is this a tube issue?

[causeBASS]

anyone with a David Eden or similar amp (with preamp tube) ever have this issue? was playing a gig, and started getting crackling/distortion... I examined all the cables, volume tone controls and plugged into dif cab and nothing helped. Took it home next day to do some more investigation, and it played fine for awhile , then problem came back. I started to wonder if there was an issue with the amp sitting on the cabinet and when I moved it off the cab all was well. I put a piece of foam between amp and cab and it continued to play fine. I ordered new pre-amp tube (old one probably hasn't been changed in 10+ years) thinking maybe the tube is physically compromised.... any comments??

Eden WT-550
Aguilar 112

 

[Old Garage-Bander]

Vibrations can certainly affect tubes. The term most commonly used is Microphonics. Tubes pick vibrations and amplify them as noise. Replacing the tube with a known to be non-microphonic one is one way of seeing where the problem lies. There are other possibilities that are more involved in solving the problem. Depending on an HONEST self-evaluation of your electronics skills and experience, if the new tube doesn't fix it you may want to consider taking it to a qualified amp tech.

 

[agedhorse]

Possibly.

 

[Wasnex]

anyone with a David Eden or similar amp (with preamp tube) ever have this issue? was playing a gig, and started getting crackling/distortion... I examined all the cables, volume tone controls and plugged into dif cab and nothing helped. Took it home next day to do some more investigation, and it played fine for awhile , then problem came back. I started to wonder if there was an issue with the amp sitting on the cabinet and when I moved it off the cab all was well. I put a piece of foam between amp and cab and it continued to play fine. I ordered new pre-amp tube (old one probably hasn't been changed in 10+ years) thinking maybe the tube is physically compromised.... any comments??

Eden WT-550
Aguilar 112

It could be a tube problem...but it could be a lot of other things as well.

If you don't have an electronics background, there is not a lot you can do. Reseat the tube and if that does not work replace it. If that does not work, the only other thing that comes to mind is insert a short jumper into the effects loop. Most effects loops have a switching contact that the signal passes through when the loop is not used. This contact can degrade or get dirty/corroded. Inserting a jumper bypasses the switching contact, and the signal passes through the jumper.

I believe the WT550 has a single 12AX7, but I have not poked around in this amp so I don't know how hard it is to access. Before replacing the tube, I would try reseating it. In some instances I have seen small signal tubes that are barely sitting in the tube socket.

Be careful about what you touch in the amp. There may be lethal voltages on some of the electronic parts, and tubes often run at a hot enough temperature to burn you. Before fiddling with the tube, turn the amp off, disconnect it from the AC wall socket, and let the tube cool for awhile.

To remove the tube, pull up and rock it side to side a bit. You have to be careful to not use to much force or rock the tube too far, or you may damage the circuit board. This can be tricky if you don't have any experience with tubes, because you don't know what to expect in regards to required force. You don't necessarily have to pull the tube all the way out. Work it in and out a few times and then reseat it. The intent here is to reestablish good continuity between the pins on the tube and the contacts in the tube socket.

If you pull the tube all the way out, inspect the pins and contacts on the tube sockets. Look for signs of arcing and debri. If the tube sockets contacts are loose, arcing can occur which tends to cause a carbon deposit. The carbon deposit serves as an insulator, so the pins do not make good contact.

When it comes time to put the tube back in, note that the base is keyed and you have to make sure all of the pins are lined up...getting it right can be tricky, especially if you try to take it too fast. If you get it wrong, you will bend at least one pin. Also if you turn the amp on the tube improperly inserted, a lot of collateral damage may occur.

If neither the tube nor effects loop prove to be the source of the problem, I suggest finding a good technician to go through the amp. If the problem occurs consistently and regularly, it should be fairly easy to troubleshoot. If the problem is random and infrequent, then troubleshooting can be difficult to impossible.

Good Luck!

 

[causeBASS]

It could be a tube problem...but it could be a lot of other things as well.

If you don't have an electronics background, there is not a lot you can do. Reseat the tube and if that does not work replace it. If that does not work, the only other thing that comes to mind is insert a short jumper into the effects loop. Most effects loops have a switching contact that the signal passes through when the loop is not used. This contact can degrade or get dirty/corroded. Inserting a jumper bypasses the switching contact, and the signal passes through the jumper.

I believe the WT550 has a single 12AX7, but I have not poked around in this amp so I don't know how hard it is to access. Before replacing the tube, I would try reseating it. In some instances I have seen small signal tubes that are barely sitting in the tube socket.

