#1
Hey people tomorrow my JJ's are coming and I'm looking to install them and rebias my amp, however I've never done it before.

Ive got a multimmeter and a bios probe coming as well I've just watched an instructional video

http://www.eurotubes.com/euro-Generic-Bias.htm

Here's what i understood


1.Take the amp out of the chassis, take the 4 screws out and grab the transformer and pull out

2.Clean the sockets by using a de-ox/electrical contact cleaner and putting it on an old tube and placing in and out of socket on both power and pre amp tubes

3.Hook 8 pin bias probe and multi-meter into sockets

4.Put new tubes over the Bias probe and Multi-meter (bit confused about this)

5.Turn power on and allow tubes to heat up

6.Make sure there is a speaker load (what exactly does this mean?) Insturument cable plugged into speaker as usual?

7.Flip on standby and get a reading

8.Adjust the bias to ahhhhhhhhhhhhhh! I've lost it all when he gets his calculator out

Help please :P

Is it necessary to adjust plate voltage?
Ibanez PGM301 signed by Paul Gilbert
Ibanez PGM 500
Ibanez Fireman custom
Saving for a GH100L/VH100R
Orange PPC212 2X12
#2
Help me out here guys plx!
Ibanez PGM301 signed by Paul Gilbert
Ibanez PGM 500
Ibanez Fireman custom
Saving for a GH100L/VH100R
Orange PPC212 2X12
#3
Tubes are here guys :P one last bump, if i get no replies this time I'll delete the thread
Ibanez PGM301 signed by Paul Gilbert
Ibanez PGM 500
Ibanez Fireman custom
Saving for a GH100L/VH100R
Orange PPC212 2X12
#4
The speaker load thing mean have the speaker plugged in.

His caluclations are to figure out exactly what bias current is safe in the amp based on it's voltage. The actual calculations just over complicate things and so does measuring the plate voltage. All you really need is to know what is the "safe" bias current for your tubes and bias them within that range then play around with it and see what sounds best to you.
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#5
Many thanks for that response! helps a lot. Wouldn't it help to be precise with calculations just so i know how to do it again in the future?
Ibanez PGM301 signed by Paul Gilbert
Ibanez PGM 500
Ibanez Fireman custom
Saving for a GH100L/VH100R
Orange PPC212 2X12
#6
I just popped the new tubes in. You're making it more complicated than necessary
#7
Quote by sharpant
Many thanks for that response! helps a lot. Wouldn't it help to be precise with calculations just so i know how to do it again in the future?


Not really. Different amps sound better with different setting and just because everything looks good on paper doesn't mean it's going to sound good so the formula isn't really the best thing to go by. Make sure you have the tube opperating at safe levels and then tune it to tast.
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