MTM Floorstander (TDL RTL3's)


My beloved TDL RTL3's which served me well during my Uni years are now collecting dust. They have great bass and a big soundstage, but after opening them up for a peek, I'm appalled by the flimsy cabinet and kiddie-toy crossover - so I have decided to use the drivers and build a new enclosure for them.

Measuring the Drivers

The drivers seem to be a variant of Monacor's SPH-175. They look slightly different to the current SPH-175's, and measure even more differently. The tweeter is the Vifa D20TD-05-06.

The drivers are now over 7 years old, and this shows when I measure the T/S parameters in the way of large inconsistencies between drivers. I decided to pair them as best as I can and plough on regardless. I used my dedicated DIY speaker measurement clamp to hold the drivers firmly for impedance measurements, and used Speaker Workshop to do the measurements.

The T/S measurements were averaged out for the four midbass drivers and this was the result:

Fs 32.94 Hz Qes 0.786
Vas 43.7 litres Qms 9.739
Re 10.78 Ohms Qts 0.728
Le 0.361 mH Sd* 137 cm2
L1 0.521 mH Xmax* 2mm

* Parameters taken from current SPH-175 spec sheet.

Enclosure Design
Copyright © 2006 Vikash Chauhan. All rights reserved.