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Cant stop popping

Crang

Crang

Well-Known Member
My RM-9 started making popping sounds about 3-5 minutes after startup. Removed tubes till I figured out which socket- reinserting the tube was enough to fix it or so I thought. A week later it happens again, so I deoxit all sockets and tube pins. Buys me 3 more days and just started again just a few minutes after startup.

Bad contact in the socket? Bad solder joint? What to do when I open it back up?

Reseating the tube every few days isnt a good long term solution......
 
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Crang said:
My RM-9 started making popping sounds about 3-5 minutes after startup. Removed tubes till I figured out which socket- reinserting the tube was enough to fix it or so I thought. A week later it happens again, so I deoxit all sockets and tube pins. Buys me 3 more days and just started again just a few minutes after startup.

Bad contact in the socket? Bad solder joint? What to do when I open it back up?

Reseating the tube every few days isnt a good long term solution......
Click to expand...
Replacing the tube with a new would answer this.
 
peterh said:
Replacing the tube with a new would answer this.
Click to expand...

Since its one of a matched quad that requires a lot more tubes. Hoping to diagnose without spending a couple hundred dollars. I had one tube of the quad go bad already (was flashing along with popping) and it took me months of talking to vendors to find one single tube that could match this set. And it was a one time deal so I probably cant get a single to fill in.

I have swapped in a non matched tube- amp ran fine. Switched the 'bad' tube back and amp ran fine for 5 days then back to popping.
 
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Depending on where you bought the tube, if they were matched, the specs should be on the box or on a sticker on the base of the tube. You can contact the company you bought them from and get a new tube that matches what they sold you. I had to do this with a quad of KT-77's.
 
Lavane said:
Depending on where you bought the tube, if they were matched, the specs should be on the box or on a sticker on the base of the tube. You can contact the company you bought them from and get a new tube that matches what they sold you. I had to do this with a quad of KT-77's.
Click to expand...
Its a RAM tube only offered by them. I have the specs and contacted them. As mentioned I already bought the only one they have left that matches this set when another one went bad. There are no more so it would require a new quad which Im trying to avoid.

With all the focus on the tube no one thinks its the socket or solder then?
 
Crang said:
Its a RAM tube only offered by them. I have the specs and contacted them. As mentioned I already bought the only one they have left that matches this set when another one went bad. There are no more so it would require a new quad which Im trying to avoid.

With all the focus on the tube no one thinks its the socket or solder then?
Click to expand...

I have had a failing coupling capacitor cause popping.
Since I didn't have the equipment necessary to check capacitors at high voltage, and the capacitor was inexpensive, I just went ahead and replaced it solving the problem in my amp.
 
If you can determine who made the tube for them, you can get one made by the company that originally made the tube. Mesa uses a Chinese brand a lot. Rebranded tubes are pretty common.
 
Pablodeux said:
I have had a failing coupling capacitor cause popping.
Since I didn't have the equipment necessary to check capacitors at high voltage, and the capacitor was inexpensive, I just went ahead and replaced it solving the problem in my amp.
Click to expand...

All the electrolytic capacitors were replaced last year. The only ones not replaced are the original film Wondercaps used as output coupling capacitors. I dont know enough about this stuff- would one of those going bad be able to cause this? There are 2 per channel so would need 4 new ones of decent quality- looks like about $80.

Lavane said:
If you can determine who made the tube for them, you can get one made by the company that originally made the tube. Mesa uses a Chinese brand a lot. Rebranded tubes are pretty common.
Click to expand...

Shuguang. Havent had much luck sourcing a replacement.
 
Crang said:
All the electrolytic capacitors were replaced last year. The only ones not replaced are the original film Wondercaps used as output coupling capacitors. I dont know enough about this stuff- would one of those going bad be able to cause this? There are 2 per channel so would need 4 new ones of decent quality- looks like about $80.



Shuguang. Havent had much luck sourcing a replacement.
Click to expand...

I wouldn't expect electrolytic power supply caps to cause popping, but coupling caps are suspect.
For diagnostic purposes, installing an inexpensive film cap such as Solen brand or other film cap of the same capacitance and voltage rating as the original can be used.
These should only cost a couple of dollars each.
If you are careful removing the original caps one at a time, and doing a listening test after each replacement, you can reinstall good caps, and only spend the big bucks on the bad one.
If this wasn't causing the problem, you're only out a couple of bucks for one cap used for testing.
 
Crang said:
Its a RAM tube only offered by them. I have the specs and contacted them. As mentioned I already bought the only one they have left that matches this set when another one went bad. There are no more so it would require a new quad which Im trying to avoid.

With all the focus on the tube no one thinks its the socket or solder then?
Click to expand...
You might consider switch supplier.. and buy a new quad at a serious supplier.
You already diagnosed one tube as your problem, changing other stuff won't help. It's
a bad tube.
Eurotubes.com sells matched quads and will most likely supply replacement tubes if
you need.
 
peterh said:
You might consider switch supplier.. and buy a new quad at a serious supplier.
Click to expand...

