Anyone know how to BIAS power tubes in a guitar amp if there is only a multi meter in my tool quiver for such a purpose. Where would you be able to access a reading on the tube plate voltage if there were no test points and without BIAS probes??
I ain't touchin' this one! :)
Actually, if I'm not mistaken, almost any amp that has bias pots will have biaz POINTS for you to put your probes. I don't think anyone would make adjustable bias and no easy way to get a reading.
On the gear page, they say to use bias probes, I will just buy them at Eurotubes, when and if it needs JJ's, if it sounds cool as is I will let it lay until it don't, if not I will send it back.
ok, if they say to use probes, it probably has bias points inside. I doubt they want you to be placing it on the circuit board....
Never know though. In my valve junior, I check it right on the tube socket pins.
This http://www.amp-head.com/product_info.php?cPath=21&products_id=31 and my own multi meter
Here is another response I got on another forum to the same question, interesting and the Calc Bias page on Weber's site is amazing.
I have one of the weber BIAS-rites I it works really well. I have the 4 octal socket version (BR-4). https://taweber.powweb.com/biasrite/br_page.htm
If you haven't decided on the adapters you posted a link to, you may want to consider the bias-rite that has 2 octal sockets and 2 9-pin sockets.
Then you'd be set to to the EL-84s as well as 6L-variants and EL-34s/KTs.
Personally, I like having the meter a dedicated meter as well. It seems faster and more straight-forward and I like independent tool-kits for different tasks.
Here's good site on calculating your bias point. http://www.webervst.com/tubes1/calcbias.htm
I've found there not really one magic percentage of max dissipation point for every amp of a given type of output tube.
I tend to run the marshall around 66-68% max dissipation. I find the fenders with 6L6 are chimeyier closer to 60% +/-. I like the fender 6V6 amps pushed just a little. I think EL-84s sound best begging for mercy in just about any amp but then you have to replace them more often.