Biasing an amp yourself: How dangerous is it really?

[Bengal65]

Bengal65, has everything got back to normal since the hurricane?

No, it's going to be a long time. I just got my roof replaced last Friday. The inside is next (drywall, carpets and electrical), but I can't even get a contractor to quote on it. They are all busy fixing the "War Zone". If you are in the the roofing or home remodeling business, your booked for at least a year! I re-built my fences myself because I got tired of looking at it. There are a lot of "phony" contractors out there as well trying to cash in on the work. Basically, the inside of my house is a construction zone, but at least I have a house. I have neighbors living in RV's and FEMA housing. Crazy stuff!

[phill_up]

No, it's going to be a long time. I just got my roof replaced last Friday. The inside is next (drywall, carpets and electrical

you mean all of the sheetrock has to be replaced? Have you already ripped out all of the carpet? I hope you have enough electricity for heat & air and all the appliances

[Bengal65]

you mean all of the sheetrock has to be replaced? Have you already ripped out all of the carpet? I hope you have enough electricity for heat & air and all the appliances

Well, we're getting a little off topic. Sorry folks, but yes, walls and ceilings in 2 rooms. The carpet is OK, I saved it with lots of buckets and trays. I have electricity. It's just the wiring in the walls that got wet have to be inspected and/or replaced in my living room. I'm in a single story and I think that saved my butt. As a comparison, my neighbors 2 story house to the West, had to be completely stripped. HVAC, wiring, drywall, wood floors and carpets. Basically, the house was a studded frame with siding on it with windows after the contractor gutted the place. Amazingly, none of us had glass breakage. All the cabinets and appliances were junked in their house. It's amazing what water will do to your home. None of my gear was affected. I had all of it sealed in double plastic bags or plastic tubs. I'm considering a fire/waterproof vault for my expensive gear just in case I ever get hit by a tornado full force!
Phill_up, where do you live? Have you been through one of these biggies?

[emperor_black]

No wonder you're not afraid of a little thing like opening up a tube-amp. You're literally living amidst water and electricity? Good luck Bro.

[phill_up]

Bengal65 I still have family in TX, my sister is in Garland and I have family in west texas. I Haven't been in a hurricane but I have had my fill of F5 and F4 Tornadoes. I wound up in Oklahoma City, don't ask how because I'm still trying to figure that one out. I really like Corpus Christie and hanging out @ port Aransas. I don't know much about Houston though, except you fukkas are mean and drive fast.

[Ben...]

It's still hard for me to comprehend hurricanes or living in that area in general. My current location is so far from any major bodies of water that a hurricane couldn't even reach here. I've lived here my whole life and I've never even seen an ocean. All we have to deal with is winter weather so cold that it can freeze your skin in less that 3 minutes. I guess that's the trade off. No hurricanes or any of that but we get to freeze half the year and burn up the other half.

[Bengal65]

Some Biasing pics for your enjoyment

I'm biasing/re-tubing one of my Fender '65 Blackface Showmans. I'm using a matched quad of JJ 6L6's. I just finished cleaning everything with Contact cleaner/lubricant and installed new preamp and output tubes. I'm standing in a puddle of water while doing this. (No, just joking)



I'm set at 31mV using the adjustable pot on the amp chassis. With the switch on the Amp-Head adapter in the up position, I'm measuring mV. With the switch in the down position, I can measure plate voltage. My plate voltage is 460VDC with is perfect for this type of amp. (this is the voltage that can hurt you when taking an amp apart if the caps are on drained.



The infamous "Death Cap" on older Fender amps using a Ground Switch (blue cap, some are brown, but most are these molded blue ones). I just finished installing a 3 prong grounded "earthed" plug on this one which will negate the death cap. No need to remove/re-wire the circuit like some websites say. This will keep the amp "vintage" in case I sell it, and some nut wants the old 2 plug back:ROTF:

[phill_up]

Bengal65, I noticed you threw the contact cleaner statement in there, did you clean the tube sockets working the old tubes in and out of the sockets with "Contact cleaner/lubricant"?

[emperor_black]

Bengal, nice pics. Thanks. Is this the bias tester that you bought from eurotubes?

[Bengal65]

Bengal65, I noticed you threw the contact cleaner statement in there, did you clean the tube sockets working the old tubes in and out of the sockets with "Contact cleaner/lubricant"?

That's good stuff. Radio Shack also has a similar product.

[Bengal65]

Bengal, nice pics. Thanks. Is this the bias tester that you bought from eurotubes?

No, the one pictured is the MPD I got from Amp-Head. I have the basic Eurotube adapter as well, but it does not have the switch to get plate voltage. You could still get the plate voltage, with a meter and leads, but it's more of a hassle since you have to find the correct pin on one of the tube sockets. The Amp-Head (same guy on eBay by the way) has these which makes it a simple task.

[emperor_black]

I just want to measure the mV. I dont care much for the plate voltage.

[Bengal65]

89% of the time you need not be concerned with the plate voltage. With older amps, or amps that are questionable or have had mods in the circuitry, it's a good idea to check plate voltage. So, basically if you are just replacing tubes and have a manufacturer's bias range, that's all you need to set. Pretty straight forward and easy.

[phill_up]

you have already sold me on the one you have bengal65, because it will come in handy for troubleshooting the amp if you need to, instead of just biasing the tubes.

[phill_up]

new how to biasing video "clicky"