Tube bias ?

[sonic 7]

Ok , I have a "new to me " Trace Elliot Vr350 tube power amp . Just fully serviced , with new tubes so it sounds great right now. At some point though I will need to swap out those tubes, and would like to do it myself. I've been doing some resesrch and it seems well within my ability. Most all of the info I've got so far involves the use of a bias probe socket and a multi meter which I pretty much understand. However, my amp (6 x 6550) has the two bias pots , one for each row of 3 , but also has a little probe thing next to each bias pot, is there a different procedure to bias this amp using those "probes" ( they are just little peices of exposed wire protruding through the chasis mext to each bias pot)

 

[beans-on-toast]

Those are tests points that you connect a voltmeter to. They are used in setting the bias. You don't need a bias probe, although you can still use one if you want.

If you can get hold of a service manual, the procedure to set the bias is outlined there. I don't have one for your amp but if you look, there are manuals for other tube based Trace Elliot amps available. Reading the procedure can give you an idea of what to do. For the V8 (400W) bass amp for example, connect the voltmeter to the zero test point (ground) and to a bias test point and adjust to 0.3V. After reading the procedure for that amp, since your amp is currently properly biased, you can connect the meter and see what your bias should be set for.

 

[sonic 7]

Thanks alot , it would be easier with a service manual but I'll probably never find one.

 

[beans-on-toast]

Try requesting one here from British Audio Service. They have some of the more popular ones available online but you can ask about others.