#1
How do I tell if my preamp tube is going bad in my Vox AD30VT?
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#2
You plug in your spare tube and see if it changes. You do have a spare don't you? If not, why not? They're like $10.

PS: it isn't actually a preamp tube, it's a power amp driver.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#3
Haha yeah I do have a spare. But the thing is such a hassle to get to. I wanted some info before I tore the amp down to get to it.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#4
Just plug the new one in you lazy bastard.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#5
You can't get to them without taking the entire chassis out and flipping it upside down. Its a really awkward way to get to them.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#6
Then pull the chassis out and flip it upside down. Come on man, it's not like you are trying to rebuild a gearbox. Bite the bullet and just do it. Don't forget to unplug it from the wall will you?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#7
Nah I wont forget to unplug it. Guess its time to work. haha
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#8
Good man.



Still be careful of those filter capacitors won't you. Discharge them. They won't be particularly big to power a single 12AX7 but they'll still hurt. Once you get the chassis out just short them out with a bit of insulated wire. Just use one hand when you do it if you can. Keep the other one in your pocket. Just bend the wire into shape and touch the two ends to the capacitors contacts.
If you are unsure take a photo once you get the chassis out and post it here so I can point it out to you.
You should be ok even without discharging them, they'll mostly discharge through the tubes down to a voltage that will just give you a zap but not really damage you - but the heart is a funny thing. I may have survived countless shocks but who knows how your heart reacts?
You could just wear a glove when you reach in there to change the tube and keep the other hand in your pocket. If you don't know what a cap is, that's probably easiest. A rubber glove from the kitchen is fine as long as it's dry. Iirc those things are laid out pretty well.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Dec 8, 2011,
#9
I always wear something over my hand when I'm changing tubes. I don't touch tubes with bare skin. I heard the oil from your hand can cause a hot spot and weaken the glass.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#10
Urban myth. The only thing you have to worry about is burning your fingers (or zapping yourself if it's inside). A bit of oil isn't going to break the glass on those things, you could smear them with pig fat if you wanted to - DON'T. The glass on a tube is tough, man, really tough. Try to break one one day and see for yourself.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#11
Well, I have it in, and its time for the moment of truth. See if the problem I was having is gone.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#12
See? That didn't take long now did it?

*crosses fingers*
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#13
Seems to be fine now. The problem was some crackling behind the note coming out of the speaker...and a lot of ridiculous hum. I guess that would explain why I felt I was only getting half the volume out of it.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#14

Now don't forget to replace your spare.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#15
Haha yeah. I'll have to go get a few more. Btw. I love that Jack Daniels amp of yours.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#16
Thanks. There's another one just needing the finishing touches sitting right next to me.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#17
How much do you typically sell those for?
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#18
Has been $650 plus postage but this one may have to be $700. Blame Julia Gillard, she screwed with the Aussie $ just as I placed the order for the parts from the US.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#19
Damn. Those are pretty awesome looking though. Keep it up man.
My gear:
1982 Peavey Falcon
2004 Les Paul
2006 Peavey Transtube
2007 Youngblood 100w cab
2002 Dean Playmate Bass
2002 Dean Bassola
#20
They rock too, if I do say so myself. Real old fashioned Marshall roar.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#21
One thing you can do is unplug your guitar from the amp, turn it on, turn up the volume and tap on the tubes. If the amp makes a little ping, then the tube is pretty worn.

Of course I don't know how easy it is to access the tubes on those.
BOOM-SHAKALAKALAKA-BOOM-SHAKALAKUNGA
#22
Quote by Cathbard
You plug in your spare tube and see if it changes. You do have a spare don't you? If not, why not? They're like $10.

PS: it isn't actually a preamp tube, it's a power amp driver.

hey cath, anywhere in aus where you can get tubes at eurotubes prices? been meaning to get a retube for my kustom for ages but can't be arsed organising overseas shipping.
#23
Quote by NakedInTheRain
hey cath, anywhere in aus where you can get tubes at eurotubes prices? been meaning to get a retube for my kustom for ages but can't be arsed organising overseas shipping.

Nah. Ebay is your best bet really. I've been buying them from the states when I put in an order of trannies from america. I'm already paying for the freight on a couple of transformers anyway so ............
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band