[dhunte21]

I have a slight popping from time to time in my right channel, on my RM9 MKII I have check for cold solder joint, on both input and output tubes, I have changed out the pots on both sides, Just seems to be a little weird. Sometimes you hear it sometimes you dont, tends to go away after the amp heats up. I also checked the tubes. Just has me scratching my head.

I a currently using Ei 6CA7 from yugoslavia Fat boy tubes.

Also can I use KT88 tubes in my amp, and if so what is the difference?

Thanks.

[dhunte21]

Ok after reading more and more, I think I should change out my tubes and get the ones from roger for this amp, Maybe that could be the reason. I also understand that the 6922 in V1 is very Critical, what about the output tubes.

[Ericus Rex]

I had a similar popping in my Mk I, usually only while warmup.  In my case, it turned out to be failed solder joints at the input tubes' sockets due to rolling.  If you're handy, pop off the bottom and carefully inspect the solder joints on the PCB.  Check the tracings as well.  Could also be a failing tube socket.  These types problems usually effect the input sockets only as the octal sockets don't employ a PCB.

If it's a tube then switch the L and R channel's tubes, one pair at a time.  The popping will then follow the bad tube into the other channel.

I personally suspect the solder joints based on experience so don't go buying new tubes until you've had the amp inspected.  And don't roll the inputs in this amp!!!!

Keep us informed!

[dhunte21]

Well this is the problem when I got the amp, it did not have input tubes so before I truly understood what I had I purchased some 6922 from off ebay and have been using those. Humm could this be the problem..... Also are the output tube as critical as the input? and can I use kt88?

[Ericus Rex]

Well, popping at warmup implies a failed connection, be it a solder joint or a failing socket.  As the socket warmups up, from the tube's filament, the metal parts expand slightly and the connection gets more solid.  Cheap tubes from ebay might be noisy ("shhhhh" sounding) but tube popping is less likely their fault.  The solder connection, and even socket replacement, is a very easy fix.  There is mention of this issue with the RM9 throughout the MR circle.  Next time it's popping at warmup, go over to the amp and tap the top of the input tubes with your finger.  Where your failed connection is will likely become obvious then.

Yes, you can use KT88s in this amp.  I think you can safely run any of the following:  6L6, 6CA7, EL34, KT66, KT77, 6550, KT88 and I believe you can run KT90 in it as well.  Check with Roger about the KT120.  Not sure about that one.

"Critical" is kind of a funny word to use here.  All the tubes in the amp are critical to its functioning.  I personally have found that rolling the inputs and drivers has a very subtle effect on the sound whereas power tube rolling has a drastic effect.  Another reason to buy good 6922s from Roger, install them and leave them put.  You can roll power tubes to your heart's content with no worry of the same problem happening (of course, you can wear out the tube sockets but that takes a LOT of rolling).

[rbwalt]

yea probably a bad driver socket connection on the MB. i had the same problem with my MK2. sometimes you will get a scratchy sound also. yea tube rolling on the drivers not recommended. get the 6922's  or the yugo tube. as far as output tubes  it is going to depend on your speakers. i would stay with the el34's or e34l's. they are the most balanced sounding tube. i am running JJ e34l's in my RM9SE and they are great. very continuous sounding , dam smooth, mids that are more fleshed out and natural, not small sounding and a great bottom end. top end is oh so smooth and silky and not spitty. i had EL34's in it before. KT88's are pushed in the mids. great tube if you have a British style speaker which tend to have holes in the middle. so it makes it sound bigger and fuller.6550's? have not heard great things about them and i was told to stay away from them buy my speaker manufacture.

have fun but choose wisely.

[dhunte21]

Gentlemen thank you, I have the beast up on the bench with the bottom plate off. I have went over the whole amp no bad traces, No puffed Caps, she looks pristine on the inside. You might be right. I did find the original 2 ram 6922 tubes, No if it is a bad tube socket, how the hell do you clean the dam thing, I dont have a brush small enough  . But I will use some Deoxit and try. Oh another thing to add is when it starts to pop the bias light does flicker as well.

[rbwalt]

is it limited to the one channel? if you move the tube to the other side does it do on that channel? might be best to give roger a call. he will know right away.

[GMuffley]

Gentlemen thank you, I have the beast up on the bench with the bottom plate off. I have went over the whole amp no bad traces, No puffed Caps, she looks pristine on the inside. You might be right. I did find the original 2 ram 6922 tubes, No if it is a bad tube socket, how the hell do you clean the dam thing, I dont have a brush small enough  . But I will use some Deoxit and try. Oh another thing to add is when it starts to pop the bias light does flicker as well.

I would suggest resoldering all the tube socket connections to the circuit board.  You may not be able to see a tiny crack with the naked eye.  A microscopic break is enough to cause noise.

[dhunte21]

Well I did move the tubes to the other side and it did not move. So I know it is isolated to the right side.

[thorman]

I had almost exactly what you describe in my Thor Audio preamp. ( Right channel only )  Popping mostly during start up and during the warm up period . Once it warmed up the popping stopped.. The popping got worse as time went on ........I eventually found out from the person who purchased my unit ( noise was disclosed for selling ) that there were 2 bad solder joints . Once re-soldered noise was no longer an issue...As another person described, once the solder joint heated up, it expanded and closed enough for the solder to work properly...Hope that helps.

[dhunte21]

Thanks, are we talking about the solder joint on the Input tubes?

[Ericus Rex]

Thanks, are we talking about the solder joint on the Input tubes?

That's the most suspect location.  But all solder joints should be checked.

As for cleaning tube sockets, I have a hearing aid cleaner that an audiologist friend gave me.  It's the perfect size for getting into tube sockets.  It's got a small brush that looks like a miniature pipe cleaner.  You probably can find them (or something similar) at a drug store.

Keep in mind that the socket could possibly be worn out and no amount of cleaning would fix it.  If that's the case, you may be able to bend the contacts back to shape and keep on truckin but it depends on the design.

[GMuffley]

That's the most suspect location.  But all solder joints should be checked.

As for cleaning tube sockets, I have a hearing aid cleaner that an audiologist friend gave me.  It's the perfect size for getting into tube sockets.  It's got a small brush that looks like a miniature pipe cleaner.  You probably can find them (or something similar) at a drug store.

Keep in mind that the socket could possibly be worn out and no amount of cleaning would fix it.  If that's the case, you may be able to bend the contacts back to shape and keep on truckin but it depends on the design.

Yes

[thorman]

Yah, the solder connections on my Thor unit were problems probably from Tube Rolling. My guess is from years of pulling and pushing in tubes it cause wear and tear on the solder connections on tube sockets. As mentioned check all solder joints and most likely you will find it to be a bad solder....Good luck

[dhunte21]

Thank Gentlemen, I am on it... will keep you posted.