So when you bias an amp just with a multimeter...

[Lockbody]

Can you leave the resistors to ground on, or do you have to take them off every time after you bias the amp?

My Mesa DC-10 came with a bias pot installed, and instead of spending the coin on a Bias-Rite when the time comes to replace the power amp tubes, I'm thinking of just doing it with my Fluke instead. I've read that you replace the pins to ground with a 1k resistor, but no where does it say to remove them after you get through. As opposed to releasing the magic smoke, I'd thought I'd ask first.

[Jimbilly]

My amp tech alsoo tells me that the 1k resistor is the secret ingredient in my Allessandro Bias meter.

He (my tech) built me a 9pin plug for EL84s with the 1K resistor built in, with 2 plugs on an output wire to plug right into my Fluke. Would it be easier in the long run just to build yourself an in-between octal plug with the resistor built in?

Same tech built me a custom bass head, based on a Showman, it's got ports by each tube with 1k resistors in each that I can plug my Fluke probes into for really simple and easy bias checks.

[Thundernotes]

I would seriously doubt that it's a 1K resistor. A 1 ohm, 1% resistor is more likely. Using a 1K would dramatically shift the bias point of the amp by itself. To add one yourself, find the cathode lead on each power tube and replace its connection to ground with a 1 ohm 1/2 watt 1% resistor. I've done it on almost all of my amps. In the event of a tube failure, it also acts as a fuse which can save your output transformer.

[Lockbody]

I would seriously doubt that it's a 1K resistor. A 1 ohm, 1% resistor is more likely.

1 ohm! I knew that, but didn't fact check before I posted.

[Jimbilly]

I just know it has something to do with an ohm or some sort!

[specialk]

it has something to do with an ohm or some sort!

Better an ohm than a mho!

[Brewmaster]

I would seriously doubt that it's a 1K resistor. A 1 ohm, 1% resistor is more likely. Using a 1K would dramatically shift the bias point of the amp by itself. To add one yourself, find the cathode lead on each power tube and replace its connection to ground with a 1 ohm 1/2 watt 1% resistor. I've done it on almost all of my amps. In the event of a tube failure, it also acts as a fuse which can save your output transformer.

Bingo!

Brian knows his sh*t. Helped me out a few years ago when I "misremembered" a few things I had learned back in the day.