box calculations

Status
Not open for further replies.
Jump to Latest
B

back

Member
Joined 2005
#1
i was trying to calculate a ported box for the dls rw15.
dls gives different parameters for series or parallel connection of the voice coils.
when i calculate for parallel i get i box close to the dls recomendation.
but if i calculate for the series connection i get 150 liters box and much deeper f3.
i am i doing something wrong?DLS RW15 SPECIFICATION Pdf Download.
 
Last edited:
#2
Basic box calculations only require Vas, Qts'. *

When you wire a DVC subwoofer, series or parallel, only its inductance [L], Qts' and underlying values change; Fs, Vas and their underlying values do not, etc., so any variance is in test conditions.

*Qts' = Qts + any added series resistance [Rs], which can [dramatically] increase box size: mh-audio.nl - Home

Short of measuring your drivers, use the largest Vas spec of the three + appropriate Qts'.

Not much of a 'reference' subwoofer, what with such a high Fs and no [L] specs, so assume it will be high, making your sim [very] inaccurate WRT its frequency response.

GM
 
#4
Glad you questioned it............not per se, I apparently had a 'senior moment' [not enough caffeine?], typing it up wrong 🙁 in that while underlying specs change [Re, BL], they change in complementary ways, so Qes stays ~ the same as noted in being 0.42/series, 0.38/parallel with 0.75/single VC, though if true, then published Qts is wrong and even recalculated seems from dim memory having a bit too much discrepancy: 0.371/series, 0.34/parallel Qts.

Then there's [Rs] to consider as just adding the typical 0.5 ohms for speaker wiring changes series Qts' = 0.394 [not much], 0.43/parallel [a bunch].

In short, really need to measure your driver, otherwise use calculated Qts' and hope it's big enough or if size isn't an issue, design based on a 0.5 Qts and fine tune it as required.

GM
 
#5
GM said:
Glad you questioned it............not per se, I apparently had a 'senior moment' [not enough caffeine?], typing it up wrong 🙁 in that while underlying specs change [Re, BL], they change in complementary ways, so Qes stays ~ the same as noted in being 0.42/series, 0.38/parallel with 0.75/single VC, though if true, then published Qts is wrong and even recalculated seems from dim memory having a bit too much discrepancy: 0.371/series, 0.34/parallel Qts.

Then there's [Rs] to consider as just adding the typical 0.5 ohms for speaker wiring changes series Qts' = 0.394 [not much], 0.43/parallel [a bunch].

In short, really need to measure your driver, otherwise use calculated Qts' and hope it's big enough or if size isn't an issue, design based on a 0.5 Qts and fine tune it as required.

GM
Click to expand...


thank you
 
Status
Not open for further replies.
Top Bottom