The supertweeter project
by Hans Hilberink

Tannoy offers 3 versions of its supertweeter, intended to accompany their famous Dual Concentric loudspeakers and may also their vintage models like the Monitor Gold and HPD. Pictures of these tweeters are shown below.

ST50 ST100 ST200


Reading the whitepaper of Tannoy about supertweeters I got interested in these ST-series tweeters.

But I decided to built my own ones.


This Is the result of some days of selection of materials and parts and of building the parts together. 


The stand is a solid brass gasconverter spare part from an Italian car manufacturer. The tube is ordinary grey drain pipe, sprayed black with a high quality plastic paint. 
The two parts were glued together with construction glue, hot-glue is also applicable. 


The speaker is a tweeter from Peerless Danmark Europe. It employs a 3/4 inch laminated aluminium dome 
and a 1 Tesla magnet, average efficiency is 93 dB SPL at 7-23 KHz, moving mass is 0.16 gramms. The dustcover is supplied with the tweeter by Peerless. 


The connectors are simple and cheap speaker connectors from the local parts shop. 
Each unit has 3 connectors, Grey is  ground,  Red is 2 uF in series and White is 1 uF in series.


Just put the tweeter on top of the Monitor Gold and connect it to the speaker terminals to get the promised high-extension in your sound image.
Remember that I do not recommend the use of supertweeters with this Tannoy Monitor Gold, its just an example.

The filter is to be made in 6 dB or 12 dB Butterworth version, just on what your preference is. For now I chose for the 6 dB version as it is simpler, but for better performance the 12 dB version might be an option. The filter parts are from Wima Germany and Midwec USA, but any quality filters parts will do the job. 


The component values I used were 2 uF and 1 uF for different crossover frequencies for the 6 dB version, for the 12 dB version I added a 0.08 mH coil. In this way I can use 3 different configurations: 1uF, 2 uF and 3 uF, the last value is simply done by connecting the White and the Red connectors together, so you have both capacitors in parallel, making 3 uF. The approximate crossover frequency with 2 uF is in my case 15 KHz. 
Values for different tweeters and configurations may differ.


Here the parameters of the tweeter:




Thiele Small parameters: 
Nominal impedance Zn (ohm) 4 
Minimum impedance/at freq. Zmin (ohm/Hz) 3.2/3500 
Maximum impedance Zo (ohm) 4.0 
DC resistance Re (ohm) 3.0 
Voice coil inductance Le (mH) 0.1 
Resonance Frequency fs (Hz) 1400 
Mechanical Q factor Qms 1.13 
Electrical Q factor Qes 3.53 
Total Q factor Qts 0.86 
Mechanical resistance Rms (Kg/s) 1.26 
Moving mass Mms (g) 0.16 
Suspension compliance Cms (mm/N) 0.08 
Effective cone diameter D (cm) 2.6 
Effective piston area Sd (cm²) 5.3 
Force factor Bl (N/A) 1.1 
Reference voltage sensitivity
Re 2.83V 1m at 3500 Hz (Measured) (dB) 91.5 
Magnet and voice coil parameters: 
Voice coil diameter d (mm) 13 
Voice coil length h (mm) 1.8 
Voice coil layers n 2 
Flux density in gap B (T) 1.0 
Total useful flux (mWb) 0.1 
Height of the gap hg (mm) 2.5 
Diameter of magnet dm (mm) 40 
Height of magnet hm (mm) 7.5 
Weight of magnet (kg) 0.04 

Power handling: 
Long term Max System Power (IEC) (W) 100 


This cheap supertweeter performs very well, but I do not recommend supertweeters with all High Quality speakers.
Only with speakers that have an early roll off or lack performance around the 10 to 30 kHz frequency band.


More on Tannoy ST-series supertweeters click here



Below you can click a logo to get more information about the used products in this project.


Peerless inc. stopped the production of the above tweeter in 2007.
They still make nice tweeters that may be usable for projects like this.




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© Copyrights Hans Hilberink - PE1MMK ® 2001 / last update: 15-08-2018.