Goldwood GW-12PC/8 Thiele-Small & Curve Data

Unit #1

Fs = 28.81 Hz
Qms = 4.300
Qes = 0.1.2213
Qts = 0.9512
Vas = 137.95 Liters
Cms = 3.664E-04 M/N
Re = 7.53 Ohms
BL = 9.641 N/A*
Sd = 0.051774 Sq. Meters
Mms = 0.083284 Kg
Ref Efficiency = 0.2596 %
Predicted Output = 86.342 dB/1W/1M
Predicted Sensitivity =  86.61 dB/2.83v/1M**
Xmax = 3.55 mm (Goldwood’s figure)
Xmech = 16 mm p-p
Le = 2.67 mH

*Direct BL crosscheck = 9.567 N/A.

**LMS curve shows 200-300Hz output @  87.5 dB/2.83v/1M and
    sloping downward; output @ 550 Hz is down to 84 dB, before
    it comes back up to approx. 86 dB around 1000Hz.  It spikes
    sharply at ~2kHz, and then rolls off for good.)

Measurement conditions:

Broken in 12+ hours, Rest 12+ hours.
Temperature = 25.8° C,   Humidity = 68%

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Unit #2

Fs = 28.74 Hz
Qms = 4.445
Qes = 1.5130
Qts = 1.1288
Vas = 136.88 Liters
Cms = 3.638E-04 M/N
Re = 7.51 Ohms
BL = 8.710 N/A*
Sd = 0.051774 Sq. Meters
Mms = 0.08435 Kg
Ref Efficiency = 0.206 %
Predicted Output = 85.35 dB/1W/1M
Predicted Sensitivity =  85.61 dB/2.83v/1M
Xmax = 3.55 mm (Goldwood’s figure)
Xmech = ~16 mm p-p
Le = 2.69 mH

*Direct BL crosscheck = 8.620 N/A.

** LMS curve shows 200-300Hz output @  85.5 dB/2.83v/1M and
    sloping downward; output @ 550 Hz is down to 83 dB, before
    it comes back up to approx. 84.5 dB around 1000Hz.  It spikes
    sharply at ~2kHz, and then rolls off for good.)

Measurement conditions:

Broken in 12+ hours, Rest 12+ hours.
Temperature = 25.3° C,   Humidity = 67%

Curves

1/4 watt, 1/2 meter curves on Unit 1 and Unit 2:
(Click image to enlarge)

Their T-S data (LOL):

 
Fs= 32 Hz
Qms= 3.85
Qes= .56
Qts= .49
Vas= 2.79 cu. ft.
Re= 7.14 ohms
SPL= 89.7 dB 2.83w/1m
Xmax= 3.55mm

What’s going on with the motor efficiency of the units we received is hard to say.  Evaluating the unit from what we can see externally, and making a few educated guesses, it seems at least possible that a driver like this could perform to Goldwood’s specifications.  The most likely explanation is that perhaps Goldwood’s Chinese mfgr. did not get these magnetized correctly.  Of course, that’s not much of a positive commentary on the QC.

With a little fancy crossover work, these would appear to be perhaps useable with crossovers up to 2.3kHz or so. That 2k peak appears to be nastier in this 8 ohm version, than the 4 ohm version, however. These might be best in a giant W-W-M-T-M sealed cabinet, or maybe in an infinite baffle, at modest power? They’d certainly be for the “high Q crowd” in any normal size cabinet.

Other Goldwood data / info. on this driver (seems to be reasonably correct):
Power handling= 140 watts RMS/270 watts max
Voice coil diameter= 2.0″
Le= 2.06 mH
Frequency response= 32-4,000 Hz
Magnet weight= 50 oz.
Net weight= 9.6 lbs.