First time putting new tubes into Peavey VB-2

No idea but @BassmanPaul might.

 

Nope, sorry but I’m coming up blank. They could be from some kind of rig that the vendor uses to match his tubes. I’d give them a call for an explanation.

I feel that going out and buying a set of tubes without first verifying what the problem is was premature.

With a new set of output tubes the bias needs to be checked and reset as required. There again, it’s possible that the bias has drifted and that’s why the amp sounds bad.

Honestly I think that a look see by a tube amp tech might well be worth it.

Just for interest, in what way does the amp sound like crap?

 

I would want to verify that the tubes that are in the amp are in fact bad before just replacing tubes. There could be other damage that under some conditions ruin a new set of tubes. I would really recommend having a tech go through it to be sure everything is good (and to identify WHY the amp sounds like "crap"... have you played another one that sounds better side by side?) before installing the new tubes and biasing the output stage properly. Very important.

 

The tuner output is tapped from the input signal so you’re missing most of the preamp in your assumption that it’s power tubes.

I’d say find a better tech, the one you used doesn’t seem interested in actually servicing your amp.

 

Agreed.

 

PC = plate current, TC = tube transconductance....as measured from the tube tester that the vendor/distributor used. Gives a hint about the tube characteristics. Similar values indicates a good match (in the tube tester scenario that was used at that time, not necessarily in your amp (but very likely)). And as previous posters have stated, bias needs to be set for new tubes, and it's very possible that the problem could be something else.. power tube failure most often lead to blown fuses etc. It's possible that the tubes may have drifted over time, sometimes a bias setup is all that's needed instead of replacing the tubes. If the preamp sounds crappy (the VB2 has a DI out from where you can tap the preamp signal to another power amp), the troubleshooting should start with the preamp..
That being said, I've serviced amps that have had power tube issues , not blowing fuses. Partly working with blown screen resistors etc...sounds bad, but no fuses blow. The whole circuit needs to be checked at such times to find the issue.

 

Yep Very much agreed.

 

Interesting, creative and unproductive way to proceed with your amp. I would not put a new set of output tubes into an amp without verifying that there are no problems. It's a quick way to ruin a perfectly good set of new tubes.

 

Good amp techs!
Good amp techs!

 

When you own a tube amp, you should also know a trusted tech. It's like a Dr./patient thing. Not saying tube heads new a lot of service, but you should know where to go when the need arises. Most music store 'techs' are not experts (with exceptions- apologies to the stores with great techs.)

 

What are you measuring, voltage or current?

What is the current of each tube? You may have to calculate this.

In order to know the range so acceptable plate currents, you also need to know that plate voltage that the amp operates at.

You might need to contact the manufacturer to see if that information is available. A good tech would do all these things.

 

It is great that you want to learn, but continuing to power on a sick amp risk you causing more damage every time you turn it on to do more trial and guess work. This will cause your current problem to have to be fixed plus whatever just went. More cost and less likely to be repairable.

Using an amp you do not mind losing forever is one you practice to learn on, not one you need to work.
Take it to another Tech now before something else goes.