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Post subject: Fender Blues Jr. Rattle help needed
Posted: Thu Mar 03, 2011 10:24 pm
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I know rattle in a small combo amp this isn't anything new and I've read several posts on various forums about rattle (specific or not specific to a BJ), but I can't seem to solve this problem. And this is a little worse than minor rattle...so I will go through what the issue is, what I've done so far to attempt to solve it, and hopefully someone can give me another option to figure something out! Thanks for any advice!!!

Ok...so I have a Made in USA version of the BJ...plug in and turn volume up fairly loud (halfway for both Master Volume and Volume knobs). When I hit a certain note on one of the E, A, or D strings I get a metal-ish sounding rattle that sounds like it comes out the back of the amp. If I'm on the A string, it appears to be around the 7-10 fret mark, if I move up or down the neck, the rattle goes away or is very minor. Same for E and D strings, although different points on the fretboard induce the rattle for each string.

When I play a rattle note and sit behind the amp and examine the rattle, I notice a few things: The top of the cab vibrates a ton (it is worse around the center/middle of the top around the handle, working its way towards the control panel at the top rear of the amp). Towards the sides of the top of the cab is almost no vibration, down the sides is basically vibration free as well. When I sit there and just intently listen to the rattle, it just sounds like the aluminum chassis or inards of the chassis shaking and vibrating, thus making the rattle.

So here's what I've done so far (to no avail :( )...

1. I took the back panel off...played...rattle still present.
2. I tightened every screw I could get a screwdriver to (kept panel off)...rattle still present.
3. I removed the chassis completely from the cab...now this is where I thought I'd see/hear something...when I plugged it in and played it...rattle still present. It still sounded like it was coming out the top/back of the amp.!!!!
4. I tightened every screw inside the cab and every socket I could get a wrench to inside/outside the chassis. I reassembled the amp (except the back panel)..played, and rattle present.
5. I put the back panel back on and ordered some new tubes. I Replaced the tubes tonight and tested it out (fully assembled). Rattle still present...and possibly even worse to the upgraded tubes!!!

I'm at a loss. I love the sound and tone of the amp...except when I hit those certain notes and that horrible rattle booms out! If I can't fix it I will have to sell it, because it's that annoying. I have a Fender Tweed Deluxe (handwired) amp and it has small rattle...so I know the difference between rattle that you have to live with (with a small combo) and rattle that makes you want to toss the amp out of a plane!

Am I missing something obvious? I've read a few dampening techiques some places? ie - putting weather stripping or some foam between where the chassis and cab connect on top. The rattle is powerful enough I just thought it would blow away and little wimpy foam trying to tame this beast!

Could the speaker possibly be it? I've already invested $$$ in new tubes...so I don't wanna drop some more dough into a speaker and it not be the culprit.

The best way I could describe the rattle is if you sat next to the amp with your eyes closed and a rattle note was played, you would think it was thin, loose pieces of metal (like aluminum...it's not a heavy sound) rattling around.

I'm sorry for the long post, but I wanted to describe it the best I could so I could get some answers to this damn rattle! :evil:

Thanks again for any help.


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Fri Mar 04, 2011 1:53 am
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Hi rian4224,

Maybe it's the reverb tank. It should have soft mounting feet, and the screws should NOT be very tight, so the tank should be able to move a little. But you could unplug the cables and remove the tank from the cab, and see if the rattle goes away. Check the tank while it's out to make sure that the four springs at the corners are still there, sometimes they can come loose. Another possibility is the speaker baffle might be loose. You have to hold the nuts inside the cab while tightening the screws on the outside. :idea:

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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Fri Mar 04, 2011 9:42 am
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Thanks for the tip...I don't think the rattle is coming from the reverb tank, as it sounds as if it is coming from the inside out through the top...but I will definitely give it a try! I will leave no stone unturned I guess until this is fixed :?

I have already tightened the baffle, but I will recheck that as well.

