Bottlehead Forum

General Category => General Discussion => Topic started by: troplin on March 31, 2017, 10:42:02 PM

Title: What's harmful to tubes?
Post by: troplin on March 31, 2017, 10:42:02 PM: Hi all,

I have a few questions about how (not) to treat tubes for maximum lifetime:

1. Is it harmful to start playing music just after turning the amp on? Or do I have to wait until it is warmed up?

2. Is it harmful to keep playing music after switching the amp off? If I do, the music slowly fades out and gets more and more distorted.

3. Is it harmful to handle the tubes with bare hands? I've read contradictory information to this, but tend to think it's ok.

4. Is it harmful to switch the amp back on shortly after turning it off? I've read an old thread on this forum that suggests that. If yes, why and how long should I wait?

Thanks,
Tobias
Title: Re: What's harmful to tubes?
Post by: Doc B. on April 01, 2017, 05:41:42 AM: Don't worry about any of that stuff. Just don't pull a tube out of an amp that's on.
And don't drop them.
Title: Re: What's harmful to tubes?
Post by: troplin on April 01, 2017, 06:38:54 AM: That's good to know, thanks!
Title: Re: What's harmful to tubes?
Post by: Paul Joppa on April 01, 2017, 03:27:39 PM: When sockets are new, they might require a lot of force to pull a tube out, in which case pull from the tube bass if it's an octal or 4-pin. In lder tubes, sometimes the glue that holds the glass envelope has dried out and lost strength.

Paramount in 2A3 form (now discontinued), if recent production v1.1 or with the soft-start upgrade, should rest for 20 minutes before re-starting. It's in the manual (p.67 for Paramount), but not everyone reads the whole manual, or remembers every word in the manual.
Title: Re: What's harmful to tubes?
Post by: Gerry E. on April 02, 2017, 04:29:09 AM: Quote from: Paul Joppa on April 01, 2017, 03:27:39 PM
Paramount in 2A3 form (now discontinued), if recent production v1.1 or with the soft-start upgrade, should rest for 20 minutes before re-starting. It's in the manual (p.67 for Paramount), but not everyone reads the whole manual, or remembers every word in the manual.

PJ - I thought this also applies to Paramount v1.1/with soft-start in 300B form. If not, why is there a difference between 2A3 and 300B configurations (filament strength)? Thanks.

Gerry
Title: Re: What's harmful to tubes?
Post by: Paul Joppa on April 02, 2017, 06:36:38 AM: The 2A3 Paramount is direct-coupled, so the 2A3 grid is at full positive voltage (very bad for some tubes) when the C4S is conducting but the driver cathode is not yet hot enough. The delay in the C4S on startup resolves that problem.

The 300B version is cap coupled, so the 300B grid is referenced to ground and cannot go so high so fast.
Title: Re: What's harmful to tubes?
Post by: glynnw on April 02, 2017, 01:29:43 PM: Once I caught my girlfriend's dog licking the tubes in my amp. Don't know if it was harmful to the tubes, but it was to the relationship.