#1
Hello, this is essentially a continuation of https://www.ultimate-guitar.com/forum/showthread.php?t=1680429 , but since this has developed into something completely different than what that thread was actually about, I guess it makes more sense to create a new one.

So, the amp is Laney IRT60, and it's honestly beyond awesome - still learning a bit to EQ it the best for my tastes, but it's genuinely amazing for metal, and sounds great for pretty much everything from clean through all stages of gain.

The only issue is the annoying crackling, which has been there since the beginning. It's rather inconsistent, sometimes it gets louder and more intense, sometimes it fades almost completely, but as a general rule, it's pretty much completely drowned out when playing with high gain and not an issue, but is a bit of a nuisance when playing clean or low-gain.



I did as you advised me and checked if the tubes are loose. They seem all to be firmly in place (generally it feels the way this amp is built, nothing that isn't supposed to move has the right to move in any way everything is screwed firmly in place), the only one I found mildly suspicious is the first preamp tube, labeled ECC83S, which looks different than the other three, and when tapping it lightly, it sounds like if something was loose inside it. I have no idea if this is normal due to it being different than the others.

After putting everything back together (I did literally nothing meaningful inside), it seems now fairly obvious that one of the tubes might be the issue, as for the first time the tone started getting weirdly muddy with high gain, especially with chords, and also for the first time absurd feedback started appearing. It still sounds fine with clean or lower gain (besides the crackling of course).

So, to the point, my questions:
1) Based on this, is this likely to be one of the power tubes, or the preamp tubes?
2) In order to determine which one it is, can I turn on the amp without one of the tubes without any risk? This is the most important question, it would be nice to determine which one has to be replaced before actually ordering a new one.
3) If it's the preamp tubes, can I swap just the one that turns out to be the culprit, or do I have to change all of them like the power tubes?
4) And, well, is there any reason why I shouldn't change the tube(s) myself if it turns out to be necessary? It seems like a simple enough process.

I'd be immensely grateful for help, if I get this fixed I can officially enter the "can no longer blame anything on gear" club discussed in the other thread.
Last edited by TheLiberation at Aug 3, 2015,
#2
Sounds like a preamp tube, swap them out individually. Always worth having a few spares anyway so buy one if you don't have any. Take one out, put the new one in, if the issue persists replace the original and continue with the rest b

Could be a microphonic tube if you're experiencing feedback issues too.

As for changing them yourself, pull out and plug in. Just make sure the power is off.
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#3
tap on each tube with the amp on and see if the crackling sound occurs.
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#4
Quote by jon_six
tap on each tube with the amp on and see if the crackling sound occurs.

If you are gonna do this, use the eraser end of a pencil, NOT your finger.
#5
Quote by GABarrie
Sounds like a preamp tube, swap them out individually. Always worth having a few spares anyway so buy one if you don't have any. Take one out, put the new one in, if the issue persists replace the original and continue with the rest b

Could be a microphonic tube if you're experiencing feedback issues too.

As for changing them yourself, pull out and plug in. Just make sure the power is off.

OK, I guess that's what I'll do.

The manual claims the preamp tubes are "4x 12AX7/ECC83 preamp tubes" (so they're supposed to be identical), it seems like I can easily order the EHX 12AX7EH tubes (exactly these: http://www.musiciansfriend.com/preamp-tubes/electro-harmonix-12ax7eh-preamp-tube ) - these should do? (On a related note, I think the stock tubes inside are these: http://www.musiciansfriend.com/preamp-tubes/ruby-ecc83-12ax7a-preamp-tube?pfm=sp ) Sorry if this question is immensely dumb but just not sure how to read the "EH" at the end and I don't want to screw anything up.

And so, in that case, I can just order one or two, no need to change all four if just one turns out to be bad?

tap on each tube with the amp on and see if the crackling sound occurs.

Thanks, but I think I'll go with the option of just trying with a new one after swapping them with the power off... I'm not really comfortable doing anything inside with the amp plugged in.
Last edited by TheLiberation at Jul 26, 2015,
#6
No. Go for one of these.
https://www.tubedepot.com/products/jj-ecc83s-12ax7-preamp-vacuum-tube

The EH suffix just means Electro Haromics. Ignore it. They're a pretty shitful tube. Ignore it altogether.
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Last edited by Cathbard at Jul 26, 2015,
#7
Quote by Cathbard
No. Go for one of these.
https://www.tubedepot.com/products/jj-ecc83s-12ax7-preamp-vacuum-tube

The EH suffix just means Electro Haromics. Ignore it. They're a pretty shitful tube. Ignore it altogether.

