YAQIN MC-13S I have read this is a good amp, I have been getting a very soft popping sound from it i believe. It does not really make sense to me but I hear the noise more when music is playing. Do you think this is related to the amp? My source is my computer and schitt dac.
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Pull the EL34 power tubes and clean the pins and socket contacts with electronics contact cleaner. Replace each tube in it's original position, checking that the pins make nice tight contact in the socket. If they don't, you can carefully bend the contacts with a micro screwdriver.
Do this with the power turned "OFF".
jeff
Do this with the power turned "OFF".
jeff
Reminder, when you pull the tube off, some of the pins in the socket has high voltages even with the power in "off". Depending how the amp is designed, those voltage can stay there from seconds to days. If you are going to poke something into the tube socket, make sure you are insulated and the free hand not touching any thing. The normal process is to discharge all the high voltages before you do this.
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Also check for dry joints, especially grounds and capacitor connections. You can also use a wooden or other non conductive stick to gently prod different parts of the circuit whilst live, but as the others have said, be very careful. This method is only to be used if you have some experience working with high voltage and are familiar with valve amplifiers.
Andy.
Andy.
That's a good point. I always use the "free hand in the back pocket" rule.
jeff
I recently experienced a soft popping sound in one channel of my system. I traced it back to my preamp. One of the 12sn7 tubes was failing. I replaced it and the problem disappeared.
Is your problem only in one channel? I would test with known good tubes before doing anything else.
Steve
Is your problem only in one channel? I would test with known good tubes before doing anything else.
Steve
I also struggle with popping noise.
I’ve already replaced the EL84 power tubes pairs, the drive tubes, yet popping comes out.
After a cold start, the first one arrives ~ 18-20 minutes (whether EL84 or 6p14p is inside), and then approx. It bounces every 15-20 minutes. Sometimes quietly, sometimes quite loudly.
The resistors are SMDs, as shown in the picture.
I measured them in their soldered state, except for 2 resistors, they were around the factory value.
I soldered those two out and measured them so they were already showing absolutely good value (R48-49).
I know I should measure the resistors by off soldered, but I wouldn’t avoid having to desolder every single SMD resistor.
Currently, instead of the EL84 pairs, 6p14p pipes are the power pipes, and maybe it pops up a little quieter, but from time to time it pops up a bit quieter, sometimes louder.
I’ve already replaced the EL84 power tubes pairs, the drive tubes, yet popping comes out.
After a cold start, the first one arrives ~ 18-20 minutes (whether EL84 or 6p14p is inside), and then approx. It bounces every 15-20 minutes. Sometimes quietly, sometimes quite loudly.
The resistors are SMDs, as shown in the picture.
I measured them in their soldered state, except for 2 resistors, they were around the factory value.
I soldered those two out and measured them so they were already showing absolutely good value (R48-49).
I know I should measure the resistors by off soldered, but I wouldn’t avoid having to desolder every single SMD resistor.
Currently, instead of the EL84 pairs, 6p14p pipes are the power pipes, and maybe it pops up a little quieter, but from time to time it pops up a bit quieter, sometimes louder.
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I had previously replaced the original capacitors with those from an official vendor (Mouser), but they didn’t stop popping with them either. I just tried to solder the factory capacitors back, but the same.
Just to cover other possibilities, it's sometimes useful to re-solder the pins on older tubes, particularly the heater pins.
Re-solder the vacuum tube pins themselves? I confess I have never tried. But for lack of a better one, I will watch a youtube video about it.
Miniature tubes like EL84 don't have soldered connections outside the glass afaik - they are welded or crimped. Resoldering pins on the tubes themselves is only valid for tubes with soldered pin bases (octal etc).
I would reflow all the pins on those PCB mount tube sockets and if that doesn't help reflow or replace all the SMD components. Possible that there is a microcrack in an SMD component and it becomes intermittent when it gets warm.
I would reflow all the pins on those PCB mount tube sockets and if that doesn't help reflow or replace all the SMD components. Possible that there is a microcrack in an SMD component and it becomes intermittent when it gets warm.
