Monacor Cheap Trick CT 213 (Mindstorm) floorstanding speaker by Theo Winterscheid (as CT in K+T 3/05)

Price kit CT 213 without housing per piece

The CT 213 uses a sound guide based on the TQWT principle in the bass range. The structure is initially reminiscent of a transmission line. However, with the TQWT, the cross-section increases towards the outside, and the chassis is not located at the beginning but rather in the middle of the line. At the end of the line there is a bass reflex tube. The MindStorm was designed by Theo Winterscheid hifi-selbstbau.de and first appeared in the MONACOR construction booklet in 2004 before it was also tested in K&T. Thus, two phase-shifting elements are involved here: the line of the TQWT, which shifts the phase due to the running time, and the bass reflex tube at the end, whose air mass in the tube plays an important role. Hence the name: Mass loaded TL or Mass loaded TQWT. The TQWT contains two Monacor chassis: - a Number One tweeter DT-107 - a Number One SPH-176 woofer

Technical data:

• Dimensions (HxWxD): 88 x 20 x 47 cm 
• Impedance: 8 Ohm
• Sensitivity (2.83V/1m): 88 dB 
• Frequency range (-8dB): 40 - 22000 Hz 
• Crossover frequency: 3 kHz
• Principle: TQWT

Highlights

• Number One tweeter DT-107
• Number One woofer SPH-176 
• Bass reflex tube MBR-110 or identical IT tube
• Convoluted foam MDM-40 or N25 
• Polyester insulation material MDM-2 or insulation wadding 
• a round terminal with gold-plated brass terminals
• 18 PAN screws
• 3 meters of cable 2x1.5 mm2
• the construction plan 
• crossover components, to be attached to wood: 
• 1x 0.56 mH coil, 1.0 mm
• 1x 3.0 μF MKT capacitor (2 pieces 1.5 μF connected in parallel)