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Post subject: Cybertwin tube rattle
Posted: Sun Jan 25, 2009 10:06 pm
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I have searched a bunch, but came up a bit short on this. I have an original CT delux and the damn tubes are rattling. I'm guessing there is a mod to fix this and I do have a service center around but it's not all that close. Anything I can do myself? A part I could order and install myself? I opened it up and noodled for a bit with not much luck except to put acoustic foam between the two tube covers. It helped a little bit but of course, the problem isn't solved. I'm the original owner but the amp is out of warrenty by now. Thanks for any help on this.

Dan


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Posted: Mon Jan 26, 2009 8:54 pm
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As far as I know, it's a factory upgrade to version 1.3 (the last of the upgrades for the CT). I do not believe this is a consumer installable kit, only fender authorized dealers.

ciao,
johnny.


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Posted: Mon Jan 26, 2009 9:00 pm
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Thanks so much for your response. I'll have to give the service center a call.


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Posted: Mon Jan 26, 2009 9:25 pm
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Come to think of it, it could very well be the tubes themselves. Some tubes are just plain microphonic. Try a different set of tubes, if the rattle disappears, then that is the problem.

I also misread the amp you have, it's the CT Deluxe, right, not the CT? Version 1.3 upgrade applies to the CT. I do not know if a similar upgrade was available for the CT Deluxe, but both amps were similar so I suspect there might have been a similar upgrade, but I am not sure about this.

Ciao,
Johnny.


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Posted: Mon Jan 26, 2009 10:42 pm
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Yes, that's correct Johnny- it's the original CT deluxe.

Interesting about the tubes. They are the original tubes in there right now.

Any suggestion of good replacement tubes?

I took the covers off of the two tubes and by holding the tubes with my thumb on the top of them, the rattle stopped. It seemed to me that the tubes were hitting the sides of the thin metal seat holder ever so slightly and causing a rattle when playing low A & E notes. As I said, I could stop it by holding the tubes down with a little pressure and kinda centering them. In fact, it seems to be only one tube causing the problem. But the minute I let go, rattle. So I replaced the covers and put acoustic foam between the two tube covers to try and dampen it, and it works a bit. The rattle is not as bad. But over time, I'm sure the heat from the tube cases will wear out the foam and it may dislodge. I'm also not happy to have anything in there right at a heat source, but no problems playing a four hour gig that night- no fires or smoke! LOL! I did find mention of tube rattle in the 'cybertwin club' thread, but I wasn't able to put together the solution, short of a trip to service. Thanks for your continued help.

Dan


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Posted: Tue Jan 27, 2009 7:10 pm
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Your experimenting generally confirms a rattly tube. In the old days I used to quick test tubes by tapping them with a pencil. If I saw even a flick, I would change the tube - first signs of eminent failure. I would suggest your rattly tube is on its way to checking-out.

There are tonnes of opinions on which tubes are good and so on. I believe EVH screens tubes for microphonics and are pretty good sounding from all reports. Groove tubes are ok too as are the Russian ones. I do not know enough about the Chinese ones. I have not kept up to date on tubes, sorry I can not guide you better than this.

good luck,
johnny.


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Posted: Tue Jan 27, 2009 7:49 pm
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I'll post the the question of good tubes in the other thread. Your insights about the tube itself is very helpful. I would have summized that last, not first- and it's an easy thing to try next to see if it solves it. Thanks again.

Dan


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Posted: Tue Jan 27, 2009 9:02 pm
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Try these.
http://cgi.ebay.com/VACUUM-TUBES-AMP-DA ... 1|294%3A50

My HRdlx rattles like a dog crappin bones. The tube dampers help. Either that or get some new tubes.


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Posted: Tue Jan 27, 2009 9:26 pm
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I just took a look at the "dampers". I would strongly suggest that you invest your money in better tubes. Reminds me of the dude who put snake oil into his blown engine and said "gee... the clack-clack noise stopped...".

ciao,
johnny.


