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This design uses a single 10" sub and a single passive radiator in a compact
enclosure. I selected the drivers based on cost and required enclosure volume,
which took me quite quickly to the well regarded Peerless 10" XLS range.
On arrival, the subwoofer packaging is less than inspiring. Off course it
does its job perfectly as you would expect, but it does look budget,
and there's nothing in there but the driver (no leaflet, T/S spec, plastic wrapping).
The drivers however are a nice weight and apart from minor imperfections in the
aesthetics (I really am picky about these things), they are ruggedly built and look
like they are ready to pound to their stated excursions.
Both the actual driver and the passive radiator are identical except that the PR
has no magnet structure (hence passive). These tiny 10" drivers look,
simply put, cute. Even though their enormous innertube-like surrounds
give a hint that they mean business, their overall size makes them look like
a cute puppy with a loud bark.
Peerless XLS 10" (830452)
I wanted to see how T/S specs change before and after being
run in so I measured the driver three times: at zero hours run-in, after 30 hours run-in
and after 50 hours run-in.
Here's a log of the running-in details:
| Log sweep 5Hz - 20Hz |
1/2 xmax |
00:00 |
11:00 |
11 |
| 15Hz |
3/4 xmax |
11:00 |
19:30 |
8.5 |
| 25Hz |
1/2 xmax |
01:00 |
11:30 |
10.5 |
| 15Hz |
xmax |
20:30 |
00:00 |
3.5 |
| 15Hz |
1/2 xmax |
00:00 |
10:30 |
10.5 |
| 15Hz |
xmax |
10:30 |
16:30 |
6.0 |
Here's a clip of the 830452 being run-in (1.08Mb).
To measure the driver, it is fixed to my dedicated measuring clamp and the impedance plot is taken with the aid of Speaker Workshop (SW) and
the Wallin Jig II.
To calculate VAS, eight 2 pence coins are stuck to the driver dustcap using blu-tac. A 2p coin weighs
7.13g, and I used a further ~7.13g of blu-tac (by using a crude balance scale and a 2p coin).
So in total, 64.17g is used to calculate VAS.
The added mass method is not the best way to measure a subwoofer's VAS, but it is much quicker to implement than the sealed box method.
For SW to give acceptable results with my hardware combo, I found that using a calculation bandwidth starting above 12.5 Hz is sufficient to
avoid spurious impedance spikes affecting the measurements. This was enough to convince me that the added mass method will suffice for this
particular sub.
The following parameters are provided:
| Re |
3.4 ohms |
DMM |
| Sd |
352 cm2 |
Peerless |
| Sens. |
88.4 db W/M |
Peerless |
| Pe |
300 W |
Peerless |
| BL |
17.5 Tm |
Peerless |
| xmax |
12.5 mm |
Peerless |
The following shows the T/S parameters calculated after 0, 30 and 50 hours, and compared to
the specs provided by Peerless.
| 0 hours |
21.2 |
69.52 |
3.90 |
0.22 |
0.21 |
0.82 |
1.06 |
11.8 |
| 30 hours |
19.8 |
84.98 |
3.58 |
0.21 |
0.20 |
0.81 |
1.07 |
11.5 |
| 50 hours |
18.5 |
89.25 |
3.27 |
0.18 |
0.17 |
0.79 |
1.10 |
12.1 |
| Peerless |
18.9 |
89.70 |
2.63 |
0.18 |
0.17 |
4.30 |
|
|
| Difference * |
2.0% |
0.5% |
19.5% |
1.1% |
1.7% |
81.6% |
|
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* between break-in results and manufacturer specs. Note figures are rounded.
The results show that the T/S parameters after 50 hours of run-in are remarkably similar
to the Peerless published specs, with the exception of Le (which is not critical for modeling
enclosures).
Peerless XLS 10" Passive Radiator (830481)
Because a PR can't be measured using SW in the regular way, the Peerless specs are
assumed:
| Fs |
13.7 Hz |
| Qms |
11.4 |
| Vas |
80 l |
| Rms |
2 Kg/s |
| Mms |
265g |
| Cms |
0.508 mm/N |
| Sd |
333 cm2 |
| xmax |
22 mm |
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