"Thiele & Small Parameters"

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 box-types. 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:


Tannoy Speakers

   
 Monitor Silver 12"
 Monitor Silver 15"
 Monitor Red III LZ
 Monitor Red 12"
 Monitor Red 15"
 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 Q-factor    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 half-space (2-pi)            
 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 (mech-Ohm)    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
             

Note: Data for Monitor Silver 12" and 15" units sourced from Tannoy North America ( supplied courtesy [email protected] ).
Data for Monitor Red 12" & 15" units sourced from Tannoy UK data ( supplied courtesy [email protected] )

 
 Mon. Gold IIILZ
 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 Q-factor    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 half-space (2-pi)            
 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 (mech-Ohm)    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
             

Note: Data for Monitor Gold 12" and 15" units sourced from Tannoy UK data (supplied courtesy [email protected] )
Data for Monitor-HPD315 12" supplied by Tannoy Ltd via [email protected]
Data for Monitor-HPD385 15" supplied by Tannoy Ltd via [email protected]

  DU386 / K3828 K3808 K3838 Monitor Gold 12" Rubber Surround:
LSU/HF/12/8RS		 3836 HPD385A *
(from private measurements)
 Vas, volume equivalent compliance 0.483 m3  8.8 cu ft  17 cu ft  206.6 litres  430 litres  15 cu ft *
 Fs, free air resonance  22 Hz  35 Hz  22 Hz  27.85 Hz  27.4 Hz  20 Hz *
 Qt, total Q-factor  0.18  0.16  0.18  0.287  0.427  0.2 *
             
 Qa, mechanical & acoustic Q  2.4  1.1  2.4  5.58  2.1  
 Qe, electrical Q  0.2  0.19  0.19  0.302  0.537  
 Mmd, Dynamic Mass, excl. air load  68 g  47 g  68 g  61.05 g    
 Cms, dynamic compliance  0.58 mm/N  0.3 mm/N  0.58 mm/N  0.535 mm/N    
 Mma, air load in free air  22 g  22 g  22 g      
 Sd, piston radiating area  0.077 m2  0.077 m2  0.077 m2      0.077 m2
 B, gap flux  0.78 T  0.78 T  0.78 T      1.35T *
 L, voice coil conductor length (in gap)  24 m  24 m  24 m      14.1 m *
 BL, force factor (=B*L) Newtons per Amp  18.7 N/A  18.7 N/A  18.7 N/A      19 N/A
 Re, voice coil resistance  5.7 Ohm  5.5 Ohm  5.5 Ohm  5.19 Ohm  5.5  
 Re+Res, resistance at Fs  77.5 Ohm  38 Ohm  70 Ohm      
 Z, efficiency into half-space (2-pi)  2.6 %  5.4%  3.8%      
 VD, Peak linear displacement volume  0.00031 m3  0.00031 m3  0.00031 m3      
 a, effective piston radius  0.156 m  0.156 m  0.156 m      
 Pth, thermal power rating  85 W  120 W  120 W      85 W
 Sensitivity (@2.83V, 1m, 20C)    94 dB  92 dB    94 dB  
 Rms, mechanical resistance (mech-Ohm)            
             
             
             

Data for Monitor-HPD385A 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 Q-factor        
         
 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 half-space (2-pi)      
 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 (mech-Ohm)        
         
 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), Telsa-m, 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), Telsa-m, 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 K-Series and DC-series data from published Tannoy UK data.
Test results for Monitor Gold 12" Rubber-Surround unit kindly supplied by David Meraner.
Parameters for 3836 drive unit courtesy Elton Toma (results averaged from 2 drive units).

 

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