Is bias setting necessary on matched tubes?

Hi Marty,

Thanks, and I'm with you on that! The tech said that he would show me the procedure for biasing when I picked the amp up. The real reason for it costing $125 is that he's going to go over the amp to make sure there's no other problems. Right now I've got one fried tube (I'm assuming that it was damaged in shipping) but I want to make sure that the amp isn't compromised in a way that would fry another.

Soon to be a master bias'er (that sounds really wrong!)

Geoff

On the MingDah the voltage from earth to pin 8 is to be set between 32 and 35 milli volts adjustment it is easy with the correct screwdriver but if the amp is started from cold set the bias at the low side and wait till all warms up properly and recheck until it stays where you adjust. I smoked my MingDah last year (well someone else did it for me while I was a way sailing) one of the tubes got smashed while it was running and the intestines didn't like having this done to them. I found an service request box on their web site and left them a message and within ten minutes I had been contacted by one of their service techs who explained what was needed and passed on the schematic for the amp and the instructions on how to adjust the bias etc very good service I thought.

PS no one owned up to dropping anything on to the amp and the cats carried the blame for the damage ;(