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Posted: Tue Jan 27, 2009 11:05 pm
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Thanks for your help guys- especially you Johnny. I'll continue on with this in the cybertwin club thread if needed. Got a great lead in that thread for tubes. Thank you again! And thank God for this place! Don't know what I'd do without ya's!

Dan


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Posted: Wed Jan 28, 2009 7:18 am
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Tube dampers have been around for many many years. Audiophiles would use them. The build quality of tube has gone down hill too which just aggravates the problem. They work great for me and always have. I've been using them for the past 15 years or so. Tube rattle does not mean the tube has failed. I've used tubes that have rattled for 3 or 4 years with tube dampers on them. They don't always work, but many times they do. If your tubes are old though, they're probably due for a change.


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Posted: Wed Jan 28, 2009 3:55 pm
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Tube rattle is caused by chassis rattle which is caused by speakers mounted to the the frame to which the chassis is also mounted. I guess you see where I'm going with this: to stop tube rattle, you gotta stop the vibration starting at the speakers from making its way into the tubes...

Real rubber dampers at the mounting points, chassis and frame stiffeners, metal tube covers and hold-downs, etc... generally alleviate the rattle. A well designed tube in good shape is not supposed to rattle - it is supposed to be stiff/rigid. Now think of the mechanics and physics behind all of this and how it all connects. Think of what possible contribution the "tube dampers" might have. Besides the fancy name, all they do is add mass to the tube and lower the resonance frequency of tubes shaking in their sockets. That's good if the tube resonance moves out of the chassis resonance not so good if it moves into the chassis resonance. Well how about stopping the resonance to begin with? That's what I was driving at, I was a little too lazy to write all down. Sorry about that. I hope this explains things a bit.

Ciao,
Johnny.


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Posted: Wed Jan 28, 2009 5:51 pm
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They work on my HRDlx, my Twin and my Vibrolux Reverb. It's worth the couple of bucks to give it a shot. I've also had new tubes rattle. Tubes will rattle in most combos. The Hot Rod series are the worst. I never had a Tube rattle in my Bandmaster or Sunn piggy back amps when I had them.
If you put a pencil eraser against a rattling tube it generally will stop. That's what the dampers do. They absorb the vibration in many cases. I remember guy's showing me the O ring trick in the late 60's.


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Posted: Wed Jan 28, 2009 7:55 pm
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I picked up a matched pair of tubes specifically for the cybertwin from eurotubes. I'm gonna give them a try. Even JJ says it's so-so with tube dampers actually working, and that combo amps are prone to this. My putting some acoustic foam in between the tube cases is acting like a damper too and it is helping a little bit, but the problem is still there. The problem I see with the dampers is the tube case itself, employed in the cybertwin. I'm not sure there is enough clearence to install a damper AND put the case back on too. I guess the case could be left off though, although it's on the tubes for a reason, perhaps to shield RF, I don't know. Fender did seem to try and help the situation by installing a spring in the case cover to effectively hold the tube down in place, which you would think would help, but it doesn't. The one tube in my amp that's rattling started doing it early on, after purchasing the amp new. In fact, if memory serves it did it right out of the box, which I understand can happen as well. The reason I've been able to deal with it is because this isn't audible in a live situation, not to mention I play mostly jazz, so I'm not pushing things to a killer level. And for recording, I generally use the XLR outs or SPDIF and I silence the amp by sticking in a headphone jack in the HP socket, so all is clean as a whistle. But it is long overdue to try and correct this and I'm confident new tubes will do it. I may give the dampers a shot too. For the little expense that they are, you never know. But, I'm usually not that lucky! I'll certainly keep you posted as to the outcome.

Dan


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Posted: Thu Jan 29, 2009 7:15 am
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The funny thing is Bob at Eurotubes who sells nothing but JJ's is the guy who recommended Herbies Audio Dampers. If space is a limitation they won't work. They are a steel ring with high temp foam on them.

Eurotubes makes a specially designed 6l6 that is supposed to help rattle in the HRDlx, I'm not sure about for the Cyber win.


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