I can't vouch for RAM Tubes now, even though they have the same extensive and unique tube matching equipment, but when Roger M. (RIP) was running it you could not find a more serious supplier. Hopefully the new people are doing their best and learning.

FWIW Eurotubes is pretty far down on my list for purchases here in the US.
 
Noise in one channel or both?

Both channels implies something common between the channels. One channel would obviously be not-common. If its not common, switch the tubes side to side and see if it moves.
 
Could also be a resistor causing noise as it heats up. If a tube socket is the culprit, when it starts making noise, carefully and gently rock the tubes in their sockets and observe the outcome.
 
cademan said:
Could also be a resistor causing noise as it heats up. If a tube socket is the culprit, when it starts making noise, carefully and gently rock the tubes in their sockets and observe the outcome.
Click to expand...

That may be the ticket. Its either the tube or the socket and intermittent which is always fun. I realized I could run the amp with only a pair of EL34s per side so I pulled half of them and have some extra tubes to move around. The only one I replaced was at the tube/socket location and its running fine now BUT that doesnt mean to me its the tube. When I pull just the bad tube and put that one it back in it also fixes it for a few days. I'll run this alternate there for a week and see if it comes back. If it doesnt it was the tube. If it does maybe the socket.

opnly bafld said:
I can't vouch for RAM Tubes now, even though they have the same extensive and unique tube matching equipment, but when Roger M. (RIP) was running it you could not find a more serious supplier. Hopefully the new people are doing their best and learning.

FWIW Eurotubes is pretty far down on my list for purchases here in the US.
Click to expand...

This was my first tube amp project- I got it for part or repair and Roger (RIP) was helping me rebuild it long distance when he passed. I had some health issues too so it sat for another year or so and I finally got it working so still working out the gremlins. The guy who works there now is probably sick of me trying to get replacement tubes to match the quad I bought from Roger 2 years ago. Ive been trying for about a month to get the first replacement sent but its at the warehouse so apparently not a place he is often. Guess its a moot point if I lost a 2nd of the quartet. Kind of leery about buying 4 more if 2 of the last 4 didnt even make it to 60 hours use.
 
Crang said:
My RM-9 started making popping sounds about 3-5 minutes after startup. Removed tubes till I figured out which socket- reinserting the tube was enough to fix it or so I thought. A week later it happens again, so I deoxit all sockets and tube pins. Buys me 3 more days and just started again just a few minutes after startup.

Bad contact in the socket? Bad solder joint? What to do when I open it back up?

Reseating the tube every few days isnt a good long term solution......
Click to expand...

Inspect the solder points on the sockets. One cold solder, especially across a wire under tension, can cause periodic pops that'll drive you crazy. I usually re-flow some good solder, as a preventative measure.
 
I think the amp has probably got a gremlin that needs to be sorted and corrected prior to expecting a set of tubes to match up and work together long term.
Once the amp works and makes reasonable power (~90 % of rated) reliably, for days on end then buy a set of matched tubes.

Forgive the automotive analogy but if your tire is worn out due to failed suspension, the next new tire is also going to fail. It would be a colossal waste of money to put 4 tires on a car with bad ball joints for instance.
The tires will be wasted in no time and the ball joints will not be any better and you'll still need to fork over the same amount of cash, for another set of tires and done new ball joints.
Putting new tubes in an amp that wastes tubes because it has a problem is going to smoke those tubes and the problem will remain.
Do you have a tech you can trust?
 
Mr Boochie said:
Inspect the solder points on the sockets. One cold solder, especially across a wire under tension, can cause periodic pops that'll drive you crazy. I usually re-flow some good solder, as a preventative measure.
Click to expand...

One of the known pitfalls of this amp is the driver tube sockets are soldered onto a PCB and in an area of high heat. Random popping is often these joints going bad just from changing tubes. I reflowed those when I changed the caps but I did not touch the EL34s sockets hard mounted to the top plate. Ive changed the driver tubes one single time since redoing the solder but thats not a whole lot of stress- will reflow them again next time its opened back up. For now we are on day 2 of it functioning pop free changing the one tube out. I do suspect its that socket since reseating the potentially bad tube would fix it a few days.

If it starts popping with the current tube in I just realized I have an empty pair of sockets on each side since Im running it with a half compliment of tubes. Try those sockets next and see if it comes back.

trainbuftony said:
Do you have a tech you can trust?
Click to expand...

Yes but they are a 6 week wait and quite expensive. Only one person in town who will touch this amp (Ive tried everyone). The tech had it a month ago after I had a mishap firing it up with a short, and wanted to get a health check. It got a clean bill of health- he had it run for 5 days checking periodically.
 
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