Be careful about what you touch in the amp. There may be lethal voltages on some of the electronic parts, and tubes often run at a hot enough temperature to burn you. Before fiddling with the tube, turn the amp off, disconnect it from the AC wall socket, and let the tube cool for awhile.

To remove the tube, pull up and rock it side to side a bit. You have to be careful to not use to much force or rock the tube too far, or you may damage the circuit board. This can be tricky if you don't have any experience with tubes, because you don't know what to expect in regards to required force. You don't necessarily have to pull the tube all the way out. Work it in and out a few times and then reseat it. The intent here is to reestablish good continuity between the pins on the tube and the contacts in the tube socket.

If you pull the tube all the way out, inspect the pins and contacts on the tube sockets. Look for signs of arcing and debri. If the tube sockets contacts are loose, arcing can occur which tends to cause a carbon deposit. The carbon deposit serves as an insulator, so the pins do not make good contact.

When it comes time to put the tube back in, note that the base is keyed and you have to make sure all of the pins are lined up...getting it right can be tricky, especially if you try to take it too fast. If you get it wrong, you will bend at least one pin. Also if you turn the amp on the tube improperly inserted, a lot of collateral damage may occur.

If neither the tube nor effects loop prove to be the source of the problem, I suggest finding a good technician to go through the amp. If the problem occurs consistently and regularly, it should be fairly easy to troubleshoot. If the problem is random and infrequent, then troubleshooting can be difficult to impossible.

Good Luck!

 

[causeBASS]

thanks ... yes it has one preamp tube...and long time ago when I had no grey hair, I worked as an audio tech, so I am aware of how to do some basic things in an amp and how not to electrocute myself.. but you were right to advise..

 

[S-Bigbottom]

Plug a cable into the Effects Loop then see if it comes back.

 

[KenD]

Very difficult to tell from what you describe but it does sound tube related. I had an almost identical issue with my guitar combo amp and it turned out to be faulty/cracked solder joints on one of the preamp tube sockets.

 

[Rip Van Dan]

It could be a tube problem...but it could be a lot of other things as well.

If you don't have an electronics background, there is not a lot you can do. Reseat the tube and if that does not work replace it. If that does not work, the only other thing that comes to mind is insert a short jumper into the effects loop. Most effects loops have a switching contact that the signal passes through when the loop is not used. This contact can degrade or get dirty/corroded. Inserting a jumper bypasses the switching contact, and the signal passes through the jumper.

I believe the WT550 has a single 12AX7, but I have not poked around in this amp so I don't know how hard it is to access. Before replacing the tube, I would try reseating it. In some instances I have seen small signal tubes that are barely sitting in the tube socket.

Be careful about what you touch in the amp. There may be lethal voltages on some of the electronic parts, and tubes often run at a hot enough temperature to burn you. Before fiddling with the tube, turn the amp off, disconnect it from the AC wall socket, and let the tube cool for awhile.

To remove the tube, pull up and rock it side to side a bit. You have to be careful to not use to much force or rock the tube too far, or you may damage the circuit board. This can be tricky if you don't have any experience with tubes, because you don't know what to expect in regards to required force. You don't necessarily have to pull the tube all the way out. Work it in and out a few times and then reseat it. The intent here is to reestablish good continuity between the pins on the tube and the contacts in the tube socket.

If you pull the tube all the way out, inspect the pins and contacts on the tube sockets. Look for signs of arcing and debri. If the tube sockets contacts are loose, arcing can occur which tends to cause a carbon deposit. The carbon deposit serves as an insulator, so the pins do not make good contact.

When it comes time to put the tube back in, note that the base is keyed and you have to make sure all of the pins are lined up...getting it right can be tricky, especially if you try to take it too fast. If you get it wrong, you will bend at least one pin. Also if you turn the amp on the tube improperly inserted, a lot of collateral damage may occur.

If neither the tube nor effects loop prove to be the source of the problem, I suggest finding a good technician to go through the amp. If the problem occurs consistently and regularly, it should be fairly easy to troubleshoot. If the problem is random and infrequent, then troubleshooting can be difficult to impossible.

Good Luck!

