Quick BSC Circuit Question

[cogitech]

When calculating a BSC circuit (for example, with MJ King's spreadsheet calculator) for a loudspeaker with two identical drivers wired in series, am I correct to assume that the Re and Lvc of the two drivers are simply added together and entered into the calculator?

For example, each of my drivers has a Re of 3.6 ohms and Lvc of .251mH - therefore I would use 7.2 ohms and .502mH to calculate the BSC (and Zobel) circuit. Correct?

 

[cogitech]

Sometimes I fail to read instructions. In this case, the answer is on the spreadsheet itself.

"Enter values in yellow cells. For multiple drivers, be sure to use net values for Re and Le"

However, let's not let this thread go to waste!

I would love some pointers on which components (type of capacitors, type and wattage rating of resistors and type of inductors) to use in a BSC circuit.

I don't need to go overboard on "high end"(?) stuff but I also don't want to cheap out and/or buy components that are inappropriate for the task at hand.

Any tips would be greatly appreciated.

 

[Scottmoose]

Note that values taken off a nominal Re value are likely to be somewhat off; you'd be better off simulating it if possible.

Little to say. You should be OK with 10w rated resistors; try to avoid electrolytic caps if possible. Quality cored inductors are fine, providing you don't drive it into saturation. If you're concerned about that, heavy-gauge air-core to keep DCR down.

 

[cogitech]

Note that values taken off a nominal Re value are likely to be somewhat off; you'd be better off simulating it if possible.

Little to say. You should be OK with 10w rated resistors; try to avoid electrolytic caps if possible. Quality cored inductors are fine, providing you don't drive it into saturation. If you're concerned about that, heavy-gauge air-core to keep DCR down.

Thanks very much, Scott!

Is inductor DCR of 1 ohm going to really mess things up? Going up to 15 gauge is A LOT more money but the DCR drops to 0.38 ohm.

 

[xrk971]

For a small full range driver, I have used really really cheap bag of 10x 1mH cored inductors with a resistor surprisingly sounded good. I have them in my Tabaq’s which never see more than 5W. Even 20ga air core is fine. It will add an ohm or so DCR. No big deal.

 

[cogitech]

For a small full range driver, I have used really really cheap bag of 10x 1mH cored inductors with a resistor surprisingly sounded good. I have them in my Tabaq’s which never see more than 5W. Even 20ga air core is fine. It will add an ohm or so DCR. No big deal.

Excellent! Thank you!

 

[cogitech]

One more question...

I am also building Zobels for these speakers. MJ King's spreadsheet calculates a Zobel resistance of 9ohms. I could do 2 4.7ohms in series for 9.2ohms, or should I buy 5ohm and 2ohm resistors and do 5+2+2= 9ohm? I guess what I am asking is will 0.2ohms make much difference in a Zobel?

 

[Inductor]

Hi, I don't think less than 5% makes a great difference.

 

[cogitech]

Hi, I don't think less than 5% makes a great difference.

Thank you!

I went ahead and ordered 10 pieces each of 5ohm, 4.7ohm, and 2ohm. I'll eventually need them for other speakers, and it gives me lots of options. I can measure each one before grouping them to get as close to 9ohms as is reasonable (let's face it, some of the 4.7s could be as low as 4.5 - time will tell)