How to restore an old tube amplifier ?

[TrevorBarten]

So I have quite a few old tube amps (mostly philips) however they are all mostly original (inside) and while most of them do work I feel like I should try and get them to sound as good as possible. So what should I do ?

 

[cademan]

Just replace the old stock (50+ year old) capacitors and any out-of-tolerance resistors. Tubes last longer than expected nowadays but they are usually still good as long as they are not shorted or the glass bulb isn't cracked or broken.

Pics?

 

[trobbins]

What electrical experience and electronics skills do you have?

Any circuit operation testing, as well as part replacements require competant awareness of electrical safety.

 

[TrevorBarten]

Just replace the old stock (50+ year old) capacitors and any out-of-tolerance resistors. Tubes last longer than expected nowadays but they are usually still good as long as they are not shorted or the glass bulb isn't cracked or broken.

Pics?

I needed one to test some 800 ohm speakers I recently bought so I have a couple on hand atm here is a pic of 2 of the philips amps

I have quite a few more if I recall correctly I have 2x ag 9013 2x ag 9014 1x ag 9015 1x ag 9016 2x ag 9018 a full set of hf 309 mono blocks (2 mono amps pre amp tuner) 6400s ag 9006 etc

 

[cademan]

800 ohms? Are those output transformerles amplifiers?

 

[Plimpington2]

Those are lovely.

 

[savatage1973]

If you don't already have one--a variac should be one of your first investments.

 

[gadget73]

Oh, Phillips BiAmpli stuff. Yeah, no output trafo on those. Its a fairly interesting arrangement thats basically a cathode follower circuit. I have a tabletop radio that used those speakers, unfortunately the 6x9 was dead. I ended up subbing a normal one along with a transformer for a PA speaker to make it go.