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December 02, 2021, 01:37:32 AM

Author Topic: Volume independent noise on right channel  (Read 172 times)

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Offline dima424658

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Volume independent noise on right channel
« on: November 22, 2021, 10:25:42 AM »
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
« Last Edit: November 22, 2021, 10:33:38 AM by dima424658 »

Offline Thermioniclife

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Re: Volume independent noise on right channel
« Reply #1 on: November 22, 2021, 10:52:16 AM »
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.
Lee R.

Offline Doc B.

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Re: Volume independent noise on right channel
« Reply #2 on: November 22, 2021, 12:17:01 PM »
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.
Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline dima424658

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Re: Volume independent noise on right channel
« Reply #3 on: November 23, 2021, 03:33:34 AM »
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 ()
« Last Edit: November 24, 2021, 10:54:28 AM by dima424658 »

Offline Thermioniclife

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Re: Volume independent noise on right channel
« Reply #4 on: November 23, 2021, 05:28:14 AM »
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.
Lee R.

Offline dima424658

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Re: Volume independent noise on right channel
« Reply #5 on: November 23, 2021, 08:35:00 AM »
I live in Russia in an old apartment building and i have only phase and zero carried out

Offline Doc B.

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Re: Volume independent noise on right channel
« Reply #6 on: November 23, 2021, 09:11:12 AM »
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.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline dima424658

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Re: Volume independent noise on right channel
« Reply #7 on: November 24, 2021, 10:52:33 AM »
It's not harsh, the sound is more like a beep ??? at a few kilohert
ive tried to record it, but nothing came out :-[
« Last Edit: November 24, 2021, 10:56:05 AM by dima424658 »

Offline Deluk

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Re: Volume independent noise on right channel
« Reply #8 on: November 24, 2021, 12:45:15 PM »
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.

Offline Doc B.

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Re: Volume independent noise on right channel
« Reply #9 on: November 24, 2021, 03:16:40 PM »
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.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline dima424658

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Re: Volume independent noise on right channel
« Reply #10 on: November 25, 2021, 03:37:58 AM »
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
« Last Edit: November 25, 2021, 04:05:22 AM by dima424658 »