TL;DR: I'm looking for some help understanding a circuit design, and where to place a switch on a crossover.
I few years back I built a pair of Roman Bednarik's Microbe in a 2.5 way MTM. At the time Roman had offered a standard 4ohm and a tweaked circuit 6 ohm design for those with less efficient power sources. Since that time I have a power amp and would like to add a switch to go between the two.
I'd like to add a switch to the crossover to bypass the 2 ohm resistor, however there appears to be an LRC also included in the high efficient design. Roman seems to have moved on and is no longer reachable, so I'm not sure if the LRC was added as part of the efficient design, or if this was some other improvement added later. The Microbe's were a design that was always being tweaked and redone, so one theory is that perhaps that LRC was added as part of some "improvement" between the original and the high efficient version.
Links to speaker workshop files of the High efficient version: http://rjbaudio.com/misc/Microbe 2.5 way MTM w-2ohm.JPG
The original design lacks the 2 ohm resistor, but also the 400uH/8ohm/15uF LRC circuit before the 3mH inductor. Does this need to be bypassed? Why is it there, but not in the original?
I'd appreciate any help out there. I would need a dumbed down explanation of where to add a switch if that is the best option. I can see that I'd probably need a 1.2mH inductor and switch to make this work.
Thank you
I few years back I built a pair of Roman Bednarik's Microbe in a 2.5 way MTM. At the time Roman had offered a standard 4ohm and a tweaked circuit 6 ohm design for those with less efficient power sources. Since that time I have a power amp and would like to add a switch to go between the two.
I'd like to add a switch to the crossover to bypass the 2 ohm resistor, however there appears to be an LRC also included in the high efficient design. Roman seems to have moved on and is no longer reachable, so I'm not sure if the LRC was added as part of the efficient design, or if this was some other improvement added later. The Microbe's were a design that was always being tweaked and redone, so one theory is that perhaps that LRC was added as part of some "improvement" between the original and the high efficient version.
Links to speaker workshop files of the High efficient version: http://rjbaudio.com/misc/Microbe 2.5 way MTM w-2ohm.JPG
The original design lacks the 2 ohm resistor, but also the 400uH/8ohm/15uF LRC circuit before the 3mH inductor. Does this need to be bypassed? Why is it there, but not in the original?
I'd appreciate any help out there. I would need a dumbed down explanation of where to add a switch if that is the best option. I can see that I'd probably need a 1.2mH inductor and switch to make this work.
Thank you
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First of all, let me say one thing. That 2R resistor is the worst component in the crossover, adding a resistor in series to a woofer is really a bad thing, it reduces the output, change Q of the drivers, and can overheat quickly. So removing it altogether (i.e. no switch), is a good thing.
You don't need to do anything else, as the LCR you noted is there to flatten the impedance: the small bump you see between 500 and 5K Hz would be very bigger without it. It was added probably to offer a more tube-friendly impedance.
So my advice is to simple remove the resistor, and forget about it.
Ralf
You don't need to do anything else, as the LCR you noted is there to flatten the impedance: the small bump you see between 500 and 5K Hz would be very bigger without it. It was added probably to offer a more tube-friendly impedance.
So my advice is to simple remove the resistor, and forget about it.
Ralf