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Post by dermottrellis on Apr 18, 2021 15:40:35 GMT -7
I bought a used Jetta last summer. It sounded absolutely glorious, and I fell in love with everything about the amp (except for the effects loop). After playing it for five months or so, I began to notice that there was a noise like someone in a far off room moving heavy furniture around. I did the chopstick thing on the tubes and this didn't produce any usable information. I had some of the silicone tube dampers and put one on the second power tube (it now had three) -- I don't know why, but I just suspected it might be the culprit. This stopped the rattle. I promptly ordered a new matched set of Tung-Sol 7591A tubes.
I put the new tubes in the amp in February and the problem was solved.
...until today. I've put about 50-60 hours on the amp since the tube swap. It's interesting in that both the previous problem and today's problem centered around resonance of the 'd' note, particularly on the 7th fret of the G string. The problem resonance starts at 'c' on the G string but it's slight. It gets stronger on the 'c#"; the 'd' is the most noticeable; the 'd#' is a little less noticeable; the 'e' is slight and it has all but disappeared by the time I get to 'f'.
A friend and longtime Dr. Z user suggested I try running the Jetta through my Morgan 1x12. Surprise -- no rattle. However, to be thorough, I swapped the 12" Celestion Gold from the Morgan into the Jetta cab. The rattle in the tubes is still there.
So, it's something in the resonance of the cab that is making the tubes go south eventually? Swapping tube positions yields the same problem.
Has anyone ever experienced this sort of problem? Is there a solution? I don't really want to run the amp with extra tube dampers as it might contribute to overheating because it covers up more of the tube. It seems like it would fail due to heat sooner.
Help!
Sorry, first time poster, but I would really like to solve this problem.
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Post by mrcapers on Apr 18, 2021 16:10:44 GMT -7
My Jetta came with 3 dampers per tube from the factory, so that shouldn't be a problem. One of my first set of power tubes red plated. Don sent me a pair of spares and I haven't had an issue since.
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Post by perryr on Apr 18, 2021 22:41:40 GMT -7
No prob putting extra dampers on, mine have 3. Combos are hostile environments for tubes, and some tubes are more susceptible than others. And yep, certain frequencies are generally worse than others.
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Post by dermottrellis on Apr 19, 2021 5:36:52 GMT -7
Thank you for that information/assurance. I will follow your advice.
I've played combo amps for many years -- Fender, Supro, Marshall, Morgan -- but this was the first time that it has become (apparently) a persistent problem.
What tubes do you use? If I might ask.
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Post by Seńor Verde on Apr 19, 2021 6:17:52 GMT -7
My solution isn't for everyone, but this is why I use a head/cabinet for all but 2 of my amps. I also use dampers on the output and rectifier tubes, just to be safe.
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Post by dermottrellis on Apr 19, 2021 6:44:12 GMT -7
My solution isn't for everyone, but this is why I use a head/cabinet for all but 2 of my amps. I also use dampers on the output and rectifier tubes, just to be safe. You are absolutely right, and it's often the best-sounding solution. I have a couple head/cab arrangements. However, sometimes I just want to sling my pedal board over my shoulder, put a guitar in one hand and a combo in the other. One trip in/one trip out has been my ideal since living on the east coast and playing at clubs in cities where it wasn't convenient to run back and forth. My best sounding rig is a Goodsell Super 17 (lunchbox/backlit logo) head through a Morgan 1x12. Both are light, but in order to conform to the above notion I need another arm. |
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Post by doctorice on Apr 19, 2021 9:32:31 GMT -7
I had the exact same issue with my Jetta in the last couple weeks. Don at Z told me he was pretty sure it was a tube issue, and advised me to push the new tubes hard after installing them.
I ordered a new pair of tubes (Tung Sols as used by Z). The problem went away for a few hours then came back. After much tube swapping I concluded that one of the new tubes had gone microphonic too. A replacement (matched) is on its way.
I was going to start a thread on this to alert folks about the Tung Sols.
I'm having the same problem with my Nova, which is not self-biasing. I have the new tubes but I loaned my bias tool to a buddy.
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Post by dermottrellis on Apr 19, 2021 9:37:15 GMT -7
I think I will give JJ's 7591 tubes a try. One thing that the Tung-Sols don't seem to provide is a lot of sparkly treble content. Maybe the JJs won't turn microphonic, while at the same time having a bit more in the upper range.
