Measuring TSP of a DVC speaker

[e-side]

Hi,

i want to measure the t/s parameters of a 6.5" DVC driver. Each VC is 6 Ohms. I'm going to use this driver with the coils wired in series, and when i measure the TSP (VC in series: Re=10,8 ohms) i get the following results:

qms = 6,4
qes = 0,197
qts = 0,2
fs = 40,4 Hz (voltage at fs: 0,0238)
vas = 23,13 L

This results in a 2 L bass-reflex enclosure. Too small for this driver i think. I also measured the tsp with 1 vc, the results were 'better' (24 L bass-reflex).


My question: how do i have to wire the voice coils when measuring the TSP: voice coils in series, parallel or do i have to use only 1 coil?

 

[DanWiggins]

You are measuring correctly - measure with the voice coils wired how you intend to use the driver.

If you want to wire in series, then try an 8 liter box tuned to 70 Hz. There is ~1.5 dB of dip centered at 140 Hz - not really an audible amount. Should maximize the efficiency of the system (both voice coils running) and extension.

You won't get real deep output because this driver has a high Fs and a very high BL (low Qes). Both of those indicate a higher F3 for the driver; together they mean it will be difficult to get extension much lower than 65-70 Hz.

Dan Wiggins
Adire Audio®

 

[e-side]

thanks for the effort!

68 Hz @ -3 dB is too high, but when i measure with only 1 coil connected the results become much better

qts = 0,41
qms = 7,37
vas = 25,7
qes = 0,43
fs = 37,84

this results in a 27 L BR, 36 hz @ -3 dB. The problem here is that power handling is reduced by a half compared to using 2 vc's.

I read on a website that those drivers are used with a mechanical crossover. when frequency comes below 250 hz the voice coils work in parallel, otherwise only 1 coil is driven.

maybe i have to wire the coils in parallel to get good results, problem here is that my amp can handle only 8 ohms or more, so i can't turn up the volume to its maximum.