Bottlehead Forum

General Category => General Discussion => Topic started by: mtheshark90 on August 29, 2021, 06:41:41 AM

Title: Power Tube Loud Pop and Spark?
Post by: mtheshark90 on August 29, 2021, 06:41:41 AM

Just switched on my crack this morning, and after a few seconds my Tung Sol power tube made a loud pop with a visible white spark inside. I immediately turned off the amp and inspected the tube. It looks fine, and after turning it on again it seems to run fine. However, I'm now worried that this tube has some integrity issues that could lead to damage to my crack w/ speedball. I'm also worried about the pop happening when I have headphones on and having my ears blown out.

I just bought this tube recently and have used it for less than 10 hours. Should I contact the seller? Should I stop using the tube?

Of note, leading up to this event I've had ongoing issues with this particular tube in terms of sound. Commonly, there's a phenomenon in which the right channel becomes very "hollow and airy" and is suddenly incredibly sensitive to any vibration. I believe I've heard this termed microphony, unsure though. I was always able to resolve it by tapping on my desk, or lightly on the amp itself. I imagine I was vibrating something back into place within the tube.

Title: Re: Power Tube Loud Pop and Spark?
Post by: Paul Birkeland on August 29, 2021, 06:43:40 AM

It might be a good idea to just not use that tube.

When I see this on tubes we test prior to putting them into kits, they go in the garbage.

Title: Re: Power Tube Loud Pop and Spark?
Post by: mtheshark90 on August 29, 2021, 06:50:06 AM

Thanks as always for the fast reply, Paul. Will do.

Just a quick question on tube buying etiquette..
I purchased this from a reliable seller, Andy from Vintage Tube Services. It was not cheap. Is it reasonable to reach out, or is a tube pretty much void on any guarantee once in the buyer's hands?

Title: Re: Power Tube Loud Pop and Spark?
Post by: Paul Birkeland on August 29, 2021, 06:55:30 AM

You might e-mail him to ask if he would consider exchanging it for a different one. 

Another thing you can try is to fire the amp up with that tube running and leave the amp on for three or four days.  If the arcing is from a little residual gas, cooking the tube in may get rid of it entirely.

Title: Re: Power Tube Loud Pop and Spark?
Post by: mtheshark90 on August 29, 2021, 06:59:30 AM

Oh wow, interesting. I've never heard of needing to cook out the gas. Thanks Paul!

Title: Re: Power Tube Loud Pop and Spark?
Post by: EricS on September 02, 2021, 04:58:27 PM

Paul: should a tube be cooked like this with the speaker attached, or with a big 8R resistor instead?

Title: Re: Power Tube Loud Pop and Spark?
Post by: Paul Birkeland on September 02, 2021, 06:57:43 PM

The Crack does not require a load to be attached.