Thiele-Small Parameters, Explained
The standard driver measurements behind every serious enclosure design — and how to get them for a model in this catalogue.
What Thiele-Small parameters are
Thiele-Small (T/S) parameters are the standard set of electrical and mechanical measurements that describe how a loudspeaker driver behaves at low frequencies. They are named after A. Neville Thiele and Richard H. Small, whose work made it possible to predict a driver's performance in an enclosure before building it. Enclosure design software takes these parameters as its input — without them, box design is guesswork.
The parameters that matter most
| Fs | Free-air resonant frequency — the frequency at which the moving system naturally resonates; a first guide to how low the driver can usefully play. |
|---|---|
| Qts | Total Q of the driver — summarises damping; a key input to choosing sealed vs ported enclosures. |
| Vas | Equivalent air volume of the suspension compliance — scales with the enclosure volume the driver will want. |
| Re / Le | Voice-coil DC resistance and inductance — the electrical load the amplifier and crossover actually see. |
| Sd | Effective cone area — with excursion (Xmax), sets how much air the driver can move. |
| Xmax | Linear excursion limit — how far the cone can travel while staying controlled. |
| BL | Force factor (magnet strength × coil length in the gap) — the motor's grip on the cone. |
T/S parameters and this catalogue
The product specification tables published in this catalogue state rated power, impedance, sensitivity and frequency response — they do not include T/S parameters. The manufacturer states that its acoustic sound testing provides Thiele-Small parameters for its speakers. So if you are designing an enclosure around a GRANVOZ driver — most often a subwoofer or woofer — ask the sales team for the T/S parameter set for the exact model as part of your enquiry, and ask them to confirm the figures belong to the current production version of that model.
A note on using published parameters
T/S parameters vary with production tolerances and with how a driver has been run in. Professional buyers treat a published set as the design starting point, then verify with a sample measurement when the programme justifies it. Ask for samples of the exact model before you finalise an enclosure tool or a production cabinet design.
Send your target model and quantity
Tell us the model, size and quantity you are sourcing. Ask the sales team to confirm the specification, minimum order quantity, packaging and lead time for your exact model in the written quotation before you place an order.