+1

The only place I'd use an EH is as a reverb driver/recovery if you wanted a bright sparkly reverb. They're very bright tubes, and the quality isn't there to put them in the main signal path.
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#8
Alright, I found a store that has these available. The fun part is that they're actually cheaper than the EHX. Thanks.

The even funnier part: the first preamp tube that's in the amp seems to be exactly this one. The remaining ones are the Ruby tubes.
#9
EH (ElectroHarmonix) is one of a whole bunch of brand names owned by a company called New Sensor. The tubes are all made by the same Russian plant that makes Sovtek tubes. If you insist on having that branding paint slathered on your tubes, you can still buy them at Tube Depot for $11.95.

The JJ's recommended by Cathbard ($9.95) are made in the Slovak republic and are excellent.

I pay another buck each for mine - $11.00 -- and buy them from Bob at Eurotubes: http://www.eurotubes.com/store/pc/viewCategories.asp?idCategory=37

Tube Depot tubes are just fine and there's no reason for you to do that. Eurotubes has more sophisticated testing gear and I can get some tubes within a particular spec, which is not something that you need to deal with.
#10
Quote by TheLiberation
Alright, I found a store that has these available. The fun part is that they're actually cheaper than the EHX. Thanks.

The even funnier part: the first preamp tube that's in the amp seems to be exactly this one. The remaining ones are the Ruby tubes.


You didn't buy this amp new?

Do some reading and learn about the significance of the V1 tube in most tube amps.
Or go to the encyclopedia and ask Catbreath....er...Catbard.

And while you're at it, feel free to replace the Ruby branded tubes with JJ's down the line.

There ARE some differences in preamp tubes, mind you, but these get a bit cork-sniffy, and at this point in your tube amp career, not worth messing with.
#11
Quote by dspellman
EH (ElectroHarmonix) is one of a whole bunch of brand names owned by a company called New Sensor. The tubes are all made by the same Russian plant that makes Sovtek tubes. If you insist on having that branding paint slathered on your tubes, you can still buy them at Tube Depot for $11.95.

The JJ's recommended by Cathbard ($9.95) are made in the Slovak republic and are excellent.

I pay another buck each for mine - $11.00 -- and buy them from Bob at Eurotubes: http://www.eurotubes.com/store/pc/viewCategories.asp?idCategory=37

Tube Depot tubes are just fine and there's no reason for you to do that. Eurotubes has more sophisticated testing gear and I can get some tubes within a particular spec, which is not something that you need to deal with.

Nah, I honestly don't care about the brand (especially, that, you know, I didn't know which one has any kind of reputation in this field...), it's just that these were the ones that were available in the store that I usually order stuff from and thought they should be fine.

I just ordered two of the JJs though (and as I said, actually for even cheaper), I found a store that seems to sell just tubes of all sorts so if I ever need more it seems I'm covered.

Thanks a lot for the answers - waiting for them to arrive (I won't have that much time to play the next two days anyway), and hopefully I'll find out which one has been the cause of this.
#12
Quote by TheLiberation
Thanks, but I think I'll go with the option of just trying with a new one after swapping them with the power off... I'm not really comfortable doing anything inside with the amp plugged in.

It is not hard to do and you're going to need to learn to do it anyway.

I made a video with people just like you in mind. It will help you. You can actually pull preamp tubes (not the phase inverter) while the amp is on. They do get hot though so a good pair of work gloves are good to have.

http://vid545.photobucket.com/albums/hh384/buckethead_311/Amp%20stuff/Microphonicpreamptube.mp4

I've bought a bias probe from Bob at Eurotubes but I don't buy into all the snake oil hype on tubes the way he sells them and his biasing video's are lacking.

I prefer Doug at www.dougstubes.com and Laura at www.valvequeen.com

JJ's are what I'd go for as well, unless you want to spend a bit more and a.) get NOS tubes or b.) experiment with different tones.
#13
Well, worst case scenario (sort of): seems like it's none of the preamp tubes.

The new JJs arrived today (I got two, one extra to have as a backup), I picked one of the two new ones and tried replacing each of the four preamp tubes one by one, turning on the amp after each swap, and the crackling was there in every case. Also tried swapping them all around, with no difference whatsoever. The sound also still gets weirdly muddy and "deformed" with chords on high gain.

