baddog1946 wrote:Main issues I see between Ma and Mv. metering are; one is wired in series and can affect the bias reading.
Main issue I saw with mA vs mV is the mA meters were purtier ... ;-}
Surprising the limited selection available. Especially anything that has back lighting. The ones I used are surface mount and consistent.
Good deal too, at $10 each. Also easy enough to get inside to snip the dropping resistor. Clear cover pops off, two screws to remove the faceplate, and snip the resistor that bridges the two terminals. I just bent mine out of the way so I could reconnect if things went horribly wrong.
Same process should apply to any such conversion.
Accuracy? As mentioned, that's controlled with the matching pot on each bias point. As is, my "55" reading is arbitrarily set to the tick just below 60, as that's easy to read. Technically, it should be set somewhat below that as each tick represents 2 points on the scale. So shoot me already ...
I still use the VOM to double check every now and then, but feel comfortable setting for minor deviations just using the meters. Readings are well in the ballpark to get a good balance on the amp. If nothing else, they certainly take the work out of tube swapping, as adjusting one tube affects all the rest, and it's a lot easier to just flip a switch and turn a pot then it is to move the probes until you get a good match all around. Once that happens, THEN I'll use the VOM to dial it in perfect.
PS ... these meters are quite large, but that's what I wanted and designed the chassis for. IMHO, the larger the scale, the more accurate the set.