In the table below you will find "Thiele & Small" parameters for many Tannoy dual concentric speakers.
The "Thiele & Small" parameters allow the low frequency performance of a loudspeaker and box to be mathematically modelled, and thus enable the prediction of the frequency response for various boxtypes. The three most important parameters are: Vas, Fs, and Qt. Other parameters can be used to extend the modelling, and are also listed below where available. There are many computer programs available that can model the LF performance using the three T&S parameters: Vas, Fs, and Qt. (One example for the Windows operating system is Boxplot version 3).
In general, the older Tannoy drive units had stiffer suspensions with higher resonant frequencies  making large cabinets necessary to get good bass extension below 40Hz. Another point to note is that the low frequency resonance for the Monitor Silver, Monitor Red and Monitor Gold may higher than the nominal figures published when the drive units were new. The plasticiser used on the surround may have stiffened with time, thus raising the resonant frequency.
Contents:




 
Vas, volume equivalent compliance  99.7 litres  266 litre  99.6 litre  266 litre  
Fs, free air resonance  49.7 Hz  32 Hz  27 Hz  48.6 Hz  32 Hz  
Qt, total Qfactor  0.24  0.26  0.154  0.26  
Qa, mechanical & acoustic Q  1.29  1.3  6.25  1.3  
Qe, electrical Q  0.29  0.32  0.158  0.32  
Mmd, Dynamic Mass, excl. air load  40.2 g  72 g  43 g  72 g  
Cms, dynamic compliance  0.26 mm/N  0.32 mm/N  0.249 mm/N  0.32 mm/N  
Mma, air load in free air  
Sd, piston radiating area  0.0527 m2  0.077 m2  0.0531 m2  0.077 m2  
B, gap flux  1.0 T  1.2 T  
L, voice coil conductor length (in gap)  
BL, force factor (=B * L), N/A  22.4  21.25  22.35  21.25  
Re, voice coil resistance  11.8 Ohm  9.5  6 Ohm  9.5 Ohm  
Re+Res, resistance at Fs  
Z, efficiency into halfspace (2pi)  
VD, Peak linear displacement volume  
a, effective piston radius  
Pth, thermal power rating  15 W  25 W  15 W  30 W  50 W  
Sensitivity (@2.83V, 1m, 20C)  93.4 dB  93 dB  97.8 dB  93 dB  
Rms, mechanical resistance (mechOhm)  9.76  2.1  11.6  
LF Voice Coil Diameter  2"  2"  2.5"  2"  2"  
HF Voice Coil Diameter  2"  2"  2"  2"  2"  
HF Gap Flux, B  1.5 T  1.8 T  1.5 T  1.5 T  1.8 T  
Magnet Mass  6.25 lb  7.5 lb  13 lb  
LF to HF crossover frequency  1,700 Hz  1,000 Hz  1700 Hz  1700 Hz  1000 Hz  

Gold 12" (see also 12" Gold RS) 
Gold 15"  HPD 295A  HPD 315A (Tannoy state same for 3128 & DU316 driver) 
HPD 385A (Tannoy state same for 3828 & DU386 driver)  
Vas, volume equivalent compliance  99.7 litres  350 litres  276 litres  483 litres  
Fs, free air resonance  30 Hz  49.7 Hz  26 Hz  22 Hz  25 Hz  22 Hz 
Qt, total Qfactor  0.24  0.2  0.2  0.18  
Qa, mechanical & acoustic Q  1.29  2  1.75  2.4  
Qe, electrical Q  0.29  0.22  0.22  0.2  
Mmd, Dynamic Mass, excl. air load  40.2 g  90 g  62g  90 g  
Cms, dynamic compliance  0.26 mm/N  0.42 mm/N  0.65mm/N  0.58 mm/N  
Mma, air load in free air  
Sd, piston radiating area  0.0528 m2  0.077 m2  0.055 m2  0.077 m2  
B, gap flux  1.0 T  1.15 T  1.35 T  
L, voice coil conductor length (in gap)  
BL, force factor (=B*L) Newtons per Amp  22.4 N/A  19.2 N/A  16 N/A  15.6 N/A  18.72 N/A  
Re, voice coil resistance  11.8 Ohm  5.5 Ohm  5.5 Ohm  5.7 Ohm  
Re+Res, resistance at Fs  
Z, efficiency into halfspace (2pi)  
VD, Peak linear displacement volume  
a, effective piston radius  
Pth, thermal power rating  15 W  30 W  50 W  50 W  60 W  85 W 
Sensitivity (@2.83V, 1m, 20C)  93.4 dB  94.8 dB  93.4 dB  94.3 dB  
Rms, mechanical resistance (mechOhm)  9.76  7.45  5.6  5.1  
LF Voice Coil Diameter  2.5"  2"  2"  2"  2"  2" 
HF Voice Coil Diameter  2"  2"  2"  2"  2"  2" 
HF Gap Flux, B  1.5 T  1.5 T  1.8 T  
Magnet Mass  6.25 lb  7.5 lb  13 lb  
LF to HF crossover frequency  1200 Hz  1000 Hz  1000 Hz  1000 Hz  1000 Hz  1000 Hz 
Data for MonitorHPD385A immediately above taken from private measurements (*) and some published Tannoy data.
Monitor Black 12" 
Monitor Black 15" 

Vas, volume equivalent compliance  
Fs, free air resonance  35 Hz (Tannoy published)  40 Hz (Tannoy published)  
Qt, total Qfactor  
Qa, mechanical & acoustic Q  
Qe, electrical Q  
Mmd, Dynamic Mass, excl. air load  
Cms, dynamic compliance  
Mma, air load in free air  
Sd, piston radiating area  
B, gap flux  1.0 T  1.2 T  
L, voice coil conductor length (in gap)  25.1 m  23.1 m  
BL, force factor (=B*L) Newtons per Amp  25.1 N/A  27.7 N/A  
Re, voice coil resistance  
Re+Res, resistance at Fs  
Z, efficiency into halfspace (2pi)  
VD, Peak linear displacement volume  
a, effective piston radius  
Pth, thermal power rating  15 Watts  25 W  
Sensitivity (@2.83V, 1m, 20C)  
Rms, mechanical resistance (mechOhm)  
Crossover Frequency (Hz)  1,700  1,000  
LF Gap flux (T)  1.0 Tesla (10,000 gauss)  1.2 Tesla (12,000 gauss)  
LF Force Factor (B*L), Telsam, or Newtons/Amp  25.1 N/A  27.7 N/A  
HF Gap Flux  1.5 Tesla  1.8 Tesla  
HF Force Factor (B*L), Telsam, or Newtons/Amp  10.5 N/A  11.8 N/A  
LF voice coil diameter  2 inches  2 inches  
HF voice coil diameter  2 inches  2 inches  
Working impedance via crossover  18 Ohms  15 Ohms 
Note: All KSeries and DCseries data from published Tannoy UK
data.
Test results for Monitor Gold 12" RubberSurround unit kindly supplied
by David Meraner.
Parameters for 3836 drive unit courtesy Elton Toma (results
averaged from 2 drive units).
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