Rattle n' Roll!

N

Newbie-Doo

Member
My Carvin tube amp has started making a rattling noise lately and I'm not sure what the cause is. It seemed to be louder with the reverb turned up so I thought it might be the tube or a loose spring. I completely disconnected the reverb tank and it still makes the sound. I purchased a new 12AX7 and switched it out with the existing tubes one at a time and it still rattled. I had an old set of power tubes and switched those out and it still made the rattling sound. Checked all the nuts on the speakers and those appear to all be tight. I suppose I could buy a whole new set of power tubes to verify if that was the cause, but was wondering if it could be something else.

Any ideas? :confused:
 
You might check for a loose speaker, one of the nuts that hold them in place may have loosened. :confused:

Oops, I didn't read to the end...nevermind~~ :o
 
I put some GT 12AX7M reissues in my Rivera last summer. They were just about immediately microphonic.

I swapped them all out for a matched trio of these:

http://thetubestore.com/tungsol12ax7.html

A little chirpy once in a while, nothing like the GT's which were doing what sounded like a guitar cable dead-shorted to ground.

Be careful swapping power tubes. I don't know if the Carvin's need re-biasing or not.

Now I've got a pair of THD Yellowjackets in it. Has a weird transparency it didn't have before on the clean channel. Like a little crunchy but really defined. Really makes chord voicings stand out. First time I've ever messed around with Class-A type tubes and guitar.
 
c7sus said:
Now I've got a pair of THD Yellowjackets in it. Has a weird transparency it didn't have before on the clean channel. Like a little crunchy but really defined. Really makes chord voicings stand out. First time I've ever messed around with Class-A type tubes and guitar.
Click to expand...

Interesting. I've got a pair of them in a Marshall 50w and they sound pretty good, but I never looked into why exactly. Class A, you say? Just curious here... How is it that putting something into the tube sockets can change a push pull pair of power tubes into a parallel pair? It seems to me that the flipped polarity of the tubes into the output transformer is locked in by the wiring of the socket to the tranny, and merely changing one of the tubes to be in phase with the other would simply produce the same waveform at both terminals of the primary, which would mean no signal at the secondary. Maybe they somehow change the wiring in the bases to somehow rewire the tranny? Anybody know?

EDIT: Never mind; I think I figured it out.
 
Thurgood said:
Well Ggunn tell us what you figured out? You may want to start a new thread.
Click to expand...

Well, what I figured out is that the tubes can be in push-pull and still be class A.

In class B, one tube carries the positive swing and one carries the negative. In class AB, the waveforms from each of the tubes are sort of squashed together so that they overlap, where one carries the positive half and a bit of the lower, and the other carries the lower half and a bit of the upper. If you keep squashing them into each other until both of them carry the entire waveform, then they are in class A operation.

How the YJ's do that electrically, I don't know, but I figure that has to be what they do to convert a class B or AB amp to class A operation. Anyone with a deeper understanding of this, please feel free to expand on this or tell me I'm out to lunch.
 
I think JJ is suppose to be the hot ticket.

But I don't think your problem with rattling would be tube related. I would tighten every single screw, nut, etc.

What you could do is hook up another cablinet and disconnect the built in speaker if it is a combo amp. See if the problem disappears if it doesn't then you know it is coming from the amp. Double check your impedance, you may have to hook the cabinet up to the built in speaker output.

I have a Fender Supersonic that feedsback through the reverb channel if it is turned past 3. When I tilt it back with the tilting legs I can turn it to 10 with
no problems anyone ever experience anything like that.
 
An important thing to discern is whether the rattling sound is coming electrically through the speaker or acoustically from somewhere in the amp. Determining that will send you off in one direction or the other.

The source of rattling can be deceptive. I had a rattle once that turned out to be a beer can in a metal trash can behind the amp. ;^)
 
ggunn said:
...I had a rattle once that turned out to be a beer can in a metal trash can behind the amp. ;^)
Click to expand...

Hahaaaaa classic!

You ever rattle a burned out light bulb?? It sounds kind of like that. I figure it has to be a tube. It seems to get worse once they warm up and certain frequencies seem to really set it off.

Man...I didn't want to buy a whole new set of tubes because I might have to sell the amp.
 
Newbie-Doo said:
c7sus said:
"According to the manufacturer, this Tungsol 12AX7 is the Ultimate 12AX7...
Click to expand...

Of course they say that. Does it make coffee, too? ;^)


"That's right, it filets, it chops, it dices, slices,
Never stops, lasts a lifetime, mows your lawn
And it mows your lawn and it picks up the kids from school
It gets rid of unwanted facial hair, it gets rid of embarrassing age spots,
It delivers a pizza, and it lengthens, and it strengthens
And it finds that slipper that's been at large
under the chaise lounge for several weeks
And it plays a mean Rhythm Master,
It makes excuses for unwanted lipstick on your collar
And it's only a dollar, step right up, it's only a dollar, step right up"

- Tom Waits
Click to expand...
 
Newbie-Doo said:
Hahaaaaa classic!

You ever rattle a burned out light bulb?? It sounds kind of like that. I figure it has to be a tube. It seems to get worse once they warm up and certain frequencies seem to really set it off.

Man...I didn't want to buy a whole new set of tubes because I might have to sell the amp.
Click to expand...

Does the sound emanate from the speaker or is it an acoustic rattle?
 
The Tung-Sol have had good reviews elsewhere.

The GT-M reissues were microphonic almost out of the box. I heard sounds from those damned things I have never heard from a tube amp.

Buy something else if the ad copy rubs you the wrong way. The Tung-Sols were recommended by somebody else to me and they sound really good.

I'd say my comment about a few pops and clicks is a damned sight more honest that GT selling off the remaining stock of the M-reissues.

YMMV. :rolleyes:
 
Pull the tubes and shake them next to your ear. If they rattle at all (any noise what-so-ever), they have loose filaments. Even new tubes can have this problem, since quality control is at an all time low. This has been the cause of a couple of my amps making a rattling that you described.
 
c7sus said:
The Tung-Sol have had good reviews elsewhere.

The GT-M reissues were microphonic almost out of the box. I heard sounds from those damned things I have never heard from a tube amp.

Buy something else if the ad copy rubs you the wrong way. The Tung-Sols were recommended by somebody else to me and they sound really good.
Click to expand...

It was a joke. Stand down. ;^)
 
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