Has anyone tried the JJ 7591's, or the Electro-Harmonix (the base of which doesn't look too robust).
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Post by timmytva on Apr 20, 2021 17:16:32 GMT -7
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Post by doctorice on Apr 21, 2021 9:53:48 GMT -7
I considered it as I've been happy with prior purchases from them, but I decided to stick with Doc's choice. If I continue to have a problem, I'll give KCA a shout and get their recommendation. |
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Post by daddyelmis (Greg) on Apr 21, 2021 10:10:05 GMT -7
Thinking a bit out of the box (or cabinet) here, what if you put some rubber spacers on the chassis bolts and remount the chassis? If the offending vibration is being transmitted physically to the chassis, that could help. If it’s purely acoustic transmission, maybe try a layer of insulation under the chassis or at the top of the speaker box - anything to try to affect the resonant frequency.
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Post by dermottrellis on Apr 21, 2021 13:43:08 GMT -7
Thinking a bit out of the box (or cabinet) here, what if you put some rubber spacers on the chassis bolts and remount the chassis? If the offending vibration is being transmitted physically to the chassis, that could help. If it’s purely acoustic transmission, maybe try a layer of insulation under the chassis or at the top of the speaker box - anything to try to affect the resonant frequency. That's a great idea. As I've got FA going on this weekend I will give it a try. Thank you. |
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Post by nicholas on Apr 25, 2021 6:58:05 GMT -7
Has anyone tried the JJ 7591's? I use the JJ's in an old Ampeg combo. So far so good. I did buy a pair of NOS from a reputable dealer. I had issues with extreme bias drift in one of them after a few weeks. They were expensive, and after that I gave up on them. I decided to just use modern production and have been happy with the JJ's. I'm not sure how many quality NOS 7591's are actually out there. For the price I'm not gambling on them anymore. |
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Post by doctorice on Apr 25, 2021 14:56:40 GMT -7
Further caution on Tung-Sol 7591s: It turns out I'm now on my third set, and each set has had a tube go microphonic. (I'm still waiting for a replacement for the tube that failed almost immediately in the third set.) I can't imagine my Jetta has more than 100 hours of play time in total so far -- because the tubes keep dying! -- so it's not me expecting way more life from the tubes than is appropriate.
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Post by dermottrellis on Apr 26, 2021 6:43:39 GMT -7
Further caution on Tung-Sol 7591s: It turns out I'm now on my third set, and each set has had a tube go microphonic. (I'm still waiting for a replacement for the tube that failed almost immediately in the third set.) I can't imagine my Jetta has more than 100 hours of play time in total so far -- because the tubes keep dying! -- so it's not me expecting way more life from the tubes than is appropriate. Thanks for the info. Based on this, I just ordered a set of JJs. I've used Tung-Sols in other amps, but never the 7591, and never had any trouble with them. These, however, seem to be a problem. |
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Post by premiumplus (Dave) on May 11, 2021 4:12:48 GMT -7
When I first got my Z-Lux I went through a similar issue with JJ 6V6 tubes, they rattled like crazy. I went through at least three sets, then I switched to Tung-Sol 5881's. By the time I changed the tubes again, JJ had resolved the rattle issue and it's been good ever since.
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Post by Jaguarguy (Mike) on May 11, 2021 6:35:01 GMT -7
Modern tubes are a real crapshoot these days. I believe manufacturing capabilities have deteriorated and cost reductions both contribute to the problem. I feel sorry for Doc having to use these tubes in his amps!
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Post by doctorice on May 11, 2021 8:01:08 GMT -7
Further caution on Tung-Sol 7591s: It turns out I'm now on my third set, and each set has had a tube go microphonic. (I'm still waiting for a replacement for the tube that failed almost immediately in the third set.) I can't imagine my Jetta has more than 100 hours of play time in total so far -- because the tubes keep dying! -- so it's not me expecting way more life from the tubes than is appropriate. Thanks for the info. Based on this, I just ordered a set of JJs. I've used Tung-Sols in other amps, but never the 7591, and never had any trouble with them. These, however, seem to be a problem. Did you get the JJs? Any update?
