When is a bias needed?

[nrwoodman]

Hey the used amp I'm getting needs new tubes, it has ruby 6l6's, i was just wondering if i get a different brand tube, but still 6l6, will i need to bias my amp?
Oh and the amp was biased about 6 months ago with the rubys in it.

 

[MaxOfMetal]

It depends on the amp, but typically yes, you'll need to re-bias it when you get new tubes.

 

[col]

Unless you get tubes that are the same type (6L6) and have the same rating as those that are in your amp, it's a good idea to bias them.

 

[nrwoodman]

cool, I researched into how to bias an amp yourself it seems pretty straight forward, any links where i'd be able to get that tool that they use for biasing?

its a 5150 btw.

 

[Leuchty]

Eurotubes.com or you can get a multimeter from any electronics store.

 

[JJ Rodriguez]

cool, I researched into how to bias an amp yourself it seems pretty straight forward, any links where i'd be able to get that tool that they use for biasing?

its a 5150 btw.

I'm assuming it's bias modded then? Because you can't bias a 5150 unless it's been modded.

Search on eBay for a bias probe, you can get cheap ones that plug into any multimeter so you don't have to pay a fortune for a Weber. Make sure you get one that reads plate voltage as well.