I have read elsewhere of the voicecoil in the speaker rubbing and causing a rattle. Since I took the chassis out of the cab and it still made the rattle, this could make sense.

But I'll be honest, I don't really know what that means. If it is the voicecoil...is that something I can fix, or does that mean I have to replace the speaker? And is there any way to test that and see if the voicecoil is in fact the problem?


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Fri Mar 04, 2011 10:03 am
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If the voice coil is the source of your problems, the speaker is toast and will require re-coning. Temporarily replacing it with a known-good driver will reveal whether or not the amp rattle problem is related to your speaker.

Best of luck, HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Fri Mar 04, 2011 3:57 pm
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Probably a long shot and you may have already tried it, but make sure the speaker mounting screws aren't unevenly tightened or over-tight. Try loosening them off and then re-tension, evenly and not too tight, maybe the speaker's frame has been distorted.


Snowy


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Sun Mar 06, 2011 1:53 pm
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Believe it or not, your rattle issue may or may not be coming from your amp! I have a tweed NOS, and if I play louder than bedroom volume and hit certain notes, I got a rattle (or two) that took me a while to locate. And the rattles all really sounded like they were coming from inside the amp. I checked all the usual stuff, and nothing seemed to work. After thinking "outside the box" (no pun intended), I finally discovered that the rattles were not actually coming from my amp, but from the light fixture above my amp. After further review, I also found that the fins in the heat register next to my amp would also vibrate and make a "metallic" sounding rattle. Move the amp to a new spot, or put it on an amp stand, and the rattles all disappeared! Problem solved. Oddly enough, "A" and "E" notes/chords induced this rattle the most, and I suspect different objects will react differently to certain frequencies. Good luck, but don't give up on your amp yet! :wink:


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Sun Mar 06, 2011 5:43 pm
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once, I had to try 3 diffent preamp tubes before i got one that didn't rattle.
Just weird luck i guess
-------------------
my ss 22 had 1 12ax7 and also 1 of the 6v6's that rattled BAD

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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Mon Mar 07, 2011 7:55 pm
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Hi rian4224:

I think maybe BillM has a possible problem and solution for your issue on his site. If you read the whole article, at the bottom he talks about noise with power transformers. I don't know if this is the problem you have, but here's a link to the page for you.

http://billmaudio.com/wp/?page_id=882


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Mon Mar 07, 2011 11:26 pm
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Well, I think I am soundly beat by Mr. Rattle. :evil:

First I would like to thank everyone for their input, it was very valuable and appreciated.

After hooking the amp up to an external speaker to test, then hooking the amp back up and removing the chassis from the cab to test, I'm 99% sure I (kind of) located the source of the rattle. It is definitley a mechanical rattle produced somewhere in the chassis due to the vibrating top of the cab or just the speaker sound vibrations.

My last ditch attemp was a method I came across online. I removed the chassis screws from the sides of the amp and loosened the top two chassis screws to lower the chassis (after I removed the back plate). I inserted some thick foam cushioning in between the space where the cab meets the control panel and screwed it back in place real tight. (It appears that the cab isn't level or the chassis screw holes weren't even because there is a bit of a gap betwen the cab and chassis, but the right side is a larger gap) I tried it out and at first I thought I might have dampened it quite a bit, but then the rattle came right back and even a little worse.

So I give up. I removed the foam and just put the amp back to the way it was. I will remove the brand new tubes and put the original ones back in and sell it. Maybe the next owner either won't care about the rattle or will be smarter than me and be able to fix it.

Too bad, I like the amp and wish I could get it to where I am happy with it. I live down the street from the cities top amp repair guy, but I don't know if I want to bother with this and spend the money for something he possibly can't repair...dang, I'm so frustated!!!! :evil:

Thanks again for everyone's input.


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Post subject: Re: Fender Blues Jr. Rattle help needed
Posted: Mon Mar 07, 2011 11:30 pm
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It's possible that this "top amp guy" might just know the fix to eliminate your rattle problem. Why not call him up and at least hear what he has to say?

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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