Like you, I plugged the amp into a separate cab and got the noise to go away. I have a little more experimenting to do: I want to aim the cab right at the amp chassis and see if I can induce the noise. Not that I want it!
I'm starting to wonder if something may be going awry with a tube socket, so I'm also going to do some more tube swapping. I have plenty of Tung-Sol 7591s  |
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Post by dermottrellis on May 25, 2021 14:23:59 GMT -7
Yes, sorry, I've been away. I did get the JJs and popped them in. Same result, and maybe even a more unpleasant sound than the Tung-Sols. I am beginning to think it is not the tubes causing the rattle -- maybe the tube sockets need tensioning? I wouldn't think it would be that, but I am running out of ideas. I will probably give the chassis the rubber bumper treatment -- I've just been too busy with house repairs/painting to make some time for it.
Drives me nuts. I think I will just play the Goodsell and Morgan. I don't want to sell the Jetta, but it is pretty useless unless I can get this sorted. I also couldn't sell it in good conscience because of the rattle. First Dr. Z, but not a happy first impression.
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Post by adam on May 25, 2021 18:15:12 GMT -7
Drives me nuts. I think I will just play the Goodsell and Morgan. I don't want to sell the Jetta, but it is pretty useless unless I can get this sorted. I also couldn't sell it in good conscience because of the rattle. First Dr. Z, but not a happy first impression. I'm sure it's "just" the tubes. And sorry if I missed it, but I'm guessing you tried the amp into another cab and it went away? I might also say that I have a few other combos that do that if I turn them up and it drives me batty too. Even my wife can hear it in a split second. My fender DRI, same thing, complete retube and it's good for a couple hours. Kind of makes you wonder if the chassis could be be shock mounted in some way with springs or something. I wonder if loosening the screws holding the chassis in would help. Also makes me wonder if it's really a precision fit, maybe it's taking vibration from all over the place and then guessing that older stuff with less tolerance might have much less point of contact to transmit those vibrations. Maybe even cheesier wood joints would help dissipate the vibration. Totally guessing here, but trying to be helpful. |
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Post by doctorice on May 26, 2021 6:56:51 GMT -7
Yes, sorry, I've been away. I did get the JJs and popped them in. Same result, and maybe even a more unpleasant sound than the Tung-Sols. I am beginning to think it is not the tubes causing the rattle -- maybe the tube sockets need tensioning? I wouldn't think it would be that, but I am running out of ideas.
Thanks for that update. It seems you and I have reached a similar point in wondering if something else is going on rather than bad tubes.
I'm going to check in with the Z shop about them taking a look at my Jetta. I plan to send all three sets of tubes I've tried so far.
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Post by dermottrellis on May 26, 2021 7:52:05 GMT -7
I loosened the chassis bolts a little and it reduced the rattle somewhat. It is still noticeable, but when I get the opportunity I am going to take it apart and insert rubber grommets in between the cabinet and chassis. It won't be this weekend, but once I do that I will report back as it seems to be a not uncommon occurrence.
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Post by dermottrellis on May 26, 2021 7:55:45 GMT -7
Yes, sorry, I've been away. I did get the JJs and popped them in. Same result, and maybe even a more unpleasant sound than the Tung-Sols. I am beginning to think it is not the tubes causing the rattle -- maybe the tube sockets need tensioning? I wouldn't think it would be that, but I am running out of ideas.
Thanks for that update. It seems you and I have reached a similar point in wondering if something else is going on rather than bad tubes.
I'm going to check in with the Z shop about them taking a look at my Jetta. I plan to send all three sets of tubes I've tried so far.
Yeah, I've had three sets of tubes in mine, as well. It is always tube position 1 that has the rattle. I held a heavy-duty piece of cardboard in between the two power tubes and had a friend play whilst I listened -- no rattle from 2, but 1 always rattles. I bought mine used, so no warranty?, I guess. Please let us know what you discover. |
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Post by DRZ on May 26, 2021 8:02:27 GMT -7
Yes, sorry, I've been away. I did get the JJs and popped them in. Same result, and maybe even a more unpleasant sound than the Tung-Sols. I am beginning to think it is not the tubes causing the rattle -- maybe the tube sockets need tensioning? I wouldn't think it would be that, but I am running out of ideas.
It seems you and I have reached a similar point in wondering if something else is going on rather than bad tubes.
