My Vox head crapped out...

[astrozombie]

It started last night. I was playing and all of a sudden it just stopped, dead silence. I look at the tubes, they're glowing OK, I take out the fuse and see that it's burnt.

I take it to my local guitar shop this morning and take out the tubes, they have a machine that's Orange branded that checks tubes to see how their health is. They all checked out except one power tube, I buy a set of JJ EL34s and go buy the replacement fuse. I get back and plug everything in... and the tone is super thin and lacking volume.

What the hell is going on?

 

[CTN]

Re: My Vox head crapped out...

did you get it biased?

 

[uOpt]

Re: My Vox head crapped out...

I think a broken tube was probably not the primary reason for the original failure.

 

[astrozombie]

Re: My Vox head crapped out...

I think a broken tube was probably not the primary reason for the original failure.

It's starting to seem that way. I checked the fuse at the AC cord jack, it's fine.

 

[kilphody]

Re: My Vox head crapped out...

Make sure the output trans impedence matches the speakers.
PC

 

[astrozombie]

Re: My Vox head crapped out...

Make sure the output trans impedence matches the speakers.
PC

It should... I don't understand why it sounds like that. The cab is supposed to be 8 OHMS, I have it set to 8 OHMS. would sending 16 OHMS to it from my head damage the amplifier?

 

[CTN]

Re: My Vox head crapped out...

It should... I don't understand why it sounds like that. The cab is supposed to be 8 OHMS, I have it set to 8 OHMS. would sending 16 OHMS to it from my head damage the amplifier?

yes.


so, did you get it biased for the new tubes?

 

[kilphody]

Re: My Vox head crapped out...

You can fry the output tranny with a mismatch in a tube amp. Not really so with SS, but a tube amp can crap out in minutes.
PC

 

[astrozombie]

Re: My Vox head crapped out...

yes.


so, did you get it biased for the new tubes?

No. I haven't biased it. , but it's just so strange... with everything cranked there's barely any volume and the tone is thin as hell. It doesn't just "sound bad", i barely get any volume.

 

[kilphody]

Re: My Vox head crapped out...

Take it to a tech. Get the tubes biased. If it still sounds weak get the output trans checked out.
PC

 

[astrozombie]

Re: My Vox head crapped out...

Take it to a tech. Get the tubes biased. If it still sounds weak get the output trans checked out.
PC

It's easy to bias, I'll bias it myself.

 

[astrozombie]

Re: My Vox head crapped out...

Last tech in PR closed shop.

I guess it's time to get handy...


Sent from my iPhone using Tapatalk

 

[kilphody]

Re: My Vox head crapped out...

Just remember that voltage can kill you.
PC

 

[jon the art guy]

Re: My Vox head crapped out...

^^^^^^^^^ WORK WITH ONE HAND ONLY. Put the other one in your pocket.

also my sincerest condolences. I hope it's just a bad connection or a blown cap and not the OT. That amp's pretty awesome and I hope it stays around.

 

[uOpt]

Re: My Vox head crapped out...

I don't think we are talking a bias problem here, nor that the old tube blew the fuse.

 

[zzmoore]

Re: My Vox head crapped out...

Yeah...first you need to deal with checking the bias...but is this a Cat Bias amp.?
What Vox do you have.?
If it has tube diodes...try installing a new rectifier tube.
A rectifier will Usually work or not work, but I have seen them cause problems besides just a quick death. Something snapped the fuse.....
As others have said...Set the impedance to match your cab.
Do Not use the Stand-By switch.
Let us know what you find out.
good luck

 

[LatsMcGee]

Re: My Vox head crapped out...

Well at least Vox gave you head until it was dead....

 

[Oinkus]

Re: My Vox head crapped out...

I had an issue like that and it was my fx loop going crazy,just had to jump it for a quick fix. Yeah I know that is really odd and it has never been fixed ,tech guy worked on it said it was fixed and nope.

 

[astrozombie]

Re: My Vox head crapped out...

V3 had crapped out. Just goes to show that those tube testing machines aren't all they're cracked up to be. I put in a new preamp tube and it's working fine, Biased the EL34s I bought to around 37mv each. Korg (Vox) claim that 35mv is the way to go but the plate voltage on these amplifiers is a lot closer to 500mv than it is to 450...

These JJs are rough man, I previously had some EHx tubes in there and when I put these in I had to turn up the bias pots a few notches just to get them to that 37.

 

[uOpt]

Re: My Vox head crapped out...

Does the old power amp tube still work?