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Tubes rattle noise with Fender Pro Junior amp


Daniel Canton

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Hi everybody!

 

I'm new to this forum, so first I will introduce myself a bit. I'm a 24 years old, spanish guitar player who owns a Fender American Deluxe Stratocaster and a Fender Pro Junior amp.

 

I write here because I have a problem with my amp. I bought it second hand and since I have it, the tubes rattle a lot when playing certain notes on the guitar. I've searched on the Internet and I see it's a common problem with this amp, and it's derived of the filaments vibration of the tubes, because of the small cabinet the amp has. It has the stock Groove Tubes from Sovtek (12XA7 for the preamp and EL84 for the power section). Some people recommend me to change the tubes for another brands like JJ and Electro Harmonix. Would this stop the noise or would it came again after a time playing? I don't know what tubes to replace, the preamp or the power ones, because both of them can have this problem. Another problem is that if I change the power ones I will have to rebias the amp.

 

I hope anyone can help me.

 

Thank's a lot.

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Preamp tubes will give more trouble with this. The earlier in the circuit a tube is, the more any noise from it gets amplified.

 

Sovtek's 12AX7WB is a ruggedized version that's not as subject to microphonics as some types.

 

Tubes are fragile to shock and vibration. Rough handling of amps will loosen internal tube parts and cause microphonic problems. Always handle a tube amp like a box full of eggs.

"A cheerful heart is good medicine."
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hi... first thing you want to do is unplug the thing and let it sit so the voltage drains from the filters.... now one ata a time remove the tubes and check the sockets to make sure they're gripping the tub real good (cant tell ya how many times ive had to charge someone for tighting sockets) when you reseat the tube shove firmly from top try to avoid jiggling it "to seat it" you may have just fixed it.... play for awhile if not while its still a lttle hot tap each tube litely... start with the smaller (preamp) this finds most problems with crackling tubes...
"style is determined not by what you can play but what you cant...." dave brubeck
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I had the same problem with a Vox AC30 and these dampers did the trick for me... http://herbiesaudiolab.home.att.net/

 

He has changed prices and materials since I got mine, they are rather costly at about $12 each. I paid around $9 each, but they solved my problem and so were worth every penny. You have a 90 day return window if not satisfied.

 

Be aware you need one type for preamp tubes and another for the hotter operating temperature of the EL84s. Best of luck...

 

Tea.

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Thank you very much for all your comments.

I removed the springs and the metal plate that holds the tubes some time ago, and then the rattle was reduced notably. That's what they told me to do at a Fender dealer where I took the amp. The problem is that when playing at high volume (6 or more), the noise is practicaly unperceivable, but when playing at low volume at my apartment becomes very annoying.

Also I've tried to tap eache tube when they are hot and at high volume, and the power tubes rattle in a similar way(but at a lower volume) than when I play the guitar. So I think that the power tubes are the problem and not the preamp ones.

EmptinessOFYouth, you say that you replace the tubes and you couldn't fix the rattle. Could you tell what brand and model of tubes did you put? That's what I'm afraid of, changing the tubes whithout any effect.

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I also changed tubes to no avail, the problem was exactly the same. Just like you, my amp was fine at stage volumes, but tinkled at home.

 

A pair of dampers for your power valves might very well be worth trying out to start with. Same price as a pair of new EL84s and they will last you a lifetime of quiet amp performance.

 

Just be glad you don't have to check as many valves as I had too! :freak: Here's a picture of my amp's chasis with the dampers installed...

 

http://i5.photobucket.com/albums/y155/Teahead/dampers.jpg

 

Originally posted by Joe Bbach:

Great link Teahead. :thu:

More than welcome! :thu:
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Originally posted by Daniel Canton:

"I removed the springs and the metal plate that holds the tubes some time ago, and then the rattle was reduced notably."

 

"The problem is that when playing at high volume (6 or more), the noise is practicaly unperceivable, but when playing at low volume at my apartment becomes very annoying.

