Comments on: Changing Tubes on Vacuum Tube Amplifiers : How to Set Bias for Right Power Tube of Amplifier

By: ectskater

ectskater — Sun, 16 May 2010 15:56:51 +0000

Thanks for posting this info.
I have a Hughes and Kettner tube 50 head that I am replacing all of the tubes in it.
It has (2) EL34′s for the output, and (3) 12ax7, the head has reverb, so I imagine one of the tubes is a driver for that signal path.
In any case, I would like to know if you have any tips on doing the bias to it, I can’t find any info on the spec for it from H&K, so I am hoping if it can’t be biased,(fixed?), that the tubes will be OK.
God Bless- Joshua

By: ectskater

ectskater — Thu, 13 May 2010 22:43:19 +0000

Oh yeah, the amp sounds great for 15 min, then gets brown sounding. Hmmmmmm?

By: Charliemusslewhite

Charliemusslewhite — Mon, 10 May 2010 16:21:50 +0000

Sorry, but I didn’t get that. You said there is NO adjustment pot at the right side, so what did happen? The current adjusts itself magically? Not very well made how-to video.

By: insektuo

insektuo — Mon, 10 May 2010 08:33:36 +0000

this *****!!

By: aziker

aziker — Fri, 07 May 2010 05:31:06 +0000

Great job, Jeff! People should be lining up on Main St. in downtown Mesa to use your expertise.

By: 6661VengeanceHarlot

6661VengeanceHarlot — Wed, 05 May 2010 00:19:20 +0000

i have a B-52 ST-100 and i opened up the back to heck the tubes. and when i turned it on, i noticed that all the power tubes turn a blueish color. and one of them didnt light up blue at all. does that mean i need new tubes??
please help??
im not a pro with tube amps..

By: ImprintAudio

ImprintAudio — Sat, 01 May 2010 15:55:54 +0000

Blue is normal and not all tubes exibit color so NO you don’t need to replace your tubes. You only need to replace them if you hear hiss, pops, or other noises.

By: ImprintAudio

ImprintAudio — Wed, 28 Apr 2010 10:49:54 +0000

Great video bro!

By: oldGNRfan23

oldGNRfan23 — Sun, 25 Apr 2010 19:19:19 +0000

How often do you need to replace tubes? Is it pretty often or…? Any help there would be great. Thanks in advance!

By: ImprintAudio

ImprintAudio — Fri, 23 Apr 2010 18:36:47 +0000

Depends on who you talk to. Most people wait until their tubes start to make funny noises. Pre amp tubes can last years and power tubes depending on bias setting last a year or so, depending on how often the amp is used.