Fender champ

[Hiho]

Hello all,

I have just received (from the states) a fender champ circa 1974. This time my consignment arrived intact, clean and tidy!

What should I check on it before I fire it up?

I have a set of Mullard 6v6's of unknown condition from an old PA amp, can i just stick them in a single ended amp without concern?

Thanks

Matt

[Chuck H]

What should I check on it before I fire it up?

Make sure there is a speaker load in place and an istrument plugged in and see what happens.

I have a set of Mullard 6v6's of unknown condition from an old PA amp, can i just stick them in a single ended amp without concern?

No?!? Why would you put tubes of unknown condition in a new amp for testing??? Sorry, but that just makes no sense at all to me. Your better off testing it as it arrived. Chances are better that the seller sent it in working order than randomly plugging tubes of unknown condition into it.

You really need tubes of known working condition to determine anything right from the start. If you plug in tubes that are an unknown quantity, or the tubes that are already there are an unknown quantity (if there is no guarantee from the seller) then where do you start diagnosing any problems without having to buy tubes anyway?!?

Chuck

[Hiho]

Thanks Chuck,

The amp is tested and sounds really sweet, except for what may be microphonics. When played, there is a rattling/ringing sound at certain playing intensities.

With regards to the Mullards, I would like to use them in the future, not for testing the amp now. If I do have a microphonic valve, I may like to use them sooner rather than later. How should I go about determining the condtion of the valves?

Cheers,

Matt

[Chuck H]

Check the bias condition and plate voltage of the amp in question. If it checks out it's as safe as any for testing the tube. Just plug it in and see how it goes. But before that, if you have a spare preamp tube (that isn't microphonic) swap it in there to see if the problem goes away. Sometimes power tubes become microphonic with extreme age or use too. But try the preamp tube first.

Chuck