Buying Tubes

[the*doctor]

Hi everyone,

I have a couple of questions about buying new tubes for my amp.
It's a Fender Bassman 100 head, silverface, mid 70's.

It was my first tube amp and I'm pretty sure it needs new tubes. It crackled a bit for a while and then it got way quiet. At full volume it sounded like it was around 5 watts.

So is this the tubes, and if so is it the output or preamp tubes?

These are the tubes the diagram says it uses:

x4 6L6GC

12at7
7025
7025

And if it is the tubes, does it really matter if you buy really expensive well known brand ones that are like $80-$100 for 4 of them, or is it just as good to buy NOS no name russian tubes from the 70's and 80's for like $35.

If it's only a slight difference in sound quality, I don't think I'd mind because it seems a bit steep to pay that much for tubes

Thanks in advance

[Franz 1997]

It might be best to change all the tubes, if they are original. With an amp this old, the problem could be tubes, or something else like screen resistors or leaking caps - time to get it checked by a tech.
It's not worth buying cheap, unknown-brand tubes,IMO. Tube replacement is a running cost for tube amps like oil changes for a car.Would you buy no-name oil?

[the*doctor]

Ok, thanks.
I suppose it would be best to get it checked by a tech, that just means that it will be out of action until after Christmas and the holidays and I can afford it

[marcwhy]

Check with the guys at Eurotubes.

[the*doctor]

Originally Posted by marcwhy

Check with the guys at Eurotubes.

Do you mean ask them what needs replacing or check out their tubes?

[Franz 1997]

There's no point in checking out anyone's tubes until you get the amp checked! It might not be tubes at all; what you have described could be lots of things. Anyway, when tubes fail they can take out screen resistors, for example.
If you just put new tubes in you run the risk that, if it's a circuit fault, it could take out any new tubes you put in it. No-one who hasn't looked inside the amp can tell you what the fault is - they would just be guessing.

If you are not familiar with tube amps, it really is best to get it properly checked out. Tube amps sound great but they do need regular maintenance, unlike other amps. Don't try doing anything yourself - the voltages inside these amps are very dangerous.

[the*doctor]

Originally Posted by Franz 1997

There's no point in checking out anyone's tubes until you get the amp checked! It might not be tubes at all; what you have described could be lots of things. Anyway, when tubes fail they can take out screen resistors, for example.
If you just put new tubes in you run the risk that, if it's a circuit fault, it could take out any new tubes you put in it. No-one who hasn't looked inside the amp can tell you what the fault is - they would just be guessing.

If you are not familiar with tube amps, it really is best to get it properly checked out. Tube amps sound great but they do need regular maintenance, unlike other amps. Don't try doing anything yourself - the voltages inside these amps are very dangerous.

Cool,
thanks for the info.

[marcwhy]

Originally Posted by the*doctor

Do you mean ask them what needs replacing or check out their tubes?

Well, both. The guys there are very knowledgeable, and could help diagnose some basics (obviously there's only so much they could do over the phone).