plumsolly
Well-known member
In my quest for monitoring solution I decided on variable u-pad for the volume control. I bought a four-gang 5k alps pot for the shunt and wired 2 gangs in parallel for each channel (left and right). I used 2k6 for the series resistors. So I have a u-pad with 2k5 shunt pot and 5.2k series resistance. I hooked it between my D2A outs and my powered speakers and it worked well, except at very low volumes the right side was noticeably louder. I figured the pot just didn't track well at the bottom - pretty normal. I checked the resistance between hot and cold at different spots in the pot's throw and they were spot on between left and right. Hunh?, I said. Then I switched which side of the pot was feeding each speaker, the same speaker was louder! Then I did this experiment with each input on my Echo Audiofire interface. At very low volumes, the attenuation of the pad changes drastically depending on which input it is going into. For instance the same setting on the pot (either side) when plugged into channel one on my converter might attenuate 50db and only attenuate 45db when plugged into channel 2. My suspicion: poorly matched components in the balancing circuitry between channels, which wouldn't matter in most situations, is compounded when using a u-pad at high attenuation levels - maybe a few ohms can make a difference of several db in attenuation? Does this sound plausible? Anyway the whole thing is very curious - are people having this problem with their m-patches, and their ATTY's? It's roughly the same circuit (5k instead of 2.5k for shunt, and maybe no series resitance?) Thanks and Best, Ben
