Resistance effects on Q

[augerpro]

I did a little experiment to see how changing resistance changes driver Qts. I thought some of my fellow newbs might find it interesting. I used teh RS150.

RS150 Nominal Qts= .4947

RS150 8 Ohm in series (16 Ohm nominal) Qts= .9122

RS150 8 ohm parallel (4 Ohm nominal) Qts= .4625

I also did one with 2 Ohm in series which is more representative of what the inductors in an actual XO might be. RS150 2 Ohm series Qts= .6212
I'll try two RS150s in series and parallel next and post those results.

[augerpro]

two RS150 in series Qts= .5109, and in parallel Qts= .6136
I'm not sure how accurate that is. SE might not be accurate calculating Q for this sort of setup.

[Dennis H]

two RS150 in series Qts= .5109, and in parallel Qts= .6136
I'm not sure how accurate that is. SE might not be accurate calculating Q for this sort of setup.

I'm not that familiar with SE but check your (hidden) settings for wire resistance etc. Series or parallel wiring the two drivers shouldn't change Qts from the single-driver's .49 if the amp/wire resistance is zero.

[augerpro]

Well I go through a calibration first. That should account for the wire yes? Maybe I'll post this on the SE usergroup and see if it still accurate this way. Anyone use an MLS based system to do this measurement? If it works on one then it should work on them all I think...

[Davey]

If you attach your reference probe to the far end of the speaker wire (as close to the DUT as possible) then you will (theoretically) exclude the wire from the test.

However, testing two identical drivers in series or parallel might yield some interesting results because the two drivers won't be identical. This could skew the Q calculations relative to the single driver case.

I think just testing a single driver by itself and in conjunction with a series resistor is a more interesting test because it shows more clearly how the modification of Qes directly effects Qts.

I find myself not using MLS testing for impedance measurements any more. I usually sweep the driver and go get another beer while it's testing.

Cheers,

Davey.