One of the things that may be very well be causing your problem is some corrosion on your jacks. I would highly recommend cleaning all your 1/4" jacks with a small amount of Deoxit 5 (red can). Easiest way to do that is to take a 1/4" plug, spray a little Deoxit on it and move it in and out of each jack 10 to 15 times. The signal path on your WT550 amp and on all the Eden WT amps runs through almost every jack on the back of your amp. If one of them gets dirty, it can cause all kinds of problems, many of them intermittent that can drive you nuts trying to troubleshoot. Most commonly there will be some corrosion on one of the jacks that you don't use. That's because there's nothing rubbing against it to knock any corrosion off. So do them all. It's best to do that on an annual basis to keep everything running nice and clear.

If that doesn't fix it, the hardest part of changing the tube in any of the Eden amps with the hybrid preamp is unscrewing all those screws to remove the top of the chassis. You'll have to remove the tube cover/shield and then follow @Wasnex directions on removing and replacing. I replaced the one in my WT500/800 in 2016, not because I had any problem with it but because the amp had slid off the top of my 410 on the concrete and then distorted terribly. It was the only thing I could actually replace on my own and it made no difference at all. Rather than put the original original Ruby 12ax7 tube back in, which had probably been there since 1999, I kept the Ruby as a backup.

The big thing that was wrong with mine was that the toroidal transformer had come loose and turned a bit. They just realigned it and tightened it back up. The shop that worked on it also went on through the rest of the amp and did find a bad transistor in there that they replaced too.

The capacitors in the amp look like big black metal tubes. The WT550 should have 4 of them. DON'T TOUCH THEM. My amp with the 800-watt power supply has 6 of them whereas the original WT500 (500-watts bridged) has 4 and a smaller toroidal transformer. If the capacitor is bad, it will usually have a bulging top instead of a flat one, but that's not a fool-proof way to check it, just a visual indicator that could be the problem. Mine still has the original caps from 1999 when it was made. It was used as the test amp when David was designing and testing his cabs, so it got a lot of use before I got it in 2010. And then I gigged it a lot! They can go bad, but they can also last a very long time.

By the way, all of the Eden amps with the hybrid preamp will make a crackling sound as the tube warms up when first turned on, which is normal. But it shouldn't make that noise any time.

 

[Thumpin6string]

Plug a cable into the Effects Loop then see if it comes back.

^^^this^^^

 

[Jtown690]

Take a tiny screw driver and tap it on the glass. If you hear a noise that corresponds with the taping coming through the speaker or di signal then it’s time to change the tube. This goes for new tubes as well. Just because it makes noise doesn’t mean the tube is bad either, it just means it’s in the wrong spot. The pre-amp section is sensitive, it picks up and amplifys a tube’s imperfections. You want a tube with “low noise” and “ low microphonics” in the preamp section. Seems obvious but the point is that just cuz it makes noise doesn’t means it’s trash.

 

[BobKos]

I had a problem with the large power resistors in my WT-500 cracking the solder joints. It would play fine then cut out. Reflowing them fixed it.

 

[causeBASS]

One of the things that may be very well be causing your problem is some corrosion on your jacks. I would highly recommend cleaning all your 1/4" jacks with a small amount of Deoxit 5 (red can). Easiest way to do that is to take a 1/4" plug, spray a little Deoxit on it and move it in and out of each jack 10 to 15 times. The signal path on your WT550 amp and on all the Eden WT amps runs through almost every jack on the back of your amp. If one of them gets dirty, it can cause all kinds of problems, many of them intermittent that can drive you nuts trying to troubleshoot. Most commonly there will be some corrosion on one of the jacks that you don't use. That's because there's nothing rubbing against it to knock any corrosion off. So do them all. It's best to do that on an annual basis to keep everything running nice and clear.

If that doesn't fix it, the hardest part of changing the tube in any of the Eden amps with the hybrid preamp is unscrewing all those screws to remove the top of the chassis. You'll have to remove the tube cover/shield and then follow @Wasnex directions on removing and replacing. I replaced the one in my WT500/800 in 2016, not because I had any problem with it but because the amp had slid off the top of my 410 on the concrete and then distorted terribly. It was the only thing I could actually replace on my own and it made no difference at all. Rather than put the original original Ruby 12ax7 tube back in, which had probably been there since 1999, I kept the Ruby as a backup.

The big thing that was wrong with mine was that the toroidal transformer had come loose and turned a bit. They just realigned it and tightened it back up. The shop that worked on it also went on through the rest of the amp and did find a bad transistor in there that they replaced too.