OK attaching the amps output to an extension cab stops the rattle, and loosing the chassis connection to the cab lessens the tube rattle. So you still think the amp is responsible for the tube rattle a mechanical phenomenon. Mike what you need as a combo to head conversion. Please see Notes from DR.Z thread. |
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Post by headshrinker (Marc) on May 26, 2021 8:24:54 GMT -7
To paraphrase someone else: Suspecting or blaming your amp when you have tube rattle, is like suspecting or blaming your house wiring when a light bulb blows. Why suspect the most robust component when the least robust causes a problem.
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Post by mrcapers on May 26, 2021 9:14:14 GMT -7
Just to reassure others, I DID have a bad tube when I got my Jetta (new). The second set of Tung-sols have performed flawlessly thru practices, gigs and being hauled around quite a bit. I bought a matched quad of 7591A tubes just in case, but haven't had to use them. What a great amp, I use it more than my Z-plus and Remedy combined.
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Post by dermottrellis on May 26, 2021 9:23:53 GMT -7
To paraphrase someone else: Suspecting or blaming your amp when you have tube rattle, is like suspecting or blaming your house wiring when a light bulb blows. Why suspect the most robust component when the least robust causes a problem. That's a fine analogy as far as it goes. However, I have had three sets of tubes in the Jetta and there is tube rattle in the first power tube position no matter which set of tubes I have had in the amp. I have also swapped the same set of tubes so that the tube that was in p1 was swapped into p2 and p2 swapped into p1. The tube in p1 rattles no matter what. |
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Post by DRZ on May 26, 2021 10:03:31 GMT -7
To paraphrase someone else: Suspecting or blaming your amp when you have tube rattle, is like suspecting or blaming your house wiring when a light bulb blows. Why suspect the most robust component when the least robust causes a problem. That's a fine analogy as far as it goes. However, I have had three sets of tubes in the Jetta and there is tube rattle in the first power tube position no matter which set of tubes I have had in the amp. I have also swapped the same set of tubes so that the tube that was in p1 was swapped into p2 and p2 swapped into p1. The tube in p1 rattles no matter what. What you are stating is hard for me to believe as I have not seen this happen before as you state it. That doesn't mean its not happening , but I would need to see it to confirm that a mechanical rattle happens only on one socket position, and when the tube is moved it doesn't rattle anymore in the other position. I sense you want to believe it is a amp problem and again I would need to bench the amp to confirm that. So loosening the connection to the cab lessens the rattle right ? Have you tried connecting the speaker out to an external speaker cab to eliminate cab vibration ? |
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Post by dermottrellis on May 26, 2021 10:16:10 GMT -7
That's a fine analogy as far as it goes. However, I have had three sets of tubes in the Jetta and there is tube rattle in the first power tube position no matter which set of tubes I have had in the amp. I have also swapped the same set of tubes so that the tube that was in p1 was swapped into p2 and p2 swapped into p1. The tube in p1 rattles no matter what. What you are stating is hard for me to believe as I have not seen this happen before as you state it. That doesn't mean its not happening , but I would need to see it to confirm that a mechanical rattle happens only on one socket position, and when the tube is moved it doesn't rattle anymore in the other position. I sense you want to believe it is a amp problem and again I would need to bench the amp to confirm that. So loosening the connection to the cab lessens the rattle right ? Have you tried connecting the speaker out to an external speaker cab to eliminate cab vibration ? Yes, I've tried it with another speaker cabinet and the rattle is not there. Loosening the connection lessened the rattle, but it's still present. I have the tube dampers on the tube(s). I also put three and then four dampers on the tube with no effect. When I play and a friend puts his protected finger on the top of the tube, the rattle ceases. It doesn't require much pressure at all to effect this change. |
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Post by DRZ on May 26, 2021 10:26:16 GMT -7
Ok it is a tube rattle to be sure.
On new JETTA's I now use a different tube retainer that fixes that exact issue.
It is a spring retainer from Amplified Parts P/N S-H141.
Buy two remove the shark jaw retainers and install the spring type.
I also super glue a tube dampener to inside top of the spring retainer this adds extra complete pressure on the top of the tube like your finger would. Also make sure the springs have a bit of tension by adjusting them and the lower mounting bracket. This simple cheap retro fit should solve your problems, and Mike should try it to.
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