How to Bias your amp!

[Lev]

Found some excellent video's from eurotubes on how to bias your amp - It's the kinda thing I would normally leave to experts but these video's do make it look sort of easy.

www.eurotubes.com/euro-video.htm

 

[oldguy]

Yes, Bob is very helpful in every aspect when it comes to tube amps. His videos are great for anyone wanting to get started in biasing their amp. A properly biased amp sounds wonderful.

IF anyone decides to bias their own amp, or do any other type work inside the chassis, however, READ THE CAUTIONARY STATEMENTS before proceeding.

Because of the high voltages used in tube amplifiers, you can be seriously injured or killed poking around in there, so be damm sure you know what you're doing or don't do it. Learning about your amp is a very rewarding experience, and I encourage folks to do so, but be careful. I don't mean to sound preachy here, but having your fingertips blown off or your heart stopping from a massive jolt of electricity is a very real possibility if you mess up!

Other than that, proceed with caution, and enjoy!

 

[duhvoodooman]

IF anyone decides to bias their own amp, or do any other type work inside the chassis, however, READ THE CAUTIONARY STATEMENTS before proceeding.

Because of the high voltages used in tube amplifiers, you can be seriously injured or killed poking around in there, so be damm sure you know what you're doing or don't do it. Learning about your amp is a very rewarding experience, and I encourage folks to do so, but be careful. I don't mean to sound preachy here, but having your fingertips blown off or your heart stopping from a massive jolt of electricity is a very real possibility if you mess up!

Oldguy is right on the mark here. The point isn't to scare anybody, but to engender the healthy respect that the inside of a tube amp deserves. In particular, you need to be very careful around those big filter capacitors. Those puppies can hold a big ol' charge for days after am amp is turned off and can light you up like a Christmas tree! Take the time to read a little bit about proper procedures for working in a tube amp, esp. about how to discharge those big filter caps safely. HERE is a good place to start.

 

[Lev]

Good points Gents. I've never even looked inside my amp before so the whole voltage issue is the main reason I'd normally bring it to a tech. But I'm strating to think if I discharge the capacitors correctly and take all the necessary precautions this is a job I could do myself (famous last words!!).

I've had my Hot Rod Deluxe for about 8 years now and I'm just waiting for a tube to blow. If it happens I'd like to be able to replace and re-bias myself.
I found a great site for repairing/modding Fender Hot Rod Deluxe/Deville amps.

http://studentweb.eku.edu/justin_holton/

Much of the information here is useful for other Fender tube amps too.

 

[oldguy]

Absolutely! Not trying to discourage anyone from learning how to work on their amp, and there are newer ways (tube sockets), and better, safer ways (bleeding resistors) to check and bias amps than ever....and to be safer doing it... but PLEASE be careful doing it.
For the most part, the older school of biasing amps where you check grid, plate, heater, cathode, etc. voltage, on your tubes from the pins, is where you could get jolted if you don't remember to always keep one hand in your pocket or behind your back. In some instances,such as these, where the amp needs to be turned on and a load connected to the speaker output, you could get hurt...seriously. And you need to learn the math to know what you're doing.
Just educate yourself before you dig in... as Lev pointed out, there are sites out there, (and lots of them), where you can find the information to do the work safely.
An amp biased to a warm, touch responsive vibe is a joy to play.
But be warned... it's an addictive hobby. :R R

 

[Mark]

But be warned... it's an addictive hobby

Man o man dont I know!! I just finished retubing, recapping, biasing and new speakers in my four old Fenders and adding bias adjustment pots on the Princetons this past weekend. Ive done these over the couse of the last month or so. The difference it makes is night and days, especially when your replacing 30-40 year old caps. Id recommend before anyone gets into this do your homework get the right tools and I would even suggest building a kit amp to get your feet wet so to speak. It is fun and rewarding...no doubt!

You do have to be very careful especially using the "ole school" methods which is the way I do it. Screw up and you might wake up in a puddle of your own pee! Or worse you dont wake up at all.

My four little purring puppies all tuned up ready to play, now my neighbors can enjoy em too .....hehehe

 

[sunvalleylaw]

Man, Mark, that's purdy! I am not sure I want to try it by myself. Not so much that I could not follow directions, but my household is a little hectic with three little ones at home. Easy to be distracted. I have already put the fear into the wee ones about going around the back of my amph!! On the other hand, maybe I can get SpudSteve to come back over, bringing his Peavey C-30, and we could have a bias then jam session!