The capacitors in the amp look like big black metal tubes. The WT550 should have 4 of them. DON'T TOUCH THEM. My amp with the 800-watt power supply has 6 of them whereas the original WT500 (500-watts bridged) has 4 and a smaller toroidal transformer. If the capacitor is bad, it will usually have a bulging top instead of a flat one, but that's not a fool-proof way to check it, just a visual indicator that could be the problem. Mine still has the original caps from 1999 when it was made. It was used as the test amp when David was designing and testing his cabs, so it got a lot of use before I got it in 2010. And then I gigged it a lot! They can go bad, but they can also last a very long time.

By the way, all of the Eden amps with the hybrid preamp will make a crackling sound as the tube warms up when first turned on, which is normal. But it shouldn't make that noise any time.

great suggestions...

 

[Wasnex]

Take a tiny screw driver and tap it on the glass. If you hear a noise that corresponds with the taping coming through the speaker or di signal then it’s time to change the tube. This goes for new tubes as well. Just because it makes noise doesn’t mean the tube is bad either, it just means it’s in the wrong spot. The pre-amp section is sensitive, it picks up and amplifys a tube’s imperfections. You want a tube with “low noise” and “ low microphonics” in the preamp section. Seems obvious but the point is that just cuz it makes noise doesn’t means it’s trash.

I recommend doing the chopstick test with a wood dowel or something else that is non-conducting and not so hard. It's not a good practice to poke around inside a live amp with a metal rod. Also not a good idea to tap a thin glass bubble with metal.

Tapping the tube should cause a noise in the output of the amp. It's the quality of the noise and now obtrusive it is that determines if a new tube is needed. The noise should be a short well damped transient. If it has a metallic rattle or rings for an extended time, it may be time to replace the tube. However if the tube sounds good in the amp and does not introduce a similar ring or rattle during operation, it's not strictly required to replace it.

Some circuit are more responsive to mechanical shock than others. I have tubes in various amps that moderately fail the chopstick test, but sound fine in the amp. In particular, 6C4s generally don't pass the chopstick test. 6C4 is commonly found in vintage Ampeg SVTs.

Long plate (X)AX7 type tubes are also more prone to making noise when exposed the mechanical shock. An example is the JJ ECC803S. This is one of my favorite tubes to roll into bass amps, I have come across a few that make a bit of a ringy, mechanical rattle in V1. The same tube often works fine in other tube positions.

 

[agedhorse]

First identify the cause of the symptoms, THEN you will know what is (or isn't) bad. Don't go replacing good parts in hopes that it will miraculously cure the problem. Sometimes it can cause additional, new problems.

 

[BobKos]

First identify the cause of the symptoms, THEN you will know what is (or isn't) bad. Don't go replacing good parts in hopes that it will miraculously cure the problem. Sometimes it can cause additional, new problems.

This is the TRUTH. In my field (auto repair) I see this all the time. Unknowledgeable people start shotgunning parts into a vehicle based on 'Googlenostics'. The sad part is that they often remove high spec OEM parts and replace them with inferior grade parts available locally or next day through Prime. Often the stackup of poor spec parts results in a MUCH more complex repair that if it had simply been repaired right in the first place.

 

[agedhorse]

I just might have to use “Googlenostics” in my next service bulletin!

 

[Old Garage-Bander]

This is the TRUTH. In my field (auto repair) I see this all the time. Unknowledgeable people start shotgunning parts into a vehicle based on 'Googlenostics'. The sad part is that they often remove high spec OEM parts and replace them with inferior grade parts available locally or next day through Prime. Often the stackup of poor spec parts results in a MUCH more complex repair that if it had simply been repaired right in the first place.

"Googlenostics"! Love it!

Almost makes me wish I hadn't retired. (NOT!)
I had a guy at work who I could have use that one on all the time.

 

[Passinwind]

I just might have to use “Googlenostics” in my next service bulletin!

Yeah, love that. In my old day job debunking search engine results was a substantial part of what I was tasked with. Especially in the buying phase for new research projects, which were mostly in the publish or perish domain. So much BS, so little time...

 

[causeBASS]

Thanks everyone for their help. It seems it was an input jack problem that appears to be solved with some contact cleaner and a wiggle or two. I did replace the preamp tube because why not, hasn't been replaced in over ten years.. got a JJ ECC83MG Preamp Vacuum Tube
Low Noise & Microphonics from Tube depot ...seems quieter, not sure if much effect on tone.....got a gig Friday and have a plan B , but I'll give it a few more runs prior to gig