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Hello,
the problem of popping persists. I replaced the smd resistors, the valve sockets, other tubes are playing. Now just after turning on ~ 5 min it popped. Then approx. half an hour has passed since then and no symptoms. Strange.
the problem of popping persists. I replaced the smd resistors, the valve sockets, other tubes are playing. Now just after turning on ~ 5 min it popped. Then approx. half an hour has passed since then and no symptoms. Strange.
Make sure the popping sound is from the amp itself. What if disconnect any source, does the popping persist?
Hi jxdking,
without any source the popping sound is still there.
The last 2 hours there was only one pop
It is rare but annoying.
without any source the popping sound is still there.
The last 2 hours there was only one pop
It is rare but annoying.
If you have three-phase mains, try to use amplifier from another phase (with long extension cord).
Try to electrically shielding whole amplifier (for example with aluminium folie: Faraday cage).
Try to electrically shielding whole amplifier (for example with aluminium folie: Faraday cage).
Because this is so rare, you probably have not been able to know if it happens in one channel (and which one) or both. After you've very carefully looked at all solder joints ( the first most likely cause) then you'll want to look at the second most likely cause, a noisy valve.
If you don't have a supply of spare valves to swap in for testing, you can still find the problem by listening to each channel alone for long enough to hear (or confidently not hear) the noise by disconnecting each speaker temporarily. If only one channel pops, you can then swap valves between channels, one pair at a time, until you find the culprit. This process costs time, but no money.
If the problem is revealed to NOT be a noisy valve, look again at the solder joints. Other causes are possible, but very rare.
All good fortune,
Chris
If you don't have a supply of spare valves to swap in for testing, you can still find the problem by listening to each channel alone for long enough to hear (or confidently not hear) the noise by disconnecting each speaker temporarily. If only one channel pops, you can then swap valves between channels, one pair at a time, until you find the culprit. This process costs time, but no money.
If the problem is revealed to NOT be a noisy valve, look again at the solder joints. Other causes are possible, but very rare.
All good fortune,
Chris
Not a good idea, valve amps need a load.
This is a job for a scope really, do you have one? First you need to find out where the popping sound is coming from, IE left channel or right channel or both. Then it's a case of narrowing it down to where in the circuit the fault lies which is more tricky.
To find out what channel etc how about using Audacity to record both channel outputs then use the tools to zoom in. You'll need to rig up two attenuators on the OP to reduce the signal into your PC's audio interface. Something like a 10k and 1k resistor across the speaker OP, take an OP from the junction of these, you'll get a rough 10:1 attenuation. You might need to play with the values a bit, a 4k7 and 1k maybe? Solder a lead with a 3.5mm cable from these, plug into your PC.
Andy.
The danger for valve amplifiers without loads is that they might break into oscillation, causing over-voltage arcing in output transformers and/or output valves. This is rare but not impossible, so for classic era high feedback machines a 10R resistor across their outputs is a good idea. Zero feedback modern stuff is safe enough, but "it can't hurt".
Since the OP has disappeared, we may never know the outcome. Subtle, non-damaging, and very intermittent problems are the most difficult to resolve. But it can be done by patiently isolating to a particular channel, or both, then if one, by swapping parts between channels. Lotsa work, but fortunately not rocket surgery.
All good fortune,
Chris
Since the OP has disappeared, we may never know the outcome. Subtle, non-damaging, and very intermittent problems are the most difficult to resolve. But it can be done by patiently isolating to a particular channel, or both, then if one, by swapping parts between channels. Lotsa work, but fortunately not rocket surgery.
All good fortune,
Chris
Completely agree Chris, many guitar heads have a 1k across the OP for such cases. I've forgotten to connect a dummy load/speakers a few times and got away with it.
OP was here on Friday ( today Sunday) perhaps he's cogitating?
Love the John Dee quote BTW, he was a character, born out of time.
Andy.
OP was here on Friday ( today Sunday) perhaps he's cogitating?
Love the John Dee quote BTW, he was a character, born out of time.
Andy.