Problem with Tube?

Hello my friends,

lately I am experiencing one problem with the tubes of my Wavac MD-805.

When I switch on the amplifiers I have to wait around 10-15 minutes to listen to music. If I dont wait I hear a scratching sound from one of the speakers like "tearing paper" sort of...

If I wait and listen after 15 minutes from the switch on there is no problem, I suppose because the tubes warm up!! The problem only appears if I play music immediately.

Is this a serious problem? Do I need to change the tube causing the problem? Is my tube dying? Is this affecting the sound quality even after 15 minutes when there seems to be no problem?

Thanks in advance

Sometimes tubes will develop a bad internal connection that improves as the tube heats up. I've had some that would make that noise unitl I tapped them with a pencil. They never seemed to get much worse, and since they were my hardest to find tubes(Sylvania 6SN7Ws & 7199s), I put up with it. A connection that opens within a tube shouldn't cause any further problems. An internal short can cause a plethora of headaches.
Well, when I have a bad light bulb I change the bulb, why are tubes so hard for people to understand? I even have extra bulbs in the closet, and they are different sizes and shapes. In all fairness I do not know your amp or what ever, but change the tube.
Rodman and Jab are each correct. It's a matter of assuming a certain amount of risk (Rodman) vs. a lot more expense (for Wavac tubes ;-) Were I in your position, I'd contact Wavac and let them decide for you.
The 7199s are a thing of the distant pass. The 6SN7W tall bottles cost over $150 each. Light bulbs are somewhat cheaper, and they don't get intermittently noisy. They simply stop working(not even close). I've replaced the noisy 6SN7Ws with new ones, but I'm saving them for backups. In 30 years, I've never had a noisy tube, that could be quieted, cause any further problems. Of course- a tube that generates any noise/distortion/imbalance continuously HAS to go. I'm not trying to convince anyone of anything. Just sharing my experience, and answering the poster's questions. I'm certain the Wavac people would be happy to sell some new tubes, and if that would make Argyro more comfortable: It's the course he should take. Then again- I've seen some cold solder joints within equipment cause the same symptoms(noise went away when the gear warmed up).
Thank you very much guys, I suppose that since the tubes are not very expensive the wisest thing to do would be to change the tubes.

Kind Regards,