[Milothicus]

I want to check what voltages are being supplied to the plates of the EL84 output tubes on my amp... as of now, there's no speaker connected, and i've taken out all the tubes.

If i put the rectifier tube back in, but leave the rest out, can i measure the B+ voltages (correct term for plate voltages?) without damaging anything?

or, if i install a standby switch, can i do it then without a speaker attached and tubes all removed?

also, what gauge wire should i use to connect to a speaker? and does solid/stranded make a difference here?

 

[Adicted to Tubes]

With no tubes installed the voltage will be much higher.You run the risk of hurting old filter caps unless they are new.The speaker needs to be connected only when the power tubes are in.
what are you trying to check?If it's a new build you should consider making a light bulb current limiter to fire it up without damage.
If you are looking for problems it's an easy way to determine if there are shorts.The 100 watt bulb will light up strong if there are shorts and dull if there are none.
speaker wire should be at least 16 gauge and stranded is preferred so it doesn't break,but lots of old amps used solid core.
I would recommend always plugging in a load,i.e. speaker when doing any testing.Get a longer speaker cord and double female connector if you don't have enough length.Be carefull checking voltages,as one slip can ruin your whole day.Use alligator clips where possible.
Remember,the unloaded voltages will be quite a bit higher.I recommend checking with tubes installed unless you are trouble shooting.Use old tubes if you are worried about hurting new ones.

www.claramps.com