 

Also I've tried to tap each tube when they are hot and at high volume, and the power tubes rattle in a similar way (but at a lower volume) than when I play the guitar. So I think that the power tubes are the problem and not the preamp ones."

I've had very similar experiences with Fender tube-amps before. The spring-loaded sheild/retainers on the preamp and function tubes contributed to this, but the output-tubes didn't have those types of retainers and still had some microphonic/sympathetic noise troubles; at times the output-tubes can introduce a sort of a "BB's rattling in a jar" sound as they vibrated sympathetically. I'd expect that dampers like the ones that Teahead suggests would do the trick more effectively than anything else I can think of, short of a major invasive-mod project like mounting all the tube-sockets on a shock-mounted thing-a-ma-jig! (Even then, those dampers would probably still help in a combo-amp, what with the speaker right next to them!)

 

I haven't tried those myself- yet- but I know Teahead to typically know what he's talking about, and I think that the price is better than buying a bunch of different tubes that will wear out eventually, anyways (and might not sound the same as what you like, either)...

 

Best of luck, keep us posted! :cool:

Ask yourself- What Would Ren and Stimpy Do?

 

~ Caevan James-Michael Miller-O'Shite ~

_ ___ _ Leprechaun, Esquire _ ___ _

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Originally posted by Durockrolly:

I didn't find any by Fender (although my new Hot Rod came with dampers), but I did find these.

 

 

http://www.audiotubes.com/fender.htm

Cool! An interesting option, in two different brands.

 

http://www.musicplayer.com/ubb/icons/icon3.gifhttp://www.musicplayer.com/ubb/icons/icon4.gif I would like to point out the following, though, as I believe that it applies directly to most of the folks here:

 

As originally posted on the audiotubes.com 'site:

 

"NOTE: You should not use any brand or type of metal tube damper/cooler on a tube unit where the tubes are mounted upside down. The metal damper/cooler could fall off an upside-down mounted tube, causing damage to other components in your set.

 

We also do not recommend using metal tube damper/coolers of any brand or type on tubes directly mounted onto Printed Circuit (PC) boards where the PC board solder connections are directly exposed in the vicinity of the tube. Should the damper be dropped, or pushed down onto the solder connections of an energized PC board, it could cause a short-circuit causing equipment damage and possible shock hazard."

http://www.musicplayer.com/ubb/icons/icon3.gif I'd suspect that great care might be warranted when dealing with anything like these on any PCB-mounted tube-sockets, just to avoid physically damaging the solder-joints due to stressing and flexing during installation and with the added mass...

Ask yourself- What Would Ren and Stimpy Do?

 

~ Caevan James-Michael Miller-O'Shite ~

_ ___ _ Leprechaun, Esquire _ ___ _

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I have an original USA tweed ProJr.

The preamp tubes (specially #1) rattle.

Change them to ones that rattle less . (ifyou need to)

I have bought tubes that came wrapped in cardboard.

suming that you don't hav any of these wrappers, take a peice of cardboard, (like from a box, with ribbing inside the layers)

If it is very thick you can peel one side.

Cut to length, wrap around the tube, tape it up tight, with gaffers tape.

Just slip it on the offebding tube ( ususally you can tell if this will work by touhing the tube with your finger while it is rattling.

If your finger stops the noise so will the cardboard sleave , once it's tight enough.

Damps the noise right out. Doesn't seem to ever catch fire.

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If you go to this link (Fender Amp Manuals), go to pg. 7 of 20. Look at the illustration (Item "Y"), then read the description for "Y". This is what my Hot Rod has in it. I assumed it was made by Fender. Sorry.

 

http://www.fender.com/support/manuals/pdfs/manuals_elec/guitarpdf/Hot_Rod_DeVille.pdf

Fernando

 

If you can't say it in 12 bars... then it can't be said!

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