#1
Quick question here, I am buying some new tubes for my 6505+ combo.

I was told I should check to see if they need to be biased.

I don't understand what this means, basically I just want to know if I buy some tubes can I stick them in the amp without it exploding on me!

Thanks!
#2
Unless they've changed the circuit from the head, the 6505+ doesn't have a large enough sweep on its bias pot to give too much voltage to the tubes it uses. You can crank it all the way up, and it'll still be biased too cold for 6L6s. Many people like this sound, but many don't - Which can be seen by the countless number of bias modded Peaveys available on the market.
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.





www.SanctityStudios.com
#4
Hmm...every Peavey I've looked at has a fixed bias like Mesa's...
ESP Eclipse Standard Series W/ PRS Santana II Pickups
PRS SE Soapbar II
Peavey 5150 120w Head
Avatar 412 Traditional Cab(v30's+G12H30's)
Malekko, Rocktron, T-Rex and MXR/Dunlop pedals
#5
Quote by Arch1119
Hmm...every Peavey I've looked at has a fixed bias like Mesa's...

The 6505+ has a bias pot. All of them are fixed biased, the 6505+ is adjustable fixed biased .
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
#6
Hey Cathbard, when you say 6505+ has a bias pot are you speaking of the head or is there one hiding in my combo too? Still getting my head around tubes all though your posts have been very helpful.
#7
Afaik they are exactly the same but I could be wrong.
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
#8
I'd have the bias adjustment modded so you can actually bias the tubes correctly, but thats just me. I'm handy with this stuff so its something I could do for little more than a few bucks in parts.
I don't give a shit if you listen to me or not
#9
Agreed. How can you make it sound like EVH if you can't bias the valves to self destruct after a couple of hours?
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
#10
Thanks for the help guys.

Is there anything I need to know when the tubes arrive in terms of putting them in? Like I understand I need to take the amp out of the combo etc before anything else, but is there anything else obvious I need? (Besides unplugging it).

Basically I don't want to be electrocuted, I don't want the tubes to break and I don't want the amp to break
#11
Only thing I know about tubes is after you put them in, wipe them down to keep any oil (from fingers) to a minimum. The oil can damage tubes fast under the high heat they operate at. Also, I'd like to add a question if I may... I just looked at both of my tube amps to see if either has a bias adjustment on the outside, neither do. Peavey JSX 2x12 combo and Mesa Transatlantic TA-15 head. My question is this, if the Peavey doesn't require a bias adjustment, why on earth does it have a bias test port on the back?
#12
Quote by Random3
Thanks for the help guys.

Is there anything I need to know when the tubes arrive in terms of putting them in? Like I understand I need to take the amp out of the combo etc before anything else, but is there anything else obvious I need? (Besides unplugging it).

Basically I don't want to be electrocuted, I don't want the tubes to break and I don't want the amp to break


You don't have to take the amp out of the combo, just take the back grated panel off, remove the tube covers (they are spring loaded, push them up a bit, twist, and they will clear their notches and come off easily. Then, just pull the tubes straight out, and keep in mind the pin configuation so you can easily re-install the new tubes. A slight wiggle motion helps to pull the tubes out, but not too much; you don't want to bend the pins.

Oh, and you'll want the amp to be unplugged, lol. Good luck!
#13
Quote by IbanezBossShred
Only thing I know about tubes is after you put them in, wipe them down to keep any oil (from fingers) to a minimum. The oil can damage tubes fast under the high heat they operate at. Also, I'd like to add a question if I may... I just looked at both of my tube amps to see if either has a bias adjustment on the outside, neither do. Peavey JSX 2x12 combo and Mesa Transatlantic TA-15 head. My question is this, if the Peavey doesn't require a bias adjustment, why on earth does it have a bias test port on the back?

It's very rare for the bias pot to be external. It's either inside the back grille, by the tubes, or more than likely, its inside the chassis itself, where all the wires are.

I'm pretty sure Mesa has never made an amp with an adjustable bias pot.
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.





www.SanctityStudios.com
#14
Quote by IbanezBossShred
Only thing I know about tubes is after you put them in, wipe them down to keep any oil (from fingers) to a minimum. The oil can damage tubes fast under the high heat they operate at.

It's a myth. The glass on a valve is crazy strong and they don't run even close to a temp that will hurt them. A bit of filth does nothing. If you wanted to you could rub a pork chop on them. I've seen some unbelievably filthy tubes and I've never seen a tube crack that wasn't bashed hard or dropped on concrete.
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