Another idea that won't leave my head: could it be one of the 6L6 tubes? It won't stop bothering me, especially the left one is kind of suspicious, as a) it seems to heat absurdly quickly (after turning on the amp for half a minute or so the preamp tubes and the other power tube were just mildly warm, this one was already hot), b) it seems to have a weird blue-ish kind of glow inside it (which the other 6L6 does not have), c) and the final thing that just won't stop bothering me: they're not equal in size (the right one is visibly bigger), even though most 6L6 tube pairs I found looked identical.

I have no idea if this makes sense, but I'm not sure what to do now, and I'm sort of annoyed. Still, wouldn't it be logical if the issue is the most obvious if the amp is pushed with high gain?

If it's actually one of the power tubes, can I replace just one, or do I need to replace both at once? I'm confused.

Thanks a lot in advance for any help.
#14
I wish I'd looked in this thread sooner! I have an IRT 120 and I had similar issues. First thing I'd say is don't crank the reverb, that can add some noise that even my noise gate can't cut out. Which also leads me into suggesting you get a noise gate. It can be a noisy amp, especially with gain cranked + boost engaged. I got the ISP Decimator G String II and it's perfect, silences all noise including the weird noises the preamp produces.
I had the same weird muddy sound on chords when distorted. It's like it added a load of bass, and it sounded flabby. Turns out it was my 1st tube, so I put one in (I bought 3, can't remember what's in there. Think it was a hi grade gold groove tube or something) and it did fix that problem. The slight crackling still persists but my noise gate sorts that out
I haven't changed the power tubes yet and they seem to still be going fine (had mine about a year now) and yes all 2/4 will need swapping. I don't know if you can swap the preamps while the amps turned on, I'd like to know that too though, would make diagnosing a LOT easier! Maybe check your amp settings too. It needs tweaking depending on volume, and it depends what other stuff you have feeding your tone pedal-wise. The dynamics high can add a lot of flub, and the boost high with high preamp gain can cause some smooth clipping effect like a fuzz. I love it for lead lines, but it does muffle quite a bit when playing chords.
Let me know if there's anything else I can help with!
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#15
I'm pretty sure it's rather something being wrong rather than just regular amp noise - the crackling really gets in the way of clean tones at its worst, and as I said it doesn't get louder with more distortion, to the contrary - it gets completely drowned out by a high-gain tone.

Also, the weird muddiness with high gain started appearing later - it sounded perfectly clear and great before with the exact same amount of gain and volume. I also do have a noise gate (the regular ISP Decimator II) which does great with any regular noise, but the crackling appears even without a guitar plugged in.
#16
Quote by TheLiberation

Another idea that won't leave my head: could it be one of the 6L6 tubes? It won't stop bothering me, especially the left one is kind of suspicious, as a) it seems to heat absurdly quickly (after turning on the amp for half a minute or so the preamp tubes and the other power tube were just mildly warm, this one was already hot), b) it seems to have a weird blue-ish kind of glow inside it (which the other 6L6 does not have), c) and the final thing that just won't stop bothering me: they're not equal in size (the right one is visibly bigger), even though most 6L6 tube pairs I found looked identical.


Thanks a lot in advance for any help.


That would have been good information to include initially. Get a matched set of power tubes.
“Ignorance more frequently begets confidence than does knowledge.”
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#17
If it isn't the tubes, there's a slim chance it might be power tubes but it sounds shockingly like an issue I had with my JCA which was arcing in the cathode follower driving the tone stack.

That isn't something you can easily fix though.

Remove V3 and see if the crackling goes away
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#18
My Valveking made cracking noises at one point and I'm pretty sure it was because a pin was arcing with the board. I just put a new tube and made sure it was seated real well and the problem went away.

Good luck.

The blue hue is normal - but I would expect to see the same on all power tubes, but not necessarily. I wouldn't worry about that.
#19
If a tube is arcing you should be able to pull it and see black carbon traces on the socket. My Fender Champ was arcing across both power and rectifier tubes, I went through 3 sets of sockets before finding out it was a bad capacitor. If you see carbon traces on a tube socket, it needs to be replaced, it provides an easy path for future arcing.

Tapping the tubes to check for where the crackling is coming from won't hurt a thing. It's also done on circuit boards a lot, called the chopstick test. If you push on the board and it crackles, you just found a loose solder joint or bad part. I use an all plastic screwdriver designed for adjusting TVs because it is not conductive. Believe me you do not want to get shocked, tube amps are deadly.

You can also pull tubes while it is plugged in, just turn it off. Yes you can pull some tubes while it's on, I prefer to shut it down.

One other possibility that's not been mentioned, I just had this problem with a Fender Pro Jr I bought recently.

Bad solder joints - My Pro Jr had several bad solder joints on the power tubes, I found it wiggling the tubes. If you put your finger on just the little glass tip sticking out the "top" of the tube (mine are hanging down so it's actually bottom) you can wiggle the tube without getting burned and that will cause it to crackle. I thought it was loose tube socket pins so I tried re tensioning, that didn't work.

Opened it up and got out a magnifying glass, and I could see slight rings around several socket pin solder joints, where the sloppy factory soldering had broken. A little soldering and it sounds like a new one. I think it still has one I didn't spot, if has a very slight crackle if I crank it, still haven't found that one so I'll have to open it up and look around again. The major problem is gone, this is very minor, and I won't be cranking it that loud very often. Normally I use it in very low volume situations. We play gigs where I actually have to play quieter than I do practicing at home sometimes...

What brand tubes you use isn't critical, but how "hot" the #1 preamp tube is makes a difference. If it has a 12AX7A, any 12AX7A should work fine, and you can give it a little less gain by swapping it for a 12AT7. The 12AX7 is the hottest of the 12A*7 tubes, I think 12Z7 is the weakest. I have 12AX7, 12AT7, 12AU7 and I think one 12AZ7 tube. Mine are all older tubes, some are hotter than others, I just try one after the other and keep the one I like best.

Wiggle the tubes while it's running, if you hear the crackling, it could be bad solder joints.

Also, sometimes old resistors can cause this. They get hot and cool down repeatedly, and the expansion and contraction over the years causes microscopic cracks in the resistors, when electricity has to jump across these cracks it can start to crackle, sounding a little like bacon frying. I had to replace several of the 1 watt resistors in my Super Reverb to stop that. Tubes can cause the same thing.
Hmmm...I wonder what this button does...
#20
Thanks a lot for the replies. The first thing I'll do is get a new pair of power tubes (I'll do that right now as that means they'll most likely arrive tomorrow, and I'll actually have more time for stuff during the weekend) and replace them. The simplest thing I can do and whatever happens, I can just keep them as a backup for the future, they're not going anywhere.

I did however pay fairly close attention to the sockets and that the preamp tubes are seated well, and didn't see anything suspicious on the pins or the sockets themselves.

So, if the new 6L6s arrive tomorrow, I'll most likely replace them on Friday evening and report back.
#21
One way to check if the crackling is due to the power tubes would be to run the amp with no preamp tubes, if it gets louder then it might be power tubes. Crackling can be due to one or more of many things not related to tubes, it can be tedious to fine the source sometimes.
#22
If you think I did something dumb, feel free to say it, but please - I seriously need help this time.

The new 6L6 tubes arrived today, and I went to swap them. The problem is the metal rings holding them are supposed to be possible to "easily" hold down with two fingers while pulling out/putting in the tube, except that's apparently with the assumption you're ****ing He-Man in this case.

So I swapped the first one more or less without problems, but while changing the second one, the central part at the bottom accidentally broke off.

I'm not sure if that was a terrible decision, but after comparing with the other one (the one on the picture), I thought it's just a plastic cover and went ahead with it.

I plugged in the amp and turned it on without the guitar plugged in (as I did while checking the preamp tubes) - of course the cab was connected all the time. NO CRACKLING!

I plugged in the guitar... no sound at all. Look at all the cables - everything is connected fine.

I moved closer to the amp to look at the cables in the back, and felt a slight smell, like burning plastic.

Needless to say I turned off everything right away. I thought maybe the part that broke off started melting, but that's not the case. With trouble I removed the broken off plastic part that remained in the socket. (Note that the glass part of the tube seems completely intact, just the plastic broke off.) I'm having trouble to locate the smell.

Any ideas what happened? Is it in any way a reasonable idea to try again? Any ideas what happened? I'm scared as **** the amp got damaged in some way and I don't know why or how.
Last edited by TheLiberation at Aug 3, 2015,
#23
It can happen, the guiding pin can break, haven't broken any myself but yes its fairly common. The paint on the glass is fresh, it heats up and starts giving off odour. Unless there's smoke coming out of the amp, you haven't burnt anything yet.

Did you insert the broken pin tube properly matxhinge the order its supposed to go in? Without the guiding pin it can be confusing but the paint is usually a good enough clue to know which way it should go.
#24
You can't imagine how relieved this post made me.

I think so, I tried to put it in identically as the first one which went fine.

I think I'll just put the old tubes back in to make sure everything is all right, and then try again with the new ones.
#25
If you put them in and they worked, you did it right, end of story. A slight smell is not uncommon when replacing new tubes.
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#26
It didn't, that's the point - it was completely quiet.

I tried both with the old and new tubes, and the amp is not making any sounds at all. It's turned on, looks all fine and shiny and everything, but it's just completely and absolutely quiet. I put the new tubes in, they're sitting fine and I paid attention so that the pins are well aligned.

I even got rid of the FX loop and bypassed it completely, as well as triple checked whether the cab is plugged in correctly and it is, and of course checked 1000 times whether the volume knob on the guitar is actually turned up.

I swapped all the preamp tubes one by one again, and nothing changed. I also checked the HT fuse and it looks like shiny new. All 4 preamp tubes and both power tubes light up with the power on.

I'm out of ideas.
Last edited by TheLiberation at Aug 3, 2015,
#27
I misunderstood, I quickly read and saw that the crackling had stopped...my bad.

I guess it has, but not for the better.

Try plugging the guitar directly into the effects loop return and see if you get any sound. (Make certain the guitar is turned up.)

Do you have any way of making sure the guitar itself is working? (Another amp?)

Also, it may have been a bad solder joint on a power tube socket and your removal and replacement difficulties caused it to fail completely.
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Last edited by Arby911 at Aug 3, 2015,
#28
Nope, still no sound whatsoever. I have two guitars, also tried with the other one and it's the same.

Yep... this is starting to look like I'll have to take it to the store or a tech to have a look.
#29
It's unfortunate but it appears we've gone as far as we can remotely, time to take it to someone.
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#30
Yep. If someone has any more ideas, it's very welcome but still: honestly, thank you all for help and patience.

This is also particularly annoying because the amp is so awesome, if it was crap I wouldn't worry that much. Looks like the Bandit might be back in service for a few more days. Still, the amp is under warranty and I doubt that changing tubes is in any way an excuse to make it void, seems like a comparable process to changing pickups in a guitar to me.
Last edited by TheLiberation at Aug 3, 2015,
#32
What cables are you using for speaker & guitar connectins?

Double check to see if the 6l6 are red plating, the entire grey plate will be red like heated iron in a furnance, not talking about the normal red/orange glow light in the center. Also that amp needs to be biased if switched to different brand of power tubes, mostly likely i think. Next check by putting old stock working preamp tubes back in it. The PI tube might be malfunctioning which can make the fx loop stop working as well. I didnt follow the previous thread, mind asking what brand of tubes you have in there everywhere?

Also does that amp have a switch on the back that selects el34 or 6l6, you didnt accidentally move it to el34 if there is an option? The drive knob on it, not the gain knob, if set to zero qhen drive is engaged wont pass on sound, i guessing its similar in function to the laney gh/vh heads so it might work the same functions, i havent seen irt in awhile, so just some guesses i'll throw out there for you to look into.
#33
The guitar cables are more than solid, I use two slightly cheaper ones for the FX loop, but now I've been doing all testing plugging directly into the input with either a Fender cable or a Monster cable. The one thing I'm not really able to test is whether the speaker is actually well-functioning. I doubt it's the connection cable, although unfortunately I can't confirm that either right now.

As for the new power tubes, they seem to be behaving completely fine. One of the old power tubes, the one that I suspected (and still do, but apparently something else screwed up along the way) to be the root of all evil had this weird intense blue glow while powered up. The new ones light up but that's it. Still, I tried to put the old power tubes back in as I said (I think I tried every existing configuration of new and old tubes at this point), and there was no difference.

There was no issue with the FX loop though, just for clarification - I just meant I've been bypassing it completely to eliminate any possibility of loose cables.

The stock tubes were all Ruby, besides the first preamp tube which was interestingly enough JJ, identical to the ones I bought following Cathbard's advice.

I also paid attention to the EL34/6L6 switch, and it's definitely been set to 6L6 all along. As for biasing, I did a bit of reading on that and from what I understood it might be needed so the new tubes don't die in a few weeks, but it's rather unlikely that not doing it can kill any sound coming out of the amp completely?

(Just a note: there is literally no sound whatsoever - no guitar sound, no crackling, no hum, no "thump" when plugging/unplugging a guitar, it's dead quiet, even though the amp looks like it's all up and running)
#34
Quote by TheLiberation


(Just a note: there is literally no sound whatsoever - no guitar sound, no crackling, no hum, no "thump" when plugging/unplugging a guitar, it's dead quiet, even though the amp looks like it's all up and running)


This really seems like a lack of high voltage, like the HT fuse is blown or the standby switch is faulty, but there's no way to be sure from here.
“Ignorance more frequently begets confidence than does knowledge.”
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