I don't see a difference between mine and Dave's, but I'm turning it around in my mind.
Trying to imagine this in terms of a parallel crossover would be a mistake in my opinion. Now, if you wanted to remove the connection in question in order to reimagine the crossover and move forward with what a new designer may find a simpler approach, you'll first have to account for the differences.
Here's an example of this crossover with and without the red connection, based on my model using ideal drivers and guesses on the values. Here the dashed traces are as it currently is and the solid traces are without the connection.
Trying to imagine this in terms of a parallel crossover would be a mistake in my opinion. Now, if you wanted to remove the connection in question in order to reimagine the crossover and move forward with what a new designer may find a simpler approach, you'll first have to account for the differences.
Here's an example of this crossover with and without the red connection, based on my model using ideal drivers and guesses on the values. Here the dashed traces are as it currently is and the solid traces are without the connection.
Thanks, I can see the differences or, perhaps I should say, similarities between the two methods of connection.
However, I'm less interested in the technicalities than in finding a quick and easy resolution to Ron's crossover refurb problem.
And I am acutely aware that he has stated he is "far from an expert when it comes to crossovers" - a bit like me in fact!
However, I'm less interested in the technicalities than in finding a quick and easy resolution to Ron's crossover refurb problem.
And I am acutely aware that he has stated he is "far from an expert when it comes to crossovers" - a bit like me in fact!
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Sorry for quoting myself, but it actually would be beneficial to include the fixed resistor L pad that I illustrated.
This is because the parallel resistor in an L pad can reduce the impedance rise at the tweeter's resonance frequency.
This helps to tame the resonance and protect the tweeter from mechanical damage caused by signals at the low frequency end of its operating range.
In short, including the L pad makes the tweeter less susceptible to possible damage due to the use of a slow roll off, first order filter.
Tweeter sensitivity = 90 dB/W/m
Woofer sensitivity = 87 dB/W/m
For the required 3 dB of tweeter attenuation the L pad would comprise R1 = 1.8 ohm and R2 = 15 ohm.
Use 10 W rated resistors.
Woofer sensitivity = 87 dB/W/m
For the required 3 dB of tweeter attenuation the L pad would comprise R1 = 1.8 ohm and R2 = 15 ohm.
Use 10 W rated resistors.
That much I knew, but I must thank you for the evolutionary process since I'm too old to manipulate the circuit without getting dizzy!
For my part, I would be happy to work with the extreme left hand schematic while ensuring that the red line connection is in place.
In place of the variable control and its partnering 5.6 ohm resistor, I'd insert the Rs = 1.8 ohm and Rp = 15 ohm L pad I described earlier.
Thanks for all the replies... I've been dealing with older parent (93 year old) issues that have pulled me away from responding sooner. Just know that I appreciate all the help.
I have already ordered capacitors and inductors from parts express based on Galu's early recommendation. I also ordered some ferrofluid. That doesn't mean that I can't order more parts if necessary. 🙂
I have ordered the following for this project:
Dayton Audio 0.45mH 20 AWG Air Core Inductor Crossover Coil
Jantzen 8100 10uF 160V Compact MKT Metalized Polyester Film Capacitor
Parts Express Gold Recessed Binding Post Banana Jack 5-Way Speaker Terminal
I try to post up some better pics of the crossover later today.
I have already ordered capacitors and inductors from parts express based on Galu's early recommendation. I also ordered some ferrofluid. That doesn't mean that I can't order more parts if necessary. 🙂
I have ordered the following for this project:
Dayton Audio 0.45mH 20 AWG Air Core Inductor Crossover Coil
Jantzen 8100 10uF 160V Compact MKT Metalized Polyester Film Capacitor
Parts Express Gold Recessed Binding Post Banana Jack 5-Way Speaker Terminal
I try to post up some better pics of the crossover later today.
My series 10 uF capacitor alternative would provide a functional parallel crossover when used in conjunction with a fixed resistor L pad.
However, now that we have fully examined the original crossover topology, you may decide to use the capacitor values and 3 ohm resistor you noted on your sketch.
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Third diagram is not the same as the second. The red connection is before the L-Pad. And the inductor is ow shunted across the L-Pad insteadnof in series with the woofer.
I made a feeble attempt to try thge same thing you are trying, but gave up.
dave
Dave, can you simply put my mind at rest by confirming that the first diagram, with the red connection in place, is correct?
EDIT: It must be as the inductor is connected to the junction of the two resistors in the photograph(s) of the crossover board.
EDIT: It must be as the inductor is connected to the junction of the two resistors in the photograph(s) of the crossover board.
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Honestly at this point in time (burned out crossover, woofer randomly replaced) you are much better served in terms of your learning process and your speaker to junk the crossover altogether and do a white paper design.
At the very least, you would be well served by measuring the impedance of both drivers and at least a basic output of each driver, throwing it all into a crossover simulator like XSim or VituixCAD. It seems like a longer road, but it really isn't, plus at the end you'll be much further along in your understanding.
At the very least, you would be well served by measuring the impedance of both drivers and at least a basic output of each driver, throwing it all into a crossover simulator like XSim or VituixCAD. It seems like a longer road, but it really isn't, plus at the end you'll be much further along in your understanding.
I agree, but Ron does not presently have the measuring and simulator facilities required to produce an optimal design.
While the experts are evolving the original circuit, I'm conscious of the fact that the tweeter specs recommend a 2nd order crossover at 3,500 Hz.
Since Ron has already purchased 0.45 mH inductors, I offer him the following crossover circuit that will get him up and going until such times as he acquires the necessary crossover design facilities - should he wish to go down that route.
C2 = 4.7 uF, L2 = 0.45 mH and L1 = 0.45 mH.
Between L2 and the tweeter I would add the attenuating resistors that I described in post #25 (R series = 1.8 ohm & R parallel = 15 ohm).
I am aware that the response is likely to be far from optimal, but at least the tweeter will be safe from low frequency overload.