
1. 81.6
2. 170
3. 0
4. 170
5. 84.9
6. 0
7. 106
8. 0
9. 107
10. 0
Resistance check was perfect, except RCA jacks: red has 210KOhm, and white has 217KOhm
P.S. I looked for this problem on the forum, but found nothing
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Having no ground in your house is troubling. How do you know you do not have a ground? The fact that you used a 250k pot in lieu of the 100k pot supplied will change the resistance test. You must have a safety ground as this is what protects you if somthing shorts to the chassis, in this manor it will blow the fuse instead of blowing your eyelashes off, possibly worse.
You should reheat all solder joints except the power switch and the hlmp 6000 leds and add a tiny amount of solder as a good start.
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Double checking joints is best done by reflowing them. You can't necessarily spot anything out of the ordinary on a cold solder joint by looking at it.
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Having no ground in your house is troubling. How do you know you do not have a ground? The fact that you used a 250k pot in lieu of the 100k pot supplied will change the resistance test. You must have a safety ground as this is what protects you if somthing shorts to the chassis, in this manor it will blow the fuse instead of blowing your eyelashes off, possibly worse.
You should reheat all solder joints except the power switch and the hlmp 6000 leds and add a tiny amount of solder as a good start.
The house is not grounded at all :-\ because of this i had noise on vinyl, but buying a surge protector solved the gap.
Also I did rejoint and it doesn't help(
Could there be a problem with the tubes? When I just warmed them up, clicks were heard, as if the engine was muffled (youtu.be/GCcvOx70VA8 (http://youtu.be/GCcvOx70VA8))
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I find it hard to believe you have no ground. Do you live in the USA? Do you have three prong outlets? If you have no ground you have much more serious issues besides noise on your Crack.
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I live in Russia in an old apartment building and i have only phase and zero carried out
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That clicking sound is pretty normal and is not usually associated with hum. It's from the metal parts inside the tube expanding as they heat up.
Is the hum you are hearing in the right channel a soft low hum, or is it buzzy and harsh? A soft low hum might be from a tube, but it could be from other things. A harsh buzzy hum is usually from a cold solder joint at a ground connection, or from hardware that is not mounted tightly to the chassis panel.
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It's not harsh, the sound is more like a beep ??? at a few kilohert
ive tried to record it, but nothing came out :-[
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Are the diodes on the transformer side positioned correctly? Even if they are they are very close to touching themselves and adjacent wires. See the manual. The white wire from/to the headphone jack isn't ideally routed. Certainly not per my Crack and the manual.
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If the noise is at a few kilohertz it might be a tube oscillating or it might be that you are picking up noise from a wireless router or some other device in the apartment. You might try cleaning the tube pins with some fine sandpaper or steel wool.
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Are the diodes on the transformer side positioned correctly? Even if they are they are very close to touching themselves and adjacent wires. See the manual. The white wire from/to the headphone jack isn't ideally routed. Certainly not per my Crack and the manual.
I've double-checked diode connection and its okay. About the fact that they are located close: is it worth insulating the exposed parts of the diode? As far as I remember in the documentation they are located just as close
If the noise is at a few kilohertz it might be a tube oscillating or it might be that you are picking up noise from a wireless router or some other device in the apartment. You might try cleaning the tube pins with some fine sandpaper or steel wool.
Just polished all pins and nothing changed. Maybe I need Speedball upgrade? I've heard that it reduces the amount of noise
I think that the tube path is quite sensitive to interference, like vinyl. given the bad wiring in my apartment, the problem is most likely in it.
Despite this, the sound is just great, thanks to doc B. and community for that, I listened to much more expensive amplifiers, and they did not even come close to giving me the feelings that I get from listening now
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I listened to my crack in an audio store with high-end wires and there is no noise at all, deadly silence ;D. So Ill think towards suppressing noise in my system
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How about rigging a ground wire to a water pipe or maybe a radiator, see if it affectes the noise...John
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How about rigging a ground wire to a water pipe or maybe a radiator, see if it affectes the noise...John
nothing has changed, still the same noise
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I had a very faint fuzzy sound and sometimes a crackle in my left channel... I could only hear this with no music playing.
It was one of the 21.1k resistors at 4u 5u that didn't have good contact. I reflowed all the joints and it was still the same , only when I desolderd that resistor and made the connection better the problem went away . Reflowing didn't fix it.
Also at 5 lower I may of had a piece of insulation melted inside the connection.
So try the resistor at 1u 2u also make sure the resistor is not touching the terminal leave a gap , (mine may have also been touching or a bit close to the terminal)
Hope this helps.
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So the issue was in 6AS7G tube :-\
I've installed 6Ð5С instead and the amp is deadly silence now! ;)