Plexibreath
Well-known member
I've seen 2 basic kinds:
1) Uses 3 resistors and a DPDT switch.
Where with the pad on, a resistor is bridged across the + and - signals and a resistor is in series on both sides, when off the resistor that bridges across is taken out and the series resistors are shorted across, this seems to be the most common.
2) Uses 5 resistors and a 4PDT switch
Where with the pad on 2 resistors are in series on each side, with a resistor bridging across at the points between the 2 series resistors, the switch just bypasses the entire works. I can only see one advantage here, in the case of more than one level of attenuation this would probably be more expandible. But is there more?
Other than the fact that the first solution looks easier to emplement, is there an advantage to the second solution sound wise or other, that people have gone to that kind of trouble to build it that way. I bring this up as I saw the second solution in a schematic on the Tube Mic Pre thread for the Steve Albini modded Ampex 351 pre.
Also, are there other, possibly better solutions?
Thanks,
Kelley
1) Uses 3 resistors and a DPDT switch.
Where with the pad on, a resistor is bridged across the + and - signals and a resistor is in series on both sides, when off the resistor that bridges across is taken out and the series resistors are shorted across, this seems to be the most common.
2) Uses 5 resistors and a 4PDT switch
Where with the pad on 2 resistors are in series on each side, with a resistor bridging across at the points between the 2 series resistors, the switch just bypasses the entire works. I can only see one advantage here, in the case of more than one level of attenuation this would probably be more expandible. But is there more?
Other than the fact that the first solution looks easier to emplement, is there an advantage to the second solution sound wise or other, that people have gone to that kind of trouble to build it that way. I bring this up as I saw the second solution in a schematic on the Tube Mic Pre thread for the Steve Albini modded Ampex 351 pre.
Also, are there other, possibly better solutions